The most common causes of hair loss among women

The most common causes of hair loss among women
The most common causes of hair loss among women

The real or perceived symptom of increased hair loss can be psychologically devastating for female patients. This article is intended as a brief review of the most common causes of adult female alopecia and a thorough introduction to the evaluation of this complaint in the primary-care setting. Bear in mind that many women who experience hair loss will still require referral to a dermatology practice.


Hair follicles constantly cycle through three phases: (1) anagen—the growth phase; (2) catagen—the phase transitioning between growth and resting; and (3) telogen—the resting phase. It is normal to lose as many as 100 hairs per day.

Women who present with excessive hair loss must undergo a detailed and extensive history and thorough examination of the hair, with the clinician paying special attention to the pattern of loss and how easily the hair pulls out. The clinician also must order blood tests and examine the scalp. In some cases, pathologic analysis of a scalp biopsy may be necessary. 



The initial examination


The following information should be obtained as part of the patient history of a woman who is experiencing hair loss:



  • Duration and pattern of hair loss

  • Whether the lost hair is broken or intact

  • Current diet and any change in weight within the past six months

  • Any surgeries in the past six months

  • All medications (current and taken within the past six months)

  • Any illnesses or infections within the past six months

  • Any other symptoms (a full review of systems)

  • Whether she has ever experienced similar hair loss before

  • A family history of hair loss and other medical conditions (e.g., metabolic disorders)

  • Date of most recent menstrual period

  • Normal hair and beauty routine. 



A thorough physical examination should discern the pattern and distribution of hair loss. Assess all areas of body hair, including eyebrows, eyelashes, arm hair and pubic hair. The scalp should be assessed for erythema, flaking, or scaring. Firmly grasp approximately 60 hairs and pull. If fewer than six hairs come out, this is considered normal shedding (or a negative pull test); six hairs or more is considered a positive pull test.

Special attention should be paid to how easily the hairs break. Easily breakable hair may suggest hair damage caused by overprocessing. Overprocessing can include heat damage from curling irons, straightening, perms, or hair coloring. The diagnosis for this type of hair loss is traumatic alopecia. Pulling from braids, tight hair buns, ponytails, or hair extensions can cause traction alopecia. The treatment for such hair loss is discontinuation of the beauty regimen, addition of biotin supplementation, and adoption of a healthy diet. Other forms of female hair loss to be considered in the differential are listed in Table 1.


Table 1. Differential diagnosis for female hair loss

Alopecia areata
Cicatricial alopecia (scarring alopecia)
Female pattern hair loss (androgenic alopecia)
Telogen effluvium
Traction alopecia
Traumatic alopecia
Trichotillomania
Underlying correctable skin condition (e.g., seborrheic dermatitis or psoriasis)
Underlying endocrine abnormality (e.g., hyperandrogenemia or thyroid dysfunction)

In searching for an underlying endocrine abnormality, such as hyperandrogenemia or thyroid dysfunction, blood work should include a complete blood count with differential, serum iron, serum ferritin, thyroid-stimulating hormone (TSH), free thyroxine (T4), antinuclear antibodies, free testosterone, prolactin, 17-hydroxy progesterone, cortisol level, and dehydroepiandrosterone sulfate.



Androgenic alopecia


The terms androgenic alopecia and female pattern hair loss may be preferable to female pattern baldness. The word "baldness" may lead to unnecessary panic on the part of the patient. Androgenic alopecia describes hair loss caused by genetically determined sensitivity of hair follicles in the scalp to adult levels of androgens.

Androgenic alopecia is the most common cause of hair loss in adult women.1 The diagnosis is made by ruling out other possible diagnoses through lab work, recognition of the distinctive pattern of hair loss (Figure 1), and pathologic analysis of a punch biopsy. The biopsy should be full-thickness (at least 4 mm) sectioned horizontally.

Include the differential on the requisition slip that you want to distinguish (e.g., "androgenic alopecia rule out telogen effluvium or alopecia areata"). A sample of at least 6 mm is required to ensure that hair follicles at several stages of the growth cycle are present. Ideally, a dermatopathologist as well as a clinician who is experienced in analyzing hair biopsies should read the hair pathology. For this reason, it may preferable to have the biopsy performed by a local dermatologist who has a working relationship with different pathologists.

The pathology is particularly important because androgenic alopecia has a classic presentation of miniaturization of terminal pigmented anagen hairs to fine hypopigmented vellus hairs.


Treatment options include topical OTC minoxidil 2% (Rogaine, Theroxidil) applied twice a day1 or hair transplanation. Minoxidil increases the length of time follicles spend in anagen, wakes up follicles in catagen, and enlarges the actual follicles. The most common side effect associated with minoxidil is irritant dermatitis, which is most likely attributable to the vehicle and stabilizers rather than the active ingredient. Unwanted hair growth may be seen in other places on the body. Women who are pregnant or breastfeeding should not use minoxidil, as it can cause hypertrichosis in infants.

Patients must use minoxidil for at least four to six months to evaluate efficacy. Many patients report that minoxidil does not lead to new hair growth but simply slows the rate of hair loss. Use of the product must be continued for as long as the patient wishes to sustain the results.


Hair transplantation is a cosmetic procedure performed in the office under local anesthesia. Hair from the uninvolved area is transplanted to the area with loss. Disadvantages of this treatment option include cost and the appearance of the final result.



Telogen effluvium


Hairs are normally shed in the telogen phase. Telogen effluvium is a scalp disorder characterized by increased shedding of undamaged hairs in the telogen phase in response to a change in health status. The process that tells the hair when to enter the anagen, telogen, and catagen phase is complex.

In individuals with telogen effluvium, some external factor instructs an abnormally large number of hairs to enter the telogen phase and subsequently be shed (Figure 2). These external factors include, but are not limited to, medications, pregnancy, malnutrition and stress (Table 2).2 Since it can take up to three months for the hair loss to start or become noticeable, a thorough medical, psychological and surgical history must cover at least the past six months.


Table 2. Common causes of telogen effluvium

Childbirth, pregnancy, or miscarriage
Chronic illness (e.g., HIV, lupus)
Endocrine abnormality (e.g., hypothyroidism, hyperthyroidism, hyperparathyroidism)
Malnutrition
Medications (e.g., retinoids, high-dose vitamin A, anticoagulants [especially heparin], antithyroids, anticonvulsants, interferon, heavy metals, and beta-blockers)
Post-febrile/post-infection
Post-surgery
Psychological stress
Rapid weight loss following a crash diet or bariatric surgery
Discontinuing oral contraception

The diagnosis of telogen effluvium is one of exclusion combined with analysis of the hair-loss pattern, lab results, and patient history. Laboratory work should include thyroid and chemistry panels, erythrocyte sedimentation rate, antinuclear antibody, and a complete blood count with differential, hematocrit, and ferritin tests. If possible, stop the offending agent/medication or correct the underlying abnormality.

Consider recommending counseling and or medication if psychological stress is the underlying cause. The "tincture of time" (that is, waiting for the body to normalize) may be the best bet for a patient recovering from a change in his or her health status. Make sure the patient is otherwise healthy, eating a balanced diet, taking a multivitamin containing very little or no vitamin A (too much vitamin A can cause hair loss), and 5 mg/day of OTC biotin, which has been shown to accelerate hair growth and thicken existing hair. 



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