There are a number of conditions that may cause<unk>  and the first step is to determine the pattern: focal or diffuse. The next step is to identify if the hair loss is scarring or<unk>  scarring. A history and physical examination is necessary as this will provide clues to the ultimate diagnosis. It is essential to ask about the onset, observed pattern, hairstyles, family history, diet, and social history. Diffuse: * Androgenetic alopecia: history of gradual thinning of hair and characteristic pattern. Males start to lose hair in the front and temples while females lose hair at the top of the head * Diffuse alopecia areata: exclamation point hairs * Alopecia totalis: concomitant loss of facial and skull hair * Telogen effluvium: history of emotional or physiologic stress * Anagen effluvium: history cancer treatments such as radiation and alkylating agents * Dermatopathia pigmentosa reticularis: genetic autosomal dominant condition Focal: * Alopecia areata: smooth and round lesions * Tinea capitis: black dots with broken hair strands, may see red, scaly lesions and swollen lymph nodes on the back of head. * Traction alopecia: history of tight hairstyles and marginal hairline * Trichotillomania: history of pulling hair or evidence of traumatic follicles Pull Test This test is performed to estimate the severity of hair loss and refine the differential diagnosis. A clinician grabs sections of hair and observes for active hair loss. A positive pull test is usually caused by telogen effluvium, androgenetic alopecia, and alopecia areata. Tug Test A doctor holds the top and bottom of a strand of hair and observes for a break in the middle which may be caused by a hair shaft abnormality. Card Test A part in the hair is created and a small card is placed to contrast the color of the hair and visualize thin strands of hair (seen in telogen effluvium) vs short broken strands (seen in hair shaft abnormalities). Fungal Culture Scalp is scraped and the specimen is incubated for fungal growth commonly seen in tinea capitis. Scalp biopsy If the diagnosis of hair loss is unclear or not responsive to the treatment, a scalp biopsy may be required. Scalp biopsy will show evidence of inflammation, location, and change in the follicles. This will frequently refine the diagnosis. Blood Tests In the case of suspected iron deficiency, thyroid disease, or androgen excess a blood test may be necessary to rule in these causes. Trichoscopy A new technique which allows for magnified visualization of the hair and scalp, providing a high definition, detailed look at follicles.
Non scarring hair loss
Scarring hair loss
Pattern hair loss
Prepubertal hypertrichosis
Generalized lentiginosis
Auricular hypertrichosis
Hypertrichosis
Premature greying of hair