Rhabdomyolysis due to rapid correction of sodium in a patient with hyponatremia secondary to water intoxication

Shekhda Kalyan Mansukhbhai; Michela Rossi; Karen Anthony

doi:10.1530/endoabs.82.WH3

Hyponatremia due to water intoxication is often associated with mental disorders like schizophrenia and psychosis. Patients usually present with headaches, seizures and altered consciousness. The mainstay treatment in these cases is fluid restriction. A 31-year-old man was brought to the hospital following a fall and disorientation. He had a history of Schizophrenia which had been well controlled on risperidone. A few weeks before this presentation, he drank about 20 litres of water a day. The CT scan of head was unremarkable. On examination, he was euvolemic. Blood results showed severe hypotonic hyponatremia with low urine osmolality and low urinary sodium. (Serum Sodium: 111 mmol/l [RR: 135-145 mmol/l], Serum Osmolality 229 mosmol/kg [RR: 275-295 mosmol/kg], Urine Osmolality 55 mmol/l, Urine Sodium <20 mmol/l) with normal TFT (TSH: 0.4 mu/l [RR: 0.3-4.2 mu/l]) and random cortisol levels (602 nmol/l [RR: 172-497 nmol/l]), and slightly raised Creatinine Kinase levels of 3356 iu/l. He was diagnosed with hyponatremia secondary to psychogenic polydipsia and fluid restriction was commenced. His sodium got corrected rapidly following fluid restriction, at the same time his Creatinine Kinase (CK) levels rose significantly (See Table 1). Though rhabdomyolysis is an under-recognised complication of water intoxication, it is usually mild. However, rapid correction of sodium can lead to significant deterioration in rhabdomyolysis. This patient demonstrates that rapid correction of sodium levels in patients with water intoxication can cause rhabdomyolysis. Therefore, sodium levels and strict fluid intake/output should be monitored closely in the early phase of treatment to prevent rhabdomyolysis. 5% dextrose solution with matched urine output can be used to prevent rapid correction of sodium in these patients as fluid restriction alone can be dangerous. Though the exact mechanism for this is still controversial, it is thought to be due to rapid shift in electrolytes and osmolality during rapid correction of sodium.

Table 1 Serum sodium and CK levels.
Date and time of blood test	Serum Sodium levels	Serum CK levels (RR: 39-308 iu/l)
09/10/2021, 12:32	111 mmol/l	3356 iu/l
10/10/2021, 00:55	128 mmol/l	-
10/10/2021, 13:09	130 mmol/l	-
11/10/2021, 07:36	130 mmol/l	-
12/10/2021, 15:33	133 mmol/l	131072 iu/l
13/10/2021, 09:58	137 mmol/l	103334 iu/l
14/10/2021, 10:34	136 mmol/l	55339 iu/l
15/10/2021, 11:13	137 mmol/l	19617 iu/l
18/10/2021, 12:14	138 mmol/l	1669 iu/l

Endocrine Abstracts

WH3