Article: Hyperparathyroidism

Hyperparathyroidism is overactivity of the parathyroid glands resulting in excess production of parathyroid hormone (PTH). Increased PTH consequently leads to increased serum calcium (hypercalcemia) due to 1) increased bone resorption, allowing flow of calcium from bone to blood, 2) reduces renal clearance of calcium, and 3) increases intestinal calcium absorption.

Etiology

• Primary hyperparathyroidism results from a dysfunction in the parathyroid glands themselves, with oversecretion of PTH.
  • The most common cause is a benign parathyroid adenoma that loses its sensitivity to circulating calcium levels. Usually, only one of the four parathyroid glands is affected.
  • A less common cause is from multiple endocrine neoplasia (MEN).

• Secondary hyperparathyroidism is due to resistance to the actions of PTH, usually due to chronic renal failure. The bone disease in secondary parathyroidism along with renal failure is termed renal osteodystrophy.

Signs and symptoms

The majority of patients with hyperparathyroidism are asymptomatic. Manifestations of hyperparathyroidism usually involve the kidney (stones) and the skeletal system (bone pain due to fibrous tissue replacement, termed osteitis fibrosa cystica)

If symptomatic, hyperparathyroidism can be classically remembered by the rhyme "moans" (myalgia), "groans" (abdominal pain), "stones" (kidney), "bones" (bone pain), and "psychiatric overtones" (confusion, altered mental state, lethargy, fatigue).

Other symptoms include: headaches, sleep disorders, memory problems, gastroesophageal reflux, decreased sex drive, thinning hair, hypertension, and heart palpitations.

Diagnosis

The gold standard of diagnosis is the PTH immunoassay. Once an elevated PTH has been confirmed, goal of diagnosis is to determine whether the hyperparathyroidism is primary or secondary in origin by obtaining a serum calcium level. If the calcium level is high, then the diagnosis is very likely primary hyperparathyroidism; if low or normal, then it is most likely secondary hyperparathyroidism.

Treatment

Treatment is first and foremost directed at hypercalcemia, if symptomatic. (see hypercalcemia)

If asymptomatic, treatment can then be directed towards the underlying cause

• (see primary hyperparathyroidism)
• (see secondary hyperparathyroidism)