Primary Hyperparathyroidism in Cats

Feline primary hyperparathyroidism is a disease that occurs when a cat's parathyroid glands produce increased amounts of the hormone responsible for controlling calcium, vitamin D and phosphorus levels in the bone and blood. Increased amounts of parathyroid hormone (PTH) can trigger calcium to be released from bones and tissue into the bloodstream. Elevated levels of calcium in the blood may lead to a potentially dangerous condition known as hypercalcemia. Such imbalanced calcium levels may interfere with the proper functioning of organs like the heart and kidneys. Additional information on the symptoms, diagnosis and treatment of primary hyperparathyroidism may help relieve some of the uncertainty regarding how to care for a pet with this treatable metabolic disorder.

What Causes Primary Hyperparathyroidism

The parahyperthroid glands are part of the feline endocrine system, which is responsible for hormone regulation. These four small structures are located near the front base of the two thyroid glands, on either side of the trachea. Primary hyperparathyroidism is a relatively rare condition that can develop in cats with abnormalities in the parathyroid glands. Among the most common abnormalities are parathyroid glands that become swollen due to the development of benign tumors called adenomas. In less common cases, the disorder may also be caused by cancerous growths or injury to the parathyroid glands.

Primary Hyperparathyroidism Symptoms and Diagnosis

Some of the most common symptoms of primary hyperparathyroidism are:

  • Loss of appetite
  • Vomiting
  • Increased thirst and urination
  • Lethargy
  • Fatigue

A diagnosis of primary hyperparathyroidism is generally based on the cat's physical history, a complete exam and additional tests for evidence of hypercalcemia and hyperphosphatemia, or elevated phosphorus levels in the blood. These conditions can usually be determined by laboratory analysis of blood and urine samples. An ultrasound or radiograph (X-ray) of the neck area may be requested to help diagnose the condition. In addition, a veterinarian may want to examine and test samples of the parathyroid tissue or related tumor. In order to obtain such samples, a unilateral thyroidectomy may need to be performed. During this procedure, a part of the parathyroid is surgically removed for analysis.

Hyperparathyroidism Treatment

In most cases, treatment for primary hyperparathyroidism requires the removal of the abnormal gland and, if necessary, any associated tumors or growths. Removal of the affected gland may cause calcium levels in a cat's blood to drop significantly. This condition, known as hypocalcemia, may disrupt the function of the nervous and muscular systems. In extreme cases lack of coordination, muscle twitches and seizures may result. After surgery, a feline may need to receive calcium and vitamin D supplements in order to prevent symptoms of low blood calcium. Your veterinarian may recommend an oral supplement that is safe and well-tolerated by cats.

Although an initial diagnosis of hyperparathyroidism may seem overwhelming and unnerving, this rare condition is often treatable through surgery and careful post-operative monitoring of calcium blood levels. Owners can learn more about the risks, symptoms, diagnostic and surgical process associated with primary hyperparathyroidism to help them make the best decisions on how to care for a pet with this feline metabolic disorder.