Summary

This report describes the unusual case of a man with chronic mental illness, presenting with polydipsia and psychotic symptoms atypical of his usual episodes of illness. This report is a reminder to all doctors to beware of organic causes of mental illness, not only in new presentations but also in patients well known to services. In particular this is important when unusual symptoms are present. The report includes some discussion of why finding an organic cause in patients with psychiatric illness can pose challenges and demonstrates the need for good communication between professionals in order to best serve patients. It also highlights the importance of appropriate and timely investigations.