Human Hair: Anatomy, Physiology, Disorders & Treatment Guide
1. Introduction
- Hair plays a significant role in protection, temperature regulation, and aesthetics.
- It grows from hair follicles embedded in the skin and is made primarily of keratin.
- Common hair-related disorders include hair loss (alopecia), dandruff, scalp infections, and premature greying.
2. Anatomy of Hair
- Hair Shaft: Visible part of the hair, composed of keratin.
- Hair Follicle: Rooted in the skin, responsible for hair growth.
- Sebaceous Glands: Produce sebum (oil) to moisturize the scalp.
- Hair Bulb: Base of the follicle, containing melanocytes that give hair its color.
- Hair Papilla: Provides nutrients and oxygen to the follicle.
3. Physiology of Hair Growth
- Hair Growth Cycle:
- Anagen (Growth Phase): Lasts 2–7 years, determines hair length.
- Catagen (Transition Phase): Lasts 2–3 weeks, follicle shrinks.
- Telogen (Resting Phase): Lasts 3 months, old hair sheds.
- Hair Color & Melanin Production:
- Eumelanin (black/brown), Pheomelanin (red/blonde).
- Grey hair occurs due to melanocyte depletion.
4. Common Disorders & Pathophysiology
A. Hair Loss (Alopecia)
- Androgenetic Alopecia (Male & Female Pattern Baldness):
- Cause: Genetic sensitivity to DHT (dihydrotestosterone).
- Telogen Effluvium:
- Cause: Stress, illness, pregnancy, nutritional deficiencies.
- Alopecia Areata:
- Autoimmune attack on hair follicles.
B. Dandruff (Seborrheic Dermatitis)
- Cause: Overgrowth of Malassezia fungus, excess oil production.
- Symptoms: White flakes, itchy scalp.
C. Scalp Infections
- Tinea Capitis (Fungal Infection):
- Symptoms: Scaly patches, hair loss, itching.
- Folliculitis (Bacterial Infection):
- Cause: Staphylococcus bacteria, leading to inflamed hair follicles.
D. Premature Greying
- Cause: Genetics, oxidative stress, vitamin deficiencies (B12, D).
- Risk Factors: Smoking, stress, autoimmune diseases.
5. Signs & Symptoms of Hair Disorders
- Early Symptoms:
- Increased hair shedding.
- Scalp itching, dryness, or flaking.
- Advanced Symptoms:
- Bald patches, hair thinning.
- Scalp redness, inflammation.
- Red Flags:
- Sudden, severe hair loss.
- Painful sores or pus-filled lesions on the scalp.
6. When to See a Doctor
- Hair loss persisting for more than 3 months.
- Itchy, flaky, or inflamed scalp.
- Sudden bald patches or unexplained greying.
7. Emergency Signs Requiring Immediate Care
- Painful, infected scalp lesions.
- Hair loss combined with fatigue, weight loss, or hormonal imbalance.
- Rapid, full-body hair loss (Alopecia Universalis).
8. Diagnostic Process
- Clinical Examination: Scalp inspection, pull test.
- Laboratory Tests:
- Thyroid Panel (TSH, T3, T4): Detects thyroid-related hair loss.
- Ferritin & Iron Levels: Deficiency linked to hair thinning.
- Vitamin B12 & D Tests: Deficiencies contribute to premature greying.
- Imaging Tests:
- Trichoscopy (Scalp Microscopy): Identifies follicle damage.
- Specialist Procedures:
- Scalp Biopsy: Confirms autoimmune or fungal causes.
9. Likely Diagnoses
- Androgenetic Alopecia (Genetic Hair Loss).
- Telogen Effluvium (Stress-Related Hair Loss).
- Alopecia Areata (Autoimmune Hair Loss).
- Seborrheic Dermatitis (Dandruff).
- Scalp Infections (Fungal, Bacterial).
10. Treatment Options
A. Medications
- For Hair Loss:
- Minoxidil (Rogaine) 2–5%: Increases blood flow to follicles.
- Finasteride (Propecia) 1 mg/day: Blocks DHT, used in men.
- For Dandruff & Scalp Conditions:
- Ketoconazole Shampoo (Nizoral) 2%: Fungal control.
- Salicylic Acid, Coal Tar Shampoos: Reduce scaling.
- For Autoimmune Hair Loss:
- Topical Steroids (Clobetasol)
- Oral Corticosteroids (Prednisone)
- For Premature Greying:
- Vitamin B12 & D Supplements.
- Approximate Medication Costs (USD):
- Minoxidil: $30–$60/month.
- Finasteride: $20–$100/month.
- Ketoconazole Shampoo: $10–$50 per bottle.
- Steroid Creams: $20–$100 per tube.
B. Surgical/Procedural Interventions
- Hair Transplant (FUE/FUT) ($3,000–$15,000).
- Platelet-Rich Plasma (PRP) Therapy ($500–$1,500 per session).
- Low-Level Laser Therapy (LLLT) ($300–$1,000 for devices).
C. Lifestyle Modifications & Home Remedies
- For Hair Growth:
- Protein-Rich Diet: Eggs, fish, nuts.
- Iron & Biotin Supplements: Essential for follicle health.
- For Dandruff Control:
- Tea Tree Oil, Aloe Vera: Natural anti-inflammatory effects.
- Apple Cider Vinegar Rinse: Restores scalp pH.
11. Precautions & Prevention
- Avoid Excess Heat & Chemical Treatments.
- Gentle Hair Care: No harsh brushing, avoid tight hairstyles.
- Manage Stress: Meditation, yoga to reduce stress-related hair loss.
- Regular Scalp Hygiene: Wash hair 2–3 times per week.
12. Prognosis & Recovery
- Androgenetic Alopecia: Progressive, but can be slowed with treatment.
- Telogen Effluvium: Reversible within 6–12 months.
- Alopecia Areata: May resolve or require long-term management.
- Dandruff: Controllable with medicated shampoos.
13. Cost of Treatment
- Dermatologist Consultation: $100–$300.
- Hair Loss Medications (Minoxidil, Finasteride): $30–$100/month.
- PRP Therapy: $500–$1,500 per session.
- Hair Transplant Surgery: $3,000–$15,000.
14. Frequently Asked Questions (FAQs)
- Why is my hair thinning?
- Genetics, stress, hormonal imbalances, nutritional deficiencies.
- Does washing hair daily cause hair loss?
- No, but excessive shampooing can dry out the scalp.
- Can diet improve hair growth?
- Yes, high-protein, iron-rich foods promote healthy hair.
- Is hair loss reversible?
- Depends on the cause; stress-related hair loss often grows back.
- Does wearing a hat cause baldness?
- No, but poor scalp hygiene under a hat can cause dandruff.
- What is the best treatment for dandruff?
- Ketoconazole shampoo, tea tree oil, and regular scalp washing.
- Can stress cause premature greying?
- Yes, stress can accelerate melanocyte depletion.
- Are hair transplants permanent?
- Yes, but new hair can thin over time.
- Do hair growth serums really work?
- Some (like minoxidil) are FDA-approved, but results vary.
- Can I regrow hair after baldness?
- It depends on follicle health. Some cases require transplants.
