Undernourishment as underlying cause of a teenager with extreme shifts in serum sodium (pp. 357-359)
Authors: Eva MM Hoytema van Konijnenburg, Jaap W Groothoff, Tessa de Baat, Felix HK Kreier, and Annemarie CM van Bellegem
Abstract: Undernourishment can be complicated with impaired kidney function and electrolyte disturbances. We hereby report the case of a 17-year-old girl with a history of brain surgery and epilepsy who was admitted to the hospital, because of generalized seizures. A hyponatraemia of 115 mmol/L, combined with a very low urine osmolality was present. In retrospect, the patient had a two-year history of progressive weight loss. Thereby, she started intentional vomiting and drinking excessive amounts of water. She was diagnosed with purging type anorexia nervosa with polydipsia. Over the following months, serum sodium shifted between 125 mmol/L and 150 mmol/L together with an increase in the frequency of seizures. The shifts in serum sodium are of multivariable cause: decreased protein intake combined with excessive water intake, partial nephrogenic diabetes insipidus and hypokalaemic tubulo-interstitial nephritis. Undernourishment plays a key role and a careful refeeding regimen should always be started.