Follicular disorders - Hair loss

Did you know that dermatology deals with much more than just skin? Dermatology is concerned with the diagnosis and treatment of diseases of the skin, hair and nails in both children and adults.

Follicular disorders include any process affecting the pilosebaceous unit. Examples of these are keratosis pilaris, rosacea, acne as well as hair loss. (1) The medical term for hair loss is alopecia. Hair loss can refer to excessive shedding or baldness (or both). Balding may be localised or diffuse, scarring and non-scarring. (2).

As all our hair follicles are formed during fetal growth, experiencing some hair loss in later life is inevitable.

Hair loss can be due to: (3)

• An inflammatory skin disease that damages or destroys the hair bulb.

• Congenital or acquired hair shaft abnormalities

• Conversion of thick terminal hairs to thin vellus hairs; male and female pattern hair loss

• Increased shedding of the hair: telogen hair loss

• The decreased growth of the hair: anagen hair loss

Hair growth follows a cycle. However, these phases are not synchronised, and any hair may be at a particular phase at random.

The three main phases of the hair cycle are: (3)

• Anagen: this is actively growing hair, forms the majority of hair

• Catagen: in-between phase of 2–3 weeks when growth stops and the follicle shrinks, this is 1–3% of hairs

• Telogen: this is the resting phase for 1–4 months, makes up to 10% of hairs in a normal scalp.

Figure 1: The hair growth cycle (3)

Anagen Effluvium

Anagen effluvium refers to hair shedding that arises during the anagen or growth stage of the hair cycle.

This is in contrast to telogen effluvium or hair shedding that arises during the telogen or resting stage of the hair cycle. Anagen effluvium is due to an acute injury to the hair follicles by an endogenous or exogenous cause, resulting in sudden diffuse shedding of structurally damaged hairs. Diffuse alopecia (hair loss) may occur over a period of days. The alopecia is non-scarring. (4)

Anagen effluvium is caused by: (3)

• Autoimmune disease, including severe diffuse alopecia areata

• Medications, especially cytotoxic/chemotherapy drugs

• An inherited or congenital condition, such as loose anagen syndrome

Figure 2: Hair shedding during chemotherapy (3)

It can also be caused by an infection. An infection may interrupt hair growth in a localised area resulting in a single bald patch or several bald patches. Loose hairs can readily be extracted from the infected area, which may be swollen, boggy and crusted. (4)

Examples include:

• Boils and abscesses

• Fungal hair infection: tinea capitis or kerion

Figure 3: Anagen effluvium: fungal infection (kerion) (4)

Alopecia is an autoimmune cause of anagen effluvium and is considered an umbrella term, which encompasses a number of variants including alopecia areata totalis or universalis, ophiasis, ophiasis inversus, and diffuse alopecia areata. (5)

Figure 4: Extensive patchy alopecia areata (5)

Treatment

Anagen effluvium due to chemotherapy is expected to recover fully within 3–6 months of stopping it. The hair nearly always grows back normally, but sometimes patients with straight hair develop curly hair when it regrows. Hair colour may also change.

Suggested treatments for anagen effluvium include:

• Topical minoxidil solution

• Scalp cooling during chemotherapy

• Cosmetic camouflage to eyebrows

Anagen effluvium due to alopecia areata may persist; recovery is unpredictable. (4)

Telogen Effluvium

Telogen effluvium is a common cause of temporary hair loss due to the excessive shedding of resting or telogen hair after some shock to the system. Telogen hair is also known as a club hair due to the shape of the root. (6) It occurs 2–6 months after an event that stops active hair growth.

If there is some shock to the system, as many as 70% of the anagen hairs can be precipitated into telogen, thus reversing the usual ratio. Typical triggers include: (6)

• Childbirth: postpartum hair loss. This can resolve after a few months or transition into female pattern alopecia.

• Physiological neonatal hair loss

• Acute or chronic illness, especially if there is fever

• Surgical operation

• Accident

• Psychological stress

• Weight loss, unusual diet, or nutritional deficiency (eg, iron deficiency/)

• Certain medications

• Endocrine disorders (eg, hypothyroidism, hyperthyroidism)

• Discontinuing the contraceptive pill

• Overseas travel resulting in jetlag

• Skin disease affecting the scalp (eg, erythroderma)

• Excessive sun exposure.

Figure 5: Telogen effluvium (6)

Figure 6: Hair shedding (6)

Because nail and hair growth are under the same influences, an arrest in hair growth is often mirrored in the nails by a groove across them coinciding with the time of the shock to the system — a Beau line. (6)

Figure 7: Beau line (6)

Clinical features of telogen effluvium include:

• Hair thinning involves the entire scalp +/- loss of other body hair.

• Examination shows diffuse thinning without focal areas of total alopecia and short hairs of normal thickness.

