Explained: Testosterone deficiency and the safety of replacement therapy
Testosterone replacement therapy is the standard treatment for hypogonadism, which can cause sexual dysfunction, weakening of bones and muscles, and reduced quality of life.
In the 17 trials, 1,750 participants received testosterone and 1,681 were given a placebo. (Getty Images)
Hypogonadism is a condition caused by the deficiency of the male sex hormone, testosterone, and a new study in Lancet Health Longevity looks at the short- to medium-term safety of testosterone treatment. Analysis of data from more than 3,400 patients with hypogonadism from 17 clinical trials found little evidence that testosterone treatment increases the risk of cardiovascular events such as arrhythmia, heart attack, and stroke, in the short to medium terms.
Testosterone replacement therapy is the standard treatment for hypogonadism, which can cause sexual dysfunction, weakening of bones and muscles, and reduced quality of life. Risk factors include ageing (as testosterone levels decline with age), obesity and diabetes. Contacted via email, Dr Channa Jayasena, Reader in Reproductive Endocrinology, Imperial College London and study author, said that worldwide, 2% of men aged over 40 are affected, and this is growing as the population gets older.
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Despite being widely used, the cardiovascular safety of testosterone treatment had so far remained unclear due to inconsistent findings. Most previous clinical studies relied on aggregate data, rather than individual participant data and have not published details of individual adverse events.
“Prescribing of testosterone for hypogonadism is increasing globally, but conflicting messages about its safety may have led to many patients not receiving the treatment. Ongoing studies should help to determine the longer-term safety of testosterone but, in the meantime, our results provide much-needed reassurance about its short-to-medium term safety. Our findings could have important implications for the treatment of men with hypogonadism worldwide,” lead author Jemma Hudson from the University of Aberdeen said in the report.
Funded by the UK National Institute for Health Research Health Technology Assessment Programme, the study identified 35 eligible clinical trials published since 1992, of which 17 provided individual participant data. None of the studies were from India, Dr Jayasena said.
In the 17 trials, 1,750 participants received testosterone and 1,681 were given a placebo. The average length of testosterone treatment was 9.5 months. The rate of cardiovascular events was not significantly higher for participants receiving testosterone treatment (7.5%) compared to placebo (7.2%). Fewer deaths were reported during testosterone treatment (0.4%) than in the placebo group (0.8%]), but these numbers were too small to establish whether testosterone reduced mortality risk, according to the study authors.
The researchers found that testosterone significantly reduced serum total cholesterol, HDL, and triglycerides compared with placebo.
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However, there were no significant differences in LDL, blood pressure, glycaemic parameters, diabetes incidence, and prostate adverse outcomes between the testosterone and placebo groups, according to the report.
The authors have acknowledged some limitations to their study. There was little available data evaluating the cardiovascular safety of testosterone treatment beyond 12 months, and the very small number of deaths recorded during testosterone trials hampered the authors’ ability to analyse why they occurred. However, the longer-term safety of testosterone treatment is currently being investigated in another clinical trial, Dr Jayasena said.
Anuradha Mascarenhas is a Senior Editor at The Indian Express, based in Pune. With a career spanning three decades, she is one of the most respected voices in Indian journalism regarding healthcare, science and environment and research developments. She also takes a keen interest in covering women's issues .
Professional Background
Education: A gold medalist in Communication and Journalism from Savitribai Phule Pune University and a Master’s degree in Literature.
Author: She authored the biography At The Wheel Of Research, which chronicles the life and work of Dr. Soumya Swaminathan, the former Chief Scientist at the WHO.
Key Focus: She combines scientific accuracy with storytelling, translating complex medical research into compelling public and human-interest narratives.
Awards and Recognition
Anuradha has won several awards including the Press Council of India's national award for excellence in journalism under the gender based reporting category in 2019 and the Laadli Media award (gender sensitivity -2024). A recipient of the Lokmat journalism award (gender category-2022), she was also shortlisted for the RedInk awards for excellence in journalism-2021. Her debut book At The Wheel Of Research, an exclusive biography of Dr Soumya Swaminathan the inaugural chief scientist of World Health Organisation was also nominated in the Popular Choice Category of JK Paper AUTHER awards. She has also secured competitive fellowships including the Laadli Media Fellowship (2022), the Survivors Against TB – New Research in TB Media Fellowship (2023) and is part of the prestigious 2025 India Cohort of the WomenLift Health Leadership Journey.”
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Signature Beat: Health, Science & Women in Leadership
Anuradha is known for her COVID-19 reportage, where she was one of the first journalists to provide detailed insights into the Covishield and Covaxin trials. She has a dedicated interest in gender diversity in health and science, often profiling women researchers who are breaking the "leaky pipeline" in STEM fields. Her writing style is scrupulous, often featuring interviews with top-tier scientists and health experts from various institutions.
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