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High Creatinine Levels in Cats

Laura García Ortiz
By Laura García Ortiz, Veterinarian specialized in feline medicine. Updated: February 29, 2024
High Creatinine Levels in Cats

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Elevated creatinine levels in cats are related to kidney disease. There are other symptoms which will usually present in the cat before a test for creatinine levels is performed. The reason for these high levels is partly due to impaired function kidney function preventing the creatine from being reabsorbed after filtration. They are also related problems such as kidney perfusion disorders due to altered blood flow or inadequate elimination due to obstruction of urine flow. Most causes of high creatinine levels are pathological, although it can also be related to muscle degeneration.

If you want to know the causes of high creatinine levels in cats, AnimalWised provides the information you need. We also look at what is a normal level of creatinine in cats, as well as how to reduce high levels back into this normal range.

  1. What is high creatinine in cats?
  2. Causes of high creatinine levels in cats
  3. Types of increased creatinine in cats
  4. Symptoms of high creatinine levels in cats
  5. Diagnosis of high creatinine levels in cats
  6. Treatment of high creatinine in cats

What is high creatinine in cats?

Creatinine is a compound formed from the degradation of creatine phosphate. This is a very important nutrient in skeletal muscle and is a waste product created during normal metabolism. It is produced at a constant rate which is always dependent on the mass of the feline's muscles.

The more skeletal muscle mass a cat has, the higher the normal concentration of creatinine it will have. Creatinine is also filtered in the renal glomerulus (a network of capillaries in the kidneys), but cannot be reabsorbed afterwards. For this reason, it is secreted directly into the urine.

The normal level of creatinine in cats is between 0.6 and 2.4 mg/dL (milligrams per deciliter) and one of the most important origins of elevated creatinine is acute renal failure in cats. The underlying causes of this renal failure can be extremely varied.

Learn more about renal problems in cats with our article on the symptoms of a cat with kidney failure.

Causes of high creatinine levels in cats

High creatinine in a cat's blood can indicate two things:

  • The cat is very muscular: since creatinine is released by the metabolism of its muscles, greater muscle mass creates higher creatinine levels.
  • The cat has a glomerular filtration problem: this means the cat is suffering from kidney failure and creatinine is not filtered to be eliminated. At high levels, the creatinine in the blood of the cat becomes toxic, leading to subsequent adverse effects on their health.

Elevated creatinine due to kidney disease is often associated with increased urea. This is a small molecule produced in the final stage of protein metabolism in the urea cycle produced in the liver and also filtered by the kidney. When there are high levels of nitrogen-containing compounds which include both creatinine and urea, the cat is said to have azotemia.

Types of increased creatinine in cats

Elevated creatinine levels in a cat's blood can be of three types:

  • Increased prerenal creatinine: the reduction in glomerular filtration and the consequent increase in creatinine occurs when renal perfusion decreases. This is due to alteration of its blood flow due to dehydration, altered cardiac output, hypovolemia or a marked vasodilation, among other causes. Creatinine in this case increases at a slower rate than urea, since it is not subsequently reabsorbed.

  • Increased renal creatinine: occurs when damage to the kidney caused when an alteration, damage or disease produces a loss of its function. Consequently, its filtration rate decreases and creatinine increases. The damage in this case can be due to poisoning, hypophosphatemia, hypercalcemia, infarcts, thrombosis, infections, polycythemia, pyelonephritis, urinary tract infections, non-steroidal anti-inflammatory drugs, hypertension or hypovolemia, among others.

  • Increased post-renal creatinine: in this case, the elevation in creatinine is not due to a poor glomerular filtration rate. Instead, creatinine cannot leave the cat's body as the flow of urine is blocked for various reasons. These include obstruction of the urethra or ureters, ligation of the ureter, leakage or rupture of the urinary bladder.

Learn more about various types of urinary problems in cats with our article on feline lower urinary tract disease.

