Hypercalcaemia Flashcards
Explain the regulation of calcium in the body
- 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)
What are the clinical features of hypercalcaemia?
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
What levels of hypercalcaemia are significant?
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.
What are the parathyroid dependent causes of hypercalcaemia?
- 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)
What are the causes of parathyroid hormone independent hypercalcaemia?
- Almost always malignancy
- Other causes (rarer) include drugs (thiazides), thyrotoxicosis, Addison’s disease, Vit D excess
What is the emergency management for hypercalcaemia?
- Rehydration via IV 0.9% saline (4-6L in 24h)
- IV bisphosphonates eg Zolendronic acid
What are the second line treatments for hypercalcaemia?
- Glucocorticoids (reduced GI absorption),
- calcitonin (inhibits osteoclasts),
- calcimemetics or parathyroidectomy if PTH dependent
