Hyperparathyroidism

Primary hyperparathyroidism is a disorder resulting from excessive secretion of parathyroid hormone (PTH) by one or more of the parathyroid glands. Parathyroid glands are small glands of the endocrine system which are located in the neck behind the thyroid. There are two each side, making four in total. The parathyroid glands controls the supply & balance of calcium and phosphate in the bloodstream.

In order to do perform this function, the parathyroid glands release parathyroid hormones (just as the thyroid glands release thyroid hormones), the amount of which is closely related to the calcium levels in the body, which is sensed by calcium receptors in the glands themselves. If blood calcium is low, the parathyroid hormone level increases, which causes calcium to be taken out of the bone to maintain the correct calcium level in the blood and other tissues.

Signs & Symptoms

Symptoms can be varied but include:

• Loss of energy
• Chronic fatigue
• Osteoporosis (decrease in bone mass and density) & Osteopenia (thinning bones)
• Thinning hair coat
• Kidney Stones
• Increased urination
• Atrial arrhythmias
• General aches & pains
• Nausea & vomiting
• Gastric acid reflux

Diagnosis

Blood and urine tests to measure the level of circulating calcium. Ultrasound scans & X-rays and electrocardiogram (ECG) to monitor heart function.

Treatment

There are two forms of hyperparathyroidism, primary as mentioned above and secondary. Secondary (nutritional) hyperparathyroidism which is the more commonly found problem and occurs most frequently in puppies fed an all-meat or organ diet (such as all liver) or a diet with an imbalance of calcium and phosphorous. Meat contains an excess of phosphorous and inadequate amounts of calcium.

In secondary hyperparathyroidism, because the calcium intake is low, the parathyroid gland produces more parathyroid hormone, and calcium is removed from the bones.

Treatment for nutritional hyperparathyroidism involves feeding the puppy/dog a balanced diet. The skeletal deformities caused by a calcium/phosphorous imbalance are generally permanent & cannot be corrected.

The treatment of primary hyperparathyroidism is removal of the abnormal gland. The removal of the gland causes a sudden decrease in the amount of parathyroid hormone, and there is a corresponding sudden drop in the blood calcium level. For this reason, the dog must be monitored closely after surgery & given calcium if the level becomes too low.