Hypercalcemia (elevated calcium in the blood) has increased in frequency in cats over the last ten years. Calcium is critical to cell function and marked elevations can affect the nervous, gastrointestinal, cardiac and renal systems. Soft tissue mineralization can occur when the calcium level is too high. Hypercalcemia is most often recognized in cats undergoing blood screening at the time of wellness examinations, prior to anesthesia, and as part of the evaluation of cats with bladder stones or vague gastrointestinal signs. If repeated testing demonstrates a persistent elevation in blood calcium, additional diagnostics are needed to determine the cause and to treat appropriately.

Some of the conditions that might cause hypercalcemia
     1. Idiopathic (most common cause)
     2. Hypercalcemia of malignancy
     3. Kidney disease
     4. Hyperparathyroidism
     5. Vitamin D toxicosis
     6. Granulomatous disease (associated with fungal and other infectious agents)

The clinical signs related to hypercalcemia are variable and tend to be more pronounced when the change is rapid and the elevation is marked. The more common signs are lethargy, weakness, anorexia, vomiting, weakness, collapse, drinking and urinating excessively and in 15 % of patients the formation of stones in the bladder or kidney.

The tests needed to diagnose and manage hypercalcemia include
     1. Complete blood count
     2. Complete metabolic profile including calcium and phosphorus
     3. Test for ionized calcium
     4. Test for parathyroid hormone
     5. Test for parathyroid hormone related polypeptide (associated with calcium elevating cancers)
6. urinalysis
7. radiographs

Treatment is intended to reverse the effects high calcium has on organ function. It may include: intravenous fluids, diuretics, glucocorticoids, and dietary management. When a specific diagnosis is reached definitive therapy is directed toward the cause.

The prognosis for cats with hypercalcemia varies and depends on the underlying disease process. Many of the conditions are manageable and have a good prognosis.

~Annette Cowell, D.V. M.