To evaluate the phenotype and biochemical characteristics of boys referred for delayed puberty, to describe the frequency of associated co-morbidities and diseases, to evaluate the diagnostic criteria and the effect of testosterone treatment.

Delayed Puberty in Boys; Clinical and biochemical characteristics and effect of testosterone treatment, is a retrospective study in a large case series of Danish boys with delayed puberty. All boys were referred to the Department of Growth and Reproduction to be evaluated for delayed puberty. Medical history: Birth length, birth weight, gestational age at birth, medical history (including cryptorchidism and hypospadias), family history of delayed puberty in mother, father and possible siblings. Physical examination: Pubertal staging according to Tanners classification of boys, genitalia development (G1-G5), pubic hair development (PH1-PH6), axillary hair (yes/no), axillary sweat (yes/no), gynecomastia (yes/no), micropenis (yes/no), height, mother height, father height, target height, weight, BMI, bone age and predicted adult height. Blood sampling for measurement of hormone levels: Follicle stimulating hormone (FSH), luteinizing hormone (LH), estradiol, anti-mullerian hormone, sex hormone-binding globulin, testosterone, dehydroepiandrosterone-sulfate, androstenedione, inhibin A, inhibin B, growth hormone, insulin like growth factor-1 and insulin like growth factor binding protein-3. Gonadotropin-releasing hormone stimulation test for measurement of peak FSH and peak LH. Retrospective DNA analysis looking for common polymorphisms. If testosterone treatment were initiated, route of administration, dose and duration of treatment were registered.