If your cat's phosphorus level (in blood tests) is over 6
mg/dl (USA) or over
1.9 mmol/L (international),
it is too high and you need to get it under control.
Doing this should help slow the progression of the CKD,
reduce the risk of serious problems (including heart problems)
and make your cat feel better.
Feeding a food low in phosphorus is the first step.
Ideally you want a food with a level below 0.5% phosphorus on a dry matter
analysis basis. Prescription kidney foods are really the only foods which
meet this criterion.
If your cat will not eat the prescription diet, feeding
a food as low in phosphorus as possible and adding
a phosphorus binder to the food when appropriate can help control your cat's phosphorus
levels.
Phosphorus is a mineral essential for good health which
is contained in many foods. The body is very good at regulating its
phosphorus levels by removing excess phosphorus via the kidneys. However,
the kidneys of a CKD cat can no longer
efficiently excrete excess phosphorus, so the vast
majority of CKD cats will eventually have
levels of phosphorus in their blood which are too high:
this is known as
hyperphosphataemia.
In contrast to the protein debate, there is no
dispute about the importance of treating
hyperphosphataemia because:
High phosphorus levels can make
CKD progress more quickly.
Serum phosphate and mortality in patients with chronic
kidney disease (2010) Eddington
H, Hoefield R, Sinha S, Chrysochou C, Lane B, Foley RN, Hegarty J, New
J, O'Donoghue DJ, Middleton RJ & Kalra PA Clinical Journal of the
American Society of Nephrology5(12) pp2251-2257 found that the
risk of dying in human patients in stages 3 and 4 was higher in patients
with higher phosphorus levels, even if the phosphorus was within normal
range.
Survival of cats with naturally occurring chronic
renal failure: effect of dietary management (2000) Elliott J,
Rawlings JM, Markwell PJ, Barber PJ Journal of Small Animal Practice41(6) pp235-242, found that the cats who ate reduced phosphorus food or food
with added phosphorus binders lived more than twice as long as those who did not.
Elevated phosphorus levels can adversely affect calcium levels
and
eventually can
trigger problems with a hormone called parathyroid hormone (PTH), causing a serious condition called
In
Chronic kidney disease in dogs and cats: the pivotal
role of phosphorus control (2011) A Presentation to the 63rd
CVMA Convention, Dr D Chew states that it is possible for a CKD
cat to develop secondary hyperparathyroidism even if phosphorus levels and
ionised calcium levels are normal. He explains "In the early stages of
chronic kidney disease increased levels of parathyroid hormone (PTH) keep
serum phosphorous within the normal range by increasing phosphate
excretion into urine. This allows for normalization of serum phosphorous
at the expense of hyperparathyroidism." Therefore, even a cat with normal
phosphorus levels but with elevated PTH levels would benefit from
phosphorus restriction.
high phosphorus levels may reduce the cat's response to
ESAs, a treatment
used for severe anaemia, which is relatively common in CKD cats.
Thus, focusing on phosphorus control is one of the most
effective ways to help your CKD cat feel better and live longer. The good
news is, it's not usually too difficult or expensive to do either.
There are a number of different symptoms of high
phosphorus levels. You may not see all of these symptoms, and some of them
may have other causes as outlined under each symptom, but if you see any
of the symptoms described below, please ensure that your cat's phosphorus
level is checked (via bloodtests) and is no higher than 6 mg/dl (US) or 1.9 mmol/L
(international).
Cats who do
not eat are at risk of developing a potentially life-threatening condition
known as hepatic lipidosis;
Mar Vista Vet
has more information about this.
Therefore, it is important to try to find the cause and treat it as
quickly as possible.
Itching
Itching is fairly common in cats with
high phosphorus levels, particularly if the high phosphorus levels go
untreated, resulting in
secondary
hyperparathyroidism.
Lack of Co-ordination in the Limbs/Back
Leg Weakness
This can be
due to high phosphorus levels interfering with
the nerve messages that control the limbs, a condition known as
neuropathy. Some of the symptoms include "forgetting" where the hind legs
are (getting up and leaving without them, for instance, or leaving them in
the air after licking them), or stumbling and feet
crossing over when walking.
Plantigrade Posture
You may
also see a plantigrade posture (as demonstrated by
Ollie to the left), where the cat walks on his/her hocks
instead of his/her feet: this is most common in diabetic cats, but may
sometimes be seen in cats with high phosphorus levels,
or with neurological problems from other causes.
Ollie did this because of
low
potassium levels. Since Ollie is so fluffy, you may find this photo on
123catworldclearer.
Long Beach Animal Hospital has a photograph of a cat with
diabetic neuropathy doing this (click on Symptoms).
Newman Veterinary
has a good before and after photo of a diabetic cat with this
problem, scroll down a little to Other Common Consequences, then click on
Plantigrade Stance (in red font).
Youtube has a video of a cat grinding his/her teeth.
Knuckling
"Knuckling"
may also be seen, where the cat walks on the top of the foot with the toes
tucked underneath, appearing almost to be dragging the toes behind. I
haven't been able to find a photo of a cat with high phosphorus levels
doing this, but there is a video on
youtube
of a dog with a similar problem (but with a
different cause).
Weakness
Weakness
and muscle wastingmay be seen, especially in the back legs. This
can be caused by high
phosphorus levels leading to
secondary
hyperparathyroidism.
Weakness in
the back legs is often caused by
low
potassium levels
or occasionally by low magnesium or low calcium levels; while
muscle wasting may be caused by
metabolic acidosis.
General weakness may be caused by
anaemia. If your cat no
longer jumps, this may be thought to be weakness when in fact it is an
unwillingness to jump because of blindness caused by
hypertension. An inability
to jump or climb may also be caused by
arthritis.
If your cat suddenly cannot walk properly on one
leg, particularly a back leg, and the leg feels cold to the touch, this
may indicate a heart-related problem known as a
saddle thrombus. This is a medical emergency, and you need to contact
your vet as soon as possible.
Purina has a Body Condition diagram
showing how to gauge your cat's physical condition.
