Declining testicular function in aging men

Abstract

Age-related decline in male sex hormones, particularly testosterone, is referred to as andropause. Like menopause, andropause is associated with physical and emotional changes that may be alleviated by hormone replacement therapy. Hypogonadism in aging men, as defined by a low free testosterone index, is due to declining testosterone production and increased sex hormone-binding globulin levels. About 30% of men in their 60s and more than 80% of men over 80 y may have a low free testosterone index. Diagnosis of hypogonadism is based on clinical symptoms (eg, decreased muscle mass, fractures, loss of libido) and laboratory determinations of serum testosterone-usually total testosterone levels. Measuring bioavailable testosterone, or free testosterone, is expensive and time-consuming, but may more accurately detect hypogonadism. Testosterone replacement therapy is generally safe in aging men and may improve libido, cognition, bone mineral density, body mass composition, and serum lipoproteins. Although contraindicated in men with prostate or breast cancer, testosterone replacement therapy in aging men warrants examination. Any of the available testosterone formulations can be used, but injectable forms have certain advantages, including excellent dose adjustability, lack of skin irritation, and low cost.