Hyperparathyroidism

Question 1

Physiology of PTH

Answer 1

• Raises blood calcium by:
  
  • Increasing osteoclast activity in bones (reabsorbing calcium from bones)
  • Increasing calcium absorption from the gut
  • Increasing calcium absorption from the kidneys
  • Increasing vitamin D activity

Question 2

Primary hyperparathyroidism

Answer 2

• Uncontrolled PTH produced by a tumour of the parathyroid glands
• Leads to hypercalcaemia
• Managed by surgically removing the tumour

Question 3

Secondary hyperparathyroidism

Answer 3

• Insufficient vitamin D or CKD leading to low absorption of calcium
• Causes hypocalcaemia
• Parathyroid glands react to low calcium by releasing more PTH - over time the number of cells in the gland increase to produce more PTH
• Serum calcium can be normal or low but the PTH will be high
• Treated by correcting vitamin D deficiency or treating renal failure (i.e. transplant)

Question 4

Tertiary hyperparathyroidism

Answer 4

• When secondary hyperparathyroidism continues for a long time
• Baseline level of PTH increases dramatically
• Cause of secondary hyperparathyroidism is treated and the PTH level remains high
• Treated surgically by removing some of the parathyroid tissue

Question 5

Testing in hyperparathyroidism

Answer 5