Diagnose Before You Treat: The Hair Loss Workup That Must Precede PRP

The hair loss workup before PRP is not a formality that delays the treatment. It is the part of the encounter that determines whether the treatment can work at all.

"PRP for hair is a protocol, not a single syringe," Tatiana Sarmiento teaches. "It's very important that you diagnose the patient with the blood work. If the patient has androgenetic alopecia, if the patient has a scarring alopecia, or medical triggers like hormones — you want to run labs with your patient, you want to go through the history of the patient, and since when they started."

When she lists the mistakes that sink a hair programme, the second one on her list is skipping diagnosis: "You didn't do bloodwork and the patient is a female who is in menopause. Of course you need to assess that in that patient."

This piece sets out the process that has to happen before a needle is loaded. It is deliberately structured as a sequence, because the order matters: history narrows the differential, examination confirms the category, investigations exclude the reversible drivers, and only then does the treatment plan get written. For an overview of PRP as a hair-loss treatment option once a diagnosis is established, see Empire's existing coverage of platelet-rich plasma for alopecia; this resource covers the diagnostic work that has to come first.

Why the aesthetic practice gets this wrong

A patient presents asking for PRP. They have already decided. They have read about it, priced it, and often booked it. The commercial pressure runs entirely in one direction — toward treating.

Three structural problems follow.

The presenting complaint is a symptom, not a diagnosis. "My hair is thinning" is the chief complaint for androgenetic alopecia, chronic telogen effluvium, early frontal fibrosing alopecia, traction alopecia, thyroid disease, iron deficiency, post-partum effluvium, rapid weight loss, alopecia areata incognita and a dozen drug effects. These do not share a treatment.

A subset will get worse, not better, if you treat without diagnosing. Scarring alopecias are progressive and destroy the follicular unit permanently. Time spent on monthly PRP sessions is time not spent on the anti-inflammatory therapy that might have preserved follicles. That is the most consequential error in this field, and it is entirely preventable at the first visit.

Reversible drivers respond to treating the driver. A patient whose shedding is driven by iron deficiency or uncontrolled thyroid disease may improve substantially on correction alone. Running a PRP series in parallel without addressing the driver produces an uninterpretable outcome and, frequently, a dissatisfied patient who paid for the wrong thing.

It is also worth saying plainly, because patients ask: PRP is not FDA-approved for androgenetic alopecia. It is an autologous preparation used off-label, and the evidence base, while broadly positive, is of limited quality (Abid et al., Skin Health Dis, 2025;5(5):311–318). That reality makes a rigorous diagnostic process more important, not less.

Step one: the history that actually changes the diagnosis

Most hair-loss histories are taken as a list. They are more useful taken as four questions, each of which splits the differential.

How did it start — abruptly or insidiously?

This is the highest-yield question in the entire encounter, and it is the one Tatiana flags as essential: "since when they started."

Abrupt, diffuse shedding with a discrete onset — the patient can often name the month — points toward telogen effluvium. Ask what happened two to three months before the shedding began. That lag is not incidental; it is the length of telogen. Surgery, febrile illness, childbirth, a new medication, a crash diet, rapid weight loss, severe psychological stress.

Insidious, gradual thinning over years with no identifiable start point points toward androgenetic alopecia.

Patchy, rapid, well-demarcated loss points toward alopecia areata or tinea capitis and away from both.

What is the pattern — diffuse, patterned or focal?

This is the organising framework used in the primary-care and dermatology literature: non-scarring alopecias divide into diffuse (telogen and anagen effluvium), patterned (androgenetic alopecia) and focal (alopecia areata, tinea capitis, traction alopecia) categories, each with a different management pathway (Dakkak, Forde & Lanney, Am Fam Physician, 2024;110(3):243–250).

Ask the patient where they notice it. A widening central part with preserved frontal hairline is a different presentation from temporal recession, and both differ from "it comes out everywhere, in the shower, on my clothes."

Is it shedding or is it thinning?

Patients use these interchangeably; clinically they are opposites. Shedding is increased loss of formed hairs — the pillow, the drain, the brush. Thinning is reduced diameter and density of the hairs that remain, with normal shedding. Effluvium sheds. Androgenetic alopecia thins and miniaturises. Many patients have both, and the mixed picture is common enough that assuming a single diagnosis is a mistake.

What else is going on medically and cosmetically?

