About Hair Loss
In normal hair growth, each scalp hair follicle grows in cycles: the growth (anagen) phase lasts 2 or more years. During this time, the hair is actively growing and lengthening. Anagen phase is followed by a short period of arrested growth (catagen phase). Then the resting phase (telogen) occurs, lasts up to 3 months and ends with the hair falling out. The cycle repeats itself over a person’s lifetime. On a healthy scalp on any given day 75-100 hairs are entering the growth phase and the same number are falling out, maintaining an even balance of hair distributed across the scalp.
Hair loss in Androgenetic Alopecia, is caused by the hormone dihydrotestosterone (DHT), which is a natural hormone, present in all healthy men and women. DHT enters the cells of susceptible hair follicles located on the top of the head. Once inside of the hair follicle cells, the DHT weakens the follicle, preventing it from growing a healthy hair. Over time, hair follicles that were once able to produce healthy, strong, “terminal” hair become weak, dormant, or die. They are eventually only able to produce fine, short “vellous” hair, similar to “peach fuzz”. This is a process called miniaturization, and the result is visible thinning or balding on the scalp.
In women, the pattern of hair loss most often occurs around or after menopause, but can also begin in young adulthood. The most common pattern of loss experienced by women is diffuse thinning on the top of the head, with little change in the frontal (forehead) hairline. (Ludwig pattern)
Ludvig Chart – Female
In men, hair loss may begin at any age, often as young as the late teens or early 20s. The most common pat-tern of loss is the Norwood Pattern, in which the frontal and temporal hairline recedes, and the crown starts to thin as well, until gradually the entire top of the scalp can become bald. Alternatively, many men experience thinning similar to the Ludwig Pattern. This process can occur rapidly over a period of years, or slowly over decades.
There are certain medical conditions that can lead to hair loss, including thyroid irregularities, medications, infections, iron deficiency, and extreme stress, but 95% of adult hair loss is caused by Androgenetic Alopecia.
Norwood Chart – Male