Read this before you book. If you take biotin, including any hair, skin and nail gummy or a multivitamin that contains it, stop 72 hours before your blood draw. Biotin interferes with the assay platforms used for thyroid and hormone testing and can push your results either way. It is the most common reason a hair loss panel comes back wrong. More on this in the preparation section.
Most people who ask us about hair loss have already spent money on shampoos, oils, serums and clinic treatments before anybody thought to check their iron. That’s the wrong order, and it wastes months.
There’s also a timing problem that catches almost everyone out. Shedding shows up two to three months after whatever caused it. By the time you’re pulling hair out of the drain, the trigger is well behind you, which is why people blame the new shampoo or the water when the real answer was a bout of flu, a crash diet, or a pregnancy from the previous season.
Blood testing helps because it finds the handful of internal causes that are both common and fixable. It’s just as useful for ruling things out. This page covers which tests are worth paying for, how to prepare so the numbers mean something, and where blood testing won’t get you an answer at all.
Start by working out what kind of hair loss you have
This decides whether a blood test is even the right purchase.
Telogen effluvium
Diffuse shedding across the whole scalp. Hair comes out in handfuls in the shower, your part looks wider, density drops everywhere rather than in patches. Something knocks an abnormal share of follicles into the resting phase at once, and they all let go together a couple of months later.
This is the type blood tests are built for. Usual triggers:
- Iron deficiency, with or without anaemia
- Thyroid trouble in either direction
- Rapid weight loss, including on GLP-1 medications such as semaglutide and tirzepatide. Shedding around month three or four is well recognised, driven by the speed of the weight loss rather than by the drug being harmful, and it usually settles.
- Childbirth. Postpartum shedding tends to peak three to four months after delivery.
- A serious illness, high fever, general anaesthetic or major surgery
- Crash dieting or sustained low protein intake
- Severe stress
Because of the lag, think about what was happening two to four months before the shedding started. Not last week.
Androgenetic alopecia
Patterned thinning. In men, receding temples and a thinning crown. In women, the central part slowly widens while the front hairline stays put. It comes down to inherited follicle sensitivity to androgens.
No blood test diagnoses this. There’s no panel that confirms it and no supplement that corrects it. A dermatologist diagnoses it by looking at your scalp.
Testing is still worth doing, though, because deficiency-driven shedding often sits on top of pattern loss and makes it look considerably worse than it is. Fixing the deficiency won’t undo the pattern, but it frequently recovers a useful amount of density.
Alopecia areata
Round, smooth bald patches with clear edges. This is autoimmune and needs a dermatologist rather than a lab panel. Blood work only comes in for screening the autoimmune conditions that travel with it, mainly thyroid disease.
Scarring alopecia and scalp disease
If your scalp is red, scaly, itchy, burning or painful, or if the skin in the affected area looks smooth and shiny with no follicle openings left in it, see a dermatologist soon. Scarring alopecia destroys follicles permanently and the window to intervene is limited. A blood test is not the right first step here.
The tests worth running
Ferritin, with a full iron study
A ferritin test measures stored iron. It’s the most sensitive single marker of iron depletion because it drops before haemoglobin does, which is how you end up iron deficient with a perfectly normal blood count.
Lab reference intervals for ferritin are wide, usually somewhere around 15 to 150 µg/L in women and 30 to 400 µg/L in men. Dermatologists work to a tighter number. Shedding is commonly reported below 30 µg/L, and clinicians managing telogen effluvium often aim for 50 to 70 µg/L. That higher target is common practice rather than settled science, and it’s fair to say the evidence behind the exact figure is still argued over. What it means for you is simple enough: a ferritin sitting inside the “normal” column of your report can still be low enough to be part of the problem.
One thing changes how this result is read. Ferritin is an acute phase reactant, so infection, inflammation, liver disease and obesity all push it up regardless of how much iron you actually have. A normal ferritin can therefore hide a real deficiency. We run CRP alongside it, plus serum iron, TIBC and transferrin saturation. If ferritin looks acceptable but transferrin saturation is low and CRP is up, you’re looking at inflammation masking depletion, not at healthy iron stores.
A complete blood count goes in as well, to pick up anaemia and to show red cell size, which points towards the type of deficiency.
