Dihydrotestosterone (DHT) is a potent androgen, a type of sex hormone derived from testosterone in the body. While often associated with male pattern baldness, DHT significantly affects women’s hair health and is a primary driver of female pattern hair loss (FPHL), medically known as androgenetic alopecia. Women produce testosterone in their ovaries and adrenal glands, which is then converted into the more powerful DHT. The presence or heightened effect of DHT drives this condition.
The Biological Role of Androgens in Female Hair Follicles
The influence of DHT on hair is mediated by the enzyme 5-alpha reductase, which converts testosterone into DHT within the hair follicle and skin. DHT is a much more potent androgen than testosterone, and its action is determined by binding to androgen receptors on genetically susceptible hair follicles. This binding initiates a process called follicular miniaturization, which is the underlying cause of pattern hair loss.
Miniaturization causes the hair follicle’s growth phase, known as the anagen phase, to progressively shorten with each cycle. Consequently, the hair produced becomes shorter, finer, and lighter in color, eventually resembling vellus hair rather than thick terminal hair. Hair loss can still occur in women due to an increased sensitivity of the hair follicle receptors to even normal levels of DHT, or a slight increase in androgen production.
Identifying Female Pattern Hair Loss Associated with DHT
Female pattern hair loss (FPHL) presents with a distinctly different pattern than the recession seen in men. The primary visual manifestation is a diffuse thinning across the top and crown of the scalp, rather than a receding hairline or bald spots. This thinning often begins with a widening of the central part line, sometimes described as a “Christmas tree pattern” where the thinning is more pronounced toward the front. A notable feature of FPHL is the preservation of the frontal hairline, which generally remains intact, unlike the temporal recession characteristic of male pattern baldness. Over time, the overall volume of hair decreases, and the scalp becomes increasingly visible.
Conditions Leading to Elevated Androgen Levels
An increase in the effects of DHT stems from two main factors: an actual elevation in androgen levels or an increased sensitivity of the follicles themselves. One of the most common underlying causes of elevated androgens is Polycystic Ovary Syndrome (PCOS), an endocrine disorder characterized by the overproduction of androgens, including testosterone. PCOS-related hyperandrogenism accounts for a significant portion of female hair loss cases and is often accompanied by other symptoms like irregular periods and excessive body or facial hair growth.
Genetic predisposition also plays a role, as some women’s hair follicles are more sensitive to androgens, meaning they can experience FPHL even with normal circulating hormone levels. Furthermore, hormonal fluctuations associated with aging, particularly post-menopause, contribute to hair loss. As estrogen and progesterone levels decline, the relative influence of androgens like DHT increases, tipping the hormonal balance in favor of hair follicle miniaturization.
Treatment Strategies Targeting DHT
Addressing DHT-related hair loss involves medical strategies aimed at mitigating the androgen’s effect on the hair follicles. One class of treatments includes anti-androgens, such as spironolactone, which block the androgen receptors in the hair follicles, preventing DHT from binding and initiating miniaturization. These medications are a common systemic approach for women with elevated androgen levels or clear signs of FPHL.
Another therapeutic avenue focuses on inhibiting the 5-alpha reductase enzyme, which converts testosterone to DHT. Medications in this category reduce the overall amount of potent DHT available to act on the hair follicles.
When an underlying condition like PCOS is identified, treatment also focuses on managing the primary hormonal imbalance to regulate androgen production at the source. These medical interventions require consistent use and medical guidance, as they primarily work to halt or slow further hair loss.