Testosterone influences kidney function through multiple pathways, and the direction of that influence depends heavily on dose, context, and how you measure it. The hormone can raise blood pressure, promote sodium retention, and activate inflammatory signals in injured kidneys. Yet low testosterone is also linked to worse kidney outcomes, and replacement therapy in men with genuine deficiency appears to stabilize or even improve filtration rates over time. The relationship is not a simple “good or bad” story, and one of the biggest practical complications is that testosterone changes the very lab values doctors use to assess kidney health.
How Testosterone Reaches the Kidneys
The kidneys are not bystanders in the body’s hormonal environment. Androgen receptors are present in human kidney tissue, meaning testosterone can act directly on kidney cells rather than influencing them only through systemic effects like blood pressure changes.1PubMed. Androgen receptor-mediated regulation of the alpha-subunit of the epithelial sodium channel in human kidney Through those receptors, testosterone promotes the reabsorption of sodium and water in the kidney’s tubules and activates vasoconstrictor systems, including the renin-angiotensin system and endothelin, both of which tighten blood vessels within the kidney and raise blood pressure.2American Journal of Physiology-Renal Physiology. Testosterone supplementation in aging men and women: possible impact on cardiovascular-renal disease These mechanisms help explain a long-observed clinical pattern: chronic kidney disease progresses faster in men than in women, even though women actually have a higher overall prevalence of CKD.3PubMed Central. Sex and Gender Differences in Chronic Kidney Disease-Explained by the Brenner-Luyckx Concept of Hyperfiltration
Animal studies add more detail. When researchers induced kidney obstruction in rats, males and testosterone-treated females showed significantly more inflammation, scarring, and cell death in the kidneys compared to castrated males and untreated females. The testosterone-exposed kidneys produced more of the inflammatory molecule TNF-alpha and showed greater tubulointerstitial fibrosis, which is the type of scarring that progressively destroys kidney tissue.4PubMed. Testosterone exacerbates obstructive renal injury by stimulating TNF-alpha production and increasing proapoptotic and profibrotic signaling The takeaway from this line of research is that when kidneys are already under stress, testosterone can amplify the damage. In a healthy kidney, these effects may be manageable. In a kidney dealing with obstruction, inflammation, or disease, they tilt the balance toward worse outcomes.
The Creatinine Trap
Before discussing what testosterone therapy does to actual kidney function, it is worth understanding a measurement problem that trips up both patients and clinicians. The most common blood test for kidney health is serum creatinine, a waste product from muscle metabolism. Doctors plug creatinine into formulas to estimate your glomerular filtration rate (eGFR), which tells them how efficiently your kidneys filter blood. Higher creatinine generally means lower eGFR, which suggests worse kidney function.
Here is the catch: testosterone builds muscle. More muscle produces more creatinine, even if your kidneys are working perfectly well. A study examining men on testosterone therapy found that the correlation between creatinine and cystatin C (an alternative kidney biomarker that is not affected by muscle mass) varied dramatically depending on body fat percentage. In lean men with very low body fat, the two markers barely correlated at all, meaning creatinine was telling a very different story than cystatin C. As body fat increased, the markers aligned more closely.5PubMed Central. Creatinine and Cystatin C: A Measure of Renal Function in Men With Testosterone-Induced Muscle Hypertrophy For a muscular man on testosterone, a creatinine-based eGFR can make his kidneys look significantly worse than they actually are.
This matters in practice because a doctor seeing a dropping eGFR might order additional testing, refer to nephrology, or adjust medications, all based on an artifact of muscle gain rather than genuine kidney decline. If you are on testosterone therapy and your creatinine ticks upward, asking about cystatin C testing is reasonable. It gives a second data point that is not distorted by changes in body composition.
