Primary hyperparathyroidism

Primary hyperparathyroidism causes hypercalcemia (elevated blood calcium levels) through the excessive secretion of parathyroid hormone (PTH), usually by an adenoma (benign tumors) of the parathyroid glands. Its incidence is approximately 42 per 100,000 people. more...

It is approximately two to three times as common in women than men.

Signs and Symptoms

The signs and symptoms of primary hyperparathyroidism are those of hypercalcemia. They are classically summarized by the mnemonic "stones, bones, abdominal groans and psychic moans".

• "Stones" refers to kidney stones, nephrocalcinosis, and diabetes insipidus (polyuria and polydipsia). These can ultimately lead to renal failure.
• "Bones" refers to bone-related complications. The classic bone disease in hyperparathyroidism is osteitis fibrosa cystica, which results in pain and sometimes pathological fractures. Other bone diseases associated with hyperparathyroidism are osteoporosis, osteomalacia, and arthritis.
• "Abdominal groans" refers to gastrointestinal symptoms of constipation, indigestion, nausea and vomiting. Hypercalcemia can lead to peptic ulcers and acute pancreatitis.
• "Psychic moans" refers to effects on the central nervous system. Symptoms include lethargy, fatigue, depression, memory loss, psychosis, ataxia, delirium, and coma.

Other signs include proximal muscle weakness, itching, and band keratopathy of the eyes.

Diagnosis

The diagnosis of primary hyperparathyroidism is made by blood tests. Serum calcium levels are elevated. Intact PTH levels are also elevated. Urinary cAMP is occasionally measured; this is generally elevated.

Causes

The most common cause of primary hyperparathyroidism is a sporadic, single parathyroid adenoma resulting from a clonal mutation. Less common is hyperplasia of the parathyroid glands and parathyroid carcinoma (malignant tumor). Primary hyperparathyroidism is also a feature of several familial endocrine disorders: Multiple endocrine neoplasia type 1 and type 2A (MEN type 1 and MEN type 2A), and familial hyperparathyroidism.

Treatment

The treatment is usually surgical removal of the affected glands. Medications (such as estrogen replacement therapy in postmenopausal women and bisphosphonates) thus far have not been very effective. Future developements such as calcimemetic agents (e.g. cinacalcet) which activate the parathyroid calcium-sensing receptor may offer a good alternative to surgery.

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