The items worth asking about explicitly, because patients do not volunteer them:

• Hormonal status and events — pregnancy, post-partum period, menopause, contraception changes, features suggesting hyperandrogenism (menstrual irregularity, hirsutism, acne)
• Weight and nutrition — recent significant weight loss, restrictive eating, bariatric surgery, and now routinely GLP-1 receptor agonist therapy, where rapid weight loss is a recognised effluvium trigger
• Medications and supplements — including anticoagulants, retinoids, some antidepressants, and high-dose supplemental vitamin A
• Systemic illness — thyroid disease, autoimmune conditions, anaemia, recent COVID-19 or other febrile illness
• Styling and haircare practice — tight braiding, weaves, extensions, wigs, chemical relaxing, heat. This is not cosmetic trivia. Sustained traction produces a distinct alopecia and, if the traction continues, will defeat any treatment you provide
• Family history — pattern and age of onset in first-degree relatives on both sides
• What they have already tried — minoxidil, finasteride, supplements, other clinics, and crucially for how long and how consistently

Step two: the examination

Look at the pattern, not just the density

Assess the frontal hairline, the central part width from front to vertex, the vertex itself, and the temporal and occipital regions. Photograph while you do it — the baseline image set is discussed in the outcome-measurement material in this programme, and it is far easier to capture at the first visit than to wish for later.

In patterned loss, the occipital scalp is characteristically spared. Diffuse involvement including the occiput argues for effluvium or a systemic driver.

Look at the scalp surface, not just the hair

This is the step that distinguishes scarring from non-scarring disease, and it takes fifteen seconds.

Part the hair and look for follicular ostia. In non-scarring alopecia the openings are present even where hair is absent. In scarring alopecia they are effaced — the skin looks smooth, shiny, and empty. Look also for perifollicular erythema, perifollicular scale, tufting of multiple hairs from a single opening, and pustules.

Any of those findings changes the plan. They are the clinical signature of a primary cicatricial alopecia, and that patient needs dermatology assessment and, in most cases, a scalp biopsy — not a PRP series.

The pull test

Grasp roughly 50–60 hairs near the scalp and apply gentle steady traction along the shaft. Extraction of more than a small number of telogen hairs is consistent with active shedding. Perform it in several regions. The test is crude and is affected by when the patient last washed their hair, so record the washing interval alongside the result.

Trichoscopy

A dermatoscope on the scalp is the highest-value, lowest-cost addition most aesthetic practices can make to their hair service, and it moves you from impression to observation.

Trichoscopy has been formally assessed for reliability and validity in the evaluation of alopecia in women, where features including hair diameter diversity greater than 20%, single-hair follicular units and vellus hairs carry diagnostic weight (Saqib et al., Int J Womens Dermatol, 2021;7(4):458–465). Hair diameter diversity is the direct visual correlate of miniaturisation and is the trichoscopic hallmark of androgenetic alopecia.

Other patterns worth being able to recognise: yellow dots and exclamation-mark hairs in alopecia areata; hair casts, broken hairs, black dots and empty follicular openings in traction alopecia (Boas et al., Dermatol Pract Concept, 2025;15(2)); perifollicular scale and loss of openings in lichen planopilaris and frontal fibrosing alopecia.

Step three: laboratory evaluation, at category level

Here the guidance must be stated carefully, and this resource deliberately stops short of prescribing a panel.

Published clinical guidance for the evaluation of hair loss identifies thyroid function testing, a complete blood count, and iron studies as the recommended baseline laboratory investigations, with scalp biopsy reserved for diagnostic uncertainty or suspected scarring disease (Walker et al., JAAPA, 2026;39(9):27–34). The primary-care literature describes the same core set within a systematic approach to non-scarring alopecia (Dakkak et al., 2024).

Beyond that core, testing is directed by the history rather than ordered reflexively:

• Hormonal evaluation where the history or examination suggests hyperandrogenism, menstrual irregularity, or a perimenopausal or menopausal transition — the scenario Tatiana specifically calls out. What is measured, and whether it is measured at all, is a clinical decision made on the individual presentation.
• Nutritional assessment where the history includes restrictive eating, rapid weight loss, bariatric surgery or a vegan diet without supplementation.
• Autoimmune or inflammatory screening where there are systemic features.

Two cautions that matter more than the list.

