Too much of a good thing: A case series of rare yet pertinent causes of hypercalcaemia and acute kidney injury.

Calcium compounds and vitamin D supplements are readily available as over-the-counter preparations. Whilst integral in maintaining calcium homeostasis in certain patients, excess exogenous intake of these preparations can have deleterious effects, particularly in terms of renal function. We look at the cases of two patients, aged 52 and 34, who were referred into hospital with hypercalcaemia and acute kidney injury (AKI). Both individuals reported regular and prolonged self-medication with unregulated over-the-counter supplements containing calcium carbonate and vitamin D, respectively. Prompt investigation and treatment enabled an element of reversibility of the AKI in both the cases, with further improvement in renal function over time. We emphasise the importance of recognising the overuse of exogenous vitamin D supplements and calcium compounds as rare yet treatable causes of AKI associated with hypercalcaemia and discuss how raising public awareness into the risks posed by self-medication of over-the-counter medicines is paramount.