Thyroid: TSH, Free T4 and TPO antibodies
Thyroid hormone drives the hair follicle cycle directly. Underactive and overactive thyroids both cause diffuse shedding, usually with a texture change as well. Hair goes dry, brittle and coarse. In hypothyroidism the outer third of the eyebrows often thins too.
A thyroid profile starts with TSH as the first-line screen. Free T4 goes in when TSH comes back abnormal or borderline. Free T3 has a narrow role and most hair loss investigations don’t need it. If you want the detail on how these three relate to each other, we’ve written about T3 and T4 imbalance, which turns up often in patients here.
TPO antibodies are the part usually left out, and they matter. Autoimmune thyroiditis is the commonest cause of hypothyroidism, it’s far more frequent in women, and antibodies often turn up while TSH is still technically in range. A borderline TSH with positive antibodies is a completely different situation from a borderline TSH with negative ones, and your doctor will follow you up differently.
Set your expectations on timing. Even after thyroid function is back where it should be, visible hair recovery takes three to six months. Shedding sometimes gets briefly worse when treatment starts, which is unnerving but normal.
Vitamin D (25-hydroxyvitamin D)
The right test is 25-hydroxyvitamin D, the storage form. The active form, 1,25-dihydroxyvitamin D, tells you nothing useful about your status. If a report comes back showing the active form for a routine check, the wrong test was ordered.
Deficiency is generally taken as under 20 ng/mL (50 nmol/L). Insufficiency sits between 20 and 30 ng/mL (50 to 75 nmol/L).
The local angle here is real rather than decorative. UAE and wider Gulf studies have repeatedly found deficiency in a large majority of adults tested, despite the sun. The reasons are behavioural and environmental. Nobody goes outside voluntarily between May and September; daily life runs from an air-conditioned building to an air-conditioned car to another air-conditioned building; sun protection is widespread; and clothing coverage reduces exposure further. Deeper skin pigmentation lowers synthesis for a given amount of sunlight as well, which applies across a large share of the resident population.
The vitamin D receptor sits in the hair follicle and is involved in cycling, so the association with hair loss is well described. Whether correcting a deficiency reverses shedding is a weaker claim, and we’d rather say so than oversell it. It’s worth measuring regardless, for reasons that have very little to do with hair.
Vitamin B12 and folate
Both are needed for the fast cell division that hair matrix cells depend on. A shortage of either shows up in the blood count and can contribute to shedding.
Dietary risk concentrates in vegetarians and vegans, which makes a vitamin B12 test particularly worth having here given who lives in this country. Long-term metformin, long-term proton pump inhibitors and any history of bariatric surgery all raise the risk too.
There’s a catch with interpretation. Serum B12 measures total B12, and only a fraction of that is actually available to your cells, so results in the low-normal band aren’t reliable. If your symptoms suggest deficiency but the number lands in the grey zone, active B12 (holotranscobalamin) or methylmalonic acid will settle it. Ask about them. And if you’ve had a B12 injection or been taking supplements recently, the serum result is uninterpretable, so mention it when you book.
Androgens, when there’s a reason to look
This isn’t a routine add-on for everyone. Run it indiscriminately and you get numbers that are hard to interpret and easy to over-treat.
Look at androgens when there are clinical signs of excess: patterned scalp thinning together with acne, hirsutism, irregular or absent periods, or trouble conceiving. In that case the hormone panel is total testosterone, SHBG, DHEA-S, LH, FSH and prolactin. The question underneath is usually polycystic ovary syndrome, the commonest endocrine cause of hair thinning in women of reproductive age, and one that routinely goes unnamed for years.
Cycle timing isn’t optional. LH, FSH and oestradiol only mean something drawn on days 2 to 5 of your cycle, counting day one as the first day of full flow. Drawn at random, you get a number nobody can interpret. Book around it.
Prolactin has its own rules: morning draw, and avoid hard exercise, breast stimulation and significant stress beforehand, since all three raise it temporarily.
Zinc
Zinc deficiency does cause hair loss, but genuine deficiency is uncommon in anyone eating a varied diet and a routine zinc test isn’t first-line. It earns its place if you follow a restrictive or elimination diet, have had bariatric surgery, live with inflammatory bowel disease or another malabsorptive condition, or if you’ve noticed poor wound healing or a change in taste alongside the shedding.
We’ve listed it separately rather than in the core panel because adding it by default puts the cost up without changing what anyone does next.
