Blood Tests for Hair Loss: Which Labs Are Worth Getting

Last verified November 2, 2026. Every claim on this page links to the source we checked. Where the evidence is thin, we say so.

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The short answer

Most hair loss is diagnosed by a dermatologist from your history and a look at your scalp, sometimes with a gentle hair-pull test, a dermatoscope or a biopsy^{1, 5}. Blood tests help when something other than pattern hair loss is suspected: thyroid problems, iron-deficiency anaemia, or a hormone disorder in women with signs of androgen excess^{3, 6, 7}. Even then, the evidence that fixing a borderline ferritin or vitamin D level regrows hair is weak⁷. Large direct-to-consumer “hair loss panels” with DHT, estradiol, pregnenolone, IGF-1 and cholesterol are not what dermatology guidelines recommend. The best first step is a board-certified dermatologist, not a lab order.

Do you need blood tests for hair loss?

Often not. Male and female pattern hair loss (androgenetic alopecia) is the most common type, and the European S3 guideline says it is usually diagnosed clinically. It suggests lab tests or a biopsy only when another diagnosis can’t be ruled out on examination⁵. A review of female pattern hair loss reaches the same conclusion: history and examination are usually enough, and a biopsy is rarely needed⁶.

The AAD describes the dermatologist’s workup as questions about how long and how fast you’ve been losing hair, a close look at the scalp, nails and other hair-bearing areas, and a gentle pull test. Blood tests or a scalp biopsy come in when a disease, deficiency, hormone imbalance or infection is suspected¹.

That matters because different types of hair loss need different treatment. Shedding after an illness, childbirth or major stress usually recovers within 6 to 9 months once the trigger passes². Patchy loss from alopecia areata is an autoimmune condition with its own treatments³. Pattern hair loss responds to minoxidil, finasteride and other options¹. A big panel of blood tests doesn’t tell these apart; an exam does.

See a dermatologist promptly if

• hair is falling out in patches³
• your scalp is red, scaly, painful, burning or scarred, which can point to infection or a scarring alopecia²
• you are a woman with thinning hair plus irregular periods, acne or excess facial or body hair⁶
• shedding is heavy and hasn’t settled within several months of a known trigger²
• you have heavy periods or other reasons to suspect anaemia, or symptoms of a thyroid problem^{2, 7}

Some conditions that cause hair loss, such as untreated syphilis, need treatment in their own right; hair often regrows once the cause is treated².

Which tests, and how good is the evidence?

Grades describe how well the evidence supports using the test for hair loss. A recommended in guidelines with strong supporting studies. B recommended in guidelines or expert reviews for a specific situation. C commonly ordered, but studies linking results to hair loss or to regrowth are small or conflicting. D no good evidence it helps diagnose or manage hair loss.

Test	When a clinician might order it	Grade	What the evidence says
Ferritin and iron studies, complete blood count	Shedding (telogen effluvium), heavy periods, restrictive diet, symptoms of anaemia	C	The link between low ferritin and shedding is weak, and no controlled study shows iron regrows hair when you aren’t anaemic. Iron-deficiency anaemia should still be found and treated, because its causes matter7.
Thyroid (TSH)	Diffuse shedding, thyroid symptoms, patchy hair loss (alopecia areata)	B	Thyroid disease can cause thinning that improves with treatment2, and the AAD lists thyroid testing for alopecia areata3. Studies of routine testing in shedding are old or small7.
Vitamin D (25-hydroxy)	Alopecia areata, shedding	C	Results conflict, levels vary by season and ethnicity, and there is no evidence that supplementing regrows hair7, 8.
Zinc	Suspected deficiency, restrictive diet	C	Support rests on a 5-person case series7. Testing makes sense only with a reason to suspect deficiency.
Testosterone, DHEA-S, prolactin and related hormones (women)	Women with thinning plus signs of androgen excess	B	Expert reviews advise checking for ovarian or adrenal disorders when there are signs of hyperandrogenism6. Many women with pattern hair loss have no other signs of androgen excess5.
DHT, testosterone and hormone panels (men with typical pattern loss)	Rarely needed	D	Pattern hair loss is usually diagnosed by examining the scalp; lab tests are suggested only when another cause can’t be ruled out clinically5.
PSA (men starting finasteride)	Men over about 45 before starting finasteride	B	Finasteride lowers PSA, so the European guideline advises a baseline PSA in men starting after 45 and doubling later values when interpreting them5.
Biotin level	Almost never	D	The AAD advises supplements only for a documented deficiency1. Biotin supplements can interfere with some lab tests9.

What we left out: the original version of this page listed panels with 40 or more tests, including free DHT, free estradiol, pregnenolone, IGF-1, reverse T3, lipids, ApoB, Lp(a), urinalysis and a pregnancy test. Several of these are reasonable general health checks, but none is recommended by the guidelines and reviews we found for diagnosing hair loss^{5, 6, 7}. If you want a broad health screen, ask your doctor about it separately.

What a clinician might check, by situation

Sudden, diffuse shedding (telogen effluvium)

Lots of hairs coming out all over, often a few months after an illness, surgery, childbirth or big stress². Ferritin, a blood count, TSH and sometimes vitamin D and zinc are commonly ordered. A 2021 review of each test found the evidence for all of them limited, and noted that insurers sometimes resist covering them⁷. Testing is still worth it when the history suggests anaemia or a thyroid problem.