Nausea
High
phosphorus levels and the resulting secondary hyperparathyroidism may
cause nausea, which may be manifested as a lack of appetite.
Alternatively, vomiting
clear foam is a classic symptom for a CKD cat, and is
usually caused by high toxin levels,
particularlyexcess stomach acid. Occasionally
vomiting is caused by
constipation, particularly if your cat vomits before, during or immediately after using
the litter tray. Anaemia
or
Your vet can determine if your cat's phosphorus levels
are too high by checking your cat's bloodwork for phos, P or Pi (these are
all abbreviations for phosphorus). Most vets do this routinely, but if
yours doesn't, ask for it to be done.
Your cat may have phosphorus levels within normal
limits, but many vets forget that the higher limits
only apply to growing
kittens. In
Chronic kidney disease in dogs and cats: the pivotal
role of phosphorus control (2011) A Presentation to the 63rd
CVMA Convention, Dr D Chew states "Serum phosphate levels
are maintained within a narrow range in health. Young growing animals
often have higher levels of serum phosphorus than adults. The normal
serum phosphorus range of many laboratories includes that of adults and
growing animals which may make it difficult to detect early rises in serum
phosphorus above normal.The typical normal range for
phosphorus in the cat is 2.5-6 mg/dL (0.81 to 1.94 mmol/L)."
A few years ago the University of Texas Health Science
Center gave the following ranges for healthy cats of differing ages:
Age
Phosphorus Range in mg/dl (US)
Phosphorus Range in mmol/L (International)
10 days - 2 years
4.5 - 6.7
1.45 - 2.16
2 years - 12 years
4.5 - 5.5
1.45 - 1.80
Over 12 years
2.7 - 4.5
0.90 - 1.45
As the table shows, even a healthy older cat should
have phosphorus levels in the bottom half of most laboratory ranges. It is
even more important for a CKD cat.
In
Chronic kidney disease in dogs and cats: the pivotal
role of phosphorus control (2011) A Presentation to the 63rd
CVMA Convention, Dr D Chew states "Cats with 4.7 to 6.8 mg/dl
serum phosphorus were at increased risk for shorter renal survival despite
the fact that these values were still within the normal reference range."
Vets may also forget that,
if the cat's phosphorus multiplied by calcium is higher than 70
(US) or 5 (international), the cat is at risk of tissue calcification (see
secondary
hyperparathyroidism).
So if your vet tells you your cat's phosphorus level is
fine, don't just take that at face value, ask for the exact level. Chances
are it is too high for a CKD cat.
Ideally you want to get the level down to 4.0 (US) or
1.3 (international) but as the CKD progresses, this may become more
challenging. The tables below give goals for phosphorus control
based on the stage of CKD that your cat is in, based on guidelines from
the International Renal Interest
Society. Don't forget, these stages
apply to stable cats; if your cat is dehydrated, for example, the bloodwork will not be
accurate.
US Values
Stage of CKD
Creatinine Level in mg/dl
Phosphorus Target
IRIS Stage 2
Between
1.6 and 2.8
Below 4.5 mg/dl
IRIS Stage 3
Between 2.9
and 5.0
Below 5.0 mg/dl
IRIS Stage 4
Over 5.0
Below 6.0 mg/dl
International Values
Stage of CKD
Creatinine Level in mmol/L
Phosphorus Target
IRIS Stage 2
Between
140 and 249
Below 1.45 mmol/L
IRIS Stage 3
Between 250 and 439
Below 1.60 mmol/L
IRIS Stage 4
Over 440
Below 1.90 mmol/L
Summary of Phosphorus Goals
USA
Take action as soon asyour
cat's phosphorus level goes above6 mg/dl.
If your cat's level is between 4.5 and 6 mg/dl,
but multiplying it by your cat's calcium level gives you a reading of
60-70 or over, take action now.
Your
aim is to reduce your cat's phosphorus to a
level of 4 mg/dl. You may not
be able to get it this low if your cat is in
IRIS
Stage 3 or 4, but aim never to let it go above 6 mg/dl.
If your cat's level is above 6
mg/dl, you can read
below
about ways to reduce the level. Check phosphorus levels every month to see
if any adjustments to your treatment plan are necessary.
Low phosphorus levels (below
4
mg/dl) are extremely rare in CKD
cats, but are generally not considered to be a problem as long as they do
not fall below 2.5 mg/dl. I would try not to go below 3 mg/dl.
See
Diagnosis for more information.
If your cat is very young (6-12 months old), then a higher level is appropriate, because kittens
need phosphorus for their bones to grow properly. Check out the table
above and discuss with your vet
what would be an acceptable level.
Rest of the
World
Take action as soon as phosphorus goes above1.9 mmol/L.
If your cat's level is between 1.45 and 1.9 mmol/L,
but multiplying it by your cat's calcium level gives you a reading of 5
or over, take action now.
Your
aim is to reduce it to a level of1.3 mmol/L. You may not be able to get it
this low if your cat is in
IRIS
Stage 3 or 4, but aim never to let it go above 1.9 mmol/L.
If your cat's level is above 1.9 mmol/L, you can read
below
about ways to reduce the level. Check phosphorus levels every month to see
if any adjustments to your treatment plan are necessary.
Low phosphorus levels (below
1.3 mmol/L) are not normally present in
CKD
cats, but are generally not considered to be a problem as long as they do
not fall below 0.8 mmol/L. I would try not to go below 1 mmol/L. See
Diagnosis for more information.
If your cat is very young (6-12 months old), then a
higher level is appropriate, because kittens need phosphorus for their
bones to grow properly. Check out the table
above and discuss with your vet
what would be an acceptable level.
Veterinary References for
Phosphorus Goals
If your vet refuses to accept that a phosphorus level
above 6
mg/dl (US) or 1.9 mmol/L
(international) is too high for your cat, print out and show him/her some
of these references:
Prof Jonathan Elliott
of the Royal Veterinary College states on page 14 that "the goal
should be to keep the serum phosphorus concentration at the lower end of
the reference range."
