"Hair follicles grow in a nonsynchronized fashion. Approximately 85% to 90% of scalp hair follicles are in anagen, 10% to 15% in telogen, and fewer than 1% in catagen. Scalp hair grows approximately 0.35 mm/d or 1 cm/mo. With 100,000 to 150,000 hairs on the scalp, the daily output of hair keratin protein is an impressive 35 m (0.35 mm/d × 100,000 hairs). Average normal daily scalp hair loss in an adult is 40 to 100 hairs on a nonshampoo day and 200 to 300 hairs on a shampoo day. Each hair that is shed is replaced by a new hair."
How to Diagnose Hair Loss
Dermatologic Clinics, 2013-01-01, Volume 31, Issue 1, Pages 21-28, Copyright © 2013 Elsevier Inc.
This review presents a systematic approach to the diagnosis of hair loss. An accurate diagnosis is based on history, clinical examination, laboratory tests, and scalp biopsy. Whether the hair loss is a cicatricial or noncicatricial alopecia guides one's history taking. After assessing the patient's global appearance, the hair and scalp are evaluated, aided by a hair pull, hair tug, Hair Card, and hair mount. Scalp biopsies can confirm a diagnosis and are essential in all cases of cicatricial alopecia. In all patients with hair loss a complete blood count, ferritin, thyroid stimulating hormone, and vitamin D 25OH should be ordered.
Key Points
- • At the start of the interview, evaluate for the presence or absence of follicular orifices, because history taking will be guided by whether the problem at hand is a noncicatricial or cicatricial alopecia.
- • Determine whether the main issue is hair coming out “by the roots” or whether hair breakage is the main problem, because this will also guide the direction of history taking.
- • For the clinical examination, position the patient with a hair problem in a chair, not on the examination table, to see the hair and scalp from above, and use magnified lighting from a close light source such as a portable magnifying lamp or a dermatoscope; daylight from a window or a lamp on the ceiling is not sufficient for the hair and scalp examination.
- • The Hair Card, a 3 × 5-inch card, white on one side and black on the other, with a centimeter ruler along one edge, demonstrates new hair growth and miniaturized hair, and differentiates new hair from broken hair; the ruler portion is used for measuring length of new growth, temporal recession, and dimensions of hair loss.
- • A scalp biopsy is the essential first step if a cicatricial alopecia is suspected, taken at or just beyond an active area of inflammation where hairs are still present, not a bare area.
Introduction
The hair follicle cycle is key to understanding hair loss because all causes of hair loss affect the hair cycle in some manner. The anatomic site of hair determines its size, and the diameter is determined by the size of the matrix. The 3 main phases of the hair follicle cycle include: (1) anagen or growth phase, which lasts 2 to 6 years; (2) catagen or involution phase, which lasts 2 to 3 weeks; and (3) telogen or resting phase, which lasts 2 to 3 months. The duration of anagen determines the hair length.
Hair follicles grow in a nonsynchronized fashion. Approximately 85% to 90% of scalp hair follicles are in anagen, 10% to 15% in telogen, and fewer than 1% in catagen. Scalp hair grows approximately 0.35 mm/d or 1 cm/mo. With 100,000 to 150,000 hairs on the scalp, the daily output of hair keratin protein is an impressive 35 m (0.35 mm/d × 100,000 hairs). Average normal daily scalp hair loss in an adult is 40 to 100 hairs on a nonshampoo day and 200 to 300 hairs on a shampoo day. Each hair that is shed is replaced by a new hair.
Evaluating the patient
History
At the start of the interview, evaluate for the presence or absence of follicular orifices. Whether the problem at hand is a cicatricial (scarring) or noncicatricial alopecia guides history taking. The majority of this discussion focuses on noncicatricial alopecia, which accounts for most problems concerning hair loss.
