Androgenetic alopecia is diagnosed primarily through visual pattern recognition, family history, and dermoscopic examination of follicle miniaturization. The condition affects 50% of men by age 50, and its characteristic pattern of temple recession and crown thinning makes it the most recognizable form of hair loss. A correct diagnosis is essential because different types of hair loss require different treatments.
This article is for informational purposes only and does not constitute medical advice.
Step 1: Clinical Pattern Assessment
The first diagnostic step is evaluating the distribution of hair loss against known patterns. Androgenetic alopecia follows specific, predictable patterns in men that distinguish it from other types of hair loss.
The Norwood Classification
Dermatologists use the Norwood scale to classify the stage and pattern of male androgenetic alopecia. The scale ranges from Stage 1 (no loss) to Stage 7 (extensive loss), with each stage describing a specific configuration of hairline recession and crown thinning.
Key diagnostic patterns include temporal recession forming an M-shaped or V-shaped hairline, vertex (crown) thinning that creates a circular pattern, and gradual merging of these two zones in later stages. The presence of a well-preserved donor area (back and sides of the scalp) further supports the diagnosis.
Pattern vs. Diffuse Loss
Androgenetic alopecia is patterned, meaning it follows the Norwood template. If hair loss is diffuse (uniform thinning everywhere without a pattern), the diagnosis may be telogen effluvium, diffuse alopecia areata, or another condition. Some men do experience diffuse androgenetic alopecia, but this is less common and requires more investigation.
Step 2: Family History
Genetics play a dominant role in androgenetic alopecia. The condition involves multiple genes inherited from both parents, with the androgen receptor gene on the X chromosome being particularly significant.
What Your Doctor Will Ask
A dermatologist will typically ask about hair loss patterns in your father, maternal grandfather, and other male relatives. While the maternal grandfather's pattern is often cited as the strongest predictor, research shows that genetic risk comes from both sides of the family.
Having first-degree relatives with pattern hair loss significantly increases your probability of developing the same condition. However, the absence of family history does not rule out androgenetic alopecia, as the genetic expression can skip generations.
Step 3: Dermoscopy (Trichoscopy)
Dermoscopy, often called trichoscopy when applied to the scalp, uses a magnifying device to examine the scalp surface and hair follicles at 10x to 70x magnification.
What Dermoscopy Reveals
The hallmark finding of androgenetic alopecia under dermoscopy is follicle miniaturization. This appears as a variation in hair shaft diameter within the same area. Healthy scalp areas show uniform hair thickness, while affected areas display a mix of thick terminal hairs and thin, wispy vellus hairs.
Additional dermoscopic signs include a greater than 20% variation in hair shaft diameter, an increased proportion of single-hair follicular units (compared to the normal 2 to 4 hairs per unit), perifollicular brown halos (peripilar signs), and yellow dots representing empty or sebum-filled follicles.
Comparing Affected and Unaffected Areas
Dermatologists compare dermoscopic findings between the frontal/vertex scalp (DHT-sensitive areas) and the occipital scalp (DHT-resistant donor area). If miniaturization is concentrated in the pattern areas while the donor area remains dense and uniform, the diagnosis of androgenetic alopecia is strongly supported.
Step 4: Pull Test and Hair Count
The Pull Test
A dermatologist gently pulls on a group of 40 to 60 hairs from different scalp regions. Extracting more than 6 hairs per pull suggests active shedding. In androgenetic alopecia, the pull test is typically negative or mildly positive, because the condition involves gradual miniaturization rather than abrupt shedding.
A strongly positive pull test points toward telogen effluvium or alopecia areata rather than androgenetic alopecia.
Daily Hair Count
Losing 50 to 100 hairs per day is normal. Androgenetic alopecia does not dramatically increase daily shedding in most cases. Instead, the hairs that regrow come back thinner and shorter with each cycle until they become invisible vellus hairs. Tracking daily shed count can help differentiate androgenetic alopecia from conditions that cause acute shedding.
Step 5: Blood Work
Blood tests do not diagnose androgenetic alopecia directly, but they rule out contributing factors and other conditions that can mimic or worsen it.
Common Tests Ordered
A standard workup may include thyroid function (TSH, free T4), complete blood count (CBC), ferritin (iron stores), vitamin D levels, and in some cases, hormone panels (testosterone, DHEA-S, prolactin). Abnormal results in any of these categories suggest a contributing or alternative cause that should be addressed.
When Blood Work Is Essential
Blood tests are particularly important for men experiencing rapid onset hair loss, diffuse thinning rather than patterned loss, hair loss accompanied by other symptoms (fatigue, weight changes, skin changes), or young men (under 25) with aggressive loss.
Step 6: Scalp Biopsy (Rare Cases)
A scalp biopsy is rarely necessary for diagnosing androgenetic alopecia but may be performed in ambiguous cases. The procedure involves removing a 4mm punch of scalp tissue for microscopic analysis.
What a Biopsy Shows
In androgenetic alopecia, biopsy findings include an increased ratio of vellus to terminal hairs (greater than 0.2:1), normal follicle count per unit area (follicles are miniaturized, not absent), perifollicular fibrosis in advanced cases, and no significant inflammation (unlike scarring alopecia).
Differential Diagnosis
Several conditions can be confused with androgenetic alopecia. Telogen effluvium causes diffuse shedding triggered by stress, illness, or nutritional deficiency and is temporary. Alopecia areata produces patchy, well-defined bald spots rather than gradual thinning. Traction alopecia results from repeated tension on hair follicles from tight hairstyles. Scarring alopecia destroys follicles permanently and shows inflammation and scarring on dermoscopy.
Accurate diagnosis ensures you receive the right treatment. If your hair loss follows a Norwood pattern and dermoscopy confirms miniaturization, androgenetic alopecia is the most likely diagnosis. From there, you can explore treatment options from medication to surgical restoration.
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