Testosterone

Clinical endocrinology · 2025

Researchers found that both testosterone enanthate and testosterone undecanoate effectively produced desired masculinizing effects in transgender men over one year. They observed no significant differences in health outcomes between the two treatments, although testosterone undecanoate was preferred due to requiring fewer injections.

• Both testosterone formulations led to similar masculinizing effects.
• No significant differences in health parameters were found between the two groups.
• Testosterone undecanoate was preferred for its longer dosing intervals.

The Journal of steroid biochemistry and molecular biology · 2024

Researchers observed that high doses of testosterone cypionate in male rats affected the function of salivary glands. While saliva flow remained unchanged, the treatment altered the composition of saliva and caused changes in the structure of the glands, potentially leading to oral health issues.

• Increased salivary secretion of total protein but reduced levels of amylase, calcium, phosphate, and potassium.
• Changes in the structure of the parotid and submandibular glands, indicating potential dysfunction.
• Higher levels of total oxidants and lipid damage in the glands, suggesting oxidative stress.

Annals of family medicine · 2023

Researchers observed that while testosterone therapy for gender-affirming care can lead to increased hemoglobin levels, severe cases of erythrocytosis are rare. Specifically, only 0.6% of participants experienced significant increases in hematocrit levels during the first 20 months of treatment. This suggests that routine frequent screening for erythrocytosis may not be necessary for all patients.

• 12.6% of participants had hematocrit levels above 50.4%.
• 1.0% of participants had hematocrit levels above 52%.
• Severe erythrocytosis (hematocrit >54%) occurred in only 0.6% of participants.

The Journal of urology · 2022

Researchers observed that both intramuscular testosterone cypionate and subcutaneous testosterone enanthate significantly increased testosterone levels in hypogonadal men. However, the subcutaneous method was associated with lower levels of estradiol and hematocrit, suggesting it may have a safer profile compared to the intramuscular option.

• Both treatments significantly increased testosterone levels.
• Subcutaneous testosterone enanthate led to lower estradiol and hematocrit levels.
• No significant increase in prostate-specific antigen was observed with either treatment.

Translational andrology and urology · 2016

Researchers observed that nandrolone, a steroid similar to testosterone, may have potential benefits for male health, particularly in building muscle and aiding joint healing after injuries. However, there is limited research on its use in humans, indicating a need for further studies.

• Nandrolone has a higher muscle-building effect compared to testosterone.
• It may help improve joint healing after injuries.
• More human studies are needed to confirm its benefits.

Asian journal of andrology · 2014

Researchers observed that the understanding and treatment of testosterone deficiency have evolved significantly over centuries, from ancient practices of castration to modern therapies involving testosterone replacement. They noted that early experiments laid the groundwork for current treatments, including injectable and transdermal options.

• Historical practices of castration were used for various purposes, including punishment and preserving singing voices.
• The discovery of testosterone in the 1930s led to the development of various treatment methods for testosterone deficiency.
• Modern therapies now include safer and more effective options like transdermal gels and long-acting injections.

American journal of physiology. Endocrinology and metabolism · 2001

Researchers found that increasing doses of testosterone in healthy young men led to greater increases in muscle mass and strength, with specific dose-dependent effects. However, they observed that different body functions responded differently to testosterone levels, indicating that not all processes require the same amount of testosterone for optimal performance.

• Higher testosterone doses resulted in greater increases in fat-free mass and muscle strength.
• Changes in muscle size and strength were closely linked to testosterone levels.
• Sexual function and cognitive abilities did not significantly change with varying testosterone doses.

The New England journal of medicine · 1996

Researchers found that high doses of testosterone can significantly increase muscle size and strength in normal men, especially when combined with exercise. Those receiving testosterone and participating in weight training saw the most substantial gains in muscle mass and strength compared to those who did not exercise.

• Testosterone increased muscle size in both arms and legs compared to placebo.
• Participants combining testosterone with exercise gained more fat-free mass and strength than those who did not exercise.
• Mood and behavior remained unchanged across all groups.

Journal of applied physiology (Bethesda, Md. : 1985) · 1989

Researchers found that administering testosterone enanthate to healthy men for 12 weeks led to a significant increase in muscle mass and muscle protein synthesis. Specifically, muscle mass increased by an average of 20%, and muscle protein synthesis rose by 27%. These findings suggest that testosterone plays a role in enhancing muscle growth.

• Muscle mass increased by 20% on average.
• Muscle protein synthesis increased by 27%.
• Total body potassium also increased significantly.

Annual review of medicine · 1984

Researchers observed that androgens, particularly testosterone injections, are primarily used to treat testosterone deficiency in men with specific hormonal conditions. They found that long-acting testosterone esters are effective for this purpose, while oral testosterone derivatives may be less effective but could be useful in certain cancer treatments.

• Testosterone injections are recommended for treating testosterone deficiency in men.
• Long-acting testosterone esters like testosterone enanthate or cypionate are preferred.
• Oral testosterone derivatives may have limited use in treating male hypogonadism.