Mesterolone (Proviron) and the kidneys: what is known about the load
Mesterolone, known by the name Proviron, has a reputation as a “gentle” androgen. But is that fair when it comes to the kidneys? The editorial team gathered data on the effect of anabolic steroids on the kidneys, examined the features of mesterolone, and explained how to correctly interpret kidney tests in people with large muscle mass.
What mesterolone is and how it is excreted
Mesterolone (trade name Proviron) is an oral androgen, a derivative of dihydrotestosterone with a methyl group at position 1α. It is not 17α-alkylated and does not aromatize, meaning it does not convert to estrogens. The drug was used in medicine to treat androgen deficiency in men.
The anabolic activity of mesterolone is low, so in the sports community it is usually regarded as an auxiliary substance. However, for assessing risks what matters is not reputation but pharmacology: mesterolone is a full androgen that acts through the androgen receptor.
Like other steroids, mesterolone is metabolized in the liver, and its metabolites in the form of glucuronides and sulfates are excreted mainly in the urine. The kidneys are thus the main organ of excretion, although this function in itself does not imply toxicity.
The editorial team did not find direct clinical studies of mesterolone’s effect on kidney function. Therefore, below we rely on data for anabolic androgenic steroids in general and note where we are talking about proven facts and where about hypotheses.
What is known about the kidneys and anabolic steroids
The best-known work on this topic is the case series by Herlitz et al. (2010), in which bodybuilders who used anabolic steroids for a long time were diagnosed with focal segmental glomerulosclerosis (FSGS) with pronounced proteinuria and reduced kidney function. Some patients improved after stopping steroids.
The authors discussed two mechanisms: adaptive hyperfiltration due to a significant increase in muscle mass and a possible direct toxic effect of androgens on glomerular cells. It is still unknown which of them prevails.
Cases of acute kidney injury in bodybuilders have also been described, in which anabolic steroids, dietary supplements, high-protein diets and intense exercise were combined (Almukhtar et al., 2015). Such observations do not prove a causal link with a specific substance, but they point to a risk group.
Reviews of the consequences of anabolic steroid use classify kidney damage as a possible, though less common, complication compared with cardiovascular and endocrine ones (Pope et al., 2014; Horwitz et al., 2019).
Are there features specific to mesterolone
Several properties of mesterolone can be singled out that theoretically make it “milder” on the kidneys compared with other steroids. The absence of aromatization means less fluid retention associated with estrogens. The absence of a 17α-methyl group reduces the risk of cholestasis, which in itself can cause kidney damage through elevated bilirubin.
Low anabolic activity means that mesterolone rarely causes rapid muscle mass gain. Therefore, the hyperfiltration mechanism associated with body mass is less pronounced.
However, the real situation is rarely limited to a single substance. In the sports community mesterolone is mostly used together with other androgens, and then the kidneys are affected by the whole set of factors: total androgenic effect, pressure, nutrition, supplements.
| Factor | Mesterolone alone | In combination with other AAS |
|---|---|---|
| Fluid retention | Unlikely (no aromatization) | Depends on other substances |
| Cholestasis and bilirubin | Unlikely | Higher risk with 17α-alkylated ones |
| Hyperfiltration due to muscle mass | Weakly expressed | Possible |
| Increased pressure | Little data | Described for AAS in general |
How to correctly interpret kidney tests in athletes
The basic indicator of kidney function is serum creatinine and the glomerular filtration rate estimated from it (eGFR). However, creatinine is produced in muscles, and in people with large muscle mass or those who take creatine it is naturally higher. This can create a false impression of kidney failure.
In such cases the doctor may additionally measure cystatin C — a marker that depends less on muscle mass. Calculating GFR from a combination of creatinine and cystatin C gives a more accurate estimate.
- Creatinine and eGFR — the basic assessment, adjusted for muscle mass.
- Cystatin C — a refinement in case of doubtful results.
- Urinalysis and the albumin/creatinine ratio — detecting proteinuria, an early sign of glomerular damage.
- Blood pressure — regular home measurement.
- Urea — interpreted taking dietary protein into account.
It is important to take tests not immediately after a hard workout and with normal hydration: dehydration and muscle damage can temporarily change the values.
The appearance of edema, foam in the urine, reduced urine volume, dark urine after training or a persistent increase in pressure is a reason to see a nephrologist.
How to reduce the load on the kidneys
For any person engaged in strength sports, especially while taking hormonal drugs, the editorial team highlights several general principles for protecting the kidneys.
Blood pressure control is the main one. Prolonged hypertension is one of the leading causes of chronic kidney disease, and androgens can contribute to its development.
Nonsteroidal anti-inflammatory drugs (ibuprofen, diclofenac), which athletes often take for joint pain, can harm the kidneys with regular use and dehydration. They should be used only when needed and in short courses.
Adequate fluid intake, moderation in protein when there are existing kidney problems, and avoidance of dubious supplements also reduce risks. People with chronic kidney disease may use any androgens only by a doctor’s decision.
Editorial conclusions
There are no direct studies of mesterolone’s effect on the kidneys. The absence of aromatization and 17α-methylation, as well as weak anabolic action, theoretically make it less burdensome than many other steroids.
At the same time, FSGS and acute kidney injury have been described for anabolic steroids in general, and in real life mesterolone is rarely used in isolation.
A correct assessment of kidney function in athletes requires taking muscle mass into account: cystatin C and a urine albumin test complement creatinine.
On this topic we also recommend our articles about mesterolone and the psyche, about the effect of anabolic steroids on blood pressure, and about how to read an athlete’s biochemical blood test.
References
- Herlitz LC, Markowitz GS, Farris AB, et al. Development of focal segmental glomerulosclerosis after anabolic steroid abuse. J Am Soc Nephrol. 2010;21(1):163–172.
- Almukhtar SE, Abbas AA, Muhealdeen DN, Hughson MD. Acute kidney injury associated with androgenic steroids and nutritional supplements in bodybuilders. Clin Kidney J. 2015;8(4):415–419.
- Pope HG Jr, Wood RI, Rogol A, et al. Adverse health consequences of performance-enhancing drugs: an Endocrine Society scientific statement. Endocr Rev. 2014;35(3):341–375.
- Horwitz H, Andersen JT, Dalhoff KP. Health consequences of androgenic anabolic steroid use. J Intern Med. 2019;285(3):333–340.
- Kicman AT. Pharmacology of anabolic steroids. Br J Pharmacol. 2008;154(3):502–521.
- Kidney Disease: Improving Global Outcomes (KDIGO) CKD Work Group. KDIGO 2012 clinical practice guideline for the evaluation and management of chronic kidney disease. Kidney Int Suppl. 2013;3(1):1–150.
Andriy Melnyk
A strength-sports coach and author of programs for beginner and intermediate levels. Writes about training planning.
