The Hair Growth Cycle
Healthy hair grows in a continuous cycle of three phases: the anagen (growth) phase, which lasts three to five years; the catagen (transition) phase, which lasts about one month; and the telogen (resting) phase, lasting roughly three months before shedding. In individuals with hair loss, the anagen phase shortens, resulting in thinner and weaker strands.
This cycle also exhibits seasonal variations. While animals grow thicker fur for winter, human hair density typically peaks in spring—possibly as a protective response to ultraviolet radiation—and gradually decreases during the fall.
Alopecia, the medical term for hair loss, refers to absent or thinning hair in areas where it typically grows. It is divided into non-scarring alopecia, where follicles remain intact, and scarring alopecia, where follicles are permanently damaged.
Dr. Kwon explains, "Androgenetic alopecia—commonly known as male-pattern or female-pattern baldness—accounts for 85% to 90% of all hair loss cases." This condition is influenced by genetics, aging, and elevated levels of dihydrotestosterone (DHT), a testosterone byproduct. Its prevalence is increasing globally due to aging populations and lifestyle factors such as high-fat diets, extreme dieting, smoking, and obesity, all of which can promote inflammation in the scalp’s subcutaneous fat layer.
Telogen effluvium, a temporary condition, causes diffuse thinning due to stress, nutritional deficiencies, or hormonal shifts. It’s common postpartum: elevated estrogen during pregnancy prolongs the anagen phase, but a hormonal drop after childbirth triggers shedding, peaking around three months and typically resolving by the child’s first birthday. Persistent cases may suggest underlying female-pattern baldness.
Alopecia areata, an autoimmune disorder, results in patchy baldness, while cicatricial alopecia arises from irreversible follicle damage due to trauma, burns, or infections.
Diagnosing Hair Loss
Early signs of hair loss include thinning at the crown and frontal hairline relative to the occipital scalp, increased scalp oiliness from enlarged sebaceous glands, and a visible reduction in follicle size. Dr. Kwon advises monitoring for greasier hair or smoother brushing, which may signal alopecia’s onset. Daily shedding exceeding 100 hairs or a receding hairline calls for medical evaluation.
Early diagnosis can significantly slow progression and promote regrowth. Clinicians assess scalp health, hair density, thickness, and bald patches. A pull test—gently tugging 50 to 60 hairs to determine if more than 10% come out—helps detect abnormal shedding. Trichoscopy and digital hair analysis can assess hair density, shaft diameter, and growth rate, while scalp biopsies are used to evaluate follicle health and confirm diagnoses.
Treatment Strategies
Androgenetic alopecia, while incurable, responds to treatments that slow progression. Early intervention often involves oral finasteride or dutasteride, which inhibit 5-alpha-reductase, the enzyme producing DHT. Advanced cases benefit from topical minoxidil, which stimulates follicles to re-enter the anagen phase. Combining both approaches maximizes results.
Dr. Kwon notes, “Hair grows about one centimeter per month in the anagen phase, so six months of consistent treatment is needed for noticeable regrowth. Because hair loss is a chronic condition, discontinuing treatment may lead to relapse." Dr. Kwon advises consulting a dermatologist to determine the most suitable medications and dosages.
In severe cases, autologous hair transplantation—relocating follicles from the DHT-resistant occipital scalp to thinning areas—yields excellent outcomes. Pairing transplantation with ongoing medication preserves existing hair for optimal cosmetic results.
Telogen effluvium typically resolves once triggers like stress or nutritional deficits are addressed. Alopecia areata is managed with topical corticosteroids or immunosuppressive therapy. Cicatricial alopecia, due to permanent follicle damage, often requires surgical hair restoration.
Debunking Hair Loss Myths
1. Shaving a baby’s head boosts hair thickness: False. Shaved hair may appear coarser due to blunt ends, but follicle count and hair caliber remain unchanged.
2. Frequent washing causes hair loss: False. Losing fewer than 100 hairs daily is normal, and regular cleansing supports scalp health. Harsh shampoos or hot water, however, should be avoided.
3. Hats cause baldness: False. Normal hat use is harmless, though tight headwear worn for extended periods may cause scalp irritation or folliculitis.
4. Hair loss skips generations: False. Genetic patterns vary among siblings due to lifestyle differences, not generational skipping.
5. Male baldness is maternally inherited: Partially true. Both parents contribute genetic factors, but male-pattern baldness is linked to X-chromosome genes from the mother.
6. Plucking gray hairs increases graying: False. Plucking doesn’t affect surrounding hair color, but repeated plucking may damage follicles, worsening thinning.
Prevention and Management
Dr. Kwon observes, “Hair loss is a natural part of aging, like wrinkles or declining vision. While it cannot be fully prevented, early detection and diligent management can significantly improve outcomes. Anyone noticing thinning or excessive shedding should seek a dermatologist’s advice promptly.”
Dr. Kwon recommends several preventive strategies: maintaining a healthy weight through regular aerobic exercise to balance hormones (especially in women); following an antioxidant-rich diet while avoiding processed foods; managing metabolic conditions such as diabetes and hyperlipidemia; ensuring regular sleep patterns to support hair follicle rhythms; avoiding smoking to reduce oxidative stress; and minimizing the use of tight hairstyles and excessive heat styling tools.
By understanding hair loss and adopting proactive habits, individuals can effectively manage this common condition, preserving both hair and confidence.
Lim Hye Jung, HEALTH IN NEWS TEAM
press@hinews.co.kr
