Alopecia

Alopecia (hair loss) has many causes. These can be broadly divided into scarring and non-scarring.

Causes of scarring alopecia:

• Radiation
• Burns
• Systemic disease
• Discoid lupus erythematosus
• Sarcoidosis
• Lichen planus
• Necrobiosis lipoidica diaticorum
• Infection
• Fungal
• Bacterial
• Neoplasm
• Basal call carcinoma
• Squamous cell carcinoma

Causes of non-scarring alopecia:

• Alopecia areata
• believed to be an autoimmune condition
• ‘patches’ of hair loss
• 50% of patients have regrowth within a year
• associated with
• thyroid disease
• vitiligo
• if complete loss of all hair on scalp = alopecia totalis
• if complete loss of all body hair = alopecia universalis
• Adrogenic 
• 50% of white men by age 50
• Treat with topical minoxidil or oral finasteride
• Traction alopecia
• Trichotillomania
• Telogen effluvium
• Anagen-phase hair follicles prematuraurely move to the telogen phase, resulting in increased hair loss 
• Causes:
• Pregnancy
• Chronic systemic illness
• Syphilis 
• Renal failure
• Liver failure
• Surgical trauma
• Systemic lupus erythematosus
• Thyroid disease – hyper or hypothyroidism
• Deficiency
• Iron
• Zinc
• Vitamin D
• Tinea capitis
• Drugs
• Anticoagulants
• Anticonvulsants
• ACE-i
• Lithium
• Beta blockers
• OCP

References:

Harrison, S. and Bergfeld, W. Diffuse hair loss: its triggers and managament. Cleve Clin J Med. 2009; 76(6): 361-367.

Mounsey, A. and Reed, S. Diagnosing and treating hair loss. Am Fam Physician. 2009; 80(4): 356-362.

Thiedke, C. Alopecia in women. Am Fam Physician. 2003; 67(5): 1007-1014.