Hormone Replacement Therapy (HRT) is often used to help balance hormone levels during menopause, andropause, or as part of gender-affirming care. While HRT is great for improving overall well-being, its impact on kidney function and creatinine levels is still being examined.
Creatinine is a waste product produced by your muscles and is filtered out by your kidneys. Doctors often use creatinine levels to check how well your kidneys are functioning. But the effect of hormone therapies on creatinine is not so straightforward.
Testosterone therapy and your kidney
Testosterone Replacement Therapy (TRT) is prescribed for different reasons, including to address low testosterone levels or as part of gender-affirming care. It can have some impact on creatinine levels, but that depends on a person’s health and how much testosterone they’re taking.
Testosterone therapy can increase muscle strength and overall kidney function, potentially easing kidney strain. Some kidney transplant recipients even reported feeling better with TRT, according to a 2024 International Journal of Impotence Research study.
But there’s a downside too. TRT can raise blood pressure and red blood cell count, which can stress the kidneys. Although long-term effects are still under study, a 2021 Annals of Medicine and Surgery report found that TRT might increase glomerular filtration rate (GFR), a key measure of kidney health. Another study suggested it could slow chronic kidney disease progression.
What's more, TRT increases muscle mass, which raises creatinine levels. For those with chronic kidney disease (CKD), this can make it hard to tell if higher creatinine is due to muscle growth or kidney damage. Doctors need to keep this in mind when checking kidney function for clients on testosterone.
Estrogen therapy and kidney function
Estrogen therapy—often used during menopause or for feminizing hormone therapy in transgender women—also has a complex relationship with kidney health. Some research suggests that estrogen can actually help protect the kidneys.
A 2023 study published in the general Steroids found that estrogen can improve blood flow to the kidney, which helps your kidney work more efficiently.
Yet, research out of Tulane University found that long-term estrogen treatment after menopause could raise the risk of kidney damage, especially for women with pre-existing kidney issues—despite estrogen's protective effects against high blood pressure. And a 2008 study published in Kidney International found that hormone therapy (estrogen-only, progestin-only, or both) was linked to a significant drop in kidney function compared to non-users. Higher doses of estrogen also led to greater declines in kidney health, showing that estrogen use can hurt kidney function in women over 60.
Progesterone’s role in kidney health
Progesterone replacement therapy (PRT) can benefit kidney health, particularly for women going through menopause. Studies suggest that PRT helps manage blood pressure by relaxing blood vessels, which can help reduce the risk of hypertension tied to kidney issues. It is also known for its anti-inflammatory effects, which can protect your kidney from damage caused by long-term inflammation, a common concern in CKD.
Progesterone often goes hand-in-hand with estrogen in HRT and helps manage fluid balance and sodium in the kidneys. One study found that while progesterone alone has little effect on creatinine levels, combining it with estrogen can improve kidney function by countering some negative effects like fluid retention and high blood pressure.
Yet, synthetic progesterone (progestins) might not have the same benefits as natural progesterone, which makes picking the right type of progesterone important for maintaining kidney health.
Hormone therapy for transgender and gender-diverse people
For transgender and gender-diverse people undergoing gender-affirming hormone therapy, kidney health is something to keep an eye on. Often, feminizing hormone therapy involves estrogen and anti-androgens like spironolactone; spironolactone, according to one study, can raise creatinine and potassium levels, as well as decrease kidney function.
Similarly, testosterone therapy for transgender men can lead to increased muscle mass and higher creatinine levels, which can make it difficult to properly assess kidney health. While more research is needed, people receiving gender-affirming care should monitor kidney function because hormone treatments can affect how the kidneys work and may interact with other medications, especially for those with pre-existing kideny concerns.
Bottom line: Regular monitoring matters
HRT offers many benefits, but you need to monitor your kidney function while on it. Testosterone, estrogen, and progesterone each affect the kidneys in different ways, so finding the right balance is key for your health.
During HRT, test your blood regularly to check creatinine levels and kidney filtration rates. This proactive approach helps you catch any kidney issues early and manage them effectively. To this end, schedule regular check-ins with your healthcare provider and stay informed about how HRT affects your body to keep your hormones and kidneys in sync.
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