Box 1 outlines the key features of history taking. Early in the interview, attempt to differentiate whether the hair is coming out “by the roots” or whether hair breakage is the issue. If the hair is coming out by the roots, ask whether the main concern is increased shedding or increased thinning. The patient's medical history, particularly 6 to 12 months before the onset, may be relevant for increased shedding; for example, febrile illnesses, hospitalizations, surgeries, and traumatic events. Inquire about a family history of the same type of condition (androgenetic alopecia or alopecia areata) or associated conditions (family history of autoimmune diseases in alopecia areata). In a patient with androgenetic alopecia, ask about thinning hair in each family member. Ask patients whether they eat a balanced diet and, if they are vegetarian, ask the source of their dietary protein. Hair is composed of approximately 98% keratin protein, and the average adult produces approximately 35 m of hair keratin protein per day (0.35 mm/d × 100,000 hairs), which emphasizes the importance of daily protein intake.
BOX 1
- Age of onset
- Duration
- Is hair coming out by the roots or is it breaking?
- Increased shedding or increased thinning?
- Medications
- Past health
- Family history
- Diet: is there adequate protein or iron intake?
- Menses, pregnancies, menopause
- Hair care/hair cosmetics
- Occupation and hobbies
Medical history
In female patients, assess menses, pregnancies, and menopause. Does she have a menstrual period every month, for how many days, and how heavy is her menstrual flow? Does she have a history of infertility or miscarriages? Postpartum effluvium occurs 1 to 3 months after delivery, but does not necessarily occur after every pregnancy in a given patient. With menopause, hormone replacement with progestins that have androgenic metabolites, or testosterone, may aggravate or cause hair loss, as does removal of both ovaries.
Hair coming out by the roots
Common causes of hair coming out by the roots are shown in Box 2 . Distinguish whether there is increased shedding or increased thinning. Interest is focused on increased shedding that involves excessive hair drop-out on nonshampoo days. The sudden onset of markedly increased hair shedding is typical of telogen effluvium, and may last up to 6 months. In contrast, increased thinning implies less and less coverage and a more visible scalp, and may not be associated with increased shedding. Keep in mind that hair density has to decrease by more than half before there is noticeable hair thinning ( Fig. 1 ). Increased thinning is typical of androgenetic alopecia and age-related thinning.
BOX 2
- Telogen effluvium
- Alopecia areata
- Androgenetic alopecia
- Hair loss due to oral contraceptives
- While taking oral contraceptives
- After stopping oral contraceptives
- Syphilitic alopecia
Differential diagnosis of hair coming out by the roots
Hair density has to decrease by more than half before there is noticeable hair thinning.
Oral contraceptive pills (OCP) may cause hair loss either while taking the OCP or after stopping the OCP. Taking progestins with androgenic metabolites, or testosterone, may cause increased thinning, particularly in women predisposed to androgenetic alopecia. Hair loss after stopping OCP can simulate postpartum effluvium and can occur after stopping any OCP.
Sometimes it is difficult to assess a patient's concern about shedding, and in this situation hair collections are used. Ask patients to collect all hairs shed on a nonshampoo day, from the time they wake up until bedtime, and to place the hairs in a plastic bag that is dated. Collections are repeated once every 2 weeks over an 8-week period, and the 4 collections mailed to the clinician. The patient's hair length must be documented ahead of time so that the volume of hair collected can be properly assessed. On a nonshampoo day, average daily hair loss is 40 to 100 hairs and on a shampoo day, 200 to 300 hairs. Do not count the hairs but rather make a visual estimate of each day's collection.
Hair breakage
Increased hair breakage implies increased hair fragility. The Hair Card, discussed later in this article, demonstrates whether the distal ends are tapered, as with new growth ( Fig. 2 ), or whether they are blunt or straight, which indicates hair has been cut or broken ( Fig. 3 ). Common diagnoses associated with hair breakage are noted in Box 3 . The hallmark of tinea capitis is scalp scaling in an area of hair breakage. When tinea capitis is suspected, ask if schoolmates or other family members (such as grandmothers!) are affected. Trichotillomania, on the other hand, is not the result of innate fragility but rather of an extrinsic cause of hair breakage, such as a patient pulling or breaking hair. Hair-care practices and use of hair cosmetics do not cause significant hair breakage when carried out properly and according to directions. However, when done improperly they can cause damage and breakage. Examples of improper hair care practices include excessive heat used too frequently; bleaching, chemical relaxers, and permanent waves that are left on too long, or used too frequently; or chemical relaxers and permanent waves applied on the same day as hair coloring. Some individuals undoubtedly have a greater susceptibility to breakage than others.
