Excess Calcium in the Blood in Cats

PetMD Editorial
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PetMD Editorial
Published: January 30, 2009
Excess Calcium in the Blood in Cats

Hypercalcemia in Cats

Hypercalcemia is characterized by an abnormally high amount of calcium in the blood. A cat is considered hypercalcemic when its total serum calcium level is greater than 10.5 mg/dL.

Behind the thyroid gland in the neck, there are four parathyroid glands which secrete the hormones the body needs to regulate calcium and phosphorus. Parathyroid hormones and vitamin D interactions work to release calcium from the bones, gut, and kidneys for deposit into the bloodstream. When these interactions are disturbed, or when cancerous cells secrete hormones, hypercalcemia, or excess blood-calcium levels, can result.

Symptoms and Types

  • Increased urination
  • Increased thirst
  • Lack of appetite (anorexia)
  • Vomiting
  • Decreased gastrointestinal function
  • Constipation
  • Lack of energy/fatigue/lethargy
  • Confusion
  • Depression
  • Enlarged lymph nodes (swelling in neck)
  • Bladder stones
  • Hypertension
  • Stupor and coma in severe cases


  • Abnormal functioning of the parathyroid gland
  • Over functioning of the parathyroid gland (hyperparathyroidism)
  • Cancer or tumors
  • Bone deteriorating diseases
  • Kidney failure - sudden or long-term
  • Under-functioning adrenal glands
  • Vitamin D poisoning: from rodenticides, plants, or food (including supplements)
  • Aluminum toxicity


Your veterinarian will perform a complete physical exam, including a blood chemistry profile, a complete blood count, and a urinalysis. While a high serum is crucial to the diagnosis of hypercalcemia, the results of the other tests will help to indicate the origin of the hypercalcemia.

Radiograph and ultrasound imaging can also be used for diagnosing underlying conditions, such as kidney disease, bladder stones, or cancer. Fine needle aspirates (liquids) from the lymph nodes and bone marrow can be used for diagnoses of lymphoma, or cancer of the blood.


If your cat has been diagnosed with hypercalcemia, your veterinarian will very likely want to admit it into hospital for fluid therapy. Once the underlying primary disease is diagnosed, your cat will be given the appropriate medication(s). Your doctor will continue to check your cat's serum calcium twice a day until the levels have returned to normal during its stay at the veterinary clinic.

Living and Management

Your veterinarian will set up a schedule of follow-up appointments for your cat dependent on the underlying cause of the hypercalcemia.

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