Diagnosis of Antipsychotic Medication-Induced Severe Hypertriglyceridaemia by the Phenomenon of Pseudohyponatraemia and Successful Management With Variable-Rate Intravenous Insulin Infusion: A Case Report.

Background: Hypertriglyceridaemia (HTG) is a common condition resulting from genetic and environmental factors. Second-generation antipsychotic (SGA) medications are classically associated with the development of metabolic syndrome, of which HTG is a hallmark feature. Severe HTG is the third most common cause of acute pancreatitis, which has significant associated morbidity and mortality risk. It is therefore vital to rapidly and sustainably reduce triglyceride levels in patients presenting with severe HTG. Clinical Case: A 35-year-old gentleman with a history of psychiatric illness taking SGA medications (quetiapine and risperidone) presented to our hospital with apparent hyponatraemia. With associated hyperosmolality (302 mOsm/kg), a diagnosis of pseudohyponatraemia was made. Upon further investigation, pseudohyponatraemia was identified to be due to severe HTG (72.8 mmol/L) and hyperglycaemia (26.0 mmol/L). There were no clinical or biochemical features of pancreatitis. A variable-rate infusion of intravenous insulin was commenced. Over the 10-day admission a fall in triglycerides to 10.5 mmol/L was observed without any adverse events. Acute pancreatitis did not develop during the inpatient admission or during outpatient follow-up, and triglyceride levels have fallen substantially (3.2 mmol/L at 5 months) having been switched from quetiapine and risperidone to aripiprazole, an SGA associated with less metabolic disturbance. Conclusion: This case demonstrates the safe and effective management of SGA-associated severe HTG with intravenous insulin infusion to prevent acute pancreatitis. It also highlights the utility of pseudohyponatraemia as a useful way of detecting severe HTG and the impact of SGA medications in the aetiology of severe HTG.