IV Iron Dosing Reference — India
| Product | Dose per infusion | Max single dose | Notes |
|---|
| Iron sucrose (Venofer) | 100–200 mg in 100mL NS over 15–30 min | 200 mg | Preferred in CKD/dialysis; safest profile; no test dose required |
| Ferric carboxymaltose (FCM) | 500–1000 mg in 250mL NS over 15 min | 1000 mg (20 mg/kg) | Can correct large deficits in 1–2 doses; preferred in pregnancy; check phosphate |
| Iron dextran (Imferon) | TDI — full deficit in one infusion | Total deficit (slow infusion) | Test dose 25mg required; anaphylaxis risk higher; rarely used now |
Iron Deficit Calculation — Clinical Guide
The Ganzoni equation — how it works
The Ganzoni equation calculates the total elemental iron required to restore haemoglobin to a target level and replenish depleted iron stores. It was first described by Ganzoni in 1970 as a way to individualise parenteral iron dosing instead of using flat, weight-independent regimens. The equation combines two components: a body-weight-and-haemoglobin-deficit term (which estimates the iron needed to correct anaemia) and a fixed iron-stores term (which estimates the iron needed to replenish ferritin-bound reserves).
The constant 2.4 in the formula is derived from the blood volume fraction of body weight (roughly 7%) multiplied by the iron content of haemoglobin (3.4 mg iron per gram of Hb), simplified for clinical use. Multiplying this constant by the haemoglobin deficit (target minus actual, in g/dL) and by body weight in kilograms gives the iron, in milligrams, needed to correct the circulating haemoglobin pool.
Iron stores component
For most non-pregnant adults weighing more than 35 kg, an iron-stores value of 500 mg is used as a standard depot replacement figure, broadly approximating a total body iron store sufficient to avoid early recurrence of deficiency. For children and adults under 35 kg, 15 mg/kg of body weight is used instead. In pregnancy, many obstetric protocols set the stores component to zero or a much lower value, since the immediate clinical priority is correcting the haemoglobin deficit before delivery rather than fully repleting long-term stores — this also keeps the calculated total dose, and therefore the number of infusions, lower and more practical within the time available in pregnancy.
Iron deficit in pregnancy
Anaemia in pregnancy is extremely common in India, and the National Family Health Survey has repeatedly found a high prevalence of anaemia among pregnant women, making correct iron dosing a frequent clinical task. WHO recommends a target haemoglobin of 11 g/dL in the first and third trimester, lowered to 10.5 g/dL in the second trimester to account for the physiological plasma volume expansion that occurs at that stage of gestation. FOGSI and the Government of India's Anaemia Mukt Bharat programme support a stepwise approach: oral iron first-line for mild anaemia, switching to IV iron when Hb falls below roughly 9–10 g/dL, when oral iron is not tolerated or absorbed, or when there is insufficient time remaining before delivery for oral repletion to work. IV iron is generally preferred over oral iron in the second and third trimester once the indication is met, because it corrects haemoglobin faster and avoids the gastrointestinal side effects that often cause poor adherence to oral iron in pregnancy.
Ferric carboxymaltose has become a preferred agent in pregnancy in many Indian obstetric units because a single high dose (up to 1000 mg, or 20 mg/kg) can often correct the full calculated deficit in one or two infusions — clinically useful when gestational age limits the number of antenatal visits remaining. Iron sucrose remains a safe and widely available alternative, given in repeated 100–200 mg sessions.
Iron deficit in chronic kidney disease
In CKD, especially in patients on maintenance haemodialysis, functional and absolute iron deficiency are common because of reduced dietary intake, blood loss during dialysis, and hepcidin-mediated impairment of gut iron absorption — the same hepcidin pathway that makes oral iron poorly effective in this population. KDIGO 2012 guidelines recommend a target haemoglobin range of approximately 10–11.5 g/dL when using erythropoiesis-stimulating agents, avoiding full normalisation because higher Hb targets have been associated with increased cardiovascular risk in CKD trials. IV iron sucrose, typically 100–200 mg per dialysis session, is the standard route in dialysis-dependent CKD because intravenous administration bypasses the hepcidin-blocked gut absorption pathway entirely. Observational data from large dialysis registries (DOPPS) suggest that maintenance IV iron dosing under roughly 300 mg per month is associated with similar or better haemoglobin and iron-marker responses than higher monthly doses, supporting conservative, repeated low-dose regimens over large infrequent boluses in this population.
