In some animal studies, testosterone helped relax blood vessels, which improved blood flow to the kidneys. Healthy kidneys also help make a hormone called erythropoietin, which tells the body to make red blood cells. Testosterone therapy is often used to treat men with low testosterone levels.
This is especially true for people who already have kidney problems or risk factors for kidney disease. Recognizing and managing this imbalance is important for the overall health and well-being of men with kidney disease. Many men with late-stage kidney disease require dialysis, a treatment that removes waste from the blood when the kidneys can no longer do so. As kidney function gets worse, waste products begin to build up in the blood. The kidneys help control blood pressure by adjusting the amount of salt and water in the body and by making hormones that affect blood vessels. These clots can reduce blood flow to the kidneys, which may harm kidney function.
While low testosterone may lead to health issues over time, high levels—especially from testosterone replacement therapy (TRT)—can also cause concerns. These effects may be mild in healthy people but can be dangerous in those with kidney disease. People on testosterone therapy should have their hematocrit levels (a measure of red blood cell concentration) checked regularly. For the kidneys, thick blood can reduce blood flow through the delicate filtering units, leading to reduced kidney function. Another known side effect of testosterone therapy is polycythemia, which means the body makes too many red blood cells.
This balance is important for blood pressure, nerve function, and muscle activity. The kidneys also help control how much water and salt the body keeps. Despite their small size, the kidneys do a lot of important work for the body every day. Testosterone is a powerful hormone that affects many systems in the body.
Additionally, we investigated the association of testosterone, its precursors, its active metabolites, and its supplementation with clinical outcomes in patients with CKD. This phenomenon is often referred to as the ‘CKD paradox’ (2, 3), and differences in sex hormones between men and women might underlie these existing sex differences (3, 4, 5). As such, our study highlights the importance of considering sex-specific causes and treatments for CKD and raises the question as to whether any causes of CKD specific to women exist.