Understanding Hair Loss: Clinical Presentation and Diagnosis
Diagnosing hair loss is straightforward when considering family history and clinical symptoms. In women experiencing diffuse hair loss, it is crucial to rule out other causes, such as postpartum hair loss or systemic disorders like typhoid and anemia.
Initial Changes in Hair Follicles
The earliest detectable changes occur in the connective tissue of the hair follicle, where degenerative alterations in the lower part of the hair sheath appear, often accompanied by basophilic changes around blood vessels. Over time, hair follicles shrink and diminish, eventually being replaced by vellus hair. This leads to a significant loss of both vellus hair and hair follicles, leaving behind hardened, glass-like connective tissue. As the condition progresses, the anagen (growth) phase of the hair follicles shortens, while the percentage of follicles in the telogen (resting) phase increases. Consequently, hair becomes loose and prone to falling out, with the epidermis becoming thinner.
Embryonic changes in the epidermis become flat, and the sub-epidermal network of capillaries nearly disappears. Increased deposition of sulfated mucopolysaccharides in the dermis is common, while the enzymatic activity in vellus hair follicles remains largely normal.
Clinical Presentation of Hair Loss
Hair loss typically manifests in adults aged 20 to 30 years. Approximately 80% of cases are observed in men, classified as **male pattern alopecia**, while 20% occur in women, known as **female pattern alopecia**. The incidence of this condition is notably higher among Caucasians than in other populations, such as in China, where a study conducted in Shanghai in 1976 indicated an early hair loss incidence of just 0.63%.
Male Pattern Alopecia
In men, hair loss mainly affects the vertex and frontal areas, particularly the hairline at the sides of the forehead, leading to a receding hairline. As the condition worsens, the top of the head becomes bald, while hair remains on the occipital and temporal regions. The scalp in balding areas appears smooth, with fine vellus hair observable but minimal or no symptoms such as itching.
The presentation and speed of hair loss can vary among patients, but most experience a slow course, often accompanied by seborrheic dermatitis or excess sebum production. In milder cases, hair loss may be limited to the temples, with thinning hair on the crown of the head.
Female Pattern Alopecia
Female pattern alopecia is less common and tends to be milder. It typically presents as a diffuse shedding of hair, predominantly affecting the crown area. While hair gradually thins, it does not completely fall out, and hair loss at the temples is rare. Hair may become finer and lose its luster, with the scalp potentially appearing thinner and accompanied by sensations of heat, itching, or tenderness. Complete regrowth of new hair is often challenging after the initial loss.
Conclusion
Understanding the clinical presentation and underlying causes of hair loss is essential for accurate diagnosis and treatment. By recognizing the differences between male and female pattern alopecia, healthcare providers can effectively address this common condition, offering reassurance and appropriate management strategies for affected individuals.