Testosterone replacement therapy (TRT) is one of the most effective and common treatments for testosterone deficiency today. It is often prescribed, focusing only on the level of testosterone and the presence of patient complaints about a decrease in sexual function. Quite rarely, doctors additionally assess the level of estradiol and, as a consequence, the initial presence of a symptom of hyperestrogenism. One of the likely consequences of the appointment of TRT may be an excess of estradiol, the excess formation of which is associated with the enzyme aromatase, which converts testosterone into estradiol. Despite the availability of laboratory determination of the level of estradiol, the result may not always coincide with the clinical picture, one of the reasons is the difference in the methods for determining the level of estradiol in each laboratory, there is no single standard or «reference» today. This article describes the evolution of TRT, and also focuses on the variability of estradiol levels from laboratory to laboratory, and explains in detail why the assessment of estradiol over time should be carried out in only one laboratory. A systematic literature search was carried out in the databases Medline, Scopus, Web of Science and Elibrary, CyberLeninka.

The purpose of our review was the need to engage the attention of specialists to the problem of hyperestrogenism, the not always justified prescription of TRT in patients with obesity, hypogonadism and hyperestrogenism, as well as to the problem of laboratory diagnosis of hyperestrogenism, which is acute not only in our country, but all over the world.