How Much Can Testicles Shrink As a Side Effect of Testosterone Replacement Therapy (TRT)?

Reviewed by Garrett Kneese, MD, MPH

Family Medicine

Studies show that testicles may shrink by about 10% to 30% when using testosterone replacement therapy.

Explanation

When a person starts testosterone replacement therapy, the extra testosterone tells the body, “We have enough hormone now!” This causes the testicles to slow down and make less of their own testosterone. As a result, they can shrink in size. Research, like the study by Palacios and others, has looked at men using testosterone injections and found that the testicles can reduce in volume by around 10% to 30% compared to their original size. It is important to remember that this change can be different for everyone because factors such as the dosage and duration of the therapy play a big role. Some men may notice a small change while others may see a more noticeable decrease. If you have concerns about these side effects, it is always a good idea to talk with your doctor. They can help you understand what is normal and what might require a closer look.

(References)

Palacios A, McClure RD, Campfield A, Swerdloff RS. Effect of testosterone enanthate on testis size. J Urol. 1981 Jul;126(1):46-8. doi: 10.1016/s0022-5347(17)54372-4. PMID: 6788960.
Osterberg EC, Bernie AM, Ramasamy R. Risks of testosterone replacement therapy in men. Indian J Urol. 2014 Jan;30(1):2-7. doi: 10.4103/0970-1591.124197. PMID: 24497673; PMCID: PMC3897047.
Bassil N, Alkaade S, Morley JE. The benefits and risks of testosterone replacement therapy: a review. Ther Clin Risk Manag. 2009 Jun;5(3):427-48. doi: 10.2147/tcrm.s3025. Epub 2009 Jun 22. PMID: 19707253; PMCID: PMC2701485.
Grech A, Breck J, Heidelbaugh J. Adverse effects of testosterone replacement therapy: an update on the evidence and controversy. Ther Adv Drug Saf. 2014 Oct;5(5):190-200. doi: 10.1177/2042098614548680. PMID: 25360240; PMCID: PMC4212439.

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