W. Kiess et al., HIGH LEPTIN CONCENTRATIONS IN SERUM OF VERY OBESE CHILDREN ARE FURTHER STIMULATED BY DEXAMETHASONE, Hormone and Metabolic Research, 28(12), 1996, pp. 708-710
Serum leptin concentrations and the levels of ob mRNA in adipocytes in
obese humans are elevated. Hyperphagia and obesity are characteristic
s of hypercortisolism. We have therefore asked whether or not leptin l
evels were elevated in very obese children, and whether or not dexamet
hasone would increase leptin levels in obese children. A single dose d
examethasone suppression test was performed in ten obese chldren (5 gi
rls, 5 boys; age 6 to 16 yrs, mean 12 +/- 1, median 12 yrs) to rule ou
t hypercortisolism. Body mass index (BMI) in the ten children was calc
ulated to be 27-45 kg/m(2). Venous blood was sampled before dexamethas
one was given in the evening and at 9.00 a.m. the following morning. E
ndogenous cortisol production was suppressed in all patients. Leptin l
evels, as measured by a newly developed specific radioimmunoassay, wer
e 31.6 +/- 12.9 ug/l, range 19.2-59.9 ug/l before dexamethasone and 39
.9 +/- 16.5 ug/l, range 26.3-80.3 ug/l after dexamethasone in the obes
e children (ANOVA, p = 0.01). Simple regression analysis revealed that
serum levels correlated significantly with body mass index (r = 0.82,
p < 0.001). Non-obese children (BMI < 27 kg/m(2)) had leptin levels b
etween 0.1 and 33.3 ug/l, median 2.2 ug/l (N = 713). Girls (5.5 +/- 4.
6 ug/l) (N = 401) had significantly higher leptin levels than boys (1.
7 +/- 2.1 ug/l) (N = 312) (p < 0.0001). We conclude that 1) high serum
leptin concentrations are present in obese children. 2) A single dose
of dexamethasone significantly increases the high leptin serum levels
in these children. We hypothesize that glucocorticosteroids up-regula
te leptin levels in the human.