Times change and my website needed to change too. To see the 2020 update of this page click this link
To see what normal blood and urine values are, go here
For an explanation of causes of most abnormal blood and urine tests, go here
To see how tests are grouped, go here
Creatinine is not creatine. Creatine is an energy source in your pets muscles. As it is utilized there, 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 levels. BUN can go up or down for a number of reasons that do not involve kidney damage; rising creatinine levels are more specific indicators kidney disease. A creatinine test will not detect very early kidney problems. For that, a urine microalbuminuria and the SDMA blood test are probably better options. When both BUN and creatinine are above acceptable levels, the situation is called azotemia.
Kidney disease – lack of kidney filtering ability necessary to keep the level of waste products in you pet’s blood within normal limits (60-75% loss).
High creatinine levels can also be caused by a decrease in fluid volume in the blood circulation of your pet (hypovolemia) or dehydration, severe heart disease (or ACE inhibitor drugs used to treat it). An obstruction of any sort in your pet’s urinary system that impedes the flow of urine can also raise blood creatinine levels. It is possibly that a small elevation could be caused by a very high protein diet or recent meal.
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 (ref)) 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 5.0mg/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 pet’s urine are a more accurate indications of kidney problems. (ref) 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 2.3mg/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.
Malnutrition and failure to eat, extremely low protein diets, liver disease, pregnancy, portosystemic shunts.