Question 1

Should I use the Ganzoni formula or a fixed IV iron dose?

Accepted Answer

Many modern IV iron preparations (e.g., ferric carboxymaltose 1,000 mg, ferric derisomaltose 1,000 mg) are administered as a single fixed dose to most iron-deficient patients, regardless of the Ganzoni calculation. The formula is most useful for iron sucrose (which is limited to 200–300 mg per session) and for research quantification.

Question 2

How does IV iron dosing differ by preparation?

Accepted Answer

Ferric carboxymaltose: up to 1,000 mg over 15 minutes (maximum 20 mg/kg). Iron sucrose: 200–300 mg per session, typically 2–5 sessions. Ferric derisomaltose: 1,000 mg over 20–30 minutes. Iron dextran: 1,000 mg as a test + therapeutic dose (requires test dose).

Question 3

When should I check ferritin after IV iron?

Accepted Answer

Ferritin peaks 7–14 days after IV iron administration. Do not recheck sooner, as the acute phase response and transient ferritin elevation give a falsely high reading. Wait at least 2 weeks before reassessment.

Question 4

Do I need to correct iron stores in mild iron deficiency without anaemia?

Accepted Answer

Yes, if the patient is symptomatic (fatigue, restless legs, pica) or at high risk of progression (pregnancy, heavy menstrual bleeding, GI bleeding source). The total deficit is smaller (store replenishment only), typically 200–500 mg elemental iron.