Involves overactivity of the parathyroid glands with high levels of parathyroid hormone (PTH)

Aetiology

Primary hyperparathyroidism

• Caused by uncontrolled parathyroid hormone produced directly by a tumour of the parathyroid glands
• This leads to hypercalcaemia - fatigue, depression, bone pain, myalgia, nausea, thirst, polyuria, renal stones, osteoporosis
• Treated by surgically removing the tumour

Secondary hyperparathyroidism

• Insufficient vitamin D or chronic renal failure leads to low absorption of calcium from the intestines, kidneys and bones
• This causes hypocalcaemia

Tertiary hyperparathyroidism

• This happen when secondary hyperparathyroidism continues for a long period of time (e.g. renal failure), leading to hyperplasia of the glands

Summary of blood results

Pathophysiology

Functions of PTH

• Activates osteoclasts - increased bone reabsoption, releases calcium
• Increased reabsorption of calcium by renal tubules
• Increased urinary phospate excretion
• Increased synthesis of active forms of vitamin D

Regulation of PTH