OBJECTIVESTo investigate whether the association between low birth weight and increased risk of developing premature adrenarche, adrenal hyperandrogenism, hyperinsulinism and insulin resistance is apparent in prepubertal girls born small for gestational age (SGA) and analyze when adrenarche occurs in SGA infants and normal birth weight girls.

METHODSThe study was performed in 39 prepubertal SGA girls with a mean age of 7.4 +/- 1.7 years and 42 prepubertal appropriate for gestational age (AGA) girls with a mean age of 7.4 +/- 1.7 years served as controls. All children were born at term and were prepubertal. Detailed physical examination was performed for all the children after 12 h of overnight fasting. Blood samples were taken for the measurement of fasting glucose (FPG), insulin (FIns), dehydroepiandrosterone sulfate (DHEAS), cortisol and estradiol concentrations. Insulin sensitivity was assessed by insulin sensitivity index [IAI = log(e) (FPG x FIns)].

RESULTThere was no premature adrenarche in SGA and AGA groups. Birth weight was significantly lower in SGA group (P < 0.001). Gestational age was similar in both groups. At the time of the study, the ages, body mass index (BMI), fasting glucose, cortisol and estradiol did not significantly differ between the two groups. But body height and weight were significantly lower in the SGA group (P < 0.05 for both). The fasting plasma insulin in the SGA group was higher than that in AGA group (common logarithmic transformation: 1.076 +/- 0.041 vs. 1.050 +/- 0.051, P < 0.05). The insulin sensitivity index was not significantly different between the two groups (-4.0165 +/- 0.1761 vs. -3.9768 +/- 0.2314). The serum DHEAS was significantly higher in SGA children than in AGA children (common logarithmic transformation: 2.637 +/- 0.271 vs. 2.514 +/- 0.250, P < 0.05). From about age 7 the concentration of DHEAS had a gradual rise in AGA children. The time of DHEAS rise tended to be earlier in SGA children compared with AGA children.

CONCLUSIONSAdrenarche commences at approximately 7 years of age in AGA girls. The time of adrenarche tended to be earlier in SGA girls compared with AGA girls. There were adrenal hyperandrogenism and hyperinsulinism in prepubertal girls born small for gestational age. But there was no insulin resistance as assessed by insulin sensitivity index.