Clinical Research Directory

Inclusion Criteria: Cases: * Male, aged 18 years or older. * Biochemically confirmed hypogonadism (total testosterone \< 300 ng/dL with at least one clinical symptom). * Regular follow-up at the endocrinology outpatient clinic. * Fluent in reading and understanding Turkish. * Signed informed consent. Controls: * Male, aged 18 years or older. * Diagnosed with diabetes, hypertension, or hypothyroidism under regular endocrinology follow-up. * Total testosterone ≥ 300 ng/dL. * Age-matched to a participant in the case group (±5 years). * Fluent in reading and understanding Turkish. * Signed informed consent. Exclusion Criteria: * Active psychiatric diagnosis (e.g., active psychosis, bipolar disorder). * Chronic inflammatory or rheumatological diseases affecting body composition (e.g., chronic kidney disease, IBD, rheumatoid arthritis, SLE, ankylosing spondylitis). * Uncontrolled co-existing endocrine conditions or severe complications (e.g., HbA1c \> 8.0%, diabetic neuropathy/nephropathy/retinopathy, non-euthyroid state). * Cognitive impairment or dementia precluding questionnaire completion. * Klinefelter syndrome. * Literacy limitations preventing completion of self-report measures. * Additional control exclusion: Diagnosis or clinical suspicion of hypogonadism.