Focus on BMI and subclinical hypothyroidism in adolescent girls first examined for amenorrhea or oligomenorrhea. The emerging role of polycystic ovary syndrome.

BACKGROUND

Primary amenorrhea, oligomenorrhea and secondary amenorrhea are diagnosed commonly during adolescence. Weight aberrations are associated with menstrual disorders. Autoimmune thyroiditis is frequent during adolescence. In this study, the commonest clinical and hormonal characteristics of amenorrhea or oligomenorrhea during adolescence were investigated.

METHODS

In this cross-sectional study, one hundred and thirty-eight consecutive young patients presenting with amenorrhea or oligomenorrhea referred to an adolescent endocrinology and gynecology university clinic were studied. Clinical examination and an abdominal ultrasound were performed. Testosterone, free-testosterone, estradiol (E2), follicle stimulating hormone (FSH), luteinizing hormone (LH), prolactin (PRL), dehydroepiandrosterone sulfate (DHEA-S), 17-OH progesterone, sex hormone binding globulin (SHBG), Δ4-androstenedione (Δ4A), free androgen index (FAI), insulin, glucose, thyroid stimulating hormone (TSH), total thyroxine (T4) (TT4), free T4 (FT4), total triiodothyronine (T3) (TT3) and free T3 (FT3). Concentrations were measured in blood samples.

RESULTS

Patients with primary and secondary amenorrhea presented more often with body mass index (BMI) <18.5 and BMI >25 kg/m2, respectively. BMI values correlated positively with insulin (r=0.742) and glucose (r=0.552) concentrations and negatively with glucose/insulin ratio values (r=-0.54); BMI values and insulin concentrations correlated positively with FAI values (r=0.629 and r=0.399, respectively). In all patients, BMI values correlated positively and negatively with free testosterone (r=0.249) and SHBG (r=-0.24) concentrations, respectively. In patients with secondary amenorrhea insulin concentrations correlated negatively with SHBG concentrations (r=-0.75). In patients with oligomenorrhea BMI values correlated positively with insulin (r=0.490) and TSH (r=0.325) concentrations, and negatively with SHBG (r=-0.33) concentrations. Seventy-two percent, 21% and 7% of patients presented with TSH concentrations <2.5 μIU/mL, between 2.5 μIU/mL, 4.5 μIU/mL and >4.5 μIU/mL (subclinical hypothyroidism), respectively. Following the definition of polycystic ovary syndrome (PCOS) according to either the National Institutes of Health (NIH) criteria or those proposed in the literature by Carmina and his team, patients presented mainly with oligomenorrhea or secondary amenorrhea. There was good agreement between patients with amenorrhea or oligomenorrhea fulfilling both of the PCOS definition criteria employed.

CONCLUSIONS

Among adolescent patients presenting with amenorrhea or oligomenorrhea for the first time those with low and high BMI present more often with primary and secondary amenorrhea, respectively. Obesity is involved in the development of hyperandrogenemia and hyperinsulinemia, particularly in PCOS patients. In these patients, subclinical hypothyroidism may be concealed and it should be investigated. These patients should be treated for abnormally increased or decreased BMI and be investigated for autoimmune thyroiditis.