Antacid abuse: a rare cause of severe hypercalcaemia

We discuss a case of an 81-year-old man who presented to hospital with a case of severe hypercalcaemia (5.07 mmol/L). The two most common causes of hypercalcaemia, making up around 90% of the cases, are malignancy and primary hyperparathyroidism. Initial investigations are guided by this knowledge. In this case, no underlying malignancy or evidence of a parathyroid adenoma causing primary hyperparathyroidism was found. Instead, on further history, it was found that this patient had troublesome dyspepsia symptoms for which he had ingested 10-12 calcium carbonate tablets a day for the preceding 2 years. This amounts to 6.6-7.9 g of calcium carbonate per day compared with the guideline daily intake of calcium of 1 g. His presentation of severe hypercalcaemia was therefore diagnosed as milk-alkali syndrome secondary to calcium carbonate tablet abuse.