In this special issue of IJIR: Your Sexual Medicine Journal, topics covered include advancements in the evaluation and treatment of Testosterone Deficiency (TD). TD, formerly male hypogonadism, is defined as low serum testosterone combined with symptoms such as reduced libido, fatigue, obesity, depression, loss of bone density and muscle mass [1]. Causes of TD range from issues arising either from the testes themselves (primary hypogonadism) or the hypothalamic-pituitary axis (secondary hypogonadism) [2].

In their retrospective analysis, Gurayah et al. explores the relationship between secondary TD and elevated body mass index (BMI) [3]. They found that obese men and underweight men had higher incidence of TD compared with men with normal BMI. The authors suggested routine screening and individualized approach to patients suffering from secondary TD.

One treatment for TD is testosterone replacement or testosterone therapy (TTh) and guidelines for therapy are relatively recent [1]. Rostom et al. dives into detail on the history of TTh and how our current guidelines were formed [4]. Even with the current guidelines, there is still evolution regarding optimal dosing for the various formulations. El-Khatib et al. conducted a study to compare two regimens of intramuscular testosterone one of the most used formulations [5]. There is constant change of available formulations and alternatives to maximize patient satisfaction and minimize side effects [6]. The introduction and description of a novel oral TTh, Jatenzo® produced by Clarus Therapeutics (USA) and approved by the FDA in 2019 is covered by Patel et al. [7]. Jatenzo®’s effectiveness combined with its ease of administration has the potential to completely shift the TTh paradigm. Alternative treatments to TTh are also being explored with the investigation of Selective Androgen Receptor Modulators (SARMs) by Efimenko et al. [8]. The rationale is their ability to achieve many of the anabolic effects sought after with TTh while avoiding many of the side effects.

TTh has already been shown to have great benefit for those who suffer from TD [9]. However, there are multiple fronts on which improvements can be made from varying dosages to different routes of administration and alternatives to testosterone itself. This special issue covering TTh updates will hopefully serve as a calibration to motivate further research to optimize therapy.