Phototrichogram and Wash Test: How Scalp Imaging Measures Hair Loss Accurately

How these diagnostic tests reveal hidden shedding patterns and guide sensitive scalp treatment planning

Disclaimer: This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider with any questions you may have about a medical condition.

Understanding Why These Tests Matter

When you notice more hair in the shower drain or a widening part line, it is easy to worry that something serious is happening. Yet hair shedding, to some degree, is part of the body’s normal renewal process. The challenge lies in distinguishing between ordinary shedding and early signs of a medical condition. That is where diagnostic tools like the phototrichogram and the wash test play an invaluable role.

A phototrichogram uses high-resolution imaging to measure hair density, diameter, and growth rate over time¹. It transforms what was once a subjective concern—“I think I’m losing more hair”—into quantifiable data. Similarly, the wash test offers a standardized, repeatable way to measure how many hairs are shed during a typical shampoo². When used together, these assessments provide a clear picture of scalp health and help dermatologists track treatment outcomes.

Both tests are especially useful in diagnosing telogen effluvium (temporary hair shedding after stress or illness) and androgenetic alopecia (pattern hair loss caused by genetics and hormones). They bridge the gap between what you feel and what science can measure, helping both patient and clinician make informed, compassionate decisions.

What Is a Phototrichogram?

A phototrichogram is a digital imaging technique that analyzes a small, trimmed section of the scalp. The test identifies how many hairs are growing (anagen phase), transitioning (catagen phase), or resting (telogen phase). This ratio, the anagen-to-telogen ratio, provides one of the clearest indicators of overall scalp vitality.

Common Uses

• Detecting early-stage or diffuse hair loss before it becomes visible to the naked eye.

• Measuring regrowth after treatments such as topical minoxidil, finasteride, or platelet-rich plasma (PRP) therapy.

• Evaluating the effects of hormonal changes, stress, or nutritional deficiencies on hair density.

• Providing visual evidence of progress during long-term scalp care plans.

  
  

What to Expect

During your appointment, your dermatologist will mark a small 1–2 cm² area, typically on the crown or temple, and trim it close to the scalp. High-magnification photographs are then taken using a digital dermatoscope. After 48–72 hours, the same area is photographed again, allowing clinicians to measure new hair growth and density variations. The difference between the two images reveals the speed of hair regrowth and identifies dormant follicles.

The procedure is entirely painless, though the trimmed spot may take a couple of weeks to blend back in. Results are often ready within a few days and include detailed visual charts showing your hair density and growth pattern.

What Is a Wash Test?

The wash test is a simple yet powerful home or clinic-based method that measures daily hair shedding. It helps determine whether hair loss falls within the normal range or if intervention might be needed.

Step-by-Step Instructions

1. Avoid washing your hair for 5 days. This allows shed hairs to accumulate for a more measurable count.

2. Use mild, sulfate-free shampoo and lukewarm water. Avoid harsh scrubbing or conditioner during the test.

3. Collect all shed hairs carefully. Rinse them into a sink or basin lined with a fine mesh or coffee filter to prevent loss.

4. Dry and count hairs once collected. You can separate shorter regrowing hairs from longer ones to assess active shedding versus new growth.

A normal scalp typically sheds 50–100 hairs per day, and shedding up to 150 hairs can still be within physiological limits depending on season, stress, and hormonal status³. Persistent shedding above 200 hairs per wash may indicate excessive telogen shedding or an underlying medical condition that deserves professional evaluation.

Phototrichogram Checklist: Preparation and Follow-Up

Before Your Appointment

Proper preparation ensures more accurate and reproducible results:

• Do not wash your hair within 48 hours before the test.

• Avoid styling products, oils, and serums that can interfere with imaging clarity.

• Share information about your medications, supplements, menstrual cycle, or recent illnesses, all of which may influence shedding patterns.

  
  

During the Test

• Confirm the test area and understand the trimming process.

• Keep your head still while photographs are being taken to ensure crisp imaging.

• Ask to view the captured images. Understanding what is being analyzed can help you engage more meaningfully with your treatment plan.

  
  

After the Test

• Avoid chemical treatments, hair coloring, or intense UV exposure for several days.

• You may receive high-resolution digital images or graphs showing your hair density and growth rate for future comparison.

• Schedule follow-ups every 3–6 months if you are undergoing treatment, as this allows for measurable tracking of improvement.

  
  

Wash Test Template: Home Monitoring Sheet

Date	Days Since Last Wash	Number of Hairs Collected	Notes on Texture/Breakage	Any New Stressors or Medications?

Tip: Try to perform your wash test under the same conditions each time. Keep your washing technique, shampoo brand, and water temperature consistent to avoid false variations.

By maintaining a record of your results, you and your dermatologist can identify gradual changes that may otherwise go unnoticed. A consistent increase in hair count can signal ongoing shedding, while a downward trend may suggest successful treatment.

How to Interpret Results

Interpreting results requires both context and continuity. Occasional spikes in shedding can occur naturally due to stress, postpartum recovery, or seasonal transitions. However, consistent elevations across multiple tests deserve professional evaluation.

