[Diagnostic approach to hypocalcaemia and hypercalcaemia].

A 49-year-old woman was examined for osteoporosis and metabolic bone disease after a low-trauma wrist fracture. Laboratory and additional radiological investigations revealed parathyroid hormone (PTH)-mediated hypercalcaemia caused by a parathyroid adenoma. A second patient, a 65-year-old woman with a history of abdominal complaints and tetany, appeared to have hypocalcaemia. Severe vitamin D deficiency and secondary hyperparathyroidism were detected and the patient was finally diagnosed with coeliac disease. Based on these case studies, we highlight the calcium homeostasis and the role of laboratory evaluation of serum calcium, inorganic phosphate, intact PTH, 25-OH vitamin D, magnesium and 24-hour urinary calcium excretion in the diagnostic work-up for hypocalcaemia and hypercalcaemia.