Parathyroid adenoma causing severe hypercalcaemia presenting as acute psychosis; not to be overlooked

Neuropsychiatric manifestations due to hypercalcaemia is a known entity and rarely it can be the first manifestation of the disease. It can be challenging to diagnose acute psychotic symptoms associated with hypercalcaemia in individuals with existing psychological disorders particularly if organic causes are not properly evaluated. Therefore, it's important to consider hypercalcaemia as a potential cause in these patients. Mild cases may manifest as depression and cognitive changes, while severe cases can result in confusion, agitation, delusions, hallucinations and even coma.We present a case of a 68-year-old man with a previous history of diabetes mellitus, hypertension, dyslipidaemia and recently diagnosed moderate depression who presented to psychiatry services with psychomotor agitation, loss of short-term memory, disorientation, auditory hallucinations and delusions with a history of severe constipation. The patient showed poor response to psychotic medications and during the evaluation for organic causes, the patient was found to have severe hypercalcaemia with high parathyroid hormone levels. Ultrasound scan of the neck showed a heterogeneous hyperechoic lesion adjacent to the thyroid isthmus and 4D CT (parathyroid protocol) showed parathyroid adenoma in the right tracheoesophageal groove. Hypercalcaemia was initially managed with hydration and intravenous zoledronic acid. The patient's symptoms rapidly improved following the correction of hypercalcaemia and successful surgical resection of parathyroid adenoma without any post-surgical complications.