Hypercalcaemia

Question 1

2 conditions amount for 90% of cases of hypercalcaemia?

Answer 1

1. primary hyperparathyroidism - commonest cause in non-hospitalised patients
2. Malignancy: the commonest cause in hospitalised patients. This may be due to a number of processes, including;
   - PTHrP from the tumour e.g. squamous cell lung cancer
   - bone metastases
   - myeloma,: due primarily to increased osteoclastic bone resorption caused by local cytokines (e.g. IL-1, tumour necrosis factor) released by the myeloma cells

For this reason, measuring PTH levels is the key investigation for patients with hypercalcaemia

Question 2

Other causes of hypercalcaemia include?

Answer 2

sarcoidosis
- other causes of granulomas may lead to hypercalcaemia e.g. tuberculosis and histoplasmosis

vitamin D intoxication
acromegaly
thyrotoxicosis
Milk-alkali syndrome
drugs: thiazides, calcium-containing antacids
dehydration
Addison’s disease

Paget’s disease of the bone: usually normal in this condition but hypercalcaemia may occur with prolonged immobilisation

Question 3

Features or hypercalcaemia?

Answer 3

Features
‘bones, stones, groans and psychic moans’
corneal calcification
shortened QT interval on ECG
hypertension

Question 4

Hypercalcaemia: management

Answer 4

The initial management of hypercalcaemia is rehydration with normal saline, typically 3-4 litres/day. Following rehydration bisphosphonates may be used. They typically take 2-3 days to work with maximal effect being seen at 7 days

Other options include:
calcitonin - quicker effect than bisphosphonates
steroids in sarcoidosis

Loop diuretics such as furosemide are sometimes used in hypercalcaemia, particularly in patients who cannot tolerate aggressive fluid rehydration. However, they should be used with caution as they may worsen electrolyte derangement and volume depletion.