Effect of waist circumference on reference intervals of liver-related enzyme tests in apparently healthy adult Mexican Americans, black and white Americans.

BACKGROUND: We used a more comprehensible and more physiologically valid indicator of obesity-related liver disease, waist circumference (WC), rather than BMI to study the effect of obesity on liver enzymes, easily measurable surrogates of liver disease. METHODS: WC, liver enzymes and pertinent demographic data were abstracted from NHANES III. After exclusion criteria were applied, we stratified the populations by sex and ethnicity and graphed the percentage of elevated enzymes per WC interval. RESULTS: There was a significant relationship between enzyme activity and WC (p<0.001 for ALT, p<0.01 for ALP, p<0.01 for AST, p=0.02 for GGT and p<0.05 for LD), and the relationship was stronger in females (p<0.002) and Mexican Americans (p<0.001). The enzyme-WC relationship is much weaker in non-Hispanic black females and males. CONCLUSION: As increases in liver enzyme activity can indicate potentially reversible liver disease, our graphs should be used by physicians to motivate obese, apparently healthy Mexican American and non-Hispanic white patients with elevated liver enzymes to reduce their WC.