Background: Isolated premature thelarche (IPT) is characterised by precocious breast development without any other signs of puberty.
Objective and hypotheses: The aim of the study was to analyze hormonal activity of the pituitary ovarian axis in girls with IPT.
Method: 102 girls with IPT (Tanner stage 23), mean age 2±1.4 years (0.047 years), mean weight 12.3±4.3 kg, mean height 85.0±13.6 cm (45±31 percentile), mean BMI 16.4±1.7 (46.38±27.5 percentile). The concentration of inhibin B, estradiol, FSH, LH, prolactine, TSH, FT4, lipids and liver enzymes was estimated. Inhibin B was measured by ELISA (DSL, USA), the other hormones by LIA (DPC, USA). The patients were divided into two groups depending on the time of stating the enlargement of mammal glands: group 1 before finishing 1 year of age, group 2 after finishing 1 year of age.
Results: All of the patients had normal thyroid hormones levels. Oestradiol concentration was below estimation threshold in 88% of them. Mean inhibin B level was 6.3±10.6 pg/ml, LH 0.15±0.07 IU/l, FSH 4.2±2.7 IU/l, prolactine 15.1±12 ng/ml. No significant differences were observed in both groups of patients. There was a negative correlation between FSH and the age of patients, positive correlation between FSH and inhibin levels. There was also a positive correlation between estradiol and insulin but not inhibin B and insulin levels.
Conclusion: Inhibin B is produced by granulosa cells under the influence of FSH. The activity of this axis decelerates during first months of age. The synthesis of oestradiol and insulin in patients with IPT is mutually dependent.
18 Sep 2014 - 20 Sep 2014