Causes of hair loss
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Types of Hair Loss: Non-Scarring and Scarring Alopecia
Hair loss, or alopecia, is broadly categorized into non-scarring (non-cicatricial) and scarring (cicatricial) types. Non-scarring hair loss is more common and includes conditions such as androgenetic alopecia, alopecia areata, telogen effluvium, and trichotillomania. Scarring alopecias, which are less frequent, include frontal fibrosing alopecia, discoid lupus erythematosus, lichen planopilaris, and folliculitis decalvans. Proper diagnosis often involves a detailed history, physical examination, and sometimes trichoscopy or scalp biopsy, especially for scarring forms 135.
Common Causes of Non-Scarring Hair Loss
Androgenetic Alopecia (Genetic and Hormonal Factors)
Androgenetic alopecia is the most prevalent cause of hair loss in both men and women. It is primarily driven by genetic predisposition and sensitivity of hair follicles to androgens, particularly dihydrotestosterone (DHT). In men, it typically presents as receding hairlines and balding at the crown, while in women, it appears as diffuse thinning over the scalp. Hormonal imbalances, such as those seen in menopause or endocrine disorders, can also contribute to this type of hair loss 1345+2 MORE.
Telogen Effluvium (Stress and Systemic Triggers)
Telogen effluvium is characterized by sudden, diffuse hair shedding, often triggered by physiological or emotional stress, illness, hormonal changes, nutritional deficiencies (especially iron and amino acids), or certain medications. Once the underlying cause is addressed, hair typically regrows, but chronic cases may persist if the trigger is not resolved 3456+2 MORE.
Alopecia Areata (Autoimmune Mechanisms)
Alopecia areata is an autoimmune condition where the immune system attacks hair follicles, leading to patchy hair loss on the scalp, face, or body. The condition can be self-limiting but may also become chronic or extensive. Recent advances in treatment target the immune response, but the disease can have significant psychological effects 1356+1 MORE.
Trichotillomania and Traumatic Hair Loss
Trichotillomania is an impulse-control disorder where individuals pull out their own hair, resulting in patchy hair loss. Other forms of traumatic hair loss, such as trichorrhexis nodosa, are caused by physical or chemical damage from hair styling or products 35.
Anagen Effluvium (Chemotherapy and Toxins)
Anagen effluvium is rapid hair loss during the growth phase, most commonly caused by chemotherapy or exposure to toxic substances that impair hair follicle cell division .
Scarring (Cicatricial) Alopecia: Inflammatory and Autoimmune Causes
Scarring alopecias result from inflammation that destroys hair follicles and replaces them with scar tissue, leading to permanent hair loss. Common causes include lichen planopilaris, discoid lupus erythematosus, frontal fibrosing alopecia, and folliculitis decalvans. These conditions often require biopsy for diagnosis and can be associated with systemic autoimmune diseases 156.
Systemic and Environmental Causes of Hair Loss
Hair loss can also be a symptom of systemic diseases such as thyroid disorders, lupus, infections (e.g., syphilis, tinea capitis), and even malignancies. Environmental factors like pollution and nutritional deficiencies (iron, amino acids) can further compromise hair health. Some rare genetic mutations, such as those affecting the TRPV3 gene, can also cause hair loss by disrupting hair follicle development 2457+3 MORE.
Hormonal and Endocrine Influences
Hormones play a crucial role in hair growth and loss. Androgens, estrogens, thyroid hormones, and stress hormones (cortisol) all influence the hair cycle. Imbalances, such as androgen excess, estrogen deficiency, or thyroid dysfunction, are common contributors to various forms of alopecia 78.
Conclusion
Hair loss is a complex symptom with many possible causes, including genetic, hormonal, autoimmune, nutritional, psychological, and environmental factors. Accurate diagnosis requires a thorough evaluation to identify the underlying cause and guide appropriate treatment. Addressing both the physical and psychological impacts of hair loss is essential for patient well-being 1345+3 MORE.
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