Table 1 Inclusion and exclusion criteria

Secondary amenorrhea for ≥ 6 months

Pregnancy

Negative progestin test with oral dydrogesterone 10 mg twice a day for ten days

Hypothyroidism

Together with at least one of the following:

Acne, hirsutism

- Excessive exercise group: Exercising at least 10 h per week, which included any type of exercise (dancing, aerobics, biking, etc.) or running at least 30 miles per week

Psychiatric diseases using DSM IV criteria

- Stress group:

History of emotionally stressful events preceding the onset of amenorrhea included problems within the family, at school, at work or of psychosocial stress

Eating disorders according to the ICD-10 criteria

BMI < 18.5 kg/m² and BMI > 30.0 kg/m²