Androgen deficiency in men

• The presentation of androgen deficiency may be subtle, therefore the diagnosis needs to be actively considered in the appropriate clinical context. • Klinefelter's syndrome is the most common cause of primary hypogonadism. Secondary hypogonadism is caused by hypothalamo-pituitary disorders such as pituitary tumours (especially prolactinoma) and iron overload disorders such as haemochromatosis and thalassaemia. • Serum total testosterone is the best method for assessing androgenic status. Calculated free testosterone values correlate well with actual free testosterone, but no published population-based reference ranges exist. Therefore calculated free testosterone levels must be interpreted with caution. • A low serum LH in the presence of low testosterone raises the possibility of secondary hypogonadism. Investigation may involve assessment of prolactin, anterior pituitary hormones and iron levels. • The benefits of treatment in testosterone-deficient men are well established. Clinical responses to treatment are important in determining the dose and frequency of testosterone replacement therapy. • The treatment of symptomatic ageing men with borderline serum testosterone levels remains controversial, with the benefits and risks of testosterone therapy largely unknown.