Vitamin D Treatment and Hypogonadism in Men

Hypogonadal men: Inclusion Criteria: * TT levels below 3.0 ng/ml (measured at the baseline visit and confirmed at study visit 1) * 25(OH)D levels below 30 ng/ml (measured at the baseline visit) * Male, age of ≥ 18 and \<70 years * Written informed consent before entered into study Exclusion Criteria: * \- Hypercalcemia defined as a serum calcium \> 2,7 mmol/L * Oral or transdermal testosterone supplementation in the last 2 months before entering the study * IM testosterone supplementation 6 months before entering the study * Regular intake of vitamin D supplements before study entry * Men with chronic diseases (such as diabetes mellitus, thyroid disease, endocrine disturbances in need of treatment (except hypogonadism), or diseases known to interfere with vitamin D intake or very sensitive to vitamin D intake (such as inflammatory disease with granuloma: sarcoidoses, tuberculosis, Mb Wegener, vasculitis, inflammatory bowel disease * Intake of medication influencing metabolic or endocrine parameters (insulin sensitizers, insulin, glucocorticoids,…) in the last 3 months before study entry * PSA \>4 ng/ml (or \>3 ng/ml in men at high risk for prostate cancer) (see state of the art) * Palpable prostate nodule or induration * Hematocrit \>50% * Untreated severe obstructive sleep apnea * Severe lower urinary tract symptoms * Uncontrolled or poorly controlled heart failure * A history of prostate cancer, breast cancer, orchidectomy, chromosomal disorders (e.g. Klinefelter Syndrome) Eugonadal men: Inclusion Criteria: * TT levels ≥3.0 ng/ml (measured at the baseline visit and confirmed at study visit 1) * 25(OH)D levels below 30 ng/ml (measured at the baseline visit) * Male, age of ≥ 18 and \<70 years * Written informed consent before entered into study Exclusion Criteria: * Hypercalcemia defined as a serum calcium \> 2,7 mmol/L * Oral or transdermal testosterone supplementation in the last 2 months before entering the study * IM testosterone supplementation 6 months before entering the study * Regular intake of vitamin D supplements before study entry * Men with chronic diseases (such as diabetes mellitus, endocrine disturbances in need of treatment (except hypogonadism), or diseases known to interfere with vitamin D intake or very sensitive to vitamin D intake (such as inflammatory disease with granuloma: sarcoidoses, tuberculosis, Mb Wegener, vasculitis, inflammatory bowel disease * Intake of medication influencing metabolic or endocrine parameters (insulin sensitizers, insulin, glucocorticoids,…) in the last 3 months before study entry * PSA \>4 ng/ml (or \>3 ng/ml in men at high risk for prostate cancer) (see state of the art) * Palpable prostate nodule or induration * Hematocrit \>50% * Untreated severe obstructive sleep apnea * Severe lower urinary tract symptoms * Uncontrolled or poorly controlled heart failure * A history of prostate cancer, breast cancer, orchidectomy, chromosomal disorders (e.g. Klinefelter)