Reviewed by the Evolve Health clinical team · 2026-10-16 · 8 min read
Clinically reviewed by the Evolve Health clinical team — October 2026
Every article is checked by the clinicians who care for patients at Evolve Health in Denton. Meet the care team →
Quick answer
The blood tests that explain the most hair loss are ferritin and iron studies, thyroid testing (TSH and free T4), a CBC, and vitamin D and B12 levels — with hormone levels added when the history points that way. They catch the causes that blood work can catch: iron deficiency, thyroid problems, and vitamin deficiencies. Pattern hair loss, the most common type of all, usually has normal labs and is diagnosed by the pattern on exam. At Evolve Health in Denton, the visit is $75 flat self-pay, and every lab is priced and told to you before it is run.
The questions land at our front desk in a few familiar forms. "My hair started falling out a few months after I was sick — is that connected?" "My ponytail feels thinner. Is it my thyroid?" "Do I need vitamins, or is this just getting older?" Those are exactly the right questions, because hair loss is rarely one thing. It is a short list of common causes, and most of them leave fingerprints in a basic lab panel. This guide walks through the causes, test by test, and then says plainly what treatment can and cannot do.
The common causes, grouped honestly
- Pattern hair loss (genetics). The most common cause in both men and women. Follicles gradually become sensitive to normal hormone levels and shrink over years, producing the familiar patterns — a widening part and thinning at the crown in women, a receding hairline and thinning crown in men. Blood tests are usually normal here; the diagnosis is the pattern itself.
- Telogen effluvium (stress shedding). A physical or emotional shock pushes many follicles into the shedding phase at once. Classic triggers are a serious illness or fever, surgery, childbirth, major stress, and rapid weight change. It typically starts two to three months after the trigger — which is why the connection is so easy to miss — and generally resolves once the trigger has passed.
- Thyroid problems. Both an underactive and an overactive thyroid can cause diffuse shedding, along with fatigue and a general sense that something is off. This is one of the most fixable causes on the list.
- Iron deficiency. Low iron stores are a leading cause of shedding in women, especially with heavy periods. The key test is ferritin, which measures stored iron — it can be low long before anemia appears.
- Vitamin D and B12 deficiency. Both are common, both are measurable, and both are worth correcting when low. Deficiency does not explain every case, but it is a contributor a blood test can settle in one draw.
- Hormonal causes in women, including PCOS. Polycystic ovary syndrome can thin the hair at the part and crown while causing irregular cycles, acne, and increased facial or body hair. When that cluster is present, hormone levels belong in the workup.
- Scalp conditions. Dandruff and seborrheic dermatitis, scalp inflammation, and fungal infection (tinea) can drive breakage and loss that no blood test will find — those are found by looking at the scalp itself.
The lab panel, test by test
A clinician builds the panel from your history and exam — it is not the same list for everyone. These are the tests that do most of the work, and what each result actually changes:
| Test | What it checks | What the result changes |
|---|---|---|
| Ferritin + iron studies | Stored iron — the single most useful hair test in women | Low stores mean iron treatment and a look at why (heavy periods, diet, absorption), then a recheck |
| CBC (complete blood count) | Red blood cells and anemia | Confirms whether low iron has progressed to anemia, which raises the urgency |
| TSH + free T4 | Thyroid function — underactive or overactive | An abnormal result moves thyroid treatment to the front of the plan; hair usually recovers as levels settle |
| Vitamin D (25-OH) | Vitamin D status | A deficiency gets corrected on a schedule, with a follow-up level to confirm it worked |
| Vitamin B12 | B12 status, often low with certain diets, stomach conditions, or acid-blocking medicines | Low B12 is replaced, and the reason it fell is part of the plan |
| Hormone levels (when indicated) | Androgen levels, when PCOS or another hormonal cause is on the table | A hormonal pattern shifts the plan toward managing that condition, not just the hair |
One habit that saves money and confusion: read the numbers in context. A ferritin at the bottom of the "normal" range means something different in a woman shedding heavily than the same number in someone with no symptoms. Our guide to your numbers, explained walks through how reference ranges work, and what blood tests should I ask for? covers how to talk through a panel before anything is drawn.
The exam side: what we look at, not just what we draw
Blood work is only half the visit. The other half is your scalp. A clinician reads the pattern — where the thinning sits tells a different story at the part line than at the temples or in patches. A gentle pull test shows whether shedding is active right now and how much is coming out. The scalp check looks for scaling, redness, flaking, and broken hairs that point to a skin condition rather than an internal one.
Here is the honest boundary: some scalp findings need a dermatologist. Scarring alopecias — conditions where inflammation damages the follicle itself — fungal infections that need a closer look, and anything that does not behave as expected get referred, plainly and promptly. Finding that out at a $75 primary care visit is far better than finding it out after months of the wrong shampoo.
Red flags: come in promptly if you notice these
- Rapid, patchy loss — smooth round patches appearing over days or weeks.
- Scalp pain, burning, heavy scaling, or sores alongside the loss.
