In a case of suspected bulimia nervosa, what laboratory test result would most likely be present?

In cases of bulimia nervosa, individuals frequently engage in binge-eating followed by compensatory behaviors, such as purging through vomiting or excessive use of laxatives. These behaviors can lead to significant changes in electrolyte levels. Hypokalemia, or low potassium levels, is particularly associated with purging behaviors.

Vomiting causes the loss of gastric acids, which contains potassium, and can lead to a pronounced decline in serum potassium levels. This deficiency can result in serious complications, such as cardiac arrhythmias, muscle weakness, and other health issues, making it a common laboratory finding in individuals with bulimia nervosa.

While hyperkalemia (elevated potassium levels) and other electrolyte imbalances such as hyperchloremia (elevated chloride) or hypomagnesemia (low magnesium) can occur in different contexts, hypokalemia is the most characteristic laboratory abnormality directly linked with the purging practices often seen in bulimia nervosa.