Endocrine Abstracts

Patients with chronic schizophrenia and psychosis are prone to develop hyponatremia secondary to psychogenic polydipsia. Hyponatremia secondary to water intoxication and its rapid correction are linked with rhabdomyolysis, an under-recognized yet serious condition. We report a case of 31 year old male with schizophrenia on Risperidone, who was brought to the emergency due to an unwitnessed fall and confusion. Serum sodium was 111 mmol/l, urine osmolality 55 mosm/kg and urine sodium <20 mmol/l, serum osmolality 229 mosm/kg giving a picture of hypotonic hyponatremia. He was diagnosed with psychogenic polydipsia induced hyponatremia, having drinking 20 liters water per day. Due to rapid correction of sodium in next 24hrs, he was started on 5% dextrose (Table-1), which led to an improvement in his sodium levels, however creatine kinase(CK) levels started rising from baseline. Intravenous fluid were started with fluid restriction relaxed to 3 liters/ day. Risperidone held due to suspicion of rhabdomyolysis, that resulted in significant improvement of CK levels in next 3 days with stable sodium levels (Table-1). eGFR remained >90 throughout inpatient stay. The management of this case was complicated by development of rhabdomyolysis due to rapid sodium correction, highlighting the challenges associated with managing rhabdomyolysis with intravenous fluids that can result in worsening of hyponatremia, hence emphasizing the importance of close monitoring of sodium and measurement of CK in any patient who presents with severe hyponatremia, particularly in the presence of other risk factors for rhabdomyolysis and consideration of careful fluid administration strategies in relation to the relative onset and risk of over-correcting hyponatremia