The Hair Card demonstrating tapered ends, which indicates new hair growth.
A white background demonstrating blunt ends, which indicates hair has been cut or broken.
BOX 3
- Tinea capitis
- Trichotillomania
- Improper hair care and/or hair cosmetics
- Anagen arrest
- Structural hair-shaft anomalies
Differential diagnosis of hair breakage
Chemotherapeutic drugs including antimetabolites, alkylating agents, and mitotic inhibitors temporarily arrest mitotic activity in rapidly dividing cells. Because the cells of the hair matrix of anagen hairs contain rapidly dividing cells, mitotic arrest results in narrowing of the hair shaft. When the narrowed segment of hair shaft reaches the scalp surface, the hair breaks off. Because 85% to 90% of scalp hairs are in anagen phase, approximately 85% to 90% of hairs will break off. This impressive breakage occurs 1 to 3 weeks after chemotherapy is administered ; this is referred to as anagen arrest rather than anagen effluvium ( Fig. 4 ).
Anagen arrest with chemotherapy. Mitotic arrest narrows the shafts and hairs break when they reach the scalp surface.
Box 4 includes a list of structural hair-shaft anomalies, divided into those with increased fragility and those without increased fragility. This discussion does not permit a detailed review of these anomalies.
BOX 4
Hair-Shaft Disorders with Increased Fragility
- Acquired
- Bubble hair
- Acquired trichorrhexis nodosa
- Congenital
- Congenital trichorrhexis nodosa (arginosuccinic aciduria)
- Monilethrix
- Pili torti (Björnstad, Menkes)
- Trichorrhexis invaginata (Netherton syndrome)
- Trichothiodystrophy
Hair-Shaft Disorders Without Increased Fragility
- Congenital
- Pili annulati
- Pseudopili annulati
- Woolly hair
- Uncombable hair syndrome
Structural anomalies of the hair shaft
Clinical Examination
Global examination
First, assess the global appearance of the patient ( Box 5 ). These findings may be visible across the room.
BOX 5
- Scalp visible?
- Full coverage?
- Distal ends skimpy?
- Intact frontal hairline?
- Hair loss diffuse or patchy?
- Pattern and distribution of hair loss?
- Hair curly or straight, color, length?
- Cystic acne, virilization?
Global examination
Close examination
Position all patients with hair problems in a chair, not on the examination table, to see the hair and scalp from above (unless you are 7 ft tall!). Use good lighting or a magnifying light for close inspection. Alternatively, a dermatoscope also provides magnification. The hair pull, hair tug, Hair Card, and hair mount are 4 simple tools that aid the assessment of a hair problem in the office ( Box 6 ). The authors find the Hair Card ( Box 7 , see Fig. 2 ) essential when examining hair.
BOX 6
- Pull test
- Tug test
- Hair Card
- Hair mount
- Scalp:
- Follicular markings present, diminished, or absent
- Skin-colored, white, peach-colored, or erythematous
- Perifollicular erythema, perifollicular scale, papules, pustules, crusting, telangiectasia, and tufting
- Hair elsewhere: too much or too little
Close examination
BOX 7
The Hair Card assists in the examination and visualization of hair on the scalp, brows, eyelashes, or elsewhere. The Hair Card is a 3 × 5-inch card, white on one side and black on the other, with a centimeter ruler along one edge. Any white background is a simple “make do” substitute, but will not help in the examination of white or blond hair.