Dr
David Polzin of the College of
Veterinary Medicine of St Paul's in Minnesota states that phosphorus
binders should be begun "when serum
phosphorus concentration exceeds 6.0 mg/dl."
There are two main ways to control phosphorus levels,
through dietary changes or by using phosphorus binders.
Controlling Phosphorus Levels with Diet
The most effective way to control phosphorus levels is by feeding foods low in
phosphorus.
Retrospective analysis of dietary management of
hyperphosphataemia in cats with CKD (2008) Elliott J
Veterinary Record18(2) pp45-47 concludes "This uncontrolled
retrospective analysis of cats presenting to the Renal Research Clinics at
the Royal Veterinary College demonstrates that feeding of renal clinical
diets results in effective control of plasma phosphate concentration in
about two thirds of cats presenting in Stage 2 and 3 CKD", with cats
eating the renal diet living longer than the cats in the study who ate
normal food with no phosphorus binder.
Most of the prescription kidney diets have phosphorus levels below 0.5%, which
is one of the main reasons why these foods were developed (though they also
have other attributes, see
Which
Foods to Feed).
If your cat won't
eat the prescription foods, you still need your cat to eat.
Many people seem to think that a food below 1% phosphorus on a dry
matter analysis (DMA)
basis is low phosphorus but that's not the case; you
want to get as close to prescription food levels as possible.
In the USA,
the minimum level of phosphorus in a non-prescription adult maintenance food
is 0.5%, so you are not going to find a commercial
food with phosphorus below this; but
if you check the food data tables in the
Diet and Nutrition
section, you can try to find a
food which your cat will eat with a level of
phosphorus as close to 0.5% as possible.
Although canned
foods are generally a better choice for CKD cats than dry foods, since
phosphorus control is so important, if I had a cat who was prepared to eat a
dry prescription diet, I would feed that rather than feed a non-prescription
commercial canned diet with added binders.
Even if your cat's phosphorus level is normal,
it is wise to feed a CKD cat a food as low in phosphorus as you can, because
the less phosphorus your cat eats, the less work there is for the kidneys to
do trying to process it; plus phosphorus levels tend to rise as the CKD
progresses, and usually it is easier to keep them low rather than have to
reduce them.
Controlling Phosphorus Levels with Phosphorus
Binders
If your cat will not eat a prescription diet, or if
his/her phosphorus levels are still too high despite feeding such a diet,
products called phosphorus binders are used. These are simply added to the
cat's food: they bind with some of the phosphorus in the food in the
intestine, thus preventing it from being absorbed
and therefore
reducing levels of
phosphorus in the cat's body.
Phosphorus binders are usually used when phosphorus levels are
over6 mg/dl (US) or 1.9 mmol/L
(international). Once you start using binders, the goal is to get phosphorus down to
a level of around 4 mg/dl (US) or 1.3 mmol/L (international).
To be effective, phosphorus binders
should be given shortly before or with food. You should start to see a difference
in phosphorus levels around 7-10 days after starting binders. There
are instructions on how to give binders
below.
Using binders is not as effective as feeding a low
phosphorus diet, because binders cannot bind all the phosphorus in the
food, so your cat will still be absorbing some of the phosphorus.
Therefore, if you do have to feed a non-prescription diet (because
the most important thing is that your cat eats), you should aim to
feed the lowest phosphorus food that your cat will eat. Many people seem
to think that a food below 1% phosphorus on a dry
matter analysis (DMA) basis is low phosphorus but that's not the case,
particularly when you consider that most of the prescription renal diets
have phosphorus levels below 0.5%. Aim for as low a phosphorus level as
you can. The
Diet and Nutrition section has links to food data tables for you to
check out the phosphorus levels of various cat foods. I'm not
recommending any of these foods, this is simply a list in order of
phosphorus content.
You should not normally need to use binders if your cat
is eating a prescription kidney diet, because this should be sufficient to
control your cat's phosphorus levels. However, this is not always the
case, particularly as the CKD worsens. If your cat's phosphorus levels
are over6 mg/dl (US) or
1.9 mmol/L
(international) despite feeding a prescription diet,
speak to your vet about adding binders.
If your cat isn't eating, there is little point giving
phosphorus binders because your cat isn't ingesting any phosphorus in the
food that needs binding. However, if you
assist feed (as you should if
your cat is not eating), you can add binders to the mixture.
Phosphorus binders are used if feeding foods lower in
phosphorus levels, such as prescription diets, does not keep your cat's
blood phosphorus levels in the desired range (see
above).
They work by binding with some of the phosphorus in the cat's food in the
intestine, thus preventing it from being absorbed
and therefore
reducing levels of
phosphorus in the cat's body.
Over the counter antacids are commonly used for this
purpose, and there are two main types:
aluminium-based products and calcium-based
products. Recently, branded products have also been released, including
Ipakitine/Epakitin (which is calcium-based) and Renalzin (which contains a
new type of binder called lanthanum carbonate).
The most popular binders are made from aluminium hydroxide.
Overall these are the best choice because they are very effective, are
available over the counter, are cheap, and have no taste or smell so most
cats are prepared to eat them. Therefore these are what I recommend, but I do
cover all binder types below.
Letting Other
Family Cats Eat Food Containing Binders
If possible, try not to let your non-CKD cats eat food
containing phosphorus binders. However, if they
eat a small amount occasionally, this should not be a problem as long as
you
make sure that most of the food they eat each day that does not contain
binders. This is particularly important for
kittens,
who need twice as much phosphorus each day as a healthy cat because they
are still growing.
These binders, as the name suggests, also contain magnesium.
Brand names include Maalox, Mylanta, Milk of
Magnesia or Aludrox. Binders containing magnesium are not suitable for
CKD cats because they
can cause
high
magnesium levels in the blood, which in turn can sometimes cause
urinary tract problems such as stones in some cats.
Pet Education
states "Do not use magnesium containing products in
animals with kidney failure."
