EFFECT OF REGIONAL FAT DISTRIBUTION AND PRADER-WILLI-SYNDROME ON PLASMA LEPTIN LEVELS

Variability in the relationship of plasma leptin level to body mass in dex (BMI) could be caused by imperfect estimation of adipose mass by t he BMI, heterogeneity in the pathogenesis of obesity in mixed subject groups, or variation in adipose tissue distribution. To investigate th ese possibilities, we examined the correlation of plasma leptin and BM I in an ethnically mixed population, a group of subjects with the Prad er-Willi syndrome, and a group of Japanese-American subjects who under went computerized tomographic measurement of adipose tissue cross-sect ional areas. Highly significant and indistinguishable linear relations hips between plasma leptin levels and BMI were found in the three stud y groups. Intersubject variability was also similar in the three group s and was reduced only when more accurate techniques for assessing adi pose tissue mass were substituted for the BMI. The plasma leptin level of Japanese-American subjects in the highest quartile of intraabdomin al fat area (mean area=154.5+/-38.4 cm(2)) was 12.5+/-8.7 ng/mL as com pared to 12.3+/-9.6 ng/mL (P=0.91) for subjects in the lowest quartile of intraabdominal fat area (mean area=51.2+/-20.1 cm(2), P <0.001 for difference in fat areas). We conclude that the circulating leptin lev el reflects total adipose tissue mass rather than a combination of adi pose tissue mass and distribution, and that the Prader-Willi syndrome does not alter the relationship between these two variables.