Recent perspectives on the age-related decline of testosterone

Abstract

A pivotal question is whether the age-related decline of testosterone should be viewed as hypogonadism, i.e. a deficiency of testosterone manifesting itself by the signs and symptoms of insufficient androgen action and, in the best case, reversed by testosterone treatment. There is no clear dividing line between normal and subnormal blood testosterone levels for establishing with certainty whether a man is hypogonadal or not. Rather, symptoms accumulate gradually with decreasing testosterone level, with these levels of testosterone differing between individuals, while within a subject not all symptoms of testosterone deficiency will manifest themselves at the same blood testosterone level. The diagnosis of late onset hypogonadism (LOH) and, certainly, the decision to provide androgen treatment must be made with caution, taking the specific increment of symptoms in relation to testosterone levels into account. The various symptoms of LOH might start at various concentrations of androgens. With a given plasma testosterone level, some complaints might be present and others not. This has also been confirmed in studies establishing symptom-specific thresholds of androgen levels. Symptoms of LOH do not manifest themselves at uniform threshold values of testosterone. Therefore, symptoms of testosterone deficiency are not uniformly and predictably related to blood testosterone values, which may lead to different diagnostic criteria for testosterone deficiency. So, the conclusion seems inevitable that the clinical manifestations of hypogonadism are multifactorially determined and that the diagnosis should not only depend on the measurement of testosterone but a proper assessment should comprise somatic and psychological aspects in addition to measurement of testosterone.