- Visible scarring — shiny, smooth areas where follicles seem to be disappearing.
- Loss that arrives with other symptoms — significant fatigue, unexplained weight change, feeling cold or jittery all the time, or new irregular cycles. Hair plus body symptoms is a workup, not a wait-and-see.
Treatment, stated honestly
The rule is simple: treat the cause first. Correcting iron, thyroid, or a vitamin deficiency is the treatment when those are the drivers, and hair recovery follows the lab recovery — slowly, over months, because hair grows about half an inch a month. Shedding from a passed trigger (telogen effluvium) usually needs time more than medicine.
For pattern hair loss, options split into over-the-counter topicals you apply to the scalp and prescription options you discuss with a clinician — topical treatments that support follicle activity, and oral medications that reduce the hormone effect shrinking the follicles. What we will not do is promise regrowth. No honest clinician can: response varies, results take six months or more to judge, and stopping treatment generally means losing the ground you gained. Beware anyone — clinic or influencer — selling guaranteed hair.
One prescription deserves its own paragraph because it is widely sold online: finasteride. It lowers the hormone effect behind male pattern loss and helps many men, but it has real trade-offs, including possible sexual side effects, so it should start with a clinician conversation. It must never be taken by women who are pregnant or could become pregnant — it can harm a developing baby — and it is not a standard treatment for hair loss in women. If it fits your situation, we will weigh the benefits and risks with you first, before anything is prescribed.
What the visit looks like at Evolve Health
The visit is $75 flat self-pay, and it covers the clinician exam, your history, and a treatment plan. Hair loss consults are part of what we do — for men and for women — at our Denton clinic, and many first conversations can also start by video from anywhere in Texas. If labs are part of the plan, each test is priced and told to you before it is run; nothing is drawn on a surprise basis. If you have insurance, we verify your coverage free before the visit from your insurance card, photo ID, and date of birth. When your results come back, we go through them number by number and agree on the plan: treatment, a recheck date, or a dermatology referral.
Frequently asked questions
Can blood tests really find the cause of hair loss?
Often, yes. A large share of hair loss traces back to something measurable in the blood — an underactive or overactive thyroid, low iron stores, or a vitamin D or B12 deficiency. The panel does not diagnose every type of loss: pattern hair loss, the most common kind, usually shows normal labs and is identified by the pattern on exam. The blood work rules the treatable causes in or out, and that is what decides the treatment.
What blood tests are ordered for hair loss?
A typical workup includes ferritin and iron studies to check iron stores, a CBC (complete blood count), thyroid testing such as TSH and free T4, and vitamin D and B12 levels. When the history points that way — irregular cycles, acne, or increased facial hair, for example — hormone levels may be added. Your clinician chooses the panel from your history and exam rather than ordering every test for everyone.
My iron was 'normal.' Can it still be causing my hair loss?
Yes, it can. The test that matters most for hair is ferritin, which measures stored iron, and its reference range is wide. A ferritin sitting at the very bottom of 'normal' — especially in a woman with heavy periods — can contribute to shedding even when the number is technically in range. That is why we read your results against your symptoms and your pattern of loss, not just against the flag on the lab report.
If you fix the cause, will my hair grow back?
When shedding is driven by a correctable cause — low iron, a thyroid problem, a deficiency — regrowth usually follows once the level is corrected, but it is slow. Hair grows about half an inch a month, and follicles need a few months to re-enter the growth phase, so judge any plan in seasons, not weeks. Pattern hair loss is managed rather than cured. We will tell you honestly which situation you are in before you spend money on treatment.
Is finasteride safe? Who should never take it?
Finasteride is a prescription tablet that lowers the hormone effect that shrinks follicles in pattern hair loss. It is a real medication with real trade-offs — including possible sexual side effects — so it starts with a clinician conversation, not a checkout page. It must never be taken by women who are pregnant or could become pregnant, because it can harm a developing baby, and it is not a treatment for hair loss in women in most cases. If it is an option for you, we will go through the benefits and risks together first.
What does a hair-loss workup cost at Evolve Health?
The self-pay visit is $75 flat, and it includes the clinician exam, your history review, and a treatment plan. If labs are needed, each test is priced and told to you before it is run — no lab is drawn without you knowing its cost first. If you have insurance, we verify your coverage free from your insurance card, photo ID, and date of birth before the visit.
Sources
- American Academy of Dermatology — Hair loss: overview, types, and causes (pattern hair loss, telogen effluvium, and when to see a clinician)
- MedlinePlus (U.S. National Library of Medicine) — Hair loss (causes including thyroid disease, iron deficiency, and hormonal conditions)
- American Academy of Dermatology — Hair loss: diagnosis and treatment (blood work and scalp exam in the workup)
General education only: This article explains how hair loss is commonly evaluated. It is not a diagnosis — your clinician's exam and your own lab results determine what applies to you.
Find out why — before you spend on fixes
Book a $75 hair-loss consult at Evolve Health in Denton. We will examine your scalp, order only the labs that fit your picture, and price each one before it is run — then build the plan around what the results show.