What the Hair Card Does:
- Demonstrates miniaturized hair
- Demonstrates new hair growth
- Differentiates new hair from broken hair
- The ruler portion is used for:
- Measuring length of new growth
- Measuring temporal recession
- Measuring dimensions of area of hair loss
How to Use the Hair Card:
- A good light source directed at the hair is essential when using the Hair Card
- The black or white side is used to contrast with the color of the hair:
- If dark hair is examined, use white side
- If blond or white hair is examined, use black side
- To visualize the hair, place the blank (without any writing) portion of the card under or behind the hair to be examined (the larger the blank portion of the card, the more useful it is)
- Always place the Hair Card on the skin or as close to the skin surface as possible
To Demonstrate Miniaturized Hairs in Androgenetic Alopecia:
- Select a thinning site on the scalp
- Part the hair with your fingers
- Place the Hair Card on the part you have created, directly on the scalp surface
- A good light must be directed at the selected site
- New short growth will be apparent against the contrasting color of the Hair Card, and miniaturized (thin) hair is easily identified and contrasted with the new short growth of normal size (girth)
To Differentiate New Hair Growth from Broken (or Cut) Hair:
- Place the Hair Card under the distal ends of the hair in question
- New growth is easily identified because the distal ends are tapered or pointed
- Broken hair is easily identified because the distal ends are blunt or straight
To Measure Temporal Recession:
- Using the ruler side of the Hair Card, measure the distance from the lateral end of the brow to the apex of the temporal recession. In a male without temporal recession, this distance is approximately 7 to 7.5 cm
The Hair Card
To assess hair density, serially part the hair starting at the frontal hairline, note the spacing between hairs, and repeat the parts at 1-inch (2.5-cm) intervals. Compare the hair density over the frontal scalp with the density over the occipital scalp. Make note of general erythema, perifollicular erythema, perifollicular scale, papules, pustules, crusting, telangiectasia, and tufting. If pustules are present, take a bacterial culture. Determine if follicular markings are present or absent. With patchy hair loss, note the color of the scalp: is it skin-colored, white, peach-colored, or erythematous? If scaling is present in a bare patch, include tinea capitis in your differential diagnosis.
With patchy hair loss, it is useful to document the extent of hair loss for comparison at subsequent visits. Divide the scalp into 4 quadrants and estimate the area that all the alopecic patches placed together would occupy. The hair loss can be estimated as 0% to 25%, 26% to 50%, 51% to 75%, 76% to 99%, or 100%, and is a helpful reference for follow-up visits. Photographs are also useful to document the extent and distribution of hair loss. A diagram of the anatomic areas of the scalp is shown in Fig. 5 .
The anatomic areas of the scalp.
Pull test
A pull test is helpful in determining excessive hair shedding ( Fig. 6 ). At the scalp level, grasp 30 to 40 closely grouped hairs between the thumb and index finger. Pull the grouped hairs firmly but gently away from the scalp. Repeat at 3 different locations on the scalp. With alopecia areata, pull at the margin of a patch, over new hair growth, and randomly over unaffected scalp. If a pull test yields anagen hair (positive anagen pull test), suspect a primary cicatricial alopecia.
How to do a pull test.
Tug test
A tug test is useful in demonstrating hair fragility ( Fig. 7 ). In a tug test, grasp a cluster of hairs with one hand while the distal ends are pulled away with the other hand (like plucking feathers). Fragile hair breaks into small bits, which can be examined in a hair mount.
How to do a tug test to demonstrate hair fragility.
Hair mount
Light microscopic examination of hair is an easy office procedure, much like a potassium hydroxide (KOH) preparation, and often helps in diagnosis. Decide in advance if you want to look at hair bulbs or hair shafts. Telogen hair has no inner root sheath and the bulb has a distinctive club shape with reduced or absent melanin (Fig. 8 ). Anagen hairs, in contrast, are larger and have a dark pigmented bulb, and an inner root sheath ( Fig. 9 ). With hair breakage, the small broken hairs from a tug test are useful to show trichorrhexis nodosa (TN). This most common cause of acquired hair breakage shows the typical fracture and longitudinal splitting. In hair shaft anomalies associated with fragility, mount hair shaft segments to display the anomaly (see Box 4 ). In primary cicatricial alopecia, a pull test may extract anagen hairs, which then are mounted for confirmation. Figs. 4 , 9 , and 10 illustrate the 3 situations whereby anagen hairs may be easily extracted or affected.
Telogen hair when extracted has no inner root sheath, and the bulb has a distinctive club shape with reduced or absent melanin (Original magnification ×400).
