Treatment of immobilization-related hypercalcaemia with denosumab

In this issue, de Beus and Boer [4] report the case of a patient with chronic renal failure and immobilizationrelated hypercalcaemia successfully treated with denosumab after a partial and transient response to pamidronate. The case suggests that denosumab might be a promising alternative to bisphosphonates also for the treatment of resorption-related hypercalcaemia in patients with renal insufficiency. However, particular attention should be paid to ensuring that patients are supplemented with calcium and vitamin D prior to starting therapy. In the denosumab trials, all women with osteoporosis were supplemented with daily calcium (1000 mg) and vitamin D (400 to 800 Units) and the incidence of hypocalcaemia was negligible [49]. Thus, in patients with normal renal function, adequately supplemented with calcium and vitamin D, hypocalcaemia typically is not a concern. However, in patients with conditions that predispose to hypocalcaemia, such as chronic kidney disease, malabsorption syndromes or hypoparathyroidism, symptomatic hypocalcaemia may occur. In a study of 55 patients with varying degrees of chronic kidney disease, the proportion of patients with serum calcium <7.5 mg/dL (1.9 mmol/L) or symptomatic hypocalcaemia was higher, occurring in 10 and 29% of subjects with creatinine clearance of 50– 80 and <30 mL/min, respectively [42]. Thus, in patients with chronic renal failure, calcium and vitamin D supplementation is recommended and serum calcium, phosphorus and magnesium should be closely monitored during therapy.