Alopecia / Hair Loss

Overview

Alopecia (hair loss) can be due to several pathophysiological mechanisms:

• Decreased hair growth → Anagen effluvium

• Increased hair shedding → Telogen effluvium

• Conversion of terminal hairs to vellus hairs → Androgenetic alopecia

• Congenital or acquired hair shaft abnormalities

• Inflammatory skin diseases damaging the hair bulb (e.g. scarring alopecias)

A thorough history, examination (including the scalp and hair shafts), and targeted investigations are key to distinguishing between these causes and guiding management.

Types of Hair Loss

Androgenetic Alopecia (Male & Female Pattern Hair Loss)

• Epidemiology:

  • Affects up to 50% of men by age 40, and a significant proportion of women by age 60.

• Pathophysiology:

  • Genetically determined, androgen-dependent process converting terminal hairs into finer vellus hairs.

  • Risk factors: PCOS in women, exogenous steroid use (can accelerate hair loss).

• Presentation:

  • Males: Receding hairline (temporal), vertex (crown) thinning.

  • Females: Diffuse thinning over the crown, with the frontal hairline often preserved.

• Management:

  • Men:

    • Topical minoxidil solution or foam.

    • Oral finasteride 1 mg daily (5α-reductase inhibitor).

      • Side effects: Potential sexual dysfunction, reduced libido, gynaecomastia.

    • Combination therapy if severe or refractory.

  • Women:

    • Topical minoxidil (2–5%) daily.

    • Oral spironolactone (especially if PCOS or hyperandrogenism is present).

      • Monitor potassium and blood pressure if higher doses are used.

Alopecia Areata (Autoimmune Alopecia)

• Clinical Features:

  • Sudden onset of discrete round or oval bald patches with smooth, non-scarring scalp.

  • “Exclamation mark” hairs at the periphery.

  • Can progress to more diffuse or persistent alopecia.

  • Associated conditions: Vitiligo, atopic eczema, thyroid disorders. More common in Down syndrome.

• Triggers: Infection, trauma, hormonal changes, emotional/physical stress.

• Management:

  • Education & Reassurance: Unpredictable, but spontaneous regrowth is common.

  • Mild (limited patches): High-potency topical corticosteroids (short course).

  • Severe: May require oral steroids, intralesional steroids, or other immunomodulatory therapies (e.g. topical immunotherapy with diphencyprone).

  • Camouflage: Wigs, hairpieces if extensive.

  • Investigations: Check thyroid function (TSH) given association with thyroid disease.

  • Psychological Support: High psychosocial impact; screen for mood disorders.

Alopecia Totalis & Universalis

• Alopecia Totalis: Complete loss of scalp hair (~5% of autoimmune alopecia).

• Alopecia Universalis: Loss of all body hair (<1% of cases, poorer prognosis).

• Management parallels severe alopecia areata but may be more challenging; spontaneous regrowth is less likely.

Anagen Effluvium

• Pathophysiology: Disruption of the anagen (growth) phase, leading to abrupt cessation of hair production and shaft breakage.

• Causes:

  • Autoimmune (severe diffuse alopecia areata)

  • Medications, particularly cytotoxic chemotherapy

  • Congenital disorders (e.g. loose anagen syndrome)

• Clinical Course: Rapid hair loss, often within days to weeks of exposure to the causative agent (e.g. starting chemotherapy).

Telogen Effluvium (Stress-Induced Shedding)

• Epidemiology: Very common form of diffuse hair shedding.

• Pathophysiology: Excessive transition of hairs into the telogen (resting) phase, leading to increased daily shedding of “club hairs.”

• Onset: Typically 2–6 months after a significant triggering event.

