Hypertrichosis is excessive hair growth that extends beyond what is considered normal for a person’s age, sex, and ethnic background. This phenomenon can manifest as an increase in fine, soft hair or in coarse, dark hair, appearing in either a localized area or across the entire body. While some forms are genetic or drug-induced, many acquired cases stem from a disruption within the endocrine system. The glands that manage hormone production play a direct role in regulating the hair follicle growth cycle.
Hypertrichosis Versus Hirsutism
The medical community maintains a clear distinction between hypertrichosis and hirsutism. Hypertrichosis is defined by excessive hair growth anywhere on the body and affects both men and women. This hair growth is often non-androgen-dependent, meaning it is not stimulated by an excess of male hormones. Causes for this type include certain medications, genetic syndromes, or underlying systemic illnesses.
Hirsutism, by contrast, almost exclusively affects women. It involves the growth of coarse, dark hair in a male-like pattern on androgen-sensitive areas, such as the face, chest, and lower abdomen. Hirsutism is caused by an overproduction of androgens or an increased sensitivity of hair follicles to normal androgen levels.
Endocrine System’s Role in Hair Regulation
The endocrine system regulates hair growth through hormones that directly influence the hair follicle’s life cycle. The glandular structures most commonly implicated in excessive hair growth are the adrenal glands and the gonads. These glands produce androgens, including testosterone and dihydrotestosterone (DHT). Androgens stimulate the conversion of fine vellus hair into thick, pigmented terminal hair in androgen-sensitive body areas.
The adrenal glands, situated atop the kidneys, are a primary source of androgen precursors, such as dehydroepiandrosterone sulfate (DHEA-S). They also produce cortisol, which can indirectly affect androgen balance. The pituitary gland oversees these processes by releasing adrenocorticotropic hormone (ACTH), signaling the adrenals to produce cortisol and androgens. Malfunction in the adrenal or pituitary glands can trigger excessive hair growth due to hormonal imbalance.
The gonads are the other major source of androgens. In women, ovarian overproduction of testosterone, often due to an underlying disorder, can lead to the male-pattern hair growth seen in hirsutism.
Specific Glandular Conditions Leading to Excessive Hair Growth
Several specific glandular pathologies cause hypertrichosis by disrupting androgen production. Polycystic Ovary Syndrome (PCOS) is the most frequent cause of androgen-related hair growth in women. This ovarian disorder is characterized by irregular menstrual cycles, multiple small cysts on the ovaries, and elevated androgen production.
Malfunctions of the adrenal glands represent another major category. Congenital Adrenal Hyperplasia (CAH) is a genetic disorder that impairs the adrenals’ ability to produce certain hormones, leading to a buildup of androgen precursors. This excess androgen production drives significant hair overgrowth. Adrenal tumors, whether benign or malignant, may also autonomously secrete high levels of androgens or cortisol, resulting in a sudden onset of excessive hair.
Cushing’s Syndrome involves prolonged exposure to high levels of cortisol, often due to a pituitary tumor causing excessive ACTH release, or an adrenal tumor producing too much cortisol. The resulting hormonal imbalance often includes an increase in adrenal androgen synthesis. This secondary effect contributes directly to the development of excessive hair.
Identifying the Root Cause and Management
When excessive hair growth suggests a glandular origin, diagnosis involves blood tests to measure specific hormone levels. Physicians assess androgen levels, including total and free testosterone, and the adrenal-specific androgen DHEA-S. Cortisol levels and specific tests for CAH may also be performed. The pattern and severity of hormone elevation help pinpoint the malfunctioning gland.
For example, elevated DHEA-S points toward an adrenal source, while high testosterone with normal DHEA-S suggests an ovarian origin. Following biochemical findings, imaging studies are necessary to rule out a tumor. This may involve a pelvic ultrasound for the ovaries or a CT scan or MRI of the adrenal and pituitary glands. These images help visualize abnormal growths that might be overproducing hormones.
Management focuses on treating the underlying endocrine disorder to suppress the hormonal trigger. For conditions like PCOS and CAH, treatment involves medications aimed at reducing androgen production or blocking their action on the hair follicle. If a tumor is identified, surgical removal is typically required to restore normal hormone balance.