Hair loss may be present in the family, highlighting genetic causes. Causes
Causes of noncicatricial alopecia can be separated based on focal or diffuse hair loss:Diffuse:

Androgenetic alopecia: androgenic DHT leads to catagenic miniaturization of hair follicles. Diffuse alopecia areata: diffuse autoimmune destruction of hair follicles
Alopecia totalis: unknown but thought to be autoimmune
Telogen effluvium: emotional or physiologic stress
Anagen effluvium: cancer treatments such as radiation and alkylating agents
Dermatopathia pigmentosa reticularis: genetic autosomal dominant conditionFocal:

Alopecia areata: autoimmune destruction of hair follicles
Tinea capitis: fungal infection
Traction alopecia: pulling force applied to hair
Trichotillomania (Trichotillosis)

Diagnosis
There are a number of conditions that may cause non scarring hair loss 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 non 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 conditionFocal:

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.
Female pattern hair loss is treated with spironolactone or flutamide that block the effects of DHT receptors.Anti-fungal
Topical anti-fungal treatments such as ketoconazole and pyrithione zinc shampoo are sometimes effective for male pattern hair loss. Topical therapy is not usually effective for tinea capitis for which oral therapy with terbinafine, fluconazole, or griseofulvin is superior.PRP
Patients may benefit from injections of plasma into the scalp to promote the delivery of nutrients in the plasma to the hair follicles. This has been shown to promote growth, blood supply, and collagen production.Surgical
The two common surgical methods to treat hair loss are hair transplantation and scalp reduction. Hair transplantation involves the transfer of intact growing hair follicles from areas such as the back of the head to balding spots. This occurs in multiple visits as the number of transplanted follicles increased to restore a natural look. Scalp reduction is a technique that removes balding spots of skin and stretches the remaining skin that has normal hair growth. This is typically only possible in the back and top of the head and may cover up to half of the balding area. Prognosis
It is important to note that treatment response to hair loss may be unpredictable and variable depending on the cause. 8.5% of patients with alopecia totalis may achieve complete recovery. Certain conditions such as tinea capitis and trichotillomania usually respond once the infection or hair pulling behaviors are stopped. Despite this many patients will achieve at least a temporary or partial recovery of hair loss.