Low Potassium in Cat - When to Supplement??

my vet didn't seem to think max needs supplement so i'm asking for feedback here.

my 15yo male *NONCRF* cat Feb 09 blood work shows potassium of 4.0 (ref 3.9-5.3). i read here http://www.holisticat.com/crf/Treatments-herbs-supplements-and-fluids.html that K should be kept around 4.5-5 in CRF kitties.

BLOOD WORK FEB 08
i can post complete CBC if needed.
BUN 40 (15-34 = high)
platelets 110K (170-600 = low)
triclyceride 107 (20-90= high)
absolute lymphocyte 1240 (1500-7000 = low)
T4 2.4 (not out of range but hi for an old cat???)
Creatnine 1.8 (interesting his crea went down as his T4 went up from 06 values)

BLOOK WORK JUN 06
T4 2.2 (normal ref range but still hi for an old cat???)
Creatnine 2.2 (normal ref range)
Potassium 4.2 (normal ref range)

SYMPTOMS he is exhibiting what might be attributable to low potassium but after more reading, these can also be attributed to hyperthyroidism.

So I'm leaning toward asking for another T4 and T3/tyroid scan if needed as symptoms can also be due to hyperthyroidism

*lethargy (can also be a sign of hyperthyroid)
*eats grass often (upset tummy?)
*depression - in my opinion - not much interest in playing, etc.
#sensative when touched/picked up (objects with whiney meow)
#does not seem very interested in eating. over 1-2 yrs has gone from 16LB to 14.4LB and maintaining current weight ok (weight loss can also be a sign of hyperthyroid)
#increased drinking (can also be a sign of hyperthyroid)
#increased urination (can also be a sign of hyperthyroid and can cause potassium depletion)
#seems slow to move/weak in the hind legs
#seems his lower back area is sunken in - though no weight loss
*=not a new symptom
#=new symptom within the last 3 months.

feedback or direction to more appropriate forum/reading appreciated.

thanks
michelle

Ideal values for healthy cats are different from ideal values for CRF cats, because the CRF cats' body excretes far more electrolytes due to urinating more to try to keep the urea levels down. The normal ranges for senior cats are also slightly different that those for adult cats.

Blood values do fluctuate constantly, so if the test were to be run again now the potassium level might be right in the middle of normal. Supplementing with potassium when it is not necessary can be very dangerous to the cat. Plus you need to sort out the reason for the slightly low level before supplementing as it may correct itself.

You've already mentioned in the last 3 months Max has been drinking & peeing more - this can cause a decrease in potassium.

You have bloodwork listed for Max from Feb 2008 what was the potassium from that test?

What is the BUN, T4 and Creatinine from Feb 2009 and what is your labs reference range for the T4 & Creatinine?

You can ask your vet to do a test called free T4 by equilibrium dialysis in addition to running a Total T4 that will give a more accurate diagnosis. If the Total T4 is in the upper half of normal range and the Free T4 is elevated above normal then the cat has HyperT.

Some more info here on borderline HyperT & Free T4 testing: http://www.marvistavet.com/html/body_thyroid__signs__symptoms_and_d.html