Immobilisation hypercalcaemia

Hypercalcaemia is a common metabolic abnormality and its differential diagnosis is vast. Immobility is an uncommon cause of hypercalcaemia. Immobilisation hypercalcaemia is independent of parathyroid hormone and is associated with low levels of 25-hydroxyvitamin D and 1,25-dihydroxyvitamin D. In addition, it is characterised by elevated levels of markers of bone resorption and low levels of bone-specific alkaline phosphatase, highlighting an imbalance of bone remodelling favouring osteoclastic bone resorption. Although immobilisation hypercalcaemia is a diagnosis of exclusion, physicians need to be aware of this condition to avoid excessive and invasive investigations when all other causes of parathyroid hormone-independent hypercalcaemia have been excluded. Management of immobilisation hypercalcaemia revolves around early mobilisation and rehabilitation together with pharmacotherapeutic agents such as intravenous isotonic saline, calcitonin and bisphosphonates. Denosumab may be a potential alternative yet off-label treatment for immobility hypercalcaemia in patients with renal insufficiency.