Sucrose Aluminium
Hydroxide
Sucrose aluminium
hydroxide is also known as sucralfate
or Carafate. It coats the digestive tract, so is commonly used to treat
mouth ulcers
or
gastro-intestinal bleeding. Some British vets
also recommend sucralfate
as a phosphorus binder. One old study,
Changes in serum phosphorus, calcium and alkaline
phosphatase due to sucralfate
(1986)
Vucelić B,
Hadzić N,
Gragas J,
Puretić Z
International Journal of Clinical Pharmacology, Therapy and Toxicology24(2) pp93-6, did find sucralfate was effective as a binder in
humans, but it is not usually recommended as a phosphorus binder in cats.
If you are unable to obtain aluminium hydroxide, however, it could
certainly be worth considering, though I don't know the correct dosage for
using it as a phosphorus binder.
If you are using sucralfate for mouth ulcers or
gastro-intestinal bleeding at the same time as using aluminium hydroxide
as a phosphorus binder, you might be able to reduce your dosage of
aluminium hydroxide.
This is the most effective binder and the one I
recommend because it is available over the counter (though you may have to
use mail order in the USA), cheap, and if you buy the correct type it is
odourless and tasteless. Unfortunately many vets are
reluctant to prescribe aluminium-based binders because they think
cats
hate the taste. If they do prescribe them, they
often
prescribe
AlternaGel, a
peppermint-flavoured binder which most cats
hate, so it then becomes a self-fulfilling
prophecy. AlternaGel also contains
potassium citrate, which is
not a good idea because citrate can increase the absorption of aluminium
within the body.
I recommend instead that you look into buying aluminium hydroxide binders
which are tasteless and odourless, and which
most cats do not seem to notice in their food. See
below for information on the various brands and links to mail order suppliers who can ship to UK, USA,
Canada and Australia. Contrary to what some vets and pharmacists seem to believe,
you do not need a prescription to buy these products.
Naturally you must seek your vet's advice on the most suitable dosage for
your cat; but generally speaking, the appropriate dosage for aluminium
hydroxide based binders is as follows:
USA
Current Phosphorus Level: mg/dl
Binder Dosage
Between 4.0 and 6.00*
25 mg per lb (0.5kg) of cat per day, divided and given with food.*
Between 6.0 and 8.0
50 mg per lb (0.5kg) of cat per day, divided and given with food.
Between
8.00 and 10.00
100 mg per lb (0.5kg) of cat per day, divided and given with food.**
Over 10.00
Discuss with your vet
International
Current Phosphorus Level: mmol/L
Binder
Dosage
Between 1.3 and 1.9*
25 mg per lb (0.5kg) of cat per day, divided and given with food.*
Between 1.9 and 2.6
50 mg per lb (0.5kg) of cat per day, divided and given with food.
Between 2.6 and 3.25
100 mg per lb (0.5kg) of cat per day, divided and given with food.**
Over 3.25
Discuss with your vet
*Not everybody chooses to start binders if phosphorus
levels are in this range - most people only start binders once phosphorus
levels are over 1.9 (US: 6.0). However, if your cat has previously had
high phosphorus levels which you have reduced with binders,
or if your cat has high calcium levels, you will probably need to
continue to give binders, either at this dosage or even higher, otherwise
your cat's values will probably rise over 1.9 (US: 6.0) again.
**I would not give more than 50 mg per lb of cat per
day (100 mg per kg of cat per day) without detailed discussions with your
vet. It is probably safe, but you need to balance the potential benefits
against the possible risks, including the rare possibility of aluminium
toxicity - see below.
It may be safer to use a smaller amount of aluminium hydroxide together
with another binder, such as
lanthanum carbonate (Renalzin or Fosrenol).
The amounts above are the total daily dose, but
the total amount should be divided among as many of your cat's daily meals
as possible.
Aluminium hydroxide does not have to be measured
too precisely, but as a rough guide, if you are using powdered aluminium
hydroxide, a loosely packed quarter of a teaspoon of powder contains approximately 300mg
of aluminium hydroxide. If you are using a liquid type of binder, as a
guide, a teaspoon of AlternaGel contains approximately 600mg of aluminium
hydroxide. If you prefer not to guess at
a quarter of a teaspoon,
Amazon sells a set of measuring spoons
which include a quarter and an eighth of a teaspoon for less than USD10.
The same set costs £10.61 from
Amazon UK
.
You should see an improvement in your cat's blood
phosphorus levels after about two weeks, if not earlier. You may see a
difference in your cat's demeanour sooner than this. Check your cat's phosphorus level every
two weeks until the level is acceptable, then check it every 2-3 months to see if any
adjustments to your treatment plan are necessary.
Aluminium Hydroxide
Binder Tips
Phosphorus binders must be given with food so they can bind with the
phosphorus in it. Aluminium hydroxide binders are
usually odourless and tasteless if you choose carefully (see
below), but since
they are a natural (mined) product, they can sometimes add a bit of a
gritty texture to food or make it taste a little drier.
See
above for recommended dosages. Here are some tips on how to give
aluminium hydroxide binders:
Using Aluminium Hydroxide Binders with Canned
Food
tablets can simply be crushed
and added to the food.
capsules can be opened and the contents mixed with the food.
liquid binders can either be mixed in the food or
syringed into your cat's mouth just before eating.
one retailer recommends adding a teaspoon of
water to the tinned food and binder and letting it stand for ten minutes before serving
in order to let the binder mix thoroughly. This may
help remove any grittiness.
Using Aluminium Hydroxide Binders with Dry Food
try putting the food in a freezer bag together with the crushed
or powder binder and leave them to mingle
overnight.
if you are using a liquid binder, you can syringe it
into your cat's mouth just before eating.
Sometimes phosphorus binders may cause
constipation,
so watch for this when you first start them and be
ready to start a suitable
treatment
if required.
Interactions
If you are using
potassium
citrate (perhaps to treat
metabolic acidosis), give this at least two hours apart from phosphorus
binders. This is because, as
Drugs mentions, products containing
citrate may increase the absorption of aluminium,
which could increase the risk of
aluminium toxicity. Many prescription
diets contain potassium citrate, but
apparently these findings have not been replicated in cats. In
most cases, you will not need to use phosphorus binders if you are using a
prescription diet.