• A gentle hair pull test reveals an increased number of hairs; most are telogen with a typical epithelial sac.

Treatment

Telogen effluvium is self-correcting. Recommendations include:

• Gentle handling of the hair, as well as avoiding over-vigorous combing, brushing and any type of scalp massage

• Treating any underlying scalp disorder or hormonal problem determined, if any

• Ensure a nutritious diet, with plenty of protein, fruit and vegetables.  

• Correct any abnormality in thyroid function, or levels of iron, vitamin B12 and folic acid

Pattern hair loss (androgenetic alopecia)

Pattern hair loss can be attributed to genetic programming or hormonal influences. It is also called androgenetic alopecia because it is influenced by androgens.

Pattern alopecia is apparent in about 50% of individuals by the age of 50 years.

• Male pattern alopecia affects vertex and temporal scalp.

• Female pattern alopecia is less pronounced and affects the anterior scalp.

(3,7)

Male pattern hair loss is the most common type of diffuse thinning of the hair and balding that occurs in adult males. (7)

• It is due to a combination of hormones (androgens) and a genetic predisposition. 

• Male pattern hair loss is also called androgenetic alopecia.

• It is characterised by a receding hairline and hair loss on the top and front of the head.

• A similar type of hair loss in women, female pattern hair loss, results in thinning hair on the mid-frontal area of the scalp and is generally less severe than occurs in males.

Male pattern baldness is graded using the Norwood scale.

Figure 8: The Norwood scale (8)

Male pattern hair loss is an inherited condition, caused by a genetically determined sensitivity to the effects of dihydrotestosterone (DHT) in some areas of the scalp. DHT is believed to shorten the growth, or anagen, phase of the hair cycle. (7)

Treatment

Current treatment options include: (7)

• Hair replacement / transplantation

• Cosmetics

• Micropigmentation (tattoo) to resemble shaven scalp

• Hairpieces

• Minoxidil solution

• Finasteride tablets (type II 5-alpha-reductase inhibitor)

• Dutasteride.

Female pattern hair loss (FPHL) is a distinctive form of diffuse hair loss that occurs in women with androgenetic alopecia. Many women are affected by FPHL. Around 40% of women by age 50 show signs of hair loss and less than 45% of women reach the age of 80 with a full head of hair.

In FPHL, there is diffuse thinning of hair on the scalp due to increased hair shedding or a reduction in hair volume, or both. It is normal to lose up to 50-100 hairs a day. Another condition called chronic telogen effluvium also presents with increased hair shedding and is often confused with FPHL. It is important to differentiate between these conditions as management for both conditions differ.

Figure 9: Varying severity of female pattern hair loss (9)

Treatment

Treatments are available for FPHL although there is no cure. It is important to manage expectations when seeking treatment, as the aim is to slow or stop the progression of hair loss rather than to promote hair regrowth. However, some women do experience hair regrowth with treatment. Results are variable, and it is not possible to predict who may or may not benefit from treatment.

Hair loss treatment

Treatment depends on the diagnosis. (3)

• Infections should be treated.

• Deficiencies should be remedied.

• Causative drugs may be discontinued.

• Inflammation can be suppressed.

• Treatment may be available for specific conditions.

Whilst some experience of hair loss is inevitable in our lifetime, it is important to recognise the difference between healthy hair loss and an underlying hair condition. 

There is increasing evidence confirming that experiencing hair loss is psychologically damaging. In next week’s post, we will dive deeper into the mental effects of experiencing hair loss and the mental manifestations of what an absence of hair can mean. 

References 

1. Five Follicular Disorders [Internet]. Skin Cancer & Cosmetic Dermatology Center; 2023. Available from: https://www.thedermcenters.com/five-follicular-disorders/

2. Disorders of the hair and scalp [Internet]. 2023. Available from: https://dermnetnz.org/cme/follicular/disorders-of-the-hair-and-scalp

3. Hair loss [Internet]. 2023. Available from: https://dermnetnz.org/topics/hair-loss

4. Anagen effluvium [Internet]. 2023. Available from: https://dermnetnz.org/topics/anagen-effluvium

5. Alopecia areata [Internet]. 2023. Available from: https://dermnetnz.org/topics/alopecia-areata

6. Telogen effluvium [Internet]. 2023. Available from: https://dermnetnz.org/topics/telogen-effluvium

7. Male pattern hair loss [Internet]. 2023. Available from: https://dermnetnz.org/topics/male-pattern-hair-loss

8. The Norwood scale [Internet]. Heva Clinic; 2023. Available from: https://www.dentalhairclinicturkey.com/how-many-grafts-do-i-need/

9. Female pattern hair loss [Internet]. 2023. Available from: https://dermnetnz.org/topics/female-pattern-hair-loss