Why Is My Dog Or Cat’s Blood Creatinine Level High Or Low?

Ron Hines DVM PhD

The Creatinine Level In Your Pet’s Blood = CREA

Creatinine is not the same as creatine. Creatine is an energy source for your pet’s muscles. As creatine is utilized in your dog or cat’s muscle tissue, its breakdown product, creatinine, is produced. Creatinine is a waste product. It is eliminated almost entirely through your pet’s kidneys (when those kidneys are healthy) so its level in your pet’s blood stream is a good indication of overall kidney health. Veterinarians usually look at your pet’s BUN at the same time they consider its creatinine level. BUN can go up or down for a number of reasons that do not involve kidney damage. Rising creatinine levels are more specific indicators of kidney disease. A creatinine test will not detect very early kidney problems. For that, a urine microalbuminuria test and perhaps the SDMA blood test are probably better options. Idexx Laboratories intensively markets its patented SDMA test. What value, if any, that that test has in detecting early kidney damage has yet to be determined. When both BUN and creatinine are above acceptable levels, the situation is called azotemia.

Reasons My Pet’s Blood Creatinine Level Might Be High:

Kidney disease – the lack of enough kidney filtering ability necessary to keep the level of waste products in your pet’s blood within normal limits (60-75% kidney function loss is thought to be required before creatinine levels to begin to rise).

High creatinine levels can also be caused by a decrease in fluid volume in the blood circulating in your pet (hypovolemia) or dehydration, severe heart disease (or the ACE inhibitor drugs like enalapril and benazepril used to treat it). An obstruction of any sort in your pet’s urinary system that impedes the flow of urine can also raise its blood creatinine levels. It is also possibly that a small elevation in blood creatinine level could be caused by a very high-protein diet or recent meal. It is never wise to rest your diagnosis on a single set of tests.

Depending on how the test is performed, high blood glucose, vitamin C supplements and certain antibiotics (cephalosporins) can falsely raise creatinine readings.

Greyhound dogs (probably due to their large muscle mass) and possibly also in other sight hounds have normally higher blood creatinine levels. (Whereas a blood level of 1.0 mg/dL is high-end-normal in most dogs, 1.6 is normal in a greyhound.)

Veterinarians divide kidney disease in dogs and cats into four stages. Your pet’s blood creatinine level is one important factor in determining the stage of its kidney disease.

**Stage 1 kidney disease: Creatinine less than 1.4 mg/dL (123.7 umol/L) in dogs, less than 1.6 in cats

Stage 2 kidney disease: Creatinine 1.4 – 2.0 mg/dl (123.7-176.8 umol/L) in dogs, 1.6–2.0 in cats

Stage 3 kidney disease: Creatinine 2.1- 5.0 mg/dl (185.6 – 442 umol/L) in dogs, 2.9–5.0 in cats

Stage 4 kidney disease: Creatinine greater than 5.0 mg/dl (442 umol/L) in dogs or cats

**Blood creatinine levels in Stage 1 of chronic kidney disease (CKD) in dogs and cats overlap with normal creatinine levels. In a few cases, dehydration, heart and blood pressure medications, stomach antacids, antibiotics, non-kidney disease and arthritis medications can be responsible for minor blood creatinine increases in dogs and cats. Those causes are often correctable. When your veterinarian suspects early kidney damage in your pet, tests for increases in protein leakage (microalbuminuria) into your dog or cat’s urine are a more accurate indications of kidney problems. Several national labs offer such tests. (Antech, Idexx, Heska, Gribbles, etc.)

These cut off creatinine levels are somewhat arbitrary. For instance, the UK Idexx laboratory considers the top-normal blood creatinine level in cats to be 177 umol/l, which is about 2.0 mg/dl in the American system. However, Idexx USA has a top-normal creatinine level of 2.3 mg/dl.

Another way your veterinarian can gauge the severity of your pet’s kidney problems is to add its blood calcium determination number to its blood phosphorus determination number to get a number called the sCaPP (the Serum calcium-phosphorus concentration product). When that number is over 70 mg/dL, the median survival time of the 24 dogs in one study was, unfortunately, only 30 days. You can read that study here.

Reasons My Dog Or Cat’s Blood Creatinine Level Might Be Low:

Malnutrition and/or failure to eat, feeding a diet that is too low in protein, liver disease, pregnancy, portosystemic shunts.

Complementary Tests:

BUN, SDMA, complete urinalysis including urine specific gravity, urine protein content. Kidney ultrasound, CBC / WBC and a standard blood chemistry panel including blood phosphorus level When creatinine is low, a bile acids test is indicated.

DxMe

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