Patchy hair loss (alopecia areata)

A dermatologist can often diagnose it on sight. You may need a blood test to check for thyroid disease and your iron and vitamin levels. People with alopecia areata may be at higher risk of other autoimmune diseases, so follow-up matters³.

Thinning in women

Female pattern hair loss is common and usually diagnosed clinically^{4, 6}. If you also have signs of androgen excess, a clinician should look for ovarian or adrenal causes such as polycystic ovary syndrome^{2, 6}. That workup usually includes testosterone and other hormones, chosen by the clinician.

Receding hairline or crown thinning in men

This is usually male pattern hair loss, diagnosed by examination⁵. Measuring DHT or testosterone won’t confirm it or change treatment. If you are over about 45 and starting finasteride, the European guideline advises a baseline PSA because the drug lowers PSA readings⁵.

A note on biotin

Biotin is in many hair, skin and nail supplements. The AAD says supplements should be taken only for a documented deficiency¹. Biotin can also significantly interfere with some lab tests; FDA has received reports of falsely low troponin results, a test used to diagnose heart attacks⁹. If you take biotin, tell your clinician and the lab before any blood test.

Should you take vitamins for hair loss?

A 2018 review of vitamins A, B, C, D and E, iron, selenium and zinc found that their role in hair growth is important but not clear, and called for proper placebo-controlled trials in people with both a deficiency and hair loss⁸. Too much can backfire: large amounts of vitamin A or selenium can themselves cause hair loss². Test, treat a real deficiency, and skip the rest.

What actually treats hair loss

For pattern hair loss, the AAD lists minoxidil (over the counter), finasteride for men, spironolactone for some women, platelet-rich plasma, low-level laser devices and microneedling, along with hair transplants^{1, 4}. The European guideline recommends oral finasteride 1 mg a day for men with pattern hair loss⁵. Finasteride and spironolactone are prescription drugs with side effects and must not be used in pregnancy^{1, 4}, so discuss them with a clinician.

• Our microneedling evidence review grades microneedling added to minoxidil as one of its better-supported uses.
• AHK-Cu, a copper peptide sold in hair serums, has one lab study on scalp follicles and no human trials.
• For facial hair, see our beard growth guide.

Common questions

Should I get my DHT tested?

Not to diagnose pattern hair loss. It is diagnosed by examining the scalp, and guidelines don’t call for hormone panels in typical cases⁵.

Can low ferritin cause hair loss?

Possibly, but the evidence is weak. One controlled study found no difference in ferritin between people with and without shedding, whatever cut-off was used, and no controlled study shows iron supplements regrow hair in people without anaemia⁷. There is no agreed ferritin target for hair.

Does low vitamin D cause hair loss?

Studies conflict, and there is no evidence that vitamin D supplements regrow hair^{7, 8}. Correct a real deficiency for its own sake.

Do I need labs before starting finasteride?

No hormone panel is needed. For men over about 45, the European guideline advises a baseline PSA, because finasteride roughly halves PSA readings and later values need adjusting⁵.

Will insurance cover hair loss labs?

It depends on your plan and the reason for testing. Dermatologists report some insurer resistance⁷. Tests ordered for symptoms of anaemia or thyroid disease are more likely to be covered than broad screening panels.

Can I order these tests myself?

In many places you can buy lab tests directly. Bring any results to a dermatologist; a number outside the lab’s range doesn’t tell you what type of hair loss you have, and the exam is what decides treatment^{1, 5}.

Related

Read our microneedling evidence review, the AHK-Cu and GHK-Cu peptide pages, and our beard growth guide.

References

Sources were checked on November 2, 2026. Where only the abstract or a summary was available, we say so.

1. American Academy of Dermatology. Hair loss: diagnosis and treatment. Last updated 13 December 2022. Source
2. American Academy of Dermatology. Hair loss: who gets and causes. Source
3. American Academy of Dermatology. Alopecia areata: diagnosis and treatment. Last updated 7 October 2026. Source
4. American Academy of Dermatology. Thinning hair and hair loss: could it be female pattern hair loss? Last updated 13 December 2022. Source
5. Kanti V, Messenger A, Dobos G, et al. Evidence-based (S3) guideline for the treatment of androgenetic alopecia in women and in men. European Dermatology Forum; published in Journal of the European Academy of Dermatology and Venereology, 2018. Full guideline text. Source
6. Fabbrocini G, Cantelli M, Masarà A, Annunziata MC, Marasca C, Cacciapuoti S. Female pattern hair loss: a clinical, pathophysiologic, and therapeutic review. International Journal of Women’s Dermatology. 2018;4(4):203-211. Abstract. Source
7. Kakpovbia E, Ogbechie-Godec OA, Shapiro J, Lo Sicco KI. Laboratory testing in telogen effluvium. Journal of Drugs in Dermatology. 2021;20(1):110. Source
8. Almohanna HM, Ahmed AA, Tsatalis JP, Tosti A. The role of vitamins and minerals in hair loss: a review. Dermatology and Therapy. 2019;9(1):51-70 (online December 2018). Abstract. Source
9. US Food and Drug Administration. Biotin interference with troponin lab tests: assays subject to biotin interference. Content current as of 21 June 2022. Source