Long-term steroid use can leave lasting marks on young hearts

Jonas stands in front of the mirror in the changing room and rolls up his shirt. His abdominal muscles lie like hard tiles under his skin; his chest is well developed. For six years, he has been building his body with strength training and repeated periods of using anabolic steroids: synthetic variants of the male sex hormone testosterone that cause muscles to grow faster. At first, he took them for short courses and then for longer periods, where the breaks felt more like parentheses.

Along the way, the side-effects went from temporary to permanent: at first, he only felt a little restless and had trouble sleeping. This later developed into chest tightness. Then came fatigue that was unusual for a man in his mid-thirties and a body that a little too often let his girlfriend down in the bedroom. He considered making an appointment with his doctor, but the fear of having to explain his use of illegal drugs made him decide against it.

Jonas is a fictional case, but the course of events matches what endocrinologists at Odense University Hospital sometimes see in people who have used anabolic steroids for many years.

On that basis, a research group carried out a study that for the first time systematically casts light on a group that has otherwise been invisible in the healthcare system. The group is led by Jan Frystyk, Professor of Endocrinology at the University of Southern Denmark and Senior Physician at the Department of Endocrinology at Odense University Hospital and Caroline Kistorp, Professor at the University of Copenhagen and Senior Physician at the Endocrinology Clinic at Rigshospitalet. 

The study has been published in JAMA Network Open and shows, among other things, that the hearts of many users bear the marks of years of use.

“Our data suggest that, with long-term use of anabolic steroids, the heart muscle and coronary arteries really begin to be damaged,” says Jan Frystyk.

The ambition was to gain a better understanding of Danish users of anabolic steroids – a group he and his colleagues knew was under-illuminated and about which the healthcare system had only limited systematic knowledge. And that is precisely why they want to work with them more systematically.

From the clinic’s gut feeling to a new field of research

Interest in the steroid users emerged in the outpatient clinic. Jan Frystyk, now in his early sixties with decades of work as an endocrinologist behind him, was trained in a tradition in which the textbooks mainly dealt with classic hormone disorders. Over time, he noticed that the patient picture in the clinic was shifting. Among the familiar diagnoses, another group began to appear: relatively young patients with pronounced fatigue, failing sex drive, low mood and very low testosterone levels.

“We received referrals for men who lacked testosterone because they had been taking it for many years in connection with strength training. And as soon as they stopped taking it, they lacked it because their own production had ceased,” says Jan Frystyk.

Here he faced a patient population that did not fit the usual diagnoses and for which the healthcare system struggled to find a systematic approach. Many had a long history of anabolic steroid use behind them without being registered anywhere. They took care of work and family, trained diligently and only appeared in the system when their hormone balance or heart began to fail.

Researchers still do not know precisely how many Danes use anabolic steroids.

“Anti Doping Denmark estimates that up to 50,000 Danes have experience with fitness doping,” says Jan Frystyk.

“A large proportion of young men aged 15–25 consider it acceptable to use steroids in connection with strength training,” says Caroline Kistorp, referring to a report from the Danish Institute for Sports Studies from November 2024 adding that steroid users do not have a patient association like people with chronic obstructive pulmonary disease or diabetes. No organisation stands ready to speak on their behalf.

“That is an argument for seeing them as a group with the same claim to understanding and treatment as others, regardless of the fact that their route there has gone via illegal substances,” he says.

The clinical gut feeling – that a larger, overlooked group was knocking on the door – became the starting-point for the research programme of which the new study is the first part. It was the reason he built an interdisciplinary research group around the project together with Caroline Kistorp and colleagues from both departments and hired Laust Frisenberg Buhl as a PhD student.

How the researchers uncovered the hidden heart damage

Already as the research group was writing the protocol, Jan Frystyk and colleagues invited former steroid users to discuss how recruitment and examinations could take place in a way participants would feel safe with. The experience was that many users stayed away from the system out of fear of consequences and stigmatisation. To reach them, the group chose to recruit outside the hospitals and instead go through the forums in which the users themselves spend time.

“That’s why we recruited participants through websites that give steroid users a platform to exchange knowledge and experiences,” he explains.

