Learning objectives

• common causes of hypercalcaemia
  
• investigations in hypercalcaemia
  
• management of hypercalcaemia

Take-home messages

• the commonest causes of hypercalcaemia are primary hyperparathyroidism and cancer
  
• check a PTH to direct further investigation and management
  
• manage with copious IV 0.9% NaCl

Causes of hypercalaemia

Plasma calcium concentration is regulated by PTH and vitamin D.

The commonest causes of hypercalcaemia are primary hyperparathroidism (in which PTH is not suppressed) and cancer (in which PTH is suppressed).

The first investigation to obtain is therefore a PTH level. If PTH is not suppressed then refer to endocrinology (because it can be difficult to differentiate hyperparathyroidism from familial hypocalciuric hypercalcaemia11 FHH is a disorder in which the calcium ‘set-point’ is readjusted by mutations in the calcium-sensing receptor.). If PTH is suppressed, then investigations are tailored to the clinical scenario (e.g. get imaging early if suspected cancer):

Note that PTHrP is not routinely measured in clinical practice.

Management

Severe hypercalcaemia is a medical emergency because it can cause cardiac dysrhythmia and coma.

Hypercalcaemia causes the kidney to make a dilute urine. (This effect is mediated in the loop of Henle, mimicking a loop diuretic such as furosemide.) Therefore patients are usually volume deplete at presentation. Volume resuscitation with copious IV 0.9% NaCl is an important part of management.22 This will also encourage calciuresis because sodium and calcium transport are coupled in the proximal renal tubule.

Management involves:

• copious IV 0.9% NaCl

• IV bisphosphonate (and / or denosumab)

• disease-specific therapies

Additional reading