Hair loss

Hair loss, or alopecia, is a very common presenting symptom, and more than one third of women have clinically significant hair loss during their lifetime. The effect of hair loss on patients’ emotions is often greatly underestimated by physicians. After bone marrow, hair is the second fastest growing tissue of the body. As a result, many different metabolic changes can manifest as hair loss being  the first clinical sign of systemic disease.


Hair Biology 
The scalp contains, on average, 100,000 hairs. More than 90% of these hairs are actively growing (anagen hairs). Anagen hairs are anchored deeply into the subcutaneous fat and cannot be pulled out easily. Hair is constantly cycling and regenerating on the scalp. Each hair shaft can persist on the scalp for 3 to 7 years before falling out and being replaced by a new hair. This anagen phase is followed by a 2-week phase of catagen, during which there is programmed cell death; the trigger factor for catagen phase is unknown. After catagen, the hair goes into telogen, a resting phase that lasts about 3 months. As compared with anagen hair, telogen hair is located higher in the skin and can be pulled out relatively easily. Normally, the scalp loses approximately 100 telogen hairs per day. In addition to the ratio of anagen hair to telogen hair, the diameter of the hair follicles determines scalp coverage. Vellus hairs have a hair-shaft diameter of less than 0.03 mm and terminal hairs have a diameter greater than 0.06 mm. The optimal hairs for scalp-hair growth and scalp coverage are anagen and terminal hairs. 

Hair loss key points: 
  • Determining the cause or causes of hair loss in women can be difficult and should be guided by the patient’s history
  • There are numerous possible causes for hair loss
  • Thyroid disease is not the most common cause of hair loss

Causes of Hair Loss Hair loss 
1. Scarring (which occurs in discoid lupus, lichen planopilaris, and folliculitis decalvans). Patients should see a dermatologist about this type of hair loss
2. Non-scarring (see below)

Androgenetic alopecia 
This is the most common cause of such hair loss, female-pattern hair loss. The role of male hormones like androgens in this type of non-scarring hair loss remains unclear.  This condition often runs in families. Female-pattern hair loss can develop any time after the onset of puberty. By age 70 years of age, 38% of women have female-pattern hair loss.  It affects the central portion of the scalp, sparing the frontal hairline.  Male patterns of hair loss may be associated with hyperandrogenism, but the majority of women with female-pattern hair loss have normal serum androgen levels.

Telogen Effluvium
This is another VERY common cause of non-scarring hair loss. This results from an abrupt shift of large numbers of anagen hairs to telogen hairs on the scalp, with a corresponding change in the ratio of anagen hair to telogen hair from the normal ratio of 90:10 to 70:30. It is not unusual for women with telogen effluvium to lose more than 300 hairs per day. This form of alopecia generally begins approximately 3 months after a major illness or other stress (e.g., surgery, parturition, rapid weight loss, nutritional deficiency, high fever, or hemorrhage) or hormonal derangement (e.g., thyroid dysfunction); it has also been reported after the initiation of treatment with certain medications. Chronic telogen effluvium refers to hair loss lasting more than 6 months. In some patients, this type of hair loss lasts for years.
Associated (non exhaustive list) drugs
Acetretin, heparin, interferon alfa, isotretinoin, lithium, ramipril, terbinafine, timolol, valproic acid, warfarin >5 Acyclovir, allopurinol, buspirone, captopril, carbamazepine, cetirizine, cyclosporine, gold, lamotrigine, leuprolide, lovastatin, nifedipine 1–5 Amiodarone, amitriptyline, azathioprine, dopamine, naproxen, omeprazole, paroxetine, prazosin, sertraline, venlafaxine, verapamil

Anagen Effluvium
This is hair loss associated with chemotherapeutic agents that cause immediate destruction and release of anagen hair. If the cause of telogen effluvium is removed, hair loss lasts for up to 6 months after removal of the trigger. 
Associated (non exhaustive list) drugs
Bleomycin, busulfan, cisplatin, cyclophosphamide, daunorubicin, doxorubicin, fluorouracil, vasopressin, vinblastine, vincristine

Alopecia Areata
This is a less frequent cause of nonscarring hair loss. The estimated lifetime incidence of this condition is 1.7%. 11 It is usually manifested as round patches of alopecia that may become multifocal and may coalesce into large areas. This is frequently reversible, but it tends to be recurrent, and it can progress to total loss of scalp hair (alopecia totalis) in 5% of women and total loss of body hair (alopecia universalis) in 1% of women. The cause is unknown, but it is thought to be autoimmune. 

Other causes of nonscarring alopecia are certain 
1. Hair-care practices 
2. Compulsive hair pulling (trichotillomania), 
3. Severe bacterial infections
4. Fungal infections like tinea capitis,
5. In some cross-sectional studies, iron deficiency and reduced iron levels have been associated with hair loss, including female-pattern hair loss and telogen effluvium, but data are limited. 

  • Ferritin level to rule out iron deficiency (particularly in menstruating women, vegetarians, and women with a history of anemia) . Generally If the ferritin level is less than 70 ng per milliliter, iron supplementation is recommended.
  • TSH blood testing to rule out thyroid dysfunction in women with diffuse hair loss, although the yield of such universal testing has not been proved. 
  • In women with female-pattern hair loss and other conditions suggesting androgen excess (e.g., hirsutism, acne, or irregular menses), assessment of male hormones like free testosterone is done. 
  • Also check for Syphilis. 
  • If fungus is suspected, scale from the area of alopecia should be examined by a dermatologist