ICD-11

Hypercalcaemia is a condition caused by increased calcium levels. The higher the calcium levels and the faster its level rises, the more severe will be the symptoms. When present, symptoms are caused by dehydration secondary to urinary losses of calcium, water and other electrolytes, and to an increase in membrane potential caused by the elevation in extracellular fluid ionized calcium concentration. Patients with moderate to severe hypercalcaemia often complain of nausea and vomiting, symptoms likely related to dehydration as well as to the effects of the hypercalcaemia on central nervous system function. Because hypercalcaemia tends to hyperpolarize membranes, a range of neurologic and neuromuscular signs and symptoms can occur. Patients with mild hypercalcaemia often complain of fatigue, depressed mood and asthenia. Gastrointestinal motility is impaired; this commonly results in constipation.

The severity of hypercalcaemic symptoms is related both to the degree of elevation in the ionized calcium level and to the rapidity with which the calcium level rises.

Hypercalcemia can also cause nephrogenic diabetes insipidus due to the stimulation of the calcium-sensing receptor (CaSR) in the collecting ducts of the kidney. Consequently, patients with hypercalcaemia frequently report symptoms of polyuria and polydipsia.