Polycystic Ovary Syndrome (PCOS) is a common endocrine disorder that affects women of reproductive age, characterized by a persistent hormonal imbalance. This condition frequently involves the overproduction of male hormones, known as androgens, which can lead to various physical changes. Among the most noticeable symptoms is hair loss on the scalp, medically termed Female Pattern Hair Loss (FPHL). Understanding the specific presentation of this hair thinning is the first step toward seeking appropriate management.
The Characteristic Pattern of Scalp Thinning
Hair loss associated with PCOS presents in a distinctive pattern that differs from other causes of shedding. It typically manifests as diffuse thinning across the top of the scalp and the crown area. The most telling sign is often the progressive widening of the central hair part, sometimes described as taking on a triangle or “Christmas tree” shape, where the thinning is more concentrated toward the front of the scalp.
The density of hair gradually diminishes, making the scalp increasingly visible through the remaining strands. A defining feature of this pattern is that the frontal hairline is usually preserved, meaning the hair does not recede backward from the forehead like in male pattern baldness. Dermatologists often use classification systems, such as the Ludwig Scale, to categorize the severity of this diffuse thinning, which helps monitor progression over time.
How Hormones Change Hair Structure
The visible thinning of the hair is rooted in the microscopic process of follicular miniaturization, driven by elevated levels of androgens. In women with PCOS, the excess testosterone is often converted into a more potent hormone called dihydrotestosterone (DHT). This conversion is facilitated by the enzyme 5-alpha-reductase, which is present in the hair follicle cells.
DHT binds to androgen receptors in the scalp follicles, effectively shrinking them over successive growth cycles. This process shortens the anagen (active growth) phase of the hair cycle and extends the dormant phase. As a result, the hair produced becomes progressively finer, shorter, and lighter in color, eventually resembling the soft, colorless vellus hair found elsewhere on the body. This shift from thick, terminal hair causes the overall reduction in hair volume.
Accompanying Signs of Androgen Excess
Since the hair loss on the scalp is a symptom of systemic androgen excess, it frequently occurs alongside other dermatological signs. One of the most common co-occurring symptoms is hirsutism, which is the growth of coarse, dark hair in areas typically associated with male hair patterns. These areas include the upper lip, chin, chest, abdomen, and inner thighs.
Elevated androgens can also lead to increased sebum production, resulting in adult-onset acne. This acne is often cystic and commonly appears along the jawline, chin, and upper neck, tending to be deeper and more persistent than typical breakouts.
Another physical manifestation of the underlying hormonal imbalance, particularly related to insulin resistance often seen in PCOS, is acanthosis nigricans. This condition presents as dark, thickened, and velvety patches of skin, typically found in skin folds such as the back of the neck, the armpits, and under the breasts. Recognizing these accompanying physical signs alongside scalp thinning is important in identifying PCOS as the root cause.