Tests we’ll talk you out of
Hair mineral analysis
Not a validated way to assess nutritional status. Results shift with shampoo, water, dye and whatever settles on your hair from the air, and the same sample sent to two labs can come back meaningfully different. It has no place in an evidence-based hair loss workup and we won’t sell it to you.
Serum biotin
Biotin deficiency bad enough to cause hair loss is rare outside inherited metabolic conditions and long-term tube feeding. Measuring it in an otherwise healthy adult rarely changes anything.
How to prepare
Stop biotin 72 hours before
This is the one that ruins results. Biotin interferes with the streptavidin-biotin immunoassay systems used for thyroid and hormone panels, and depending on the assay design it can produce falsely high or falsely low readings. A falsely abnormal thyroid result sends you into unnecessary investigation. A falsely normal one hides real disease.
The awkward part is that people investigating hair loss are exactly the people taking biotin supplements, so this catches more patients than any other preparation error we see. Check your gummies and your multivitamin, and stop them three days out.
Everything else
| Test | What to do |
|---|---|
| Iron studies | Morning draw, since serum iron follows a daily rhythm and peaks early. Fast 8 to 10 hours. Hold oral iron supplements for at least 24 to 48 hours, because they lift serum iron sharply and temporarily. |
| Thyroid | No fasting needed. If you take levothyroxine, take it after the draw, not before. |
| Vitamin D | No fasting, no supplement withholding. |
| Vitamin B12 and folate | No supplements or injections in the days before, or the result can’t be read. |
| Female hormone panel | Days 2 to 5 of your cycle, morning draw. |
| Prolactin | Morning. No exercise, breast stimulation or acute stress beforehand. |
Sample is a standard venous draw. Results are reported within [INSERT TURNAROUND].
What’s in the panel
| Panel | Tests included |
|---|---|
| Core hair loss panel | Complete blood count, Ferritin, Serum Iron, TIBC, Transferrin Saturation, CRP, TSH, Free T4, 25-OH Vitamin D, Vitamin B12, Folate |
| Thyroid antibody add-on | TPO antibodies |
| Female hormone add-on | Total Testosterone, SHBG, DHEA-S, LH, FSH, Prolactin |
| Zinc add-on | Serum Zinc |
Which combination you need depends on your symptoms and history, so call us and we’ll go through it before you book. Several of our health packages already cover most of the core panel, and we work with most major insurers in the UAE, so it’s worth checking your coverage first.
Home collection across Dubai
We offer home sample collection across [LIST AREAS], which solves the two scheduling problems this particular panel creates: the fasting morning slot for iron studies, and the fixed day 2 to 5 window for cycle-timed hormones. A phlebotomist comes to your home or office at a booked time and the sample travels under controlled conditions to our laboratory in Al Barsha 1.
Book on +971 50 608 6958 or WhatsApp.
What happens after your results
Every value comes back with the lab reference interval next to it. Interpreting them belongs with a doctor. Reference ranges are population statistics, not treatment thresholds, and iron in particular should never be supplemented without confirmed deficiency, because iron overload carries its own problems.
Take your report to your GP, endocrinologist or dermatologist. If you don’t have one, ask us and we’ll point you towards a referral.
If everything comes back normal, that’s still worth knowing. It moves the diagnosis away from a nutritional or thyroid cause and towards a dermatological one, most often androgenetic alopecia or a scalp condition that needs examining. Your next appointment is with a dermatologist, who can look at the scalp under trichoscopy and do a pull test or a biopsy if needed.
When to skip the blood test and see a doctor
Book a clinical review first, not a panel, if you have:
- Distinct round or oval bald patches with smooth skin
- A red, scaly, painful, burning or itchy scalp
- Areas where the skin looks shiny, and the follicle openings have gone
- Hair loss happening over days rather than weeks
- Hair loss alongside fever, weight loss, night sweats or joint pain
- A child losing hair
Genex Clinical Laboratories LLC, First Floor, Elite Business Center, Al Barsha 1, Dubai, UAE DHA Licence No. 6179400 · [ACCREDITATIONS] +971 50 608 6958 · info@genexlab.ae
This article is general information, not medical advice, diagnosis or treatment. Lab results need interpreting by a qualified doctor who knows your history. Don’t start, stop or change any supplement or medication based on what you’ve read here.
