hypercalcaemia.

Diagnosis can prove challenging when a patient with a chronic neurological disease presents with acute deterioration. This is especially true in Huntington's disease, where cognitive impairment is prominent. We present a case of hypercalcaemia causing an acute deterioration in physical and cognitive function in a patient with Huntington’s disease. Similarity in clinical phenotype between hypercalcaemia and Huntington’s disease, as well as failure to appreciate the acute nature of the deterioration resulted in diagnostic delay and prolonged admission.