Commonly known as "ghost shaving," this condition involves sudden, circular patches of hair loss. The scalp in affected areas remains normal, showing no inflammation or noticeable symptoms, and may resolve or recur spontaneously. Alopecia areata is associated with immune dysfunction and sudden increases in mental stress.
II. Caused by Excessive Androgen Secretion
Since hair follicles are target organs for androgen action, and the scalp has a high density of androgen receptors, it becomes a site prone to androgen accumulation. Combined with the condition's hereditary nature, male pattern baldness is the most common type of hair loss.Why do men lose hair? Serum and scalp dihydrotestosterone (DHT) levels in male pattern hair loss patients are significantly higher than in healthy individuals. Under prolonged DHT influence, hair follicles on the scalp, forehead, and crown gradually shrink and atrophy. Hair becomes finer, drier, and duller, eventually lightening in color and thinning.
III. Pathological Causes: Surgery, Disease, or Medication
Hair loss may occur within 1 to 3 months following high fever, severe infections, or major surgeries. Thyroid dysfunction can also trigger hair loss. Certain chronic diseases may cause hair loss, as can autoimmune conditions like severe discoid lupus erythematosus affecting the scalp.Mechanical traction, burns, chronic deep bacterial or fungal infections can likewise cause hair loss. Additionally, certain prescription medications may induce hair loss in some individuals—chemotherapy, for instance, halts hair growth, leading to shedding during treatment. Hair typically regrows after discontinuing the medication or completing therapy.
IV. Excessive Scalp Sebum Production
Seborrheic hair loss manifests clinically as excessive sebum secretion, greasy and moist scalp, itching, and sometimes inflammation. This is another major cause of male hair loss, occurring more frequently in knowledge workers than manual laborers.Clinical evidence suggests seborrheic hair loss may be linked to endocrine function, psychological state, genetics, and certain medications. Hair loss typically begins at the temples, forehead, or crown, gradually spreading across the entire scalp while sparing the hair around the sides and back. In severe cases, affected areas become greasy and shiny, with remaining hair becoming fine, brittle, and dull.