27th February 2025

Overview of hypercalcaemia

Calcium levels are predominantly maintained through: (a) parathyroid hormone’s (PTH) direct effect on bone and the kidneys and (b) activated vitamin D’s indirect effect on the gut.

The list of diagnoses underlying hypercalcaemia range from benign disorders that do not require monitoring to life-threatening illnesses that demand immediate treatment. These conditions can be grouped according to the method through which they raise calcium levels. The degree of derangement can be classified as mild (2.6-3.00 mmol/L), moderate (3.01-3.40 mmol/L), or severe (>3.40 mmol/L).

Table 1 Aetiologies of hypercalcaemia classified by cause. *Most common causes of hypercalcaemia