The interaction between the triad of, hereditary factors, male hormones, and age plays an important role in causing baldness in males. In females it is the change in the hormone levels at menopause, stress (both physical and mental), poor nutrition and ill health, which are responsible for hair loss. Damage to the follicles caused by injury, burns etc, certain medications can also lead to hair loss.
- Male pattern baldness: Male-pattern hair loss (MPHL), also known as androgenic alopecia, is hair loss that occurs due to susceptibility of hair follicles to shrinkage due to the influence of androgenic hormones. It usually includes either a receding hairline, hair loss at the crown, or charecteristic M pattern followed by horseshoe pattern
- Female pattern baldness: In women, hair loss usually includes uniform thinning across the scalp, with a preserved hairline. The crown may be affected, but hair loss rarely proceeds to baldness as in men.
- Telogen effluvium: is probably the second most common form of hair loss dermatologists see. TE appears as a diffuse thinning of hair on the scalp, which may not be even all over. Most often, the hair on top of the scalp thins more than it does at the sides and back of the scalp. There is usually no hair line recession, except in a few rare chronic cases. TE is seen post prolonged illness, malnutrition and a period of stress and recovers spontaneously with improvement of underlying condition
- Alopecia Areata: Round patches of total hair loss, usually from the scalp. The cause of alopecia is believed to be autoimmune.
- Tinea capitis (ringworm): A fungal infection of the scalp, creating round patches of hair loss. Although the patches can appear in a ring shape, no worm is involved in tinea capitis.
- Trichotillomania: A mental disorder that includes the irresistible urge to pull out one's hair. The hair pulling results in patches of noticeable hair loss; its cause is unknown.
- Postpartum alopecia- hair loss post child birth- is a form of telogen effluvium and usually resolves without treatment.
- Piedra (trichomycosis nodularis): Fungal infection of the hair shaft. Hard nodules made of fungus cling to hair fibers, sometimes causing hair loss.
Male-pattern and female-pattern hair loss do not generally require testing as they are not usually associated with an increased loss rate.
Following are few methods to determine hair loss:
- The pull test helps to evaluate diffuse scalp hair loss. Gentle traction is exerted on a group of hairs (about 40–60) on three different areas of the scalp. The number of extracted hairs is counted and examined under a microscope. Normally, fewer than three hairs per area should come out with each pull. If more than ten hairs are obtained, the pull test is considered positive.
- The pluck test is conducted by pulling hair out "by the roots". The root of the plucked hair is examined under a microscope to determine the phase of growth, and is used to diagnose a defect of telogen, anagen, or systemic disease. Telogen hairs have tiny bulbs without sheaths at their roots. Telogen effluvium shows an increased percentage of hairs upon examination. Anagen hairs have sheaths attached to their roots. Anagen effluvium shows a decrease in telogen-phase hairs and an increased number of broken hairs.
- Scalp biopsy is used when the diagnosis is unsure; a biopsy allows for differing between scarring and non-scarring forms. Hair samples are taken from areas of inflammation, usually around the border of the bald patch.
- Daily hair counts are normally done when the pull test is negative. It is done by counting the number of hairs lost. The hair from the first morning combing or during washing should be counted. The hair is collected in a clear plastic bag for 14 days. The strands are recorded. If the hair count is >100/day, it is considered abnormal except after shampooing, where hair counts will be up to 250 and be normal.
- Trichoscopy is a noninvasive method of examining hair and scalp. The test may be performed with the use of a handheld dermoscope or a video dermoscope. It allows differential diagnosis of hair loss in most cases.
The Ludwig Scale
The Savin Scale
Both track the progress of diffused thinning, which typically begins on the crown of the head behind the hairline, and becomes gradually more pronounced.
For male pattern baldness, the Hamilton–Norwood scale tracks the progress of a receding hairline and/or a thinning crown, through to a horseshoe-shaped ring of hair around the head and on to total baldness.