Monitoring and safety
- Confirm the diagnosis first: wherever feasible, confirm iron deficiency with serum ferritin and transferrin saturation (TSAT) before committing to a full IV iron course — Ganzoni-based dosing assumes true iron deficiency anaemia and should not be applied in iron overload states or anaemia of chronic disease without iron deficiency.
- Hypersensitivity risk: all parenteral iron formulations carry a risk of hypersensitivity reactions, including rare anaphylaxis. Resuscitation facilities and trained staff must be available, and patients should be observed for at least 30 minutes after each infusion.
- Test dosing: iron dextran specifically requires a test dose (around 25 mg) before the first total-dose infusion because of its comparatively higher historical anaphylaxis rate; iron sucrose and ferric carboxymaltose do not routinely require a separate test dose under current labelling, though clinical vigilance still applies.
- Avoid in active infection: parenteral iron should generally be deferred during active systemic infection, since free iron can support bacterial growth and impair host defence.
- Hypophosphataemia with FCM: ferric carboxymaltose has been specifically associated with iron-induced hypophosphataemia, occasionally symptomatic, particularly with repeated high-dose infusions; checking serum phosphate before and after large or repeated doses is advisable.
- Reassess after treatment: recheck haemoglobin roughly 4 weeks after completing the calculated course to confirm response and detect any need for further dosing; a poor response should prompt reinvestigation rather than empirical re-dosing.
Worked example
A 60 kg non-pregnant woman with Hb 7.5 g/dL and a target Hb of 12 g/dL: Iron deficit (body) = 60 × (12 − 7.5) × 2.4 = 648 mg. Adding standard stores of 500 mg gives a total iron deficit of 1148 mg. At 200 mg per session, this would require roughly six sessions of iron sucrose, or it could potentially be corrected in a single 1000 mg ferric carboxymaltose infusion plus a small top-up, illustrating why product choice materially affects the number of visits needed for the same calculated deficit.
Frequently Asked Questions
How to calculate iron deficit?+
Iron deficit (mg) = Weight (kg) × (Target Hb − Actual Hb) × 2.4 + Iron stores (mg). Iron stores are usually 500 mg for adults over 35 kg, or 15 mg/kg for those under 35 kg. The result is the total elemental iron needed for parenteral replacement, which is then divided across infusions based on the chosen product's maximum single dose.
How is iron deficit calculated differently in pregnancy?+
The same Ganzoni formula is used, but the target Hb is adjusted by trimester (11 g/dL in the first and third trimester, 10.5 g/dL in the second trimester per WHO), and the 500 mg stores component is often omitted or reduced, since correcting the circulating haemoglobin deficit before delivery takes priority over fully replenishing long-term iron stores.
How is iron deficit calculated in CKD or dialysis patients?+
Target Hb in CKD is typically set at 10–11.5 g/dL per KDIGO 2012 guidance rather than the standard 12–13 g/dL used in the general population, reflecting the cardiovascular risk associated with higher Hb targets when erythropoiesis-stimulating agents are used. The deficit and stores components of the Ganzoni equation are otherwise unchanged.
What is the maximum single dose of IV iron sucrose?+
Most protocols cap iron sucrose at 200 mg per infusion, given over 15–30 minutes, because higher single doses increase the risk of hypotension and free-iron-related adverse effects. Larger total deficits are corrected over multiple sessions, commonly 2–3 times weekly.
Why are iron stores excluded or reduced in the pregnancy calculation?+
In pregnant women with iron deficiency anaemia, the obstetric priority is restoring haemoglobin before delivery, not fully repleting body iron stores. Setting the stores term to zero (or a low value) reduces the total calculated dose and the number of infusions required within the limited remaining gestation.
Is oral iron preferred over IV iron in pregnancy?+
Yes, for mild iron deficiency anaemia with adequate time before delivery and reasonable tolerance, oral iron remains first-line. IV iron is reserved for moderate-to-severe anaemia (commonly defined as Hb below 9–10 g/dL), poor oral tolerance or adherence, malabsorption states, or late gestation where there isn't enough time left for oral repletion to take effect.
Related Calculators
References
- 1.Ganzoni AM. Eisen-