• Less than 100 hairs lost: Typically within normal limits, especially for individuals experiencing mild stress or hormonal fluctuations.

• 100–200 hairs lost: May indicate transient telogen effluvium, a reversible condition often linked to illness, stress, or diet changes.

• Over 200 hairs lost: Suggests chronic telogen effluvium, androgenetic alopecia, or systemic conditions like thyroid disease that warrant further investigation.

A phototrichogram complements this data by calculating the anagen-to-telogen ratio, which reflects the scalp’s regenerative potential. Healthy scalps generally display 80–90 percent anagen hairs and 10–15 percent telogen hairs⁴. Lower ratios can point toward disrupted growth cycles, which might respond to medical or nutritional interventions.

When to See a Dermatologist

You should book a consultation with a board-certified dermatologist if you experience:

• Ongoing shedding lasting longer than 3 months.

• Patchy bald spots, scarring, or visible scalp redness.

• Itching, scaling, or pain accompanying hair loss.

• Shedding after starting new medications or supplements.

A dermatologist can perform trichoscopy, laboratory blood tests, or scalp biopsies to uncover underlying causes. Early detection can prevent permanent follicular damage, making timely evaluation one of the most important steps in scalp health management.

Gentle At-Home Care Between Tests

While awaiting results or continuing follow-up, adopt a scalp care routine that supports recovery:

• Choose sulfate-free, pH-balanced shampoos that maintain the scalp’s natural barrier.

• Avoid vigorous brushing when hair is wet to prevent breakage.

• Use wide-tooth combs and protective hairstyles that minimize traction.

• Support hair growth nutritionally with adequate protein, iron, zinc, and omega-3 fatty acids.

• Consider gentle scalp massage or low-level light therapy devices to encourage microcirculation.

Tip: Track your progress monthly through photos or your wash test log. Seeing small, measurable improvements can help sustain motivation during recovery.

Consistency matters more than intensity. Small, repeatable steps yield better long-term outcomes than quick, drastic interventions.

Encouragement for Patients

Hair loss can challenge confidence and emotional well-being, but it is rarely a sign of hopelessness. Diagnostic tools like the phototrichogram and wash test turn uncertainty into knowledge, guiding both doctor and patient toward realistic expectations and tailored solutions. Remember that hair growth follows a cyclical rhythm, and regrowth often takes months, not weeks. Patience is part of the healing process.

If you ever feel disheartened, bring your test logs, scalp photos, and any questions to your dermatologist. Every strand tells a story, and with consistent care and expert support, that story can include visible recovery and renewed self-assurance.

Glossary

• Phototrichogram: A digital imaging method that captures and compares scalp hair density and growth rate over time.
• Wash Test: A standardized method that measures daily hair shedding by counting hairs lost during a controlled shampoo.
• Anagen Phase: Active growth stage of the hair cycle, lasting between two to six years.
• Catagen Phase: Short transitional phase signaling the end of active growth before rest.
• Telogen Phase: Resting phase before the hair naturally falls out and a new cycle begins.
• Telogen Effluvium: Temporary increase in shedding due to stress, illness, or hormonal changes.
• Androgenetic Alopecia: Common hereditary form of hair loss caused by hormonal and genetic factors.
• Trichoscopy: Non-invasive scalp imaging used by dermatologists to analyze hair shaft and follicular structure.
• PRP Therapy: Platelet-rich plasma treatment designed to stimulate dormant follicles and enhance regrowth.
• Hair Density: Measurement of the number of hair follicles per square centimeter of scalp area.

Claims Registry

#	Claim(s) Supported	Source Title + Authors + Year + Venue	Accessed (ET)	Anchor Extract	Notes
1	The phototrichogram measures hair count and growth rate over time.	Van Neste D, et al. (2004). Phototrichogram: technical improvement and validation. Skin Research and Technology.	2025-11-06	"Quantitative phototrichogram provides objective assessment of hair growth rate."	Peer-reviewed dermatological methodology paper.
2	The wash test counts hairs shed during a standardized washing routine.	Rebora A, et al. (1981). The wash test: a simple method to assess hair loss. British Journal of Dermatology.	2025-11-06	"The wash test objectively measures hair shedding in telogen effluvium."	Foundational clinical description of the test.
3	Normal shedding averages 50–100 hairs per day; >200 may suggest excessive shedding.	Sinclair R. (2015). Hair Shedding in Women: How Much is Too Much? Journal of the American Academy of Dermatology.	2025-11-06	"Normal daily hair loss ranges from 50 to 100 hairs."	Authoritative clinical review.
4	Healthy scalps usually show 80–90% anagen hairs and 10–15% telogen hairs.	Headington JT. (1993). Transverse Microscopic Anatomy of the Human Hair Cycle. Archives of Dermatology.	2025-11-06	"Anagen hairs comprise approximately 85% of the scalp follicles."	Seminal reference for hair cycle distribution.