Question 1

Why does the calculator gate men and post-menopausal women?

Accepted Answer

New iron-deficiency anemia in men or post-menopausal women is a red flag for occult GI bleeding (colorectal cancer is the most-feared cause). Hematology guidelines uniformly recommend a GI workup — CBC, ferritin, fecal-occult-blood, and consideration of endoscopy / colonoscopy — before starting oral iron, so the iron doesn't mask the bleed.

Question 2

Should I take iron daily or every other day?

Accepted Answer

For active repletion in tolerant users, daily dosing produced greater hematological gains than alternate-day in iron-deficient women in a 2026 double-blind RCT (PMID 41354563). The earlier alternate-day rationale (hepcidin softening, fewer GI side effects) still holds for maintenance and GI-sensitive cohorts. The calculator picks the schedule based on indication × tolerance.

Question 3

Ferrous sulfate or bisglycinate?

Accepted Answer

Ferrous sulfate is first-line: cheapest, most studied, 10–15% bioavailable. Ferrous bisglycinate has 20–30% bioavailability and meaningfully fewer GI side effects, at 2–3× the cost. Pick bisglycinate if you've had GI trouble with iron before, you're pregnant, an athlete, post-menopausal, or have celiac/IBD/PPI use that compromises absorption.

Question 4

What about Vitamin C with iron?

Accepted Answer

100–200 mg vitamin C with each iron dose increases absorption 2–4× by reducing Fe³⁺ to the more absorbable Fe²⁺. Diminishing returns above 200 mg. Orange juice or a 250 mg vitamin C supplement works. Skip this if you're taking ferric citrate — different mechanism.

Question 5

When should I retest?

Accepted Answer

Reticulocyte count at day 5–7 is the earliest response marker — expect a 2–5× rise. Hemoglobin at 4 weeks (expect +1–2 g/dL). Full iron panel (ferritin, transferrin saturation) at 8–12 weeks. If you don't see a reticulocyte response by day 7 or no Hb rise by 4 weeks on tolerated oral iron, see a clinician about IV iron — the most likely cause is malabsorption or ongoing blood loss.

Question 6

Can I overshoot? When do I stop?

Accepted Answer

Yes. Stop and re-evaluate if ferritin reaches ≥300 ng/mL — possible iron overload (hereditary hemochromatosis screen) or chronic inflammation masking true iron status. Routine target is ferritin ≥50 ng/mL sustained for 6 months. Reassess annually if you're maintaining (not actively repleting).