No evidence for leptin as an independent associate of blood pressure in childhood and juvenile obesity

We studied whether leptin is an independent associate of blood pressure in obese children and adolescence. 102 obese children (48 girls, age: 11.6 +/- 2.22 yr; body mass index [BMI]: 27.45 +/- 4.4; blood pressure: 122.5 +/- 1 1.1/64.7 +/- 10.6 mm Hg and 54 boys, age: 11.5 +/- 2.4 yr; BMI: 27.6 +/- 4. 4; blood pressure: 122.5 +/- 13.2/60.9 +/- 8.1 mm Hg [mean +/- SD]) were in vestigated. Serum leptin and insulin were measured by RIA; glucose was dete rmined enzymatically. Fat mass (FM) was calculated by bioelectrical impedan ce. Leptin was higher in girls than in boys (p=0.018) but no significant ge nder differences were found with respect to indices of adiposity and systol ic blood pressure (SBP). Children were divided into three groups, according to pubertal stage (Group 1: prepubertal, 32 boys/13 girls; Group 2: pubert al, 17 boys/25 girls; Group 3: late/post-pubertal, 5 boys/10 girls). SBP an d DBP correlated with body weight in the whole group (r=0.49, p<0.0001, and r=0.27, p=0.004). In Group 1, BMI showed the highest correlation to SBP; i n Group 3 no indices of adiposity were related to SBP. In no case was lepti n significantly associated with SBP after adjustment for adiposity. In Grou p 2, glucose was significantly associated with SBP after adjustment for bod y weight. In Group 3, however, no correlations were found between SBP, DBP and metabolic characteristics, perhaps due to small sample size. Stepwise m ultiple regression revealed that body weight and glucose contributed to the variation in SBP in the whole group (R-2=0.31, p<0.0001). Insulin accounte d for almost 8% of the variation in DBP (R-2=0.08, p=0.0034). Body weight c ontributed significantly to SBP in boys (R-2=0.39, p<0.0001) and girls (R-2 =0.24, p< 0.001). The results imply that body weight contributes independen tly to the variation in blood pressure. Glucose and insulin contribute to m ean blood pressure to some extent, but our data do not support the assumpti on that leptin per se serves as an independent predictor of blood pressure in obese children and adolescents.