Testosterone Replacement Therapy and Kidney Function
For men with genuinely low testosterone (hypogonadism), the observational evidence on kidney function is surprisingly encouraging. An eight-year cohort study followed hypogonadal men, comparing those who received testosterone therapy against those who did not. The treated group saw their eGFR rise from about 87 to 98 mL/min, while the untreated group’s eGFR declined from about 92 to 87 mL/min over the same period.6PubMed Central. The impact of long-term Testosterone Therapy (TTh) in renal function (RF) among hypogonadal men: An observational cohort study A separate prospective controlled study reported similar trends: men on testosterone had decreasing creatinine, falling uric acid, and rising eGFR (from roughly 87 to 99 mL/min), while the untreated comparison group drifted in the opposite direction.7Current Trends in Internal Medicine. Long-Term Testosterone Treatment Improves Fatty Liver and Kidney Function with Safe Outcomes on Cardio-, Metabolic and Prostate Health in Men with Hypogonadism
These are observational studies, not randomized controlled trials, so they come with caveats. Men who choose or are selected for testosterone therapy may differ from those who are not in ways the researchers did not fully account for. Still, the consistency of the direction across studies is worth noting. The likely explanation is that testosterone replacement addresses the downstream harms of hypogonadism itself, including metabolic syndrome, insulin resistance, obesity, and chronic inflammation, all of which independently damage kidneys. By correcting the hormonal deficiency, the metabolic environment improves and the kidneys benefit indirectly.
Low Testosterone and Kidney Disease Feed Each Other
The relationship between testosterone and kidney disease runs both ways. Advanced kidney disease, especially in men on dialysis, frequently causes testosterone levels to plummet. In a study of over 600 male dialysis patients, roughly half had total testosterone below 300 ng/dL, which is the standard threshold for deficiency. Men in the lowest testosterone quartile had more than double the mortality risk compared to those in a moderate range, after adjusting for other clinical factors.8PubMed Central. Association between Testosterone and Mortality Risk among U.S. Males Receiving Dialysis Broadly, low testosterone in CKD patients is tied to higher rates of illness and death.9PubMed Central. Testosterone deficiency and chronic kidney disease
One of the more tangible consequences is anemia, which is already common in kidney disease because the kidneys produce less erythropoietin, the hormone that stimulates red blood cell production. Low testosterone compounds this problem. A study of men with CKD found that hypogonadism was an additional and independent cause of anemia and also reduced the effectiveness of erythropoietin-stimulating agents, the medications used to treat kidney-related anemia.10PubMed. Testosterone deficiency is a cause of anaemia and reduced responsiveness to erythropoiesis-stimulating agents in men with chronic kidney disease The hope was that replacing testosterone in these men would allow lower doses of those expensive medications and improve blood counts. In practice, a small placebo-controlled study of transdermal testosterone in hypogonadal men on hemodialysis did not find a meaningful reduction in erythropoietin dose requirements, nor significant improvements in bone density, body composition, or mood.11American Journal of Kidney Diseases. Effects of Transdermal Testosterone on Serum Testosterone Levels, Insulin-like Growth Factor 1, Bone Mineral Density, and Body Composition in Hypogonadal Men on Hemodialysis The concept makes biological sense, but the clinical trials so far have not delivered the hoped-for payoff in dialysis patients.
Anabolic Steroid Abuse and Kidney Damage
The distinction between therapeutic testosterone replacement and anabolic steroid abuse matters enormously for kidney risk. Replacement therapy aims to bring testosterone back into the normal physiological range. Anabolic steroid use for bodybuilding or performance enhancement pushes androgen levels far above that range, often with multiple stacked compounds and no medical oversight.
Long-term anabolic steroid abuse has been linked to focal segmental glomerulosclerosis (FSGS), a form of scarring in the kidney’s filtering units that can lead to irreversible damage.12Nature Reviews Nephrology. Anabolic steroid abuse can lead to focal segmental glomerulosclerosis This was among the first studies to demonstrate a direct connection between steroid abuse and severe structural kidney injury. Case reports have since expanded the picture. One described a 40-year-old bodybuilder who developed both interstitial nephritis and FSGS after relatively short-term use of anabolic steroids and supplements, showing that the kidney consequences can span a range of damage patterns and do not always require years of abuse to appear.13PubMed. Coexistence of Interstitial Nephritis and the Cellular Variant of Focal Segmental Glomerulosclerosis Secondary to Anabolic Steroid Abuse
The mechanism likely involves the same processes seen in animal models of testosterone-driven kidney injury: increased inflammation, fibrotic signaling, and hemodynamic stress from elevated blood pressure. But at supraphysiological doses, these effects are amplified far beyond what the body experiences at normal testosterone levels. Anyone using or considering anabolic steroids should understand that kidney damage is on the list of possible consequences, alongside the better-known risks to the liver, heart, and reproductive system.
