Thousands of men undergoing testosterone replacement therapy (TRT) may face an elevated risk of a dangerous heart rhythm problem that can lead to stroke, according to a warning from American scientists. Researchers found that testosterone therapy could trigger atrial fibrillation, a condition causing an irregular heartbeat, if hormone levels become abnormally high or fluctuate significantly.
Atrial fibrillation can lead to heart failure and has been linked to deadly strokes. The discovery was made by scientists at the Kansas City Veterans Affairs Medical Centre in the US after reviewing existing studies that connected TRT to the heart condition.
Testosterone replacement therapy is designed to supplement testosterone in men who do not produce enough of the hormone, a condition known as hypogonadism. While testosterone levels naturally decline with age, clinical deficiency affects only an estimated two to five percent of men. Low levels can cause fatigue, mood disturbances, concentration difficulties, and reduced libido.
In recent years, however, TRT has gained popularity among men without a diagnosed deficiency, with claims that it can enhance energy and improve exercise performance. This trend has led some men to seek private treatments, which experts have cautioned against due to potential side effects like weight gain and prostate enlargement.
Personalized Treatment May Be Key
The new research indicates that men with both very high and abnormally low testosterone levels face a greater risk of developing atrial fibrillation. Men with levels within the typical normal range appear to be at the lowest risk. Scientists suggest that TRT may require individualization for each patient.
"Both too little and too much testosterone appear to raise the risk of atrial fibrillation... which means the dose and the target level matter," said Rajat Barua, chief of interventional cardiology at Kansas City VA Medical Centre and a co-author of the study. "What the review argues is that treatment should be individualised and monitored."
Understanding TRT Delivery Methods
Various methods are used to administer TRT, some of which can cause greater fluctuations in testosterone levels than others. Testosterone gel, applied to the skin daily, allows for gradual absorption. In contrast, injections administered every few weeks can initially release a large dose, leading to sharp increases in levels that then gradually decline before the next dose, creating significant swings.
Longer-acting injections, given every 10 to 14 weeks, provide steadier testosterone levels over extended periods. Researchers suggested that men at increased risk of heart rhythm problems might benefit from these more gradual delivery methods.
Assessing Patient Risk Factors
Before initiating TRT, doctors could assess patients for risk factors associated with atrial fibrillation, such as obesity, sleep apnea, high blood pressure, and alcohol use, the authors suggested. Regular monitoring of heart rhythm and blood pressure is also recommended to ensure the safety of the treatment.
The authors emphasized that their conclusions are based on a review of existing evidence and are open to interpretation. Natural testosterone decline with age, occurring at about one to two percent after age 30, does not automatically signify hypogonadism or the need for TRT. It is estimated that thousands of men, some without a deficiency, have received TRT through private clinics.