Nail and hair disorder

Hair and nail disorder is something that is not very well covered in medical school. I don't even know where to start. I am hoping to have a simple approach to common hair and nail disorders which come through the door. Below is my attempt to understand hair and nail disorders a little more.

I found that John Murtagh's General practice to be a good point to start esp. the key facts and checkpoints:

• There are two types of hair: terminal hair, which is coarse and well pigmented and vellum hair, which is fine, soft and relatively unpigmented. 
• Alopecia is a generic term for hair loss
• Hair loss (alopecia) generates considerable anxiety and the fear of total hair loss should be addressed with the patient and a realistic prognosis given. 
• Androgenic alopecia is the most common cause of human hair loss, affecting 50% of men by age 40 and up to 50% women by age 60
• In telogen effluvium, the traumatic event has preceded the hair loss by about 2 months (peak loss at 4 months)
• Although severe stress could precipitate alopecia areata, day to day stressors are not considered to be a trigger. Stress seems to be a consequence of alopecia rather than the cause of it 
• Hair loss can be patchy or diffuse where it involves the entire scalp. 
• Patchy loss - alopecia aerate and trichotillomania 
• Generalised loss - telogen effluvium, systemic disease, drugs
• Alopecia areata has a poor prognosis if it begins in childhood, if there are several patches and there is loss of eyebrows or eyelashes. 
• Scarring alopecia can be an indicator of lupus erythematousus or lichen planus

Causes of diffuse hair loss

• Androgenetic alopecia
• Telogen effluvium
• Postpartum telogen effluvium 
• Alopecia areata 
• Drugs - cytotoxic and others
• Hypothyroidism
• Nutritional 
• Iron deficiency 
• Severe dieting
• Zinc deficiency
• Malnutrition 
• Post febrile state
• Anagen effluvium

Reference:

John Murtagh's general practice 5th edition