Serum amylase in bulimia nervosa and purging disorder: differentiating the association with binge eating versus purging behavior.

OBJECTIVE: Elevated serum amylase levels in bulimia nervosa (BN), associated with increased salivary gland size and self-induced vomiting in some patients, provide a possible marker of symptom severity. The goal of this study was to assess whether serum hyperamylasemia in BN is more closely associated with binge eating episodes involving consumption of large amounts of food or with purging behavior.

METHOD: Participants included women with BN (n=26); women with "purging disorder" (PD), a subtype of EDNOS characterized by recurrent purging in the absence of objectively large binge eating episodes (n=14); and healthy non-eating disorder female controls (n=32). There were no significant differences in age or body mass index (BMI) across groups. The clinical groups reported similar frequency of self-induced vomiting behavior and were free of psychotropic medications. Serum samples were obtained after overnight fast and were assayed for alpha-amylase by enzymatic method.

RESULTS: Serum amylase levels were significantly elevated in BN (60.7±25.4 international units [IU]/liter, mean±sd) in comparison to PD (44.7±17.1 IU/L, p<.02) and to Controls (49.3±15.8, p<.05).

CONCLUSION: These findings provide evidence to suggest that it is recurrent binge eating involving large amounts of food, rather than self-induced vomiting, which contributes to elevated serum amylase values in BN.