Blood tests for male pattern baldness help rule out treatable conditions that mimic or worsen androgenetic alopecia, such as thyroid disorders, iron deficiency, and hormonal imbalances. While androgenetic alopecia itself is diagnosed clinically based on the pattern of hair loss, bloodwork ensures nothing else is contributing to your thinning.
This article is for informational purposes only and does not constitute medical advice.
Why Blood Tests Matter for Hair Loss
Androgenetic alopecia is driven by DHT and genetics, but several medical conditions can accelerate hair loss or cause patterns that look similar. Misdiagnosis of hair loss type leads to wrong treatment in roughly 28% of cases. Blood tests help your doctor confirm that pattern baldness is the primary (or only) issue and identify any secondary factors that need treatment.
If your blood work reveals a thyroid imbalance, iron deficiency, or vitamin D deficiency alongside androgenetic alopecia, treating those conditions can improve your response to hair loss treatments like finasteride and minoxidil.
The Essential Blood Test Panel
Request the following tests from your doctor or dermatologist. Most can be run from a single blood draw.
1. Complete Blood Count (CBC)
A CBC checks your overall blood health and can flag anemia, infections, or nutritional deficiencies that affect hair growth.
- What to look for: Low hemoglobin or hematocrit may indicate iron-deficiency anemia, which independently causes diffuse hair thinning
2. Serum Ferritin
Ferritin measures your body's iron stores, and it is one of the most important tests for hair loss.
- Optimal range for hair health: Above 70 ng/mL (some dermatologists recommend above 80)
- Why it matters: Ferritin can be in the "normal" lab range (12 to 150 ng/mL for men) but still too low for optimal hair follicle function. Many men with unexpectedly poor response to hair loss treatment have suboptimal ferritin levels.
3. Thyroid Panel (TSH, Free T3, Free T4)
Thyroid dysfunction is one of the most common conditions mistaken for or overlapping with androgenetic alopecia.
- Hypothyroidism causes diffuse thinning, dry brittle hair, and slow regrowth
- Hyperthyroidism causes fine, thinning hair and can accelerate shedding
- Target TSH: 0.5 to 2.5 mIU/L for optimal hair health (stricter than the standard lab range of 0.4 to 4.0)
4. Testosterone (Total and Free)
While androgenetic alopecia is not caused by high testosterone, knowing your levels provides context for treatment decisions.
- Why it matters: Men considering finasteride benefit from baseline testosterone levels to monitor for any hormonal changes on treatment
- Low testosterone can cause diffuse thinning independent of pattern baldness and may need separate treatment
5. DHT (Dihydrotestosterone)
DHT is the hormone directly responsible for follicle miniaturization in androgenetic alopecia.
- Typical male range: 30 to 85 ng/dL
- Why it matters: Baseline DHT helps track how effectively finasteride or dutasteride suppresses this hormone. Finasteride typically reduces serum DHT by 60 to 70%.
- Note: Serum DHT levels do not perfectly correlate with scalp DHT levels, so a normal reading does not rule out androgenetic alopecia
6. Vitamin D (25-Hydroxyvitamin D)
Vitamin D deficiency is linked to hair follicle cycling disruption and may worsen hair loss.
- Optimal range: 40 to 60 ng/mL
- Deficiency prevalence: Roughly 40% of adults have insufficient vitamin D levels, making this a commonly overlooked contributor
7. DHEA-S (Dehydroepiandrosterone Sulfate)
DHEA-S is an adrenal androgen precursor that can contribute to hair follicle miniaturization.
- Why it matters: High DHEA-S may indicate adrenal overactivity, particularly relevant in younger men with rapid-onset hair loss
- Useful for: Distinguishing androgenetic alopecia from other androgen-driven conditions
Additional Tests for Specific Situations
| Test | When to Request | What It Reveals |
|---|---|---|
| ANA (Antinuclear Antibody) | Patchy or diffuse loss with skin changes | Autoimmune conditions like lupus |
| Zinc | Poor diet, vegetarian/vegan, or GI issues | Zinc deficiency contributes to shedding |
| Vitamin B12 | Vegetarian/vegan diet or GI conditions | Deficiency causes diffuse thinning |
| Cortisol (AM) | Chronic stress, fatigue, rapid onset | Adrenal dysfunction affecting hair cycling |
| Prolactin | Hair loss with sexual dysfunction | Pituitary issues that affect hormone balance |
| Insulin/Glucose (Fasting) | Metabolic syndrome, obesity, PCOS family history | Insulin resistance can worsen androgen-driven loss |
How to Use Your Results
Once you have your blood work back, the results fit into one of three scenarios:
Scenario 1: All normal. Your hair loss is most likely pure androgenetic alopecia. Standard treatment with finasteride (80 to 90% halt further loss, 65% regrowth) and minoxidil (40 to 60% moderate regrowth) is appropriate.
Scenario 2: One or two deficiencies found. Address the deficiency alongside hair loss treatment. For example, correcting low ferritin while starting minoxidil often produces better results than minoxidil alone.
Scenario 3: Thyroid or hormonal abnormality detected. Treat the underlying condition first or concurrently. Hair loss from thyroid disorders often improves significantly once the thyroid is properly managed, and what remains can then be addressed with standard androgenetic alopecia treatments.
What to Bring to Your Dermatologist
Print or save your blood results and bring them to your dermatologist or hair restoration surgeon consultation, along with:
- Timeline photos showing your hair loss progression
- A list of current medications and supplements
- Family history of hair loss
- An AI-generated Norwood stage assessment from myhairline.ai/analyze
Combining blood test data with a visual assessment of your hair loss pattern gives your doctor the complete picture needed to recommend the right treatment protocol. Check your hair transplant candidacy once your bloodwork confirms no underlying conditions that need to be addressed first.