One testosterone injection and endogenous testosterone production plummets

The effect of using synthetic testosterone on the testosterone your own body produces is bigger than doctors think, according to Swedish endocrinologists at the Karolinska Institutet. The Swedes wrote about the study they did for WADA in Substance Abuse and Rehabilitation.

The researchers gave 25 men aged between 27 and 43 single injections of 125, 250 or 500 mg testosterone-enanthate on three different occasions. In the weeks that followed the researchers analysed the blood of their subjects.

Four days after the injections the concentration of the hormones LH and FSH had gone down considerably. Because FSH and LH stimulate the production of testosterone by the testes, it meant that the body’s own production of testosterone declined strongly too. The figures below show the reduction in LH and FSH levels in percentages. The higher the bar, the greater the decrease.


Two weeks after the injection the body’s own production of testosterone was still on the low side. After the 500 mg injection the production of LH and FSH had declined even further, to 92 and 94 percent respectively. That meant that the subjects were only producing 8 percent of the usual amount of LH and 6 percent of the usual amount of FSH.


By the way: six weeks after the injection of 500 mg testosterone-enanthate the subjects’ own production of testosterone was still not fully restored.

The way in which the subjects’ hormonal balances reacted to the injections varied, as the figure below shows. You’re looking at the effect on the LH level of the single injection of 500 mg testosterone.


In some subjects the LH level declined almost immediately; in others this took longer to happen. And there was one subject whose hormonal recovery seemed to be very rapid.

“Our results indicate that testosterone has a more profound and sustained endocrine effect on the hypothalamic-pituitary-gonadal axis than was previously known”, the Swedes concluded. “Scientific proof of AAS-induced adverse side effects, together with the epidemiological data showing that the nonmedical use of AASs is a global health problem, implies that public efforts should be centered on primary prevention.”

These days pharmacological bodybuilders use gram doses of testosterone. People in bodybuilding circles think nothing of taking a gram a week for two months on the trot. If you are aware of this, after reading the Swedish study you might start to wonder whether too many steroids users are going to be paying too high a price for their activities.

Effects of different doses of testosterone on gonadotropins, 25-hydroxyvitamin D3, and blood lipids in healthy men


Division of Clinical Pharmacology, Department of Laboratory Medicine, Karolinska Institutet, Karolinska University Hospital, Stockholm, Sweden

Aims: To study the effect and time profile of different doses of testosterone enanthate on the blood lipid profile and gonadotropins.

Experimental design: Twenty-five healthy male volunteers aged 27–43 years were given 500 mg, 250 mg, and 125 mg of testosterone enanthate as single intramuscular doses of Testoviron® Depot. Luteinizing hormone (LH), follicle-stimulating hormone (FSH), blood lipid profile (total cholesterol, plasma [p-] low-density lipoprotein, p-high-density lipoprotein [HDL], p-apolipoprotein A1 [ApoA1], p-apolipoprotein B, p-triglycerides, p-lipoprotein(a), serum [s-] testosterone, and 25-hydroxyvitamin D3) were analyzed prior to, and 4 and 14 days after dosing. Testosterone and epitestosterone in urine (testosterone/epitestosterone ratio) were analyzed prior to each dose after a washout period of 6–8 weeks.

Results and discussion: All doses investigated suppressed the LH and FSH concentrations in serum. LH remained suppressed 6 weeks after the 500 mg dose. These results indicate that testosterone has a more profound endocrine effect on the hypothalamic–pituitary–gonadal axis than was previously thought. There was no alteration in 25-hydroxyvitamin D3 levels after testosterone administration compared to baseline levels. The 250 and 500 mg doses induced decreased concentrations of ApoA1 and HDL, whereas the lowest dose (125 mg) did not have any effect on the lipid profile.

Conclusion: The single doses of testosterone produced a dose-dependent increase in serum testosterone concentrations together with suppression of s-LH and s-FSH. Alterations in ApoA1 and HDL were observed after the two highest single doses. It is possible that long-time abuse of anabolic androgenic steroids will lead to alteration in vitamin D status. Knowledge and understanding of the side effects of anabolic androgenic steroids are important to the treatment and care of abusers of testosterone.

Subscribe to our Newsletter!

ironmagazine.com Newsletter

Unsubscribe at anytime,  no spam & we do not sell your info!

This will close in 0 seconds

IronMag Labs Andro Creams

This will close in 0 seconds

Muscle Gelz Heal

This will close in 0 seconds