ABSTRACT
Since the advent of the automated serum biochemistry analyser in the 1970s, mild to moderate hypercalcaemia has become a common incidental finding in clinical practice. Primary hyperparathyroidism and malignancy are the two commonest causes of hypercalcaemia and account for more than 90% of cases. Biologically relevant hypercalcaemia is due to an elevated ionized calcium concentration. Primary hyperparathyroidism usually presents with borderline or mild hypercalcaemia. Parathyroid cancer should be suspected in young men presenting with parathyroid hormone (PTH)-driven hypercalcaemia. Hypercalcaemia is relatively rare until relatively later stages of chronic kidney disease. Hypercalcaemia may be absent in those patients if they are on haemodialysis. In the absence of overt skeletal metastases, humoral hypercalcaemia of malignancy may arise from the action of tumour-derived humoral factors, such as PTH-related protein. Humoral hypercalcaemia is accompanied by suppressed PTH levels on standard second- and third-generation PTH assays. Persistence of hypercalcaemia despite treatment should prompt evaluation. Hypercalcaemia has also been described in central hypoadrenalism due to hypophysitis.
