Hypercalcaemia

Question 1

Explain the regulation of calcium in the body

Answer 1

• Majority of calcium in the body is stored in the bone an the amount in the blood is regulated by:
• Parathyroid hormone which increases bone reabsorption to increase calcium, increases renal tubular reabsorption of calcium
• 1,23 dihydroxycholecacliferol (active vitamin D) which increases plasma calcium and phosphate by increasing renal reabsorption, gut absorption and stimulating osteoclastic activity
• Calcitonin which inhibits osteoclast activity and inhibits renal reabsorption (decreases calcium levels)

Question 2

What are the clinical features of hypercalcaemia?

Answer 2

Neuro - lethargy, confusion, irritability, depression or coma, slow or absent reflexes.
GI - Anorexia, nausea, constipation and abdominal pain.
Renal - Thirst, polyuria, renal calcium deposition,
Cardiac - Arrhythmias

Question 3

What levels of hypercalcaemia are significant?

Answer 3

if between 2.5-3mmol/L then its often asymptomatic.
If between 3.0-3.5mmol/L then may be symptomatic and needs prompt treatment.
If over 3.5 then it needs urgent medical correction.

Question 4

What are the parathyroid dependent causes of hypercalcaemia?

Answer 4

• Primary hyperparathyroidism (almost always adenoma)
• Tertiary hyperparathyroidism (often due to hyperplasia of all 4 glands after secondary hyperparathyroidism)
• Familial hypocalciuric hypercalcaemia (low calcium in urine and high calcium in blood)

Question 5

What are the causes of parathyroid hormone independent hypercalcaemia?

Answer 5

• Almost always malignancy
• Other causes (rarer) include drugs (thiazides), thyrotoxicosis, Addison’s disease, Vit D excess

Question 6

What is the emergency management for hypercalcaemia?

Answer 6

• Rehydration via IV 0.9% saline (4-6L in 24h)
• IV bisphosphonates eg Zolendronic acid

Question 7

What are the second line treatments for hypercalcaemia?

Answer 7

• Glucocorticoids (reduced GI absorption),
• calcitonin (inhibits osteoclasts),
• calcimemetics or parathyroidectomy if PTH dependent