Testosterone replacement therapy
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Physicians and scientists have suspected that the testes secrete a substance into the body that causes male secondary sexual characteristics for hundreds of years. However, testosterone was not synthesized until 1935 and it was not until the 1940's when scientists could accurately measure the amount of this hormone in the blood. Since then, scientists have been able to make correlations between the levels of testosterone in the body and men's health Scientists have long observed higher levels of testosterone to be associated with an increase in levels of Hematocrit (Hct). As a result, Testosterone Replacement Therapy (TRT) has been used to treat anemia associated with chronic diseases. In recent years, prescription sales for testosterone have sky rocketed due to new clinical uses such as androgen deficiency in older men. In fact, the rate of prescription for testosterone products has increased by over 170% in the previous five years. Long-term data shows that the level of testosterone in the male body begins to decrease at about the age of 30. As the life expectancy of the general population continues to increase, TRT may be a viable option for older men with low testosterone to increase the quality and duration of life. However, an increase in Hct continues to be a major side effect of TRT. New research is beginning to make clear the mechanism by which testosterone affects erythropoeisis. New research suggests TRT suppresses hepcidin and leads to an increase in the rate of iron (Fe) retention in red blood cells (RBCs). Inter-individual differences in the pharmacogenetic effects of TRT have been observed. In the future TRT could be genetically tailored based on the individuals DNA. In this case, the optimal dose of testosterone can be given to maximize benefits and reduce side effects. Here, the risks and benefits associated with TRT and a review of the updated Clinical Guidelines for its use will be presented. The effects of TRT on erythropoeisis will be investigated via a review of the literature. The main objective of this review is to provide a general understanding of TRT and a major side effect of its use, excessive erythropoeisis.