1. Androgenetic Alopecia or Male and Female Pattern Hair Loss
Androgenetic alopecia is the most common type of hair loss. It is caused by an interaction of a person’s genetic makeup and hormonal influences. Thinning and baldness occur in scalp hair progressively over time. The hairs become smaller and more fine through a process called miniaturization.
Miniaturization involves the hormone Testosterone that is circulating in our body. In the scalp it is converted into Dihydrotestosterone (DHT). DHT binds hair follicles that are sensitive to it and causes changes to the hair cycle. Over time, the hairs shrink until there is little or no hair visible.
2. Alopecia Areata
Alopecia areata is a type of nonscarring hair loss thought to be caused when the body’s immune system attacks it’s own hair. It is a recurrent disease and can occur in any hair-bearing area. The most common presentation is a round or oval patch of hair loss often on the scalp. It can progress to involve large areas of scalp or even body hair. Alopecia areata can resolve on it’s own and treatments involve topical or injected steroids and minoxidil.
3. Telogen Effluvium
Telogen Effluvium is a type of hair loss when a large percentage of scalp hairs are shifted into telogen or the “shedding phase” of hair growth. Reasons for this shift can be hormonal, nutritional, medication, or stress related.
4. Anagen Effluvium
Anagen Effluvium is a type of hair loss in which hair follicles in the anagen or “growth phase” are abnormally lost. Medications, such as chemotherapy are a common cause due to their direct toxic effects on the rapidly growing anagen hairs.
5. Metabolic abnormalities
Nonscarring hair loss can be due to abnormal metabolic conditions such as iron defieciency, thyroid disease, and polycystic ovarian syndrome. These conditions should be screened for in certain patients.
6. Trauma (Traction alopecia and Trichotillomania)
Traction alopecia is a type of traumatic hair loss resulting from a constant pulling on the hair. This may lead to temporary hair loss or over time a more permanent hair loss. Braiding and tight ponytails can lead to inflammation, broken hairs, and loss of hair. It is more common with African hair styles.
Trichotillomania is a form of traction alopecia due to the irresistible compulsion to pull one’s hairs out, causing significant psychological stress. Any body hair may be affected but scalp hair is most common. The peripheral border of hair is usually not affected and the area(s) of alopecia often show multiple, broken off hairs in irregular patches with varying lengths. Patients should have evaluation for treatment with medications used for obsessive-compulsive disorder and for behavior modification strategies.
7. Scarring Hair Loss
Scarring hair loss can be due to a variety of causes. The scarring leads to permanent hair loss. Traction alopecia and trichotillomania over time can lead to scarring. Burns or physical trauma can also lead to scarring. Other diseases that can lead to scarring alopecia include lupus, lichen planus, scleroderma, and infections.