Dose-Response of Gonadal Steroids and Bone Turnover in Older Men

Inclusion Criteria: * Healthy men age 60 to 75 Exclusion Criteria: * History of significant cardiac, renal, pulmonary, hepatic, benign prostatic hyperplasia, or malignant disease, current alcohol or illicit drug abuse, or major psychiatric disorders. * Current diagnoses of disorders known to affect bone metabolism including hyperthyroidism, hyperparathyroidism, osteomalacia, or Paget's disease. * Current use of medications known to affect bone metabolism including estrogens, androgens, anti-estrogens, bisphosphonates, calcitonin, fluoride, oral or inhaled glucocorticoids, suppressive doses of thyroxine, lithium, pharmacological doses of vitamin D (greater than 2000 IU/day), or anti-convulsants. * Cognitive or intellectual impairment that precludes complete understanding of the study protocol. * History of deep vein thrombosis, pulmonary embolism, or clotting disorders. * Serum 25-hydroxyvitamin D \< 15 ng/mL * Serum parathyroid hormone (PTH) \< 10 or \> 65 pg/mL * Serum thyroid stimulating hormone (TSH) \< 0.5 or \> 5.0 U/L * Serum calcium \> 10.6 mg/dL * Serum creatinine \> 2 mg/dL * Serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) \> 2x the upper limit of normal * Serum bilirubin \> 2 mg/dL * Serum alkaline phosphatase \> 150 U/L * Plasma hemoglobin \< 11 gm/dL * Hematocrit \> 50 * Fracture within the last 6 months. * Serum testosterone level \< 270 or \> 1070 ng/dL * Serum prostate specific antigen (PSA) level \> 4 ug/L. * International Prostate…