Ferritin thresholds for hair are contested. Iron deficiency is a well-documented contributor to female hair loss, and studies of women with diffuse hair loss have examined ferritin alongside TSH and B12 against phototrichogram findings (Lin et al., Tzu Chi Med J, 2023;35(4):322–328; Bilik et al., North Clin Istanb, 2024;11(1):38–44). But the ferritin level at which supplementation benefits hair specifically is not settled, and quoting a single cut-off as though it were established is an overreach. Interpret it in the clinical context and in conjunction with the rest of the iron studies.

Ordering a broad panel is not the same as diagnosing. A wide screen generates incidental abnormalities that consume the consultation and rarely change the hair diagnosis. The purpose of testing here is to identify reversible and systemic drivers that would otherwise be treated with the wrong intervention — not to produce a document.

If you are not comfortable ordering or interpreting these investigations within your scope and setting, that is not a reason to skip them. It is a reason to build a referral pathway to a primary care clinician or dermatologist and to make that referral part of your protocol.

Step four: decide whether PRP is the right treatment at all

Now the diagnostic work pays for itself. Sort the patient into one of three groups.

PRP is not the answer — refer or redirect

• Suspected scarring alopecia — effaced follicular ostia, perifollicular erythema or scale, tufting, a shiny atrophic patch. Refer for dermatological assessment and biopsy. Do not start a series.
• Alopecia areata — a distinct autoimmune pathway with its own established treatments, including intralesional corticosteroid and systemic options (Dakkak et al., 2024).
• Suspected tinea capitis — requires oral antifungal therapy, not injection.
• Untreated reversible driver — significant iron deficiency, uncontrolled thyroid disease, an ongoing medication effect, or an active effluvium trigger. Address the driver, then reassess.
• Ongoing traction — traction alopecia is managed by removing the tension. Treating while the traction continues is treating against an active cause.

PRP is premature — treat the driver first, reassess

Acute telogen effluvium after a defined trigger is frequently self-limiting once the trigger resolves. Committing a patient to a monthly injection series at that point is likely to mean they credit the treatment for a recovery that was going to happen, which is its own kind of clinical failure.

PRP is a reasonable option — with accurate framing

Patterned, non-scarring, miniaturisation-type loss with follicular ostia preserved, drivers addressed, expectations set. That is the population the evidence base covers, and it is a real and large population. The framing that belongs in the consultation is set out in this cluster's material on what PRP does not do and on the hair timeline; in brief, PRP supports existing follicles, it does not create new ones, and it is a series with maintenance rather than a single treatment.

Step five: establish the baseline before you treat

The diagnostic visit is also the only opportunity to capture a true baseline. Once you have injected, there is no going back to it.

At minimum: standardised photographs from fixed positions, a documented part-width or density observation, trichoscopic images of one or more defined sites, the pull test result with the washing interval, the working diagnosis, the investigations ordered, and the plan with its reassessment point.

Tatiana's reason for insisting on this is the one that persuades patients: "This is a long treatment. The patient may forget how the hairline was. It's very important that you document the first time you see the patient, and then progressively — that's the only way they will actually see the change."

These protocols reflect Tatiana Sarmiento's clinical practice as taught in Empire Medical Training's hands-on curriculum. Technique and clinical assessment are learned under supervision; this article is educational and is not a substitute for training.

Hair restoration is a diagnostic discipline before it is an injection discipline. Empire's Medical Hair Loss Treatment, PDO Threads and PRP Hair Restoration Training covers the assessment pathway alongside the treatment techniques, and Platelet Rich Plasma Training covers preparation and delivery.

Related guides in this cluster

Part of Regenerative Injectables: PRP and PRF.

Clinical GuideSingle Spin vs Double Spin PRP: What Actually Changes in the TubeSingle spin vs double spin PRP compared for clinicians — what the second spin concentrates, why volume compensates, and how processing Clinical GuideLeukocyte-Rich vs Leukocyte-Poor PRP: Matching Cell Content to the IndicationLeukocyte-rich vs leukocyte-poor PRP explained for clinicians — the cytokine data, the PAW, DEPA and Dohan Ehrenfest frameworks, and wh Clinical GuideSequencing PRP with Microneedling and Laser: Recovery and Remodelling SupportSequencing PRP with microneedling and laser — same-session versus staged delivery, what the recovery evidence supports, and the order o