Ketonuria may be associated with low serum amylase independent of body weight and glucose metabolism.

CONTEXT: Ketonuria, which reflects a preferential combustion of lipids relative to carbohydrates, is often observed in lean rather than obese people. Clinical studies have shown that individuals with diabetes and/or obesity predispose to have low serum amylase (LSA).

OBJECTIVE: To investigate the association between ketonuria and LSA.

METHODS: We examined ketonuria assessed by dipstick urinalysis and clinical parameters including serum amylase in 3638 Japanese people aged 25-79 years who underwent a health-screening checkup.

RESULTS: There was an inverse relationship between body mass index (BMI) and serum amylase. The lowest serum amylase was observed in obese subjects (BMI ≥ 25.0 kg/m2 ) with positive ketonuria. Logistic regression analysis showed that ketonuria was significantly associated with LSA (<50 IU/L), which was not altered by the adjustments for relevant confounders including age, sex, BMI, and HbA1c.

CONCLUSIONS: Current results suggest a relative unavailability of carbohydrates for energy production in individuals with LSA.