What Happens When You Suppress Testosterone
Androgen deprivation therapy (ADT) is a standard treatment for advanced prostate cancer, deliberately lowering testosterone to near-zero to starve hormone-sensitive tumors. If testosterone damages kidneys, you might expect removing it to help. The picture is more complicated than that.
A study of prostate cancer patients on ADT found their eGFR declined at roughly twice the rate of normal aging: about 0.6 to 1.0 mL/min per year over five years, compared with what would be expected in age-matched men not on therapy.14PubMed Central. Changes in Renal Function of Patients With Prostate Cancer: Focus on Androgen Deprivation Therapy And a large population-based study from JAMA reported that current ADT use was associated with roughly 2.5 times the odds of acute kidney injury compared with never-use, with combined androgen blockade (adding oral antiandrogens to GnRH agonists) carrying an even higher risk.15PubMed. Androgen deprivation therapy and risk of acute kidney injury in patients with prostate cancer A more recent population-based cohort study, however, did not find a statistically significant increase in acute kidney injury risk with hormone therapy after adjusting for confounders.16Prostate Cancer and Prostatic Diseases. Hormone therapy use and the risk of acute kidney injury in patients with prostate cancer: a population-based cohort study
The inconsistency probably reflects the complexity of ADT’s metabolic effects. Suppressing testosterone causes weight gain, insulin resistance, and dyslipidemia, all of which can harm kidneys independently. It also reduces muscle mass, which lowers creatinine and could mask a decline in true filtration. And some of the drugs used in ADT regimens carry their own nephrotoxic potential. The bottom line is that extremely low testosterone is not kidney-friendly either, and the metabolic fallout of androgen deprivation may be as hard on the kidneys as excess androgens are through different pathways.
Testosterone and Blood Pressure
One of the major indirect routes by which testosterone affects the kidneys is through blood pressure. Hypertension is the second leading cause of kidney failure worldwide, and the connection between testosterone and blood pressure is not straightforward. A large study comparing men with and without hypertension found that those with hypertension had significantly lower testosterone levels. In multivariable analysis adjusting for multiple risk factors, men with testosterone below roughly 345 ng/dL had a meaningfully higher risk of developing hypertension.17Wiley Online Library. The Serum Testosterone Level in Male Patients Is Inversely Associated With Hypertension Incidence This creates an apparent paradox: testosterone can raise blood pressure through direct kidney mechanisms (sodium retention, vasoconstriction), yet low testosterone is associated with more hypertension in population studies. The resolution likely lies in the broader metabolic picture. Men with low testosterone tend to have more visceral fat, worse insulin sensitivity, and higher levels of chronic inflammation, all powerful drivers of hypertension that outweigh the direct pressor effects of normal-range testosterone.
A clinical study in Syrian men found that lower testosterone levels correlated significantly with higher creatinine, suggesting that the metabolic environment surrounding low testosterone may itself harm kidney markers.18Research J. Pharmacy and Technology. Relationship between Testosterone levels in healthy men with Urea, Creatinine, Hemoglobin and Red blood cell properties. A Clinical study in Syria This fits the broader pattern: extremes in either direction, whether supraphysiological levels from steroid abuse or the deficiency seen in hypogonadism and advanced kidney disease, tend to be worse for the kidneys than a normal physiological range.
Androgen Excess in Women and PCOS
The testosterone-kidney question is not limited to men. Polycystic ovary syndrome (PCOS), the most common endocrine disorder in women of reproductive age, is characterized by elevated androgen levels. A systematic review and meta-analysis found that women with PCOS had significantly higher uric acid than healthy controls, though their creatinine and eGFR were statistically similar.19PubMed Central. Association between Polycystic Ovarian Syndrome, Impaired Kidney Function and Hyperuricaemia: A Systematic Review and Meta-analysis Elevated uric acid is a recognized risk factor for both kidney stones and progressive kidney disease, so while standard kidney function tests may look normal in PCOS, the metabolic environment is moving in a concerning direction.
