Causes and risk factors

ANDROGENIC ALOPECIA

 Genetically determined ( reason:Inheritance ) 95%for men and 75% for women

Development is related to age and presence of androgenic hormones/receptors
Alopecia areata:Although exact etiology is unknown, there is a genetic predisposition, and consensus favors an autoimmune response
Telogen effluvium:Normal hair cycle is interrupted so that anagen (growing) hairs are abruptly converted into telogen (resting) hairs, which are subsequently shed after 2 to 4 months
Hypothyroidism and hyperthyroidism
Postpartum, post-illness
Surgery with general anesthesia
Nutritional deficiency, particularly with iron or zinc
Psychological stress
Most telogen effluvium from medications is caused by retinoids, β-blockers, calcium channel blockers, antidepressants, and nonsteroidal anti-inflammatory drugs (including ibuprofen)
Tinea capitis:Ringworm of the scalp in which dermatophyte fungus invades the hair shaft. The most likely dermatophytes include Microsporum (from cats and dogs)

RISK FACTORS

1.Family history of baldness 2.Advanced age 3.Physical stress 4.Psychological stress 5.Pregnancy 6.Regular use of aggressive hair-styling techniques 7.Poor nutrition 8.Rapid weight loss 9.Restrictive diets (eg, low carbohydrate, low fat) 

Epidemiology

Incidence and prevalence:
About 25% of men aged 25 years have some degree of clinically apparent androgenic alopecia
About 42% of men develop androgenic alopecia
About 2% to 3% of the general population develops alopecia areata