CLINICAL SERVICES
Parathyroid Disorders and Calcium Metabolism
Calcium is needed for a range of physiological and metabolic processes including muscle contraction, nerve conduction, hormone release and coagulation of the blood. The maintenance of calcium stores depends on:
- Calcium intake in the diet
- Absorption of calcium from the intestine
- Excretion of calcium from the kidney
Although 99% of calcium is in bone, the level of calcium in the blood is closely regulated and is critical for good health.
The metabolism of calcium and phosphate is closely related and their regulation is mainly influenced by the levels of circulating parathyroid hormone and vitamin D.
Hypercalcaemia is too much calcium in the blood. Symptoms are non specific and range in severity from absent or minor to severe. There are many causes but the most common are:
- Hyperparathyroidism (too much PTH) results from overactivity of one or more of the parathyroid glands.
- Cancer – individuals will often have other signs of their malignancy
Surgical removal of the parathyroid glands may be needed for hyperparathyroidism. Otherwise treatment is determined by the underlying condition.
Hypocalcaemia is too little calcium in the blood. Symptoms are variable and can include muscle cramps. The most common causes include:
- Hypoparathyroidism (too little parathyroid hormone) – may occur in auto-immune disorders or after parathyroid gland damage during thyroid surgery
- Vitamin D deficiency (vitamin D is ingested in certain foods such as dairy products and is also made in the skin in response to sunlight)
- Kidney disease
The main treatment for hypoparathyroidism is calcium and potent vitamin D supplements. Other medical treatment may be needed.