Does Trenbolone Cause Gynecomastia?
Tren is a common abbreviated name for trenbolone, which is a synthetic testosterone analogue. Testosterone is a hormone that plays a role in the male sexual development, and has a strong anabolic effect, meaning that it promotes muscle growth [1].
Technically, the term "Tren" refers to trenbolone acetate, which is a formulation of trenbolone, that has been developed for uses in farming. In some places, it is administered to cows via an implant in the ear. Due to its anabolic effect, it promotes growth of muscle in feedlot cattle, and improves feed efficiency [2].
However, tren is predominantly known these days for its uses in fitness. Indeed, it is used by athletes in strength sports aiming to increase their athletic performance and/or appearance by increasing the muscle mass [1]. However, it must be noted that this use of trenbolone acetate is illegal.
Adverse effects of Tren
In addition to being illegal, use of Tren has been proven to lead to adverse effects, some of which can be highly serious and potentially life-threatening. Approximately 90% of users experience some adverse effects. Most of these side effects are associated with disruption of the body's natural hormone balance, from which the body does not recover.
These adverse effects can include:
- local inflammation at the injection site, muscle adhesions and fibrosis, nerve damage, or in extreme cases, necrosis of the injection site [1];
- severe acne;
- masculinisation in women, and disruptions of the menstrual cycle (irregularity, severity, or complete loss of the cycle);
- negative impacts on fertility and sexual function [3];
- excessive body hair growth;
- hypertension (high blood pressure);
- cardiac arrhythmias.
Another significant adverse effect is gynecomastia.
What is Gynecomastia?
Gynecomastia is a condition characterised by enlargement of breasts in males. It is a non-cancerous (benign) growth that is a result of an imbalance between the hormones estrogen and testosterone. This leads to the proliferation of glandular tissue and deposition of fat into the breast, causing enlargement [4]. This may be caused by physiological changing such as puberty, but also endocrine diseases or drug use.
Gynecomastia can be treated, with the main objective of the treatment being cosmetic outcome, as gynecomastia is not dangerous (but can impact the individual's self-esteem and feelings of comfort). In some cases, it is expected to resolve on its own, such as during puberty [4].
Some medications, including anti-oestrogen drugs, can be used to block the effects of oestrogen and thus reduce the rate of breast growth. However, the effectiveness of these drugs can vary, and most are not approved for treatment of gynecomastia [4, 5, 6].
In severe cases, surgery may be the recommended approach, with the removal of the fat and glandular tissue either via liposuction or direct excision [7, 6].
Tren and Gynecomastia: Reviewing the Evidence
It is well established that anabolic steroids, including Tren, cause gynecomastia.
On a molecular level, this is a result of the body combatting the excess levels of testosterone that the body is introduced to on a course of Tren. The body attempts to eliminate the testosterone by converting it into estradiol, which is a type of oestrogen hormone. This then in turn affects the oestrogen signalling leading to gynecomastia.
For example, a study conducted on bodybuilders over a six-month period showed significant hormonal changes due to the administration of anabolic steroids, including:
- a 53% reduction in serum testosterone;
- suppression of luteinising hormone by 33% (in men, luteinising hormone causes the testicles to make testosterone);
- suppression of follicle-stimulating hormone by 13% (in men, the follicle-stimulating hormone facilitates the production of sperm).
Additionally, 45% of subjects in the study showed an increase in serum estradiol levels [8].
In another study, gynecomastia was detected in 4 of the 20 current users of anabolic steroids [7].
Summary: Tren and Gynecomastia
In conclusion, the use of anabolic steroids is strongly linked to the development of gynecomastia. The condition is primarily caused by the body's response to excess testosterone, which it attempts to eliminate by converting it into estradiol, leading to the enlargement of breast tissue in males.