Diagnostic and treatment dilemmas of persistent chronic hypokalaemia in a patient with anorexia nervosa: a case report.

INTRODUCTION: Anorexia nervosa is an eating disorder that continues to have a devastating impact on the lives of both adolescents and adults worldwide. We present a case of persistent chronic hypokalaemia in a patient with anorexia nervosa.

CASE PRESENTATION: A 26-year-old Caucasian woman was admitted to our eating disorders unit under Section 2 of Mental Health Act (1983) with a body mass index of 13.5 kg/m2. On admission, biochemical tests highlighted moderate hypokalaemia (3.0 mmol/L). She was immediately put on two tablets of Sando-K® (potassium supplement; potassium bicarbonate and potassium chloride twice daily. An electrocardiogram showed signs of bradycardia with T-wave inversion in at least two chest leads. Throughout her admission, she exhibited a fluctuating potassium level (2.5 to 5.0 mmol/L). Once on the unit, she was put on Sando-K® (potassium supplement; potassium bicarbonate and potassium chloride) but her potassium still tended to drop. On one occasion when she became normokalaemic, supplementation was stopped and she was put on observations. After 24 hours of 1 to 1 observation by ward staff including fluid input and output monitoring as well as search of her bedroom, she was again found to be hypokalaemic in spite of no evidence to suggest laxative or diuretic abuse.

CONCLUSIONS: She kept reiterating to clinicians that her potassium depletion is hereditary, not associated with any purging behaviour and for that reason long-term administration of Sando-K® (potassium supplement; potassium bicarbonate and potassium chloride) tablet remained essential. Self-denial was continued until her planned discharge; however, positive behavioural change was recorded whilst her blood showed normokalaemia for a whole week until her discharge.