According to
Plumb's Veterinary Drug Handbook, phosphorus binders should be given
two hours apart from
Baytril,
an antibiotic. It's probably wise to keep binders away
from
antibiotics
generally, particularly those in the same family as Baytril (this includes
Zeniquin).
Plumb's Veterinary Drug Handbook also advises
giving phosphorus binders two hours apart fromfamotidine
(Pepcid AC), which is used to treat
excess stomach acid, because it may interfere with the absorption
of the treatment, which would make it less effective.
However,
RX Med states that "concomitant use of
aluminum hydroxide/magnesium hydroxide at commonly used doses, does not
influence the pharmacodynamics or bioavailability of Pepcid AC."
Dr Larry Nagode
of Ohio State University
has stated that phosphorus binders should
be separated from
ACE inhibitors
such as benazepril (Fortekor) because
they may interfere with the absorption
of the treatment, which would make it less effective.
I would try to err on the side of caution and still
separate famotidine from phosphorus binders and ACE inhibitors if you can,
but if this is difficult for you, e.g. because of work commitments, just
do the best you can.
Phosphorus binders should ideally be given separately from
iron, because the
binders may reduce the absorption of the iron.
Medline Plus mentions that
vitamin C may interact adversely with products containing aluminium,
such as phosphorus binders. Cats do not need Vitamin C
supplements anyway, they can manufacture all the Vitamin C they need
themselves.
I don't know if
slippery elm
bark would interfere with phosphorus binders, as far as I know this
has never been studied, but it might be possible in theory. However, if
you are adding Slippery Elm Bark to food once or twice a day, I would
still mix binders in with that food in the hope that at least some of the
phosphorus would be bound.
(2011) Pepper R, Campbell N, Yaqoob MM, Roberts NB &
Fan SLS BMC Nephrology12 found that even patients on
dialysis did not develop aluminium toxicity if changes were made to the
dialysis process (during which patients may be exposed to dialysate water
which is contaminated with aluminium), but the patients in this study were
on relatively low doses of aluminium hydroxide.
Since cats are not on dialysis, aluminium toxicity was not
thought to be a
concern for cats (or dogs), especially since even in humans it takes
years before it becomes a problem, and cats and
dogs don't live as long as humans.
Recently, however, there has been increasing concern
about the possible risk of aluminium toxicity in cats using aluminium
hydroxide based binders. This is partly because of a study which reported
on aluminium toxicity in two dogs on binders,
Aluminum toxicity following administration of
aluminum-based phosphate binders in 2 dogs with renal failure(2008)
Segev G,
Bandt C,
Francey T &
Cowgill LDJournal of Veterinary
Internal Medicine22(6) pp1432-5.
There is no abstract available for this study, but
Treatment options for hyperphosphataemia in feline
CKD: what's out there? (2009)
Kidder AC & Chew D Journal of Feline Medicine & Surgery11(11)
pp813-24 reported that the two dogs in question developed "probable
aluminum toxicity" after being on binders for only 62 and 65 days. The
symptoms seen were "severe neuromuscular abnormalities." The dogs were on
dosages of 125mg/kg per day (or 56mg per lb body weight) and 200 mg/kg (or
91mg per lb bodyweight) per day, which are not particularly high doses.
However, both these dogs had been on dialysis, though apparently the
dialysate water was not contaminated with aluminium.
Partly because of this study, vets are
becoming increasingly aware of the need for caution and awareness when
using aluminium hydroxide binders in cats too, particularly when using
large doses.
Physical symptoms to watch for include neurological
problems, such as stumbling and an awkward gait (although, just to
complicate matters, these can actually be signs of uncontrolled
phosphorus levels too, see
above). One possible sign of aluminium toxicity is a change in
MCV.
This is a measure of red blood cell size.
If your cat has a low MCV (known as microcytosis),
this means the red blood cells are smaller than usual.
Although this may simply indicate iron deficiency, it may also be a sign
of aluminium toxicity. This sign normally appears before you see physical
symptoms, so be sure to monitor your cat's MCV levels.
If you are using
potassium
citrate (perhaps to treat
metabolic acidosis), give this at least two hours apart from phosphorus
binders. This is because, as
Drugs explains, products containing
citrate can in theory increase the absorption of aluminium,
which could increase the risk of aluminium toxicity.Many prescription
diets contain potassium citrate, but apparently these findings have not
been replicated in cats. In most cases, you will not need to
use phosphorus binders if you are using a prescription diet.
Try not to worry too
much. I am not aware of any reported
cases in cats to date, and most cases in dogs have occurred in dogs taking
over 200 mg/kg. In
Updates in feline chronic kidney disease
(2008) Dr CL Langston states "Excessive absorption of aluminum can
lead to toxicity, including anemia and neurologic symptoms, but this seems
uncommon in veterinary practice." In contrast, the
dangers of elevated phosphorus control are very real, and very common, and
controlling phosphorus is essential for your cat's wellbeing.
If your cat has phosphorus levels that require large
amounts of aluminium hydroxide, or if you cannot control your cat's
phosphorus levels with aluminium hydroxide only, consider adding another
phosphorus binder. Most people in this situation use lanthanumcarbonate (Renalzin or Fosrenol).
See below
for suggestions on dosage.
If you think your cat may have aluminium toxicity, I
would ask for a referral to a vet school or a neurologist if possible.
Chelation therapy plus dialysis helped to remove the aluminium from dogs with aluminium
toxicity, and indeed following treatment the neurological problems
experienced by the dogs in the above study were successfully reversed.
Other Concerns
Itdoes not matter if your non-CKD cats eat
some of your CKD cat's food
containing phosphorus binders. However, please
make sure that they also eat
some food each day that does not contain
binders. This is particularly important for kittens,
who need twice as much phosphorus each day as a healthy cat because they
are still growing.
