Who are the fair candidates for testosterone replacement therapy in patients with late-onset hypogonadism symptoms?

要旨

The main cause of late-onset hypogonadism (LOH) symptoms is decline of testosterone according to aging. Patients with LOH suffer from various signs including physical-, psychological-, and sexual-related symptoms. It is obvious that the basic treatment for LOH is testosterone replacement therapy (TRT). However, TRT is not effective for a few patients in clinical practice, and it is so important to find out the fair candidates for TRT in patients with LOH symptoms. The measurement of serum testosterone is indispensable for diagnosis of LOH. Total testosterone (TT) is widely accepted. However, it is known that TT levels are not correlated to severity of LOH symptoms determined by Aging Male’s Symptoms (AMS) score.1,2 Instead of TT, free testosterone (FT) levels have been adopted for the diagnosis of LOH in some area such as Japan.3 Recently, there are new optional suggestions that LOH bothersome symptoms themselves are much more important factors to start TRT for LOH, and testosterone levels might not be essential elements to apply TRT.4 In addition, several symptoms observed at LOH patients are also detected in other physical, psychological, and sexual conditions. Accordingly, it is not so easy to exclude the patients with the similar symptoms which organized from non-LOH conditions. Thus, it is very important and significant to reveal the true and pure LOH patients who will be expected to obtain satisfactory effects of TRT. Only measuring testosterone level is not enough. One of the most important data is how much testosterone level dropped and decreased compared with the patients’ highest level in their young ages. This dropped gap in each patient should affect their LOH symptoms. However, it is impossible to compare their testosterone levels in the younger age. One of the logical methods to identify the true and pure LOH patients may be “the diagnostic treatment”. The group of patients who are observed the improvement of LOH symptoms after TRT could be true LOH patients. This diagnostic treatment is considered one of the most reliable procedures to diagnose the true and pure LOH. Besides this diagnostic treatment method, other biomarkers are required for predictive factors of true LOH symptoms. Kondoh et al.5 indicated that a low value for testosterone/estradiol (T/E2) ratio may predict a reduced response to TRT in Japanese LOH patients. This report is so interesting and significant. According to their report, the measurement of T/E2 ratio is considered as a very useful, significant, and rather easy method. In addition, T/E2 ratio might be related to aromatase activity which could be another significant mechanism for LOH. As the authors described, this study by Kondoh et al.5 was based on only Japanese LOH patients’ data, and it has a rather small sample number. Although more investigations with large subjects and/or different population and race data should be required, the measurement of T/E2 ratio is an attractive new concept. All the researchers of LOH have to continue to investigate and detect appropriate marker(s) for promising efficacy of TRT for LOH. COMPETING INTERESTS The author declares no competing interests.

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