Electrolyte and other blood serum abnormalities in normal weight bulimia nervosa: evidence for sampling bias

Sampling bias due to research settings might be responsible for reported high prevalence rates of electrolyte and serum abnormalities in bulimia nervosa. The aim of this study was to investigate the prevalence of electrolyte and other serum abnormalities in bulimia nervosa patients with normal weight seeking treatment in a community mental health center.

Diagnostic evaluations and laboratory tests were done for a consecutive series of 31 patients meeting DSM-III-R criteria for bulimia nervosa.

The duration and clinical severity of the eating disorder were considerable and psychiatric comorbidity was high. None of the subjects showed electrolyte abnormalities. Hypomagnesemia was found in 9.7% and hypoalbuminemia in 6.4% of the population. The severity of the abnormalities was modest.

The results suggest that previous reports on electrolyte abnormalities in bulimia nervosa were affected by sampling bias. Based on the results, there is no indication to perform routinely laboratory studies in ambulatory patients with normal weight.