High Creatinine Levels in Cats - Types of increased creatinine in cats

Symptoms of high creatinine levels in cats

When the high levels of creatinine are due to large muscle mass, it is unlikely the cat will show any particular symptoms. When they are due to an underlying disease or health disorder, the effects on their body can be serious. For example, when elevated creatinine is secondary to a renal perfusion disorder (i.e. it affects the passage of fluid through the kidneys), it is common for symptoms related to reduced blood flow such as:

  • Anemia
  • Low hematocrit levels
  • Weak pulse
  • Dryness and paleness of the mucous membranes
  • Higher skinfold compressibility due to dehydration
  • Reduced blood pressure
  • Changes in heart rate and breaths per minute

In the case of damage to the glomerular filtration due to kidney disease, signs of kidney disease may appear, such as:

  • Oliguria (reduced urine volume) or anuria (not urinating) in acute cases
  • Polyuria (increased volume of urine) and polydipsia (increased thirst) in chronic cases
  • Oral ulcers
  • Bad breath
  • Kidneys enlarged in acute disease or reduced in size in chronic disease
  • Arrhythmias
  • Anorexia and weight loss
  • Vomiting

When creatinine increases because it cannot be eliminated, signs of feline lower urinary tract disease (FLUTD) occur, as one of these diseases that compose it is the cause, such as the following:

  • Strangury (painful drop-by-drop urination)
  • Dysuria (pain on urination)
  • Hematuria (blood in urine)
  • Frequency (urination in small amounts several times a day)
  • Licking the urogenital area
  • Hyperkalemia (increased potassium)
  • Urination outside the litter box

Many of the symptoms of high creatinine levels can be related to other diseases or health conditions. Learn more with our articles on why a cat keeps licking their private area or why there is blood in a cat's urine.

High Creatinine Levels in Cats - Symptoms of high creatinine levels in cats

Diagnosis of high creatinine levels in cats

Diagnosis of increased creatinine in cats is made by hematology or blood tests. A sample will be taken after checking the cat's muscle status through a physical examination.

When a cat which is not especially muscular has an increase of creatinine, it is possible to suspect a prerenal, renal or postrenal cause after an exhaustive anamnesis (examination of medical history). They will look at the clinical signs and previous diseases. For this reason, it is important to provide your veterinarian with as much information as possible.

If the veterinarian suspects the cause of elevated creatinine in the cat is dehydration, they will assess their degree of hydration with tests such as the skinfold testing, ocular examination or the observing the mucous membranes, among others.

Urinalysis should also be performed to assess possible alterations and measure urine density. These results may serve as a guide for your veterinarian to determine the location of azotemia.

It should be noted that for elevated creatinine to appear in the blood test, 75% of the kidney must have been damaged. For this reason, high creatinine levels are a late indicator of kidney disease. This is unlike SDMA testing which can increase with only 25% kidney damage and is not influenced by the amount of muscle in your cat.

An ultrasound will allow us to assess kidney size and observe possible alterations or injuries, as well as being able to find out any cause of feline disease of the lower urinary tract or bladder leaks or rupture that block the flow of urine and cause an increase in creatinine.

High Creatinine Levels in Cats - Diagnosis of high creatinine levels in cats

Treatment of high creatinine in cats

If you are wondering how to lower elevated creatinine levels in cats, the answer is found in treating its underlying cause. Here we look at the three main issues which affect the kidneys and result in

  • Impaired renal flow: the cat should be rehydrated by fluid therapy or transfusions in some cases.

  • Treatable kidney disease: the problem should be addressed specific to the cause as well as any other associated disease. The kidney should be supported with angiotensin converting enzyme inhibitors to reduce protein excretion in the urine, treat hypertension through the use of drugs such as amlodipine, reduce hyperphosphatemia with kidney feed and, if necessary, use a phosphate binder, appetite stimulants such as mirtazapine and antiemetics such as Cerenia for dogs in case of vomiting. If infection is present, the specific antibiotics established by the antibiogram should be used.

  • Feline obstructive lower urinary tract disease: the feline should be unblocked. In some cases there are stones that can removed by diet, such as struvite. In cases where the stones are calcium oxalate, the only solution is surgery. The same will be required in cases of bladder rupture.

Learn more about removing urinary stones with our article on why my cat has crystals in their urine.

This article is purely informative. AnimalWised does not have the authority to prescribe any veterinary treatment or create a diagnosis. We invite you to take your pet to the veterinarian if they are suffering from any condition or pain.

If you want to read similar articles to High Creatinine Levels in Cats, we recommend you visit our Other health problems category.

  • Harvey, A., & Tasker, S. (Eds). (2014). Manual of Feline Medicine. Ed. Sastre Molina, SL L´Hospitalet de Llobregat, Barcelona, Spain.
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High Creatinine Levels in Cats