Question 1

What blood tests should I get for hair loss as a woman?

Accepted Answer

Common tests include ferritin, TSH, hemoglobin, estradiol, and total testosterone. However, these values must be interpreted together — not in isolation. SHBG, Free T3, CRP, and vitamin D provide critical additional context, especially in perimenopause. Equally important: when you test matters. Estradiol should be measured on cycle day 2–4, testosterone before 10 a.m., and progesterone only after confirmed ovulation.

Question 2

Why do my blood tests look normal but I'm still losing hair?

Accepted Answer

Because "normal" lab ranges are population-based and don't reflect what's optimal for hair growth. A ferritin of 25 ng/mL is technically normal but often insufficient for hair follicles. Additionally, the interaction between markers matters more than any single value — and timing can make the same number meaningful or meaningless.

Question 3

Can hormones cause hair loss even if testosterone is normal?

Accepted Answer

Yes. Total testosterone can be normal while free testosterone is elevated — because SHBG (which binds testosterone) often declines in perimenopause. More free testosterone means more conversion to DHT, which miniaturizes hair follicles. This shift is invisible on a standard panel that only checks total testosterone.

Question 4

How does ferritin affect hair loss in women?

Accepted Answer

Ferritin is the storage form of iron and is essential for hair follicle cell division. Many dermatologists recommend levels above 70 ng/mL for optimal hair growth. But whether that level is sufficient depends on thyroid function, inflammation, and hormonal status — ferritin in isolation tells only part of the story.

Question 5

Why is one blood test not enough to diagnose hair loss?

Accepted Answer

Hair loss — especially telogen effluvium — has a 6–12 week delay between trigger and shedding. A single blood draw captures one moment but cannot reveal trends, hormonal fluctuations, or the trajectory of key markers over time. Without repeated measurements and timing context, even optimal values are incomplete information.

Question 6

When should I get my blood tests done during my cycle?

Accepted Answer

For cycling women: estradiol, FSH, and LH are most informative on cycle day 2–4. Progesterone should be measured 5–7 days after ovulation (often day 19–22 in a 28-day cycle). Testosterone should be drawn before 10 a.m. due to its diurnal rhythm. Testing outside these windows can produce misleading results.