Anagen hair has an inner root sheath and darkly pigmented bulb (Original magnification ×100).
Loose anagen hair with misshapen darkly pigmented bulb, short twisted segment immediately distal to the bulb, absent inner root sheath, and “ruffled” cuticle (Original magnification ×100).
How to prepare a hair mount
Use a black or white velvet background for selecting the bulbs or hair shaft segments you wish to mount ( Fig. 11 ). A black background helps to identify white bulbs, and a white background helps to visualize dark hair. Velvet is used to keep the hairs from flying away. Good lighting is essential. Clip 1 cm segments of the hair and place them parallel on a glass slide. Place 1 to 2 drops of a mounting medium on the hairs and cover with a coverslip; try to avoid bubbles. (The mounting medium can be Permount from Fisher Scientific, Pittsburgh, PA or any mounting medium found in pathology laboratories). In a mounting medium, hair is seen sharply, light scatter is eliminated, and the mounted hair can be kept indefinitely. KOH, water, and oil are not satisfactory for a hair mount.
Hair mount supplies.
One word of caution: if you suspect pili torti (as in Menkes kinky hair syndrome), examine the hair dry (unmounted) under a coverslip, otherwise the shadows of the twists will not be visualized.
Laboratory tests
In patients with hair loss, order a complete blood count, ferritin, thyroid stimulating hormone, and vitamin D 25OH. Vitamin D 25OH and ferritin are important for a normal hair cycle. In women, if the history and examination reveal severe cystic acne, hirsutism, galactorrhea, menstrual irregularities, infertility, or virilization, check the free or total testosterone, dehydroepiandrosterone sulfate, and prolactin levels. If any one of these tests are positive, refer the patient to an interested endocrinologist or gynecologist.
Scalp biopsy
Scalp biopsies offer additional information, and in a suspected cicatricial alopecia, a scalp biopsy is the essential first step. In cicatricial alopecia, perform the biopsy at or just beyond an early active area with inflammation and where hairs are still present; the site of a positive anagen pull test is ideal, but not always available. In alopecia areata and cicatricial alopecia, do not biopsy bare areas! Anesthetize with 1% lidocaine with epinephrine, and wait 10 minutes to allow time for adequate vasoconstriction. Take 1 or 2 4-mm punch biopsies down to subcutaneous fat. Depending on the preference of the dermatopathologist, request horizontal and/or vertical sections stained with hematoxylin and eosin. Horizontal sections have the advantage of assessing large numbers of follicles for hair density, terminal-to-vellus hair ratios, anagen-to-telogen hair ratios, and the extent of any inflammatory infiltrate.
References
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View In Article | Cross Ref - 3. Mirmirani P., Huang K.P., and Price V.H.: A practical, algorithmic approach to diagnosing hair shaft disorders. Int J Dermatol 2011; 50: pp. 1-12
View In Article | Cross Ref - 4. Price V.H.: Structural anomalies of the hair shaft. In Orfanos C.E., and Rudolf H. (eds): Hair and hair diseases. Berlin, Heidelberg (Germany), New York: Springer-Verlag, 1990. pp. 363-422
View In Article | Cross Ref - 5. Tosti A.: Dermoscopy of hair and scalp disorders with clinical and pathological correlations. London: Informa Healthcare Ltd, 2007.
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View In Article - 8. Kantor J., Kessler L.J., Brooks D.G., et al: Decreased serum ferritin is associated with alopecia in women. J Invest Dermatol 2003; 121: pp. 985-988
View In Article | Cross Ref - 9. Headington J.T.: Transverse microscopic anatomy of the human scalp. A basis for a morphometric approach to disorders of the hair follicle. Arch Dermatol 1984; 120: pp. 449-456
View In Article | Cross Ref - 10. Sperling L.C., and Winton G.B.: The transverse anatomy of androgenic alopecia. J Dermatol Surg Oncol 1990; 16: pp. 1127-1133
View In Article | Cross Ref - 11. Whiting D.A.: Diagnostic and predictive value of horizontal sections of scalp biopsy specimens in male pattern androgenetic alopecia. J Am Acad Dermatol 1993; 28: pp. 755-763
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