Androgens have important effects on multiple organ systems,which play critical roles in the regulation of a myriad of male sexual,somatic,and behavioral functions critical to lifelong health.Androgen deficiency is a multisystem syndrome,presenting with typical clinical features in association with a confirmed low serum testosterone level.The clinical presentation of androgen deficiency is modified by age and other patient-specific characteristics such as comorbidities,genetic,environmental,and sociocultural factors.