If you buy aluminium hydroxide gel or powder in the
USA, you may see a warning about arsenic which bizarrely
supposedly only applies to people living in California. This is to
comply with that state's legal requirements. The fact of the matter is
that aluminium hydroxide is a naturally occurring product which is
mined, and therefore it contains a naturally occurring tiny amount of
arsenic of no more than 8 parts per million. This is no more than you
might find in soil or in vegetables grown in soil. However, if you want
to be on the safe side, you might wish to avoid inhaling the powder.
If you buy aluminium hydroxide, you may see an
expiration date on it. This is usually to comply with pharmacy laws, but
in practice, since aluminium hydroxide is a mineral that is mined from the
earth, it cannot really expire, so I would not worry too much about expiry
dates.
Sometimes your vet will recommend using a calcium-based
antacid such as Tums or PhosLo as a phosphorus binder. These are not an
ideal choice because:
these binders are not as effective as binders
containing aluminium hydroxide;
they may make your cat's calcium
levels rise too high (hypercalcaemia).
Hypercalcaemia in cats (2001), a paper by
Dr Chew presented to the World Small Animal Veterinary Association
World Congress 2001
mentions that using calcium-based
binders may cause
hypercalcaemia. Thus, if you are using a
calcium-based binder, frequent monitoring of blood calcium levels
is essential. You should not use a calcium-based binder
if your cat is taking
calcitriol.
The calcium acetates (e.g. PhosLo) bind about
three times as much phosphorus as calcium carbonate (e.g.
Tums).
On the other hand, they are more likely to cause
hypercalcaemia.
Calcium Carbonate
The risk of hypercalcaemia is lower with calcium
carbonate based binders such as Tums, though it
still exists.
However, in some cases it may be worth considering
using a calcium carbonate based binder called Ipakitine (Epakitin
in the USA).
Ipakitine/Epakitin
Ipakitine
(known as
Epakitinin the USA) is a combination
of a calcium carbonate based phosphorus binder and an
oral
adsorbent called chitosan. Adsorbents are products that bind
with something else, and adsorbents used in the treatment of CKD usually
bind with toxins, thus improving wellbeing. Phosphorus binders are an
obvious example of an oral adsorbent, but
Ipakitine contains another type of adsorbent
too, chitosan, which is said to help with uraemic toxins.
There is more information about Ipakitine, including its adsorbent
properties, on the
Treatments
page.
In the marketing literature, emphasis seems to be placed on
Ipakitine's role as a phosphorus binder, but
many vets seem to sell it to clients whose cats do not have elevated
phosphorus levels, so they are presumably advocating it for its chitosan-related
effects.
It is only supposed to be given for six months, but I
have heard of cats who have been on it for longer with no obvious
problems.
My own vet in the UK has seen falls in creatinine and
BUN (urea) in some cats when using
Ipakitine and no other treatments. I did use it
myself
for Ollie, who did not have very high
phosphorus levels, nor were his calcium levels
elevated.
For a cat with higher phosphorus levels (over 2.25 international, 7 USA),
I personally would opt to use an
aluminium
hydroxide binder instead of Ipakitine. Even for cats
with lower phosphorus levels, if the cat's phosphorus multiplied by
total calcium is higher than 70in US
values or 5 in international values, the cat is at risk of tissue
calcification (see
secondary
hyperparathyroidism). In such a case, again I would opt for
using an
aluminium
hydroxide binder in order to get the
phosphorus levels under control as quickly as possible.
Renal, made by Candioli Pharma in Italy,
is a similar product to Ipakitine. It is commonly offered to people in
Italy, and also those in Canada, where it is marketed by Aventix Animal
Health. Like Ipakitine, it contains calcium carbonate and chitosan, but
also contains potassium citrate. Since not every CKD cat needs additional
potassium, I think I would give this product a miss.
New binders are coming on the market in which the
active ingredient is lanthanum carbonate. This
is supposed to bind more effectively with phosphorus than either aluminium
or calcium, and is tasteless. Some people are using
lanthanum carbonate-based binders in addition to aluminium hydroxide when they cannot control
phosphorus levels with aluminium hydroxide alone.
See
below for
dosing if using lanthanum carbonate in addition to aluminium hydroxide
because you cannot control phosphorus levels with aluminium hydroxide
alone, or if you would prefer not to use really high amounts of aluminium
hydroxide.
In October 2008 a binder containing lanthanum carbonate known as Renalzin
was released in Europe for the feline market. Initially it was
available in UK, Germany, Austria and Benelux, but it is
now also available in a number of other countries.
Renalzin contains Vitamin E and kaolin as well as lanthanum carbonate. The
vitamin E is intended to act as an
antioxidant,
and the kaolin as a "toxin binder", by which I think they mean an
oral
adsorbent. Kaolin (which is often used to treat diarrhoea) can be
constipating, so it seems an unusual choice of ingredient, but I suspect
Bayer are jumping on the
Ipakitine/Epakitin bandwagon here by wanting to add
an oral adsorbent. Renalzin also contains the preservative Methyl
4-hydroxybenzoate (E218). This additive is apparently
banned in Australia.
Renalzin is produced in pump form and one dose provides 1 ml, which
contains 200mg of lanthanum carbonate. It can be
sprayed directly onto food, and makes canned food quite creamy.
Renalzin is supposed to be odourless and tasteless but one user in Germany
has reported that it tasted slightly bitter and mouldy to her.
Bayer recommend that two pumps (2ml) a day are used, giving a total dose
of 400mg of lanthanum carbonate each day. This compares with the
recommended human starting dose for
Fosrenol (which also
contains lanthanum carbonate) of 750-1500mg a day, so the recommended
feline dose seems relatively high.
However, veterinary sources have stated that lanthanum carbonate can be
dosed in the same way as aluminium hydroxide, in which case 400mg is
within normal levels. The
product on sale in Germany says that two pumps (2ml) a day should be mixed
with dry food or three pumps (3ml) a day with
tinned food. I have no idea what you are supposed to do
if you are feeding both dry and tinned, perhaps average it out.
