LAUSR

Objective Energy values for human milk are increasingly available clinically, though there are no standards for deriving these values. We compared published calorie methods using a common set of samples. Study design Ten human milk samples were measured for gross and digestible macronutrients using laboratory methods. Four calorie conversion factors were used: Atwater general (ATW-GEN); Atwater milk specific (ATW-MILK), human milk specific (HUM-MILK), and combustible conversions (COMBUST). Differences in derived calories were assessed using ANOVA. Results There was a significant difference ( P  < 0.001) in calorie values between methods. Gross macronutrients with COMBUST conversion factors produced the highest calorie values (19.4 ± 1.4 kcal/ounce) whereas digestible macronutrients with HUM-MILK conversion factors produced the lowest calorie values (16.3 ± 1.3 kcal/ounce). Mean difference between these values was 3.1 kcal/ounce (95% CI 2.5, 3.7). Conclusion Mean calorie difference of 3.1 kcal/ounce is clinically important for preterm infants, suggesting the need for standardization.