Androgenetic Alopecia
Androgenetic alopecia (AGA), also known as male- or female-pattern hair loss, is the most common type of hair loss in both sexes. It is driven by the gradual shrinking of hair follicles (follicular miniaturization), which makes hair progressively thinner and sparser and causes it to be lost in characteristic patterns.
AGA results from a complex interplay between genetics and androgen hormone activity:
- The role of dihydrotestosterone (DHT): In the hair follicle, circulating testosterone is converted to dihydrotestosterone (DHT) by the enzyme 5-alpha-reductase (particularly the type II isoenzyme). DHT binds androgen receptors (AR) many times more strongly than testosterone does.
- Follicular miniaturization: When DHT binds AR on dermal papilla cells in susceptible scalp areas (such as the front and crown), it sets off signals that shorten the growth phase (anagen) and lengthen the resting phase (telogen). With each hair cycle, the follicle shrinks further and produces fine, short, pale vellus hairs instead of mature terminal hairs.
- Genetics: Sensitivity to DHT is determined by polygenic inheritance, which sets the density of androgen receptors and the activity of 5-alpha-reductase in the scalp.
- Mild perifollicular inflammation and fibrosis: Chronic, low-grade microinflammation around the follicular infundibulum promotes fibrosis around the dermal papilla, so the hair loss becomes irreversible if it is not treated early.
At Haute-Derma, our approach to androgenetic alopecia starts with detailed trichoscopy to stage follicular miniaturization. We then build a multi-layered plan that combines hormonal control, improved scalp microcirculation and nutritional support for the follicles.
Clinical Features and Grading Scales
Androgenetic alopecia looks distinctly different in men and women:
- Male pattern hair loss (MPHL):
- Hair first thins and recedes at both temples, creating the typical M shape (biconcave recession).
- Thinning at the crown (vertex) follows. Over time the bald areas at the front and crown merge, leaving only a horseshoe-shaped fringe at the back and sides of the head (areas that are not sensitive to DHT).
- Norwood–Hamilton scale: Used to grade progression from stage I (no obvious balding) to stage VII (extensive balding across the front and crown).
- Female pattern hair loss (FPHL):
- The frontal hairline is usually preserved, but hair thins diffusely over the crown and along the central part (crown/centroparietal area).
- The part gradually widens (the Christmas tree pattern). Complete baldness like that seen in men is very rare.
- Ludwig / Sinclair scales: Grade thinning from grade I (mild thinning along the part) to grade III (severe thinning with clearly visible scalp).
- Trichoscopy findings:
- Variation in hair shaft diameter (> 20% of hairs with abnormal diameter).
- An increased proportion of vellus hairs.
- Brown halos around follicular openings (peripilar sign), reflecting microinflammation.
Haute-Derma's Approach to Diagnosis and Treatment
- Trichoscopy and microcirculation assessment: A high-magnification scalp scope measures follicle density, analyzes the ratio of terminal to vellus hairs and identifies perifollicular inflammation. We also take a family history and screen for hormonal disorders (especially in women with hirsutism, acne or polycystic ovaries).
- Evidence-based medical treatment:
- Topical minoxidil (2% or 5%): A vasodilator that opens potassium channels, prolongs anagen and increases blood flow to the dermal papilla.
- 5-alpha-reductase inhibitors (finasteride / dutasteride): For men (or postmenopausal women under strict indications), these block the conversion of testosterone to DHT and halt follicular miniaturization.
- Systemic anti-androgens (spironolactone / cyproterone acetate): The preferred choice for women with signs of androgen excess.
- Advanced procedures and local biostimulation:
- Mesotherapy: Growth peptides, biotin, amino acids and follicle-stimulating factors are delivered directly into the deep scalp dermis.
- Platelet-rich plasma (PRP) / PRF: Releases growth factors (PDGF, VEGF, bFGF) that regenerate dermal papilla cells and help restore shrinking follicles.
- Low-level laser therapy (LLLT): Stimulates the mitochondrial respiratory chain, boosting ATP production in the follicle.
- Scalp care and lifestyle: We advise on gentle scalp cleansing and balancing the scalp microbiome (clearing Malassezia yeast if seborrheic dermatitis is also present), along with micronutrient supplements (zinc, iron, L-cystine) to strengthen the hair's keratin structure.
Male vs. Female Pattern Hair Loss at a Glance
| Feature | Male Pattern Hair Loss (MPHL) | Female Pattern Hair Loss (FPHL) |
|---|---|---|
| Main mechanism | High sensitivity to DHT via type II 5-alpha-reductase. | Multifactorial; linked to falling estrogen or relative androgen excess. |
| Pattern | Deeply receding frontal hairline (M shape), balding at the crown (vertex). | Frontal hairline preserved; diffuse thinning along the central part (Christmas tree pattern). |
| Grading scale | Norwood–Hamilton scale (stages I–VII). | Ludwig scale (grades I–III) or Sinclair scale. |
| Outlook | Can progress to extensive balding across the front and crown. | Rarely leads to complete baldness; mainly severe loss of density. |