It is not essential to give Renalzin only twice a day, the total
daily dose can be
calculated and spread over
all meals if required. Phosphorus levels should
be checked after 2-4 weeks and the dose adjusted as required. Like
Ipakitine/Epakitin,
Renalzin is supposed to be given for up to six months
only, but most CKD cats
have an ongoing requirement for phosphorus control.
Renalzin is not absorbed into the digestive tract like aluminium hydroxide
based binders, and therefore should have fewer possible interactions with
other treatments. The most common side effects
for humans taking lanthanum carbonate are nausea, vomiting and diarrhoea,
and I have also heard of CKD cats who developed nausea and vomiting whilst
taking Renalzin. The manufacturer confirmed to one person's vet that these
were possible side effects.
Some people are using Renalzin in addition to aluminium
hydroxide when they cannot control phosphorus levels with aluminium
hydroxide alone, or if they would prefer not to use really high amounts of
aluminium hydroxide. See
below for
dosing if using Renalzin in this way.
Although Renalzin is not currently available in the USA, a human version
of lanthanum carbonate called Fosrenol has been available in the USA
since 2005 which is gradually
being used in cats. A prescription is required.
Fosrenol
comes in the form of extremely expensive tabletswhich are supposed to be chewed,
but in order to use them for cats, most people crush
the tablets.
Fosrenol dosing is the same as for aluminium hydroxide.
So, for example, if you are giving 300mg of aluminium hydroxide a day but
want to switch to Fosrenol, you would still need to give 300mg per day.
The most common side effects for humans taking
lanthanum carbonate are nausea, vomiting and diarrhoea.
In September 2011 an
Important Drug Warning
was issued warning of a risk of faecal impaction when using
Fosrenol. The warning advises caution for patients who are constipated,
diabetic or using a calcium channel blocker (such as
amlodipine, used to treat high blood pressure in CKD cats).
Eurek Alert
has a press release regarding the approval process for Fosrenol in the
USA.
Renaltan
Renaltan is a liquid lanthanum
carbonate-based phosphorus binder made by Recoactiv (RecoVet) in
Germany, though I have not been able to find the exact amount of
lanthanum in the product or a list of ingredients generally. The
manufacturer claims that this product stimulates the appetite and
increases food intake, though I'm not clear by exactly which mechanism;
perhaps because lower phosphorus levels tend to help a CKD cat feel
better. It also claims that by using this product, you can avoid using
prescription food in IRIS Stages 1 and 2 because you are controlling
phosphorus levels but leaving protein levels untouched. Whilst it is
true that it is not necessarily a good idea to reduce protein levels in
IRIS Stages 1 and 2 (see
Nutritional Requirements), prescription foods do have other
attributes (see
Which Foods to Feed for information on when and why to use
prescription food).
I have heard from a few German users who seem to like Renaltan. It is
available from the manufacturer's own website (first link above) or from
Amazon Germany, but personally I would
not use it until I knew the exact ingredients.
Using Lanthanum-Based Binders in Addition to Aluminium Hydroxide
If you are
having trouble getting phosphorus under control using aluminium hydroxide
alone, you can use Fosrenol in addition to the aluminium hydroxide. In
such cases, a suitable starting dose might be 50-100mg per kg of cat per
day, which equates to 25-50 mg per lb of cat per day. You can go up to
200mg per kg of cat
per day (just under 100mg per lb of cat per day) if necessary, but
obviously work with your vet on determining the most appropriate dosage
for your cat.
Renalan
Renalan is another lanthanum-based
phosphorus binder which is currently undergoing testing on cats. It is not
yet commercially available.
Renagel (sevelamer hydrochloride) is a relatively new
phosphorus binder approved for use in humans, with not much history
of use in cats. One possible problem is interference with blood
clotting, so it may be necessary also to give your cat Vitamin K. It
is also very expensive, but may be worth considering
if you cannot use the other types of binders for some reason. Doctor's
Guide has information on the
approval of Renagel for use in the USA.
Renvela
(sevelamer carbonate) is the next generation version of Renagel which
contains a carbonate buffer. It is intended to help with bicarbonate levels,
but in some cases it might actually worsenmetabolic
acidosis.
Please read above about which binder to use and why.
If you buy aluminium hydroxide, you may see an
expiration date on it. This is usually to comply with pharmacy laws, but
in practice, since aluminium hydroxide is a mineral that is mined from the
earth, it cannot really expire, so I would not worry too much about expiry
dates.
Sources - USA
If you buy your binders from your vet, you will often
be offered
AlternaGel, but
this is peppermint flavoured, which most cats
hate. AlternaGel also contains
potassium citrate.
Another product which vets sometimes stock,
Amphojel, comes in both unflavoured and
peppermint flavoured
version, so check before you buy that you will be getting the
unflavoured one; most vets only seem to stock the
peppermint-flavoured version.
Most people on
Tanya's CRF Support Group use the loose
aluminium hydroxide in gel or powder form. This used to be available from
a number of online pharmacies, but the only one which definitely still
sells it these days is Thriving Pets, though some local compounding pharmacies may be able to
order it for you.
The loose aluminium hydroxide gel or powder is odourless and tasteless, so is much easier to
give than the other formulations in most cases. There are three main generic brands available, Spectrum, Gallipot
and PCCA. You may be told that a prescription is required, but this is
not correct, the gel and powder formulations are over the counter products. It may
take a local pharmacy a few days to obtain it for you; it is fine to wait
that long.
sells 500g (1.1 lbs) of aluminium hydroxide dry gel for US$39.95
plus shipping. They also sell 1 oz at a time (which costs about US$7
including shipping within the USA), as well as capsule or liquid (oral)
formulations (these require a prescription, which the gel formulation does
not) . If you enter the word "tanya" (without the ") in the promotional
code box, you will receive a 10% discount on orders over US$55. Shipping
is free for orders over US$55 after the discount.
Fosrenol and Renalzin USA
Thriving
Pets
sells nine Fosrenol 500mg tablets for
US$79.95 or ten 1000mg tablets for US$89.95. A prescription is required.
If you enter the word "tanya" (without the ") in the
promotional code box, you will receive a 10% discount on orders over
US$55. Shipping is free for orders over US$55 after the discount.
