Effect of weight‐regulating practices on potassium level in patients with anorexia or bulimia nervosa

Abstract

Objective: The authors evaluated retrospectively data from 397 patients with anorexia (AN) and bulimia nervosa(BN). Method: Patients were divided into six pre-defined and symptom-related subgroups and their hypokalemia frequencies compared. The correlation between potassium level and diseaserelated patterns was assessed. Results: The two purging type AN groups were at greatest risk of hypokalemia. Vomiting frequency, body mass index (BMI) and laxative dosage had an effect on potassium levels within the overall group but only accounted for 19% of the variance of potassium level. Effects could not be proved for fasting, sport and disease duration. Discussion: Patients with anorexia or bulimia nervosa are very heterogeneous due to the considerable range of potential weightregulating measures. Taking this heterogeneity into consideration by dividing patients into diagnostic subgroups and considering their symptomatology thus considerably aids the estimation of hypokalemia risk when treating eating disorders.

Extreme anorexia nervosa: medical findings, outcomes, and inferences from a retrospective cohort

“…When examined by eating disorder sub-type, patients with AN-BP had, not surprisingly, statistically significant lower sodium and potassium levels on admission. The hyperaldosteronism resulting from the dehydration of purging along with loss of potassium and other electrolytes in emesis, stool, and urine contribute to hypokalemia [32,33]. The ability to correct hypokalemia is improved with down-regulation of aldosterone secretion, which can be accomplished with intravascular volume repletion; hence the large number of patients that received IV fluids in the treatment of their hypokalemia.…”

Electrolyte and acid‐base abnormalities associated with purging behaviors

“…Self‐induced vomiting, laxative abuse and diuretic abuse all result in the abnormal loss of potassium‐containing fluids. Of note, hypokalemia is generally not noted as a component of restricting anorexia nervosa . Therefore, the finding of hypokalemia in such a patient should raise suspicion of concomitant purging behaviors.…”

“…Of note, hypokalemia is generally not noted as a component of restricting anorexia nervosa. 8 Therefore, the finding of hypokalemia in such a patient should raise suspicion of concomitant purging behaviors. However, as will be more extensively discussed in the "sister" article on bulimia nervosa in this issue, there is an additional important cause of hypokalemia in patients with bulimia nervosa related to the adrenal gland's aldosterone secreting system.…”

Effective medical treatment strategies to help cessation of purging behaviors

“…However, given the lack of the aforementioned intrinsic renal tubular transport abnormalities, these patients were categorized as having secondary or “Pseudo‐Bartter syndrome.” Patients with eating disorders who chronically abuse laxatives and diuretics or engage in daily vomiting, fall into the category of Pseudo‐Bartter syndrome as they exhibit biochemical abnormalities of hypokalemia, hypochloremia, and metabolic alkalosis; however, their pathophysiology is not due to aforementioned impaired electron transport channels of Bartter syndrome but rather to appropriately increased production of aldosterone as a natural protective response to chronic volume depletion in an attempt to prevent hypotension and syncope. The prevalence of hypokalemia seen in the eating disorder population who purge by self‐induced vomiting or abuse laxatives or diuretics has been validated and reported to be up to 20% of patients . However, in contrast to Bartter syndrome, since Pseudo‐Bartter syndrome lacks inherent pathology in the renal tubule, the urinary chloride is normal, and Pseudo‐Bartter syndrome is fully reversible once the causative purging behavior has been discontinued and volume status normalized.…”

“…The prevalence of hypokalemia seen in the eating disorder population who purge by self-induced vomiting or abuse laxatives or diuretics has been validated and reported to be up to 20% of patients. 21,22 However, in contrast to Bartter syndrome, since Pseudo-Bartter syndrome lacks inherent pathology in the renal tubule, the urinary chloride is normal, and Pseudo-Bartter syndrome is fully reversible once the causative purging behavior has been discontinued and volume status normalized.…”