Although hypercalcaemia is often encountered during the
course of malignant disease, hypocalcaemia appears to be rather rare. We describe a 37-year-old patient with
metastatic carcinoma of the breast, who developed
extreme hypocalcaemia (as low as 0.75 mmol calcium per litre) after chemotherapy. This is caused by a combination of hungry-bone syndrome and an insufficient parathyroid response. The latter may be the result of a direct toxic effect of chemotherapy on parathyroid hormone (PTH) synthesis possibly in combination with microscopic tumour infiltration in the parathyroid glands. Correction of the extreme hypocalcaemia over a period of 100 days by oral and intravenous calcium supplementation, corresponding
to a total of 352 gram elemental calcium (1/3 of the total
body calcium), resulted in gradual symptomatic relief. The possible mechanisms for these findings are discussed and the literature is briefly reviewed.