Acute Psychosis in the Setting of Undiagnosed Normocalcemic Hyperparathyroidism: A Case Report.

Hyperparathyroidism (HPT) causes an elevation of parathyroid hormone (PTH). This can result in elevated calcium levels, which can cause bone, kidney, muscle, gastrointestinal, and neuropsychiatric symptoms, including psychosis. Our report presents a unique case of an elderly woman who presented to the emergency department in an unconscious state with a working diagnosis of metabolic encephalopathy secondary to sepsis and urinary tract infection. Despite fluids and antibiotic treatment, the patient showed hallucinations. The acuteness of her psychotic episodes prompted the medical team to further investigate the cause of her hallucinations. Additional labs revealed HPT, which she had never been diagnosed with prior to the hospital admission. Our patient's novel clinical presentation revealed elevated PTH and normal calcium levels as the cause of her psychosis. We determined that the normal calcium levels were due to the patient's calcium loss secondary to acute kidney injury. Cinacalcet administration showed resolution of the patients' hallucinations, highlighting the importance of PTH screening even in normocalcemic patients. In this report, we present a rare clinical presentation of acute psychosis in the setting of undiagnosed normocalcemic HPT.