Hypocalcemia

31 Hypocalcemia



David L. Panciera



1. What are the clinical signs of hypocalcemia?

Clinical signs of hypocalcemia are due primarily to increased neuromuscular excitability. The result is tetany, seizures, muscle fasciculations, hyperthermia, stiff gait, weakness, and generalized tremors. Tetany can sometimes be induced by exercise or testing reflexes. Occasionally tetany is localized to specific muscle groups, such as facial muscles, and may be manifest as facial rubbing or pawing due to the pain of cramping. Restlessness and apparent irritability and aggression may occur. Cataracts may occur after prolonged hypocalcemia (usually due to primary hypoparathyroidism); cataracts due to hypocalcemia are located in the anterior and posterior cortical subcapsular area of the lens. Panting or hyperventilation is also sometimes present. In addition to signs of hypocalcemia, clinical signs related to the primary disease may be present.


2. What are the most common causes of hypocalcemia?

Hypocalcemia severe enough to cause clinical signs is usually due to puerperal tetany, iatrogenic hypoparathyroidism, primary hypoparathyroidism, or administration of a phosphate-containing enema. Causes of less severe hypocalcemia include renal failure, pancreatitis, ethylene glycol intoxication, hypoalbuminemia, transfusion of blood with excessive citrate, intestinal malabsorption, and alkalosis.


3. What initial clinical approach should be taken when evaluating a hypocalcemic dog?

A thorough history and physical examination are essential for identifying the cause of hypocalcemia. History findings that may reveal a cause include recent parturition, exposure to ethylene glycol, administration of a phosphate enema, previous cervical surgery, or symptoms of renal failure or pancreatitis. Physical examination findings that can help determine a specific cause of hypocalcemia include pregnancy or evidence of recent parturition (lactation) and abnormalities related to ethylene glycol ingestion, renal failure, or pancreatitis.


The results of a complete blood count (CBC) and routine serum chemistry tests frequently aid in the diagnosis of a primary disease that could be causing the hypocalcemia, including pancreatitis (leukocytosis, elevated amylase, lipase, liver enzymes), renal failure (azotemia, hyperphosphatemia), hypertonic phosphate enema administration (hyperphosphatemia, hypernatremia), ethylene glycol toxicosis (azotemia, hyperglycemia, metabolic acidosis, increased anion gap), and hypoalbuminemia. In dogs with hypoalbuminemia, the laboratory-reported calcium level can be corrected for the decrease in serum albumin using the following formula:



Corrected calcium = 3.5 – albumin concentration (mg/dl) + serum calcium concentration

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Jul 31, 2016 | Posted by in INTERNAL MEDICINE | Comments Off on Hypocalcemia

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