Kidney disease is common among older cats. When Patches starts getting up there, you'll want to monitor her kidney function with veterinary blood tests. Nine values provide information about present health; over time, changes in the values from one test to the next help gauge kidney function and more.
Blood Urea Nitrogen
Blood urea nitrogen is a waste product passed through the kidneys. A normal BUN level is 14 to 36 mg/dL. If Patches' diet has changed, it's more apt to be shown in the BUN. If she's dehydrated, it can cause the BUN to creep higher, because she doesn't have ample fluid to excrete the waste.
Creatinine, also a waste product, is the second key indicator of overall kidney health. The normal creatinine level in a cat with healthy kidneys is between 0.6 and 2.4 mg/dL. A higher reading indicates overall declining kidney health. Typically, when both BUN and creatinine are elevated, about 30 percent of kidney function remains.
Phosphorus is an important mineral for all cats, but it's easy for cats with kidney disease to have too much of it. As kidneys deteriorate, it's more difficult for them to process phosphorus. High levels of phosphorus can make kidney disease worse, so it should be monitored regularly. A normal phosphorus range is 2.4 to 8.2 mg/dL.
Calcium, Sodium and Potassium
Calcium is measured in relationship to phosphorus; a healthy ratio is between 1-to-1 and 2-to-1, calcium to phosphorus. Calcium levels will rise when a cat with compromised kidneys doesn't process phosphorus effectively. Cats with renal failure have a difficult time excreting sufficient sodium, which can lead to hypertension. The normal ranges for this mineral is between 145 and 158 mEq/L. Insufficient potassium, called hypokalemia, can be a problem for the cat with kidney disease, leading to nausea and frequent urination. The normal potassium range is between 3.4 and 5.6 mEq/L.
Amylase, Cholesterol and Packed Cell Volume (PCV)
Amylase is an enzyme produced by the pancreas. Some vets believe an elevated level beyond the normal 100 u/L to 1,200 u/L range can be a precursor to kidney failure before other symptoms show up. Cholesterol levels need monitoring, because some cats experience higher levels if they have kidney disease; a normal range for a cat is 75 to 220. The PCV, or HCT, is monitored for potential anemia, a common occurrence in cats with kidney issues. A normal PCV is 29 percent to 48 percent red blood cells.
What the Results Mean
One isolated test or high value isn't reason to panic. A variety of factors influence lab work, including how stressed Patches was when the blood work took place and how recently she ate or drank. Track lab tests over time. Though the individual values are important, the long-term trends of her values give a much fuller picture of overall health and individual health issues. Tracking all indicators over time will give you and your vet valuable information to help Patches manage her kidney disease.
- Tanya's Comprehensive Guide to Feline Kidney Disease: How Bad Is It?
- Manhattan Cat Specialists: Chronic Renal Failure
- PetMD: Kidney Failure in Cats
- Feline CRF Information Center: Tests and Diagnostics
- 2nd Chance.info: Normal Feline & Canine Blood Chemistry Values Blood, Temperature , Urine and Other Values for Your Dog and Cat
- Michael Blann/Lifesize/Getty Images