In the clinical part of the study, they gathered just over 100 people who had taken anabolic steroids for varying periods. The group was examined according to a set programme with questionnaires, clinical interviews, laboratory measurements and advanced heart scans to assess both structure and function – and afterwards their data were compared with those of strength-training control subjects who had never used steroids.

The participants confidentially disclosed which preparations they used, in which doses and for how long – information that was recorded outside the ordinary medical record system to protect the users from having it entered into their files.

A critical break after five years

In their analysis, the researchers added together the number of years in which the users had actually used the preparations, regardless of whether the use had been continuous or periodic. Across the data, a clear pattern emerged:

A clear boundary appeared: those who had used steroids for more than five years in total most often had changes in the heart muscle, which became thickened and more stiff, corresponding to reduced diastolic function – and thus reduced ability to relax between heartbeats. In addition, there was an increased occurrence of calcification in the coronary arteries, while participants with a shorter total use more often lay closer to the control group.

When the researchers adjusted for classic cardiovascular risk factors such as blood pressure, smoking and cholesterol, they could not isolate a completely clean, independent effect of the steroids.

Even so, the picture remained clear to Frystyk: long-term use was clearly associated with a markedly higher incidence of both structural changes in the heart muscle and calcification in the coronary arteries – among recreational athletes who trained alongside an ordinary working life and were not part of elite sport.

“Even among those who had stopped, we only saw that the heart muscle could normalise again to some extent, while the calcifications in the coronary arteries seemed to remain,” he says.

The study thus challenged the widespread belief in the steroid-using community that the damage disappears when you take a break or stop.

One of the most thought-provoking observations was that even men in their thirties could already have measurable signs of calcification in the coronary arteries.

The study also showed that a markedly larger proportion of those who had taken anabolic steroids had high blood pressure and disturbed cholesterol levels compared with the control group. This underlines that the intake of steroids both leads to structural changes in the heart and is strongly associated with increased risk of developing cardiovascular disease.

The healthcare system faces a new reality

The results changed both the researchers’ view of the patient group and the way they meet them in the clinic. The focus earlier often lay on the hormonal consequences of steroid use, such as failing sex drive and persistent fatigue, but the heart now stands just as centrally in the assessment.

“Our results show that recreational athletes also pay a price. It is dangerous to take these preparations, even if you are not competing at a high level,” says Jan Frystyk.

For him, this means that doctors treating patients with many years of steroid use can no longer allow themselves only to focus on the hormones or simply correct low testosterone levels. They must also assess cardiovascular risk, examine for calcification and initiate targeted treatment of blood pressure and cholesterol when needed.

“When we meet patients with many years of steroid use and problems with erections and libido, we cannot settle for correcting the testosterone level. We must also examine whether they have calcifications and treat the heart, cholesterol and blood pressure so that we get a more coherent approach to the patient,” he says.

At the same time, the study points to a grey zone in healthcare. There are detailed treatment guidelines for most other hormonal disorders, whereas the guidelines do not yet describe long-term consequences after anabolic steroid use. Many general practitioners are therefore left alone with the assessment of what to do when a patient reports a long history of steroid use and has symptoms from both the hormone system and the heart.

The road to a new treatment option

The next step for Frystyk and his colleagues is to translate the new knowledge into more structured treatment courses. Together with Caroline Kistorp at Rigshospitalet, they are working on a clinical study that will systematically test possible treatment strategies for people with many years of steroid use who want to stop. The aim is to develop more standardised courses of treatment for patients who have hormonal changes and increased heart risk after long-term testosterone intake.

The researchers envisage assessment and treatment in specialised clinics, where fear of stigmatisation and sanctions weighs less heavily and where experiences are systematically fed back to the general practitioners, who often meet the patients first.

Jan Frystyk is fully aware that he and his colleagues are entering a field without ready-made guidelines to lean on. The patients have done something illegal but now face the health consequences – and in his view, that accentuates rather than reduces the need for help.

“If we can use our results to understand the damage better and give these people a more coherent treatment pathway, then in my eyes it is not just an opportunity but an obligation,” he says.