Question by Cat S: Blood test and Feline renal failure?
I ‘ve been doing some research for my cat (6 yrs) , and I’ve read that feline chronic renal failure cannot be detected until 70% of renal function is lost, does this mean that the blood test WILL NOT be able to detect developing CRF, or if i should keep an eye on his kidney function?
Answer by jsosjsjs
Creatinine and BUN are the two most important elements of the blood test for cats with CRF. When these are elevated and the urine is dilute, there is a very real possibility that the cat is in CRF. When the creatinine and BUN are elevated, it is likely that approximately 70% of kidney function is already gone.
The veterinarian can however detect early renal failure from the other blood values related toCRDF, here are some:
Amylase – Some vets feel that slightly elevated Amylase levels can sometimes be a pre-cursor to CRF before other symptoms occur.
BUN (blood urea nitrogen) – is a waste product excreted through the kidneys. BUN is more reflective of dietary impacts than creatinine. An increase in BUN can also be due to dehydration (a symptom of CRF and many other diseases and syndromes).
Cholesterol – Increases in cholesterol levels may occur with kidney disease.
Creatinine – is a waste product excreted through the kidneys. It is indicative of overall declining kidney function.
Calcium – A healthy cat will have a calcium to phosphorus ratio of 1:1 to 2:1. Since damaged kidneys cannot adequately process phosphorus, calcium levels must rise to compensate.
PCV (Packed Cell Volume) or HCT (hematocrit) – This number is watched carefully as it is indicative of anemia which is common in CRF cats. In this test the blood sample is centrifuged to separate the blood cells from the fluid portion (serum) of the blood. The volume of the cells is measured as a percentage of the total sample. Normally, 40% of the cat’s blood consists of cells and the rest is liquid.
Phosphorus – During CRF, high levels of phosphorus accumulate in the blood (hyperphosphatemia) because the kidneys can no longer efficiently excrete it. Excess phosphorus intake can make CRF worse. Phosphorus levels should be monitored on a regular basis.
Potassium levels are critical in CRF cats and should be regularly monitored. Potassium loss can result from frequent vomiting and in urination. Sub-Q therapy may also dilute potassium even further. Low potassium is called hypokalemia. Even if your cat’s potassium is in the low normal range, it may be necessary to give him a potassium supplement. This is because with CRF, critical stored potassium in the tissues is used, often making the blood analysis appear normal.
Sodium should be monitored closely as the kidneys of CRF cats are unable to excrete sufficient quantities of it. This may result in hypertension.
Routine (annually) blood work, urinalysis and physical exam will be the key in keeping your feline friend healthy.
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