Objective: We present this case to emphasize the need to consider the uncommon causes of hypercalcaemia and the importance of history taking.
Case report: A 79 year old man with multiple sclerosis was admitted with hypercalcaemia of 3.41 mmol/L, a suppressed PTH and AKI. He was investigated for non-PTH mediated hypercalcemia, having a whole host of investigation. He had normal serum ACE, with no radiological evidence of granulomatous disease or malignancy. He had raised free light chains which prompted myeloma investigation.
His hypercalcemia was quite resistant to IV fluids and IV bisphosphonates. Subsequent investigation revealed an exceptionally high vitamin D level of 375 nmol/L and 1,21-hydroxy-vitamin D of 195 pmol/L (43-144 pmol/L) which prompted Endocrinologist involvement only later on in his management, Given his MS, we suspected that he may have been taking high dose vitamin D to help with MS symptoms. His vitamin D levels have been above 200 nmol/L at least since 2013. However, due to delirium with a concomitant UTI, he mis-informed us that he was taking 1000 units of over-the-counter colecalciferol daily. We suggested treatment with steroids which finally improved his calcium and AKI.
His latest blood tests show normocalcaemia of 2.46, PTH 2.20, vitamin D 214.4, eGFR 50.
Retrospectively in clinic, he revealed that he had been taking 10,000 units daily of vitamin D for more than 3 years. He had been following the advice of a doctor he had contacted via the internet, who recommended high dose vitamin D to treat MS.
Conclusion: Though primary hyperparathyroidism and malignancy are the commonest causes of hypercalcaemia, less common causes should be considered, and a careful history is helpful in unraveling the underlying cause and avoid unnecessary investigations.