• Common Triggers:

  • Psychological or physical stress (childbirth, major surgery, illness, crash diets)

  • Endocrine disorders (thyroid dysfunction)

  • Autoimmune conditions (e.g. SLE)

  • Nutritional deficiencies (iron, vitamin D, zinc, B12)

  • Medications (OCP changes, ACE inhibitors, beta-blockers, anticoagulants, anticonvulsants, retinoids)

• Investigations:

  • Basic bloods: FBC, UEC, LFTs

  • TSH (thyroid function)

  • Iron studies, B12/folate, vitamin D, zinc

• Management:

  • Reassurance: Typically self-limiting, with regrowth in 6–9 months once the trigger is removed/resolved.

  • Address triggers: Correct nutritional deficiencies, manage stress, adjust medications if possible.

  • Topical minoxidil may be considered if shedding is prolonged (>6 months).

Diagnosis of Alopecia (Algorithm Overview)

1. Patchy vs. Diffuse Hair Loss?

   • Patchy

     • Normal skin surface:

       • Alopecia Areata → round/oval patches, exclamation mark hairs.

       • Trichotillomania → broken hairs of varying length, irregular borders.

     • Inflamed/scaly skin:

       • Tinea Capitis → fungal infection (scaling, itching), possible Wood’s lamp fluorescence.

       • Seborrhoeic Dermatitis / Psoriasis → characteristic scales.

   • Diffuse

     • Anagen Effluvium → following chemotherapy, severe autoimmune process.

     • Telogen Effluvium → excessive shedding (100–150 hairs/day) after stress, illness, hormonal shift.

2. Consider underlying systemic conditions, medication history, nutritional status.

Medication-Induced Hair Loss

1. Telogen Effluvium

   • Caused by many drugs, e.g. ACE inhibitors, antidepressants, antiepileptics, beta-blockers, OCPs, statins, retinoids, warfarin.

2. Androgenetic Alopecia Acceleration

   • Anabolic steroids (DHEA), danazol, testosterone.

3. Anagen Effluvium

   • Chemotherapy agents.

Physiology of Hair Growth

• Scalp hair grows at approximately 1 cm per month.

Management Overview

1. General

   • Identify and correct contributing factors (e.g. nutritional deficiencies, thyroid disease, medication side effects).

   • Consider referral to a dermatologist if the diagnosis is unclear or refractory to standard treatment.

2. Androgenetic Alopecia

   • First-line: Topical minoxidil ± oral agents (finasteride for men, spironolactone for women).

   • Hair transplantation or scalp micropigmentation may be considered in resistant cases or for cosmetic reasons.

3. Alopecia Areata

   • Reassure that spontaneous regrowth occurs in many mild cases.

   • Topical or intralesional steroids for localised patches; systemic therapy (e.g. oral steroids, immunotherapy) for extensive disease.

   • Psychological support is important.

4. Telogen Effluvium

   • Reassurance: Self-limiting once the precipitant is removed.

   • Correct nutritional/thyroid abnormalities.

   • Minoxidil for chronic or persistent cases.

5. Anagen Effluvium

   • Often related to chemotherapy.

   • Scalp cooling techniques in some cases to reduce hair loss during chemo.

   • Regrowth usually occurs once the offending agent is stopped.

6. Camouflage & Support

   • Cosmetic options: Wigs, hairpieces, volumising shampoos, hair fibres.

   • Psychological support: Alopecia can significantly affect self-esteem and mental health; consider referring to counselling or support groups.

Key Points

• Androgenetic alopecia is the most common cause of hair loss; treat with minoxidil ± finasteride/spironolactone.

• Alopecia areata is autoimmune; can improve spontaneously or with topical/oral steroids.

• Telogen effluvium is often self-limiting and linked to a preceding stressor; reassurance is crucial.

• Anagen effluvium frequently occurs with chemotherapy; usually reverses after cessation.

• Always check for scalp inflammation or scaling if patchy hair loss, as tinea capitis or psoriasis can mimic alopecia areata.

• Lifestyle: Overall health, balanced diet, stress reduction can aid hair regrowth and minimise further loss.