Blood Tests for Hair Loss: What to Ask For
Many cases of hair loss have correctable underlying causes that a blood test can identify. Knowing what to test, and what optimal levels actually look like for hair health, is the foundation of an effective treatment strategy.
of women with hair loss have iron deficiency as a contributing or primary cause
of women experience postpartum thyroiditis, a frequently missed cause of hair shedding after delivery
correctable causes of hair loss are diagnosed with a basic blood panel costing less than $200
The Complete Hair Loss Blood Panel
Here are the tests worth requesting, with priority levels and what results mean for hair specifically.
Ferritin
IronEssentialFerritin is the body's iron storage protein and the most sensitive marker for iron deficiency affecting hair. Serum iron fluctuates with meals; ferritin reflects true stores. Low ferritin is one of the most common reversible causes of hair loss.
Complete Blood Count (CBC)
AnemiaEssentialIdentifies iron deficiency anemia (low hemoglobin, low MCV) as well as vitamin B12/folate deficiency anemia. Provides a complete picture alongside ferritin. Also screens for other blood disorders.
TSH (Thyroid Stimulating Hormone)
ThyroidEssentialBoth hypothyroidism (TSH elevated) and hyperthyroidism (TSH suppressed) disrupt the hair growth cycle and cause diffuse shedding. Thyroid dysfunction is common and highly treatable. Essential in any hair loss workup.
Free T4
ThyroidRecommendedTSH alone can miss subclinical thyroid issues. Free T4 (the active thyroid hormone) provides additional information, particularly when TSH is borderline or symptoms are present despite normal TSH.
Vitamin D (25-OH)
VitaminsRecommendedVitamin D receptors are expressed in hair follicles and play a role in follicle cycling. Low vitamin D is consistently associated with alopecia areata and telogen effluvium in observational studies.
Serum Zinc
MineralsRecommendedZinc deficiency causes significant diffuse hair loss and is found at higher rates in alopecia areata and androgenetic alopecia patients. Important in vegetarians, vegans, and those with digestive absorption issues.
DHEA-S (Women)
HormonesWomen. ImportantElevated DHEA-S indicates excess androgen production from the adrenal glands. Can contribute to female pattern hair loss or indicate underlying conditions like PCOS or adrenal hyperplasia.
Free + Total Testosterone (Women)
HormonesWomen. ImportantElevated androgens in women drive follicle miniaturization. Free testosterone is more clinically meaningful than total. Important in women with signs of androgen excess (oily skin, acne, irregular periods, hirsutism).
Prolactin
HormonesWomen. SituationalElevated prolactin (hyperprolactinemia) can cause hair thinning and is associated with menstrual irregularity. Caused by pituitary adenomas, certain medications (antipsychotics, some antidepressants), or hypothyroidism.
ANA (Antinuclear Antibodies)
AutoimmuneSituationalScreens for autoimmune conditions like lupus (SLE), which can cause scarring hair loss. Ordered when hair loss is accompanied by systemic symptoms (joint pain, fatigue, skin rashes, photosensitivity).
Conditions Blood Tests Can Identify & Treat
Each of these conditions causes hair loss, and each is effectively treatable once identified.
How to Approach Your Doctor
Many GPs will order these tests readily, especially if you come prepared. Here's how to have an effective conversation.
Be specific about what you want
Ask for: "Ferritin, CBC, TSH, free T4, vitamin D, serum zinc, and [for women] DHEA-S and free testosterone." Being specific is more effective than asking for "hair loss tests."
Mention ferritin specifically
Serum iron alone is less useful and commonly ordered instead of ferritin. Ferritin specifically reflects storage levels and is most relevant to hair. Ask by name.
Ask for your actual numbers
Request a copy of your results. "Normal" on a report may mean your ferritin is 18 ng/mL, technically above deficiency thresholds but suboptimal for hair growth. Knowing your exact number matters.
Repeat tests after treatment
If you start iron supplementation or vitamin D, retest after 3 months to confirm levels are rising. This also documents treatment response and guides ongoing dosing.
Track Hair Changes Alongside Treatment
Once you've identified and begun treating a deficiency, use Trichometrics to objectively track whether your hair density is recovering, with AI-analyzed scalp photos that give you consistent, comparable data over time.
Start Tracking FreeFrequently Asked Questions
What blood tests should I get for hair loss?▾
A comprehensive hair loss panel typically includes: ferritin (iron storage, more informative than serum iron alone), CBC (complete blood count to detect anemia), TSH and free T4 (thyroid function, both hypo and hyperthyroidism cause shedding), vitamin D (25-hydroxyvitamin D), serum zinc, and for women, a hormonal panel including DHEA-S, free and total testosterone, prolactin, and FSH/LH if menopausal. This panel covers the most common correctable causes of hair loss beyond genetics.
Can a blood test diagnose androgenetic alopecia?▾
No, androgenetic alopecia (pattern baldness) is a clinical diagnosis based on the pattern and distribution of thinning, not blood test results. Blood tests are used to rule out other causes of hair loss that may co-exist with or mimic pattern baldness. A dermatologist evaluates the hair loss pattern, may use dermoscopy or trichoscopy, and uses blood tests to exclude reversible contributors before attributing loss solely to genetics.
What ferritin level is normal for hair loss?▾
Lab "normal" ranges for ferritin (typically 15–150 ng/mL for women, 30–300 ng/mL for men) are set to detect deficiency anemia, they are not optimized for hair growth. Hair specialists generally recommend targeting ferritin above 40–70 ng/mL for adequate hair cycling, with some targeting 70–100 ng/mL for best results. Many women with hair loss have ferritin between 15–30 ng/mL, technically "normal" on the lab report but insufficient for optimal follicle function.
Do I need a dermatologist or can my GP order these tests?▾
A GP (general practitioner or primary care physician) can order all the standard hair loss blood tests and diagnose most correctable causes. A dermatologist is valuable for more complex cases, including dermoscopy and trichoscopy (scalp imaging), punch biopsy if scarring alopecia is suspected, and management of conditions like alopecia areata or lichen planopilaris. Starting with your GP for a blood panel is a reasonable and cost-effective first step.