Best Pet Pharmacy in the
UK sells Renalzin for £9.35 for 50ml or £24.98 for 150ml. This
pharmacy shipped products to me in the USA with no problems.
Epakitin USA
Entirely Pets sells Epakitin for US$16.49
(50g), US$43.99 (150g) or US$68.99
(300g).
Medi-Vet sells Epakitin for US$22.82
(50g), US$54.99 (150g)
or US$76.16 (300g).
Sources - UK
Aluminium Hydroxide UK
Alucapsare an odourless
and flavourless phosphorus binder made by 3M. Members ofTanya's
CRF Support Group
in the UK have successfully obtained Alucaps from Boots, Lloyds and
Superdrug during 2011. In May 2011
they cost £8.22 for
120 capsules of 475mg aluminium hydroxide from Boots.
Don't say they are for a cat, or they may ask for a
prescription from your vet, whereas if you buy them for your own
indigestion, they are over the counter. When I asked for Alucaps in Boots, the
pharmacist had never heard of them, but - unbeknownst
to her - she
did actually have some in stock; so you
may need to be persistent or ask for them to be
ordered for you.If they need to be ordered,
theyshould only take
a couple of days to arrive, and it is fine to wait that
long.
Lloyds Pharmacy sell Alucaps online,
though for some reason they require a prescription if bought this way.
sells 500g (1.1 lbs) of aluminium hydroxide dry gel for US$43,
and will ship to the UK and elsewhere. They also sell 1
oz at a time, as well as capsule or oral forms. Contact them to obtain a
quote for shipping & handling costs.
If you enter the word "tanya" (without the ") in the promotional code box,
you will receive a 10% discount on orders over US$55.
Renalzin UK
Vet
UK sells Renalzin for £8.92
for 50g or £18.95 for 150g.
Best Pet Pharmacy
sells Renalzin for £9.35 for 50ml or £24.98 for 150ml.
Vetscriptions sells Ipakitine for £9.99
for 50g or £23.69 for 150g.
Sources - Canada
Aluminium Hydroxide Canada
Pet
Pharm sells an aluminium hydroxide
based binder called
Basaljel made by Axcan Pharma Inc.
It comes in gelcaps, each containing 500 mg of aluminium hydroxide, and
they cost CAN$26.95 for 100. Basaljel is also available over the counter
in many Canadian pharmacies.
Canada Drugs
sell a liquid aluminium hydroxide product called Alugel for CAN$17.65.
Xenex Laboratories
in Canada sells 500g of aluminium hydroxide, you
can
contact
them to
check the current price, but for reference in June 2011 one member ofTanya's
CRF Support Group paid CAN$66 plus CAN$20
shipping, whilst another paid a total of CAN$78 including shipping (she
lived closer).
sells 500g (1.1 lbs) of aluminium hydroxide dry gel for US$43,
and will ship to Canada. They also sell 1
oz at a time, as well as capsule or oral forms. Contact them to obtain a
quote for shipping & handling costs.
If you enter the word "tanya" (without the ") in the promotional code box,
you will receive a 10% discount on orders over US$55.
Fosrenol/Renalzin Canada
Thriving
Pets
sells nine Fosrenol 500mg tablets for
US$45 or ten 1000mg tablets for US$89.95. A prescription is required. If you enter the word "tanya" (without the ") in the
promotional code box, you will receive a 10% discount on orders over
US$55.
Best Pet Pharmacy in the
UK sells Renalzin for £9.35 for 50ml or £24.98 for 150ml. This
pharmacy shipped products to me in the USA with no problems.
Sources - Australia and New Zealand
Your
best bet is Alu-Tabs. These are made by Douglas Pharmaceuticals of New
Zealand. They come in 600mg tablets rather than a powder, but I imagine
you could crush them. They should be available over the counter in
pharmacies, though your pharmacist may not realise they are there. Don't say they are for a cat, or they may ask for a
prescription from your vet, whereas if you buy them for your own
indigestion, they are over the counter.
Home Pharmacy sells 100 Alu-Tabs for
AUS$26.99 (I do not know anybody who has used this pharmacy as yet).
TREATING YOUR CAT WITHOUT VETERINARY ADVICE CAN BE
EXTREMELY DANGEROUS.
I have
tried very hard to ensure that the information provided in this website is
accurate, but I am NOT a vet, just an ordinary person who has lived
through CKD with three cats. This website is for educational purposes
only, and is not intended to be used to diagnose or treat any cat. Before
trying any of the treatments described herein, you MUST consult a
qualified veterinarian and obtain professional advice on the correct
regimen for your cat and his or her particular requirements; and you
should only use any treatments described here with the full knowledge and
approval of your vet. No responsibility can be accepted.
If your cat
appears to be in pain or distress, do not waste time on the internet,
contact your vet immediately.
This site was
created using Microsoft software, and therefore it is best viewed in
Internet Explorer. I know it doesn't always display too well in other
browsers, but I'm not an IT expert so I'm afraid I don't know how to
change that. I would love it to display perfectly everywhere, but my focus
is on making the information available. When I get time, I'll try to
improve how it displays in other browsers.
You may print
out one copy of each section of this site for your own information and/or
one copy to give to your vet, but this site may not otherwise be
reproduced or reprinted, on the internet or elsewhere, without the
permission of the site owner, who can be contacted via the
Contact Me
page.
This site is a labour of love, from which I do not make
a penny. Please do not steal from me by taking credit for my work.
If you wish to
link to this site, please feel free to do so. Please make it clear that
this is a link and not your own work. I would appreciate being informed of
your link.
You may
also see a plantigrade posture
Your
best bet is Alu-Tabs. These are made by Douglas Pharmaceuticals of New
Zealand. They come in 600mg tablets rather than a powder, but I imagine
you could crush them. They should be available over the counter in
pharmacies, though your pharmacist may not realise they are there. Don't say they are for a cat, or they may ask for a
prescription from your vet, whereas if you buy them for your own
indigestion, they are over the counter. 
