Aromatase inhibition versus estradiol during 1 week

Inclusion Criteria:

• Informed consent obtained.
• Male subjects
• Age 18 - 40
• weight < 120 kg

Exclusion Criteria:

• Primary hypogonadism or secondary hypogonadism due to genetic causes (Kallman syndrome etc.), tumors, infiltrative diseases, infections, pituitary apoplexy, trauma, critical illness, chronic systemic illness or intentional.
• Treatment with insulin, corticoids, opiates (on a daily basis), androgen- or estrogen analogs or CYP2A6 substrates (Dexmedetomidine, Ifosfamide, Methoxsalen, Miconazole, Tranylcypromine).
• Impaired renal function defined as serum-creatine > 1.5 mg/dL
• Impaired liver function, defined as ALAT > 2.5 times upper limit of normal
• Clinically significant active cardiovascular disease including history of myocardial infarction within the past 6 months and/or heart failure (NYHA class III or IV) at the discretion of the investigator
• Cancer or any clinically significant disease or disorder, which in the investigator's opinion could interfere with the results of the trial
• Palpable prostate nodule or induration, PSA > 3 ng/mL, prostatism, untreated sleep apnee syndrome, erythrocytosis (hematocrit > 50%) or hyperviscosity.
• Known or suspected abuse of alcohol or narcotics
• Mental incapacity, unwillingness, or language barrier precluding adequate understanding or cooperation.