Ferritin in Women: the deficiency mistaken for menopause

A 44-year-old woman walks in with fatigue that coffee no longer touches, hair coming out in the shower, cold hands, restless legs at night, and a heart rate that seems to race up the stairs. The near-universal read is perimenopause. Sometimes it is. Very often, it's iron deficiency — and the CBC her primary care ordered came back "normal" because her hemoglobin hasn't dropped yet.

This is the most under-recognized lab pattern in women's health, and it hides behind a single number most panels don't include by default: ferritin.

Why hemoglobin is the wrong first question

what actually runs out first

Iron deficiency doesn't start with anemia. It starts with depleted storage. Your body pulls from ferritin — the storage protein — for months to years before red blood cell production suffers enough to move hemoglobin.

By the time hemoglobin flags as low, you've already been symptomatic for a long time. This stage is called iron deficiency without anemia (IDWA), and it's common: roughly 1 in 5 premenopausal women in U.S. data meet criteria when ferritin is measured, even with a normal CBC (Mei et al., Blood, 2024).

The symptoms of IDWA overlap almost perfectly with what gets coded as perimenopause:

• Persistent fatigue disproportionate to sleep
• Diffuse hair shedding (telogen effluvium)
• Brain fog and word-finding trouble
• Exercise intolerance, breathlessness on exertion
• Cold intolerance, cold hands and feet
• Restless legs, especially at night
• Pica (ice craving is the classic tell)
• Mood dips and irritability

Hormones and iron both drop in this age window, and both matter. The problem is checking only one.

The lab panel that actually finds it

tuned to your numbers

A CBC alone will miss early iron deficiency. The panel worth having is:

• Ferritin — storage. The single most sensitive marker.
• Serum iron — circulating iron at that moment.
• TIBC (total iron binding capacity) — how much transferrin is available; rises when iron is low.
• Transferrin saturation (%) — iron ÷ TIBC. Functional supply.
• CBC with indices — MCV, MCH, RDW. Late-stage changes.
• Reticulocyte hemoglobin (CHr or Ret-He) — if available, catches functional deficiency early.

A reasonable adjunct in inflammatory contexts is CRP, because ferritin is an acute-phase reactant and rises with inflammation — a "normal" ferritin of 45 in someone with elevated CRP may actually be low.

What the ferritin number actually means

in plain English

Here's where lab reference ranges do women a disservice. Most labs flag ferritin as low only below 10–15 ng/mL. But symptoms and hair follicle function suffer well above that threshold.

The clinically useful cutoffs, based on current hematology and dermatology literature:

• < 15 ng/mL — frank iron deficiency by WHO criteria.
• < 30 ng/mL — 92% sensitive and 98% specific for depleted iron stores (Guyatt et al., J Gen Intern Med). Most hematologists treat below this.
• < 50 ng/mL — associated with fatigue and cognitive symptoms in menstruating women; the British Society for Haematology 2021 guidance uses this threshold for symptomatic patients.
• < 70 ng/mL — commonly cited threshold in dermatology for iron-related hair shedding, though evidence quality is moderate (Trost et al., J Am Acad Dermatol).

So a woman with a ferritin of 22, hemoglobin of 13.1, and "normal" labs is not normal. She's iron-depleted, and it explains her symptoms.

{callout: The one thing to remember} A ferritin under 30 ng/mL in a symptomatic woman is iron deficiency, even if her hemoglobin is normal and her CBC didn't flag.

Why women in the perimenopause window are the highest-risk group

the setup no one names

Three things converge in the late 30s to early 50s:

1. Heavier, more erratic periods. As cycles shorten and ovulation becomes inconsistent, menorrhagia is common. A single heavy cycle can lose 60–80 mg of iron, roughly a month of dietary intake. 2. Lower absorption. Gastric acid production declines with age, and PPIs (used by a huge share of this cohort) further impair non-heme iron absorption. 3. Higher demands and lower intake. Many women in this decade have reduced red meat intake and increased training load — both increase net iron drain.

Then menstruation stops. Iron losses drop dramatically, and stores slowly rebuild. This is why the same woman who felt terrible at 47 often feels notably better at 54, and why the whole picture gets misattributed to "hormones settling." Some of it was hormones. A lot of it was iron.

What the workup should look like before you treat

before you supplement blindly

Oral iron is cheap and available over the counter, and there's a temptation to just start. Two reasons to look at labs first:

• You need a baseline to know it's working. Ferritin should roughly double over 8–12 weeks of adequate oral repletion. Without a starting number, you're guessing.
• A subset of women have iron deficiency from a source that isn't menstrual — celiac disease, H. pylori, or GI bleeding. Post-menopausal iron deficiency in particular warrants a GI workup, not a supplement.

If you choose to do bloodwork through us, the iron-specific markers we look at first are ferritin, transferrin saturation, CBC with RDW, and CRP for context. Thyroid (TSH, free T4) and vitamin D come along because their symptoms overlap.

Repletion, done properly

what actually changes

Standard oral repletion for iron deficiency in adults is elemental iron in the range of 40–100 mg, and current evidence favors alternate-day dosing over daily. Stoffel et al. (Lancet Haematology, 2017 and 2020) showed that daily dosing raises hepcidin, which then blocks absorption of the next dose — alternate-day dosing produced higher total absorption with fewer GI side effects.

Practical points that matter more than brand:

• Take with vitamin C or a small acidic food; avoid coffee, tea, calcium, and dairy within two hours.
• Ferrous bisglycinate is generally better tolerated than ferrous sulfate at equivalent elemental doses.
• Expect 8–12 weeks to feel meaningfully different, and recheck ferritin at 12 weeks.
• If oral iron fails or isn't tolerated, IV iron is a legitimate option and is dramatically underused in women — one infusion can restore stores that would take a year of pills.

Hair regrowth lags the ferritin recovery. Shedding typically slows 2–3 months after stores rebuild, and regrowth is visible around month 4–6.

Most women don't need more coffee, more discipline, or a new supplement stack. They need someone to run a ferritin and read it against symptoms instead of against a lab's outdated floor.

When it really is (also) perimenopause

because both can be true

Nothing above rules out perimenopause. Estradiol variability causes real symptoms — vasomotor changes, sleep disruption, mood shifts, genitourinary changes — and those deserve their own workup and, when appropriate, treatment.

The point is sequencing. Check iron first, because it's cheaper, faster, and if it's the answer, you don't need a hormone conversation at all. If ferritin is repleted to 70+ and symptoms persist, then the perimenopause workup — FSH, estradiol, and a symptom-driven history — becomes the next honest step.

Too many women spend a year on the wrong protocol because no one ordered the right $12 test.

The short version

• Fatigue, hair loss, brain fog, and cold intolerance in a woman 35–55 are not automatically hormonal.
• A normal CBC does not rule out iron deficiency. Ferritin does.
• Ferritin under 30 ng/mL is deficiency; under 50 is symptomatic territory; under 70 is where hair suffers.
• Alternate-day oral iron, taken correctly, works for most women within a season. IV iron exists for the rest.
• Recheck at 12 weeks. Numbers, not guesses.

Editorial disclosure: This article is for informational purposes only and does not constitute medical advice. All treatments at DirectCare AI are prescribed by US-licensed clinicians based on individual medical evaluation. Compounded medications are not FDA-approved and are not reviewed by the FDA for safety, effectiveness, or quality. Always consult a US-licensed clinician before starting or changing any therapy.