Relationship of serum alanine aminotransferase (ALT) to body mass index (BMI) in blood donors: the need to correct ALT for BMI in blood donor screening.

A study was carried out on 1,028 voluntary blood donors to see how body mass index (BMI) correlated with the serum alanine amino transferase (ALT) activity. The mean ALT (U/l) values were 19.35, 27.63, 40.79 and 54.41 in the four BMI categories of < or = 20, 20.1-25, 25.1-30 and > 30, respectively. This study showed that the mean serum ALT level of obese subjects (BMI > 30 kg/m2), compared with the two categories of normal subjects (i.e. BMI < or = 20 and BMI = 20.1-25 kg/m2), was increased by 2.8 and 1.96 times, respectively. Compared with the BMI group < or = 20, there was a gradual per cent increase in the mean serum ALT in the three different BMI groups: 20.1-25 (+133%), 25.1-30 (+196%) and > 30 kg/m2 (+280%). This indicates the need to correct ALT values for BMI for blood donor screening, instead of using actual ALT values.