Finasteride is a prescription medication primarily used to address male pattern baldness, also known as androgenetic alopecia, and benign prostatic hyperplasia (BPH), a condition characterized by an enlarged prostate. This medication is available in different dosages, with a 1mg tablet typically prescribed for hair loss and a 5mg tablet for managing BPH symptoms.
How Finasteride Affects DHT
Finasteride inhibits the enzyme 5-alpha reductase. This enzyme exists in different forms, with finasteride specifically targeting the type II isoenzyme of 5-alpha reductase, which is present in areas like the prostate, hair follicles, and liver. The primary function of 5-alpha reductase is to convert testosterone, a male hormone, into a more potent androgen known as dihydrotestosterone (DHT). DHT plays a significant role in the development and progression of male pattern baldness by causing hair follicles to miniaturize, and it also contributes to prostate enlargement. By blocking this enzyme, finasteride effectively reduces DHT in the body and within specific tissues, such as the prostate and scalp. This inhibition can lead to a substantial decrease in serum DHT levels, often by as much as 70%.
Finasteride’s Effect on Testosterone Levels
Because finasteride inhibits the conversion of testosterone into DHT, the testosterone that would normally be metabolized remains in circulation. This results in an indirect and modest increase in overall testosterone levels within the body. Studies have shown that testosterone levels can rise by 10% to 25% above baseline levels. This elevation is a direct consequence of reduced DHT synthesis, rather than a direct stimulation of testosterone production. While a rise in testosterone is observed, the primary hormonal impact and therapeutic goal of finasteride treatment remains the significant reduction of DHT.
Related Hormonal Changes
With the slight increase in testosterone levels due to finasteride’s action, there may be minor adjustments in other related hormones. For instance, some research indicates that luteinizing hormone (LH) and follicle-stimulating hormone (FSH), which regulate testosterone production, generally remain unaffected. However, due to the increased availability of testosterone, there might be a slight increase in estrogen levels through a process called aromatization, where testosterone is converted into estrogen.
Clinical Significance of Testosterone Changes
The increase in testosterone levels observed with finasteride use is modest and typically remains within the normal physiological range for men. This slight elevation in testosterone is not significant enough to cause noticeable symptoms or adverse health effects associated with excessively high testosterone. The main therapeutic benefit of finasteride stems from its ability to lower DHT, which is the primary driver for conditions like male pattern baldness and benign prostatic hyperplasia. Therefore, the focus of finasteride treatment is on its DHT-lowering action, not its testosterone-raising effect. For most users, this modest increase in testosterone is not a cause for concern. Individuals with specific health concerns should consult their healthcare provider for personalized advice.