More granular research tells a more worrying story. A study found that serum testosterone in women with PCOS correlated with markers of early kidney tubular injury, even when standard tests like eGFR remained in the normal range. In lab experiments, fluid from the ovarian follicles of women with high testosterone levels induced fibrotic (scarring) changes in cultured human kidney tubule cells.20PubMed Central. Serum testosterone acts as a prognostic indicator in polycystic ovary syndrome-associated kidney injury The researchers suggested that serum testosterone could serve as an early warning sign for kidney fibrotic injury in PCOS patients. This is especially relevant because PCOS affects an estimated 8 to 13 percent of women of reproductive age, and the kidney implications have received relatively little clinical attention compared to fertility and metabolic concerns.
Gender-Affirming Testosterone Therapy
Transgender men and transmasculine individuals taking testosterone as part of gender-affirming hormone therapy (GAHT) face a unique intersection of the issues described above. Testosterone raises their creatinine, their eGFR formulas were designed with sex-based coefficients that may no longer apply to their changing physiology, and the long-term kidney safety data for this population is still accumulating.
A meta-analysis of studies on testosterone GAHT found that eGFR dropped at six and twelve months after starting therapy, and creatinine and uric acid rose at all follow-up points. However, by 18 to 24 months, eGFR stabilized. The authors attributed the initial decline to the creatinine measurement artifact described earlier: more muscle, more creatinine, lower calculated eGFR, rather than a genuine loss of kidney function.21PubMed Central. Effects of gender affirming hormone therapy with testosterone on renal function of assigned female at birth transgender people: a meta-analysis A study of transgender veterans confirmed this pattern, finding that serum creatinine rose as early as three months after starting testosterone and stabilized by twelve months, without evidence of progressive kidney damage.22Clinical Journal of the American Society of Nephrology. The Effect of Gender-Affirming Hormone Treatment on Kidney Function Trajectories in Transgender and Gender-Diverse Veterans
The diagnostic challenge is real, though. Current eGFR equations include sex-based adjustment factors, and there is no consensus on whether to use the sex assigned at birth or the affirmed gender when calculating eGFR for someone on hormone therapy. Using the wrong coefficient can misclassify someone as having kidney disease when they do not, or miss early kidney problems that are masked by the calculation.23PubMed Central. Kidney Health and Gender-Affirming Hormone Therapy for Transgender and Gender Diverse Individuals For transgender individuals on testosterone, proactive conversations with clinicians about which eGFR equation is being used, and whether cystatin C-based estimates might be more reliable, can prevent unnecessary alarm or missed diagnoses.
When Testosterone Protects the Kidney
Perhaps the most counterintuitive finding in the literature involves acute kidney injury from ischemia-reperfusion, the damage that occurs when blood flow to the kidney is interrupted and then restored (as during surgery, severe blood loss, or organ transplantation). In a rat model, acute ischemia-reperfusion caused testosterone levels to plummet, and giving testosterone back after the injury actually protected the kidneys. Testosterone-treated animals had lower plasma creatinine, less of the kidney injury marker KIM-1, better blood flow to the kidney’s outer medulla, and reduced inflammatory signaling. Castrated males, by contrast, fared significantly worse than intact males, and the protective effect of testosterone was not explained by conversion to estrogen.24American Journal of Physiology-Regulatory, Integrative and Comparative Physiology. Protective role of testosterone in ischemia-reperfusion-induced acute kidney injury
This seems to contradict the findings about testosterone worsening chronic kidney injury. The reconciliation may lie in timing and context. In an acute injury scenario, testosterone’s vascular effects (maintaining blood flow to the outer medulla, reducing certain inflammatory cascades) appear to be protective. In chronic disease, the same hormone’s long-term effects on sodium retention, blood pressure, and fibrotic signaling tilt the balance toward harm. Biology often works this way: the same molecule can help or hurt depending on the situation, the dose, and how long it is present. For clinical medicine, this means blanket statements about testosterone being “good” or “bad” for kidneys miss the point entirely. The answer depends on the kidney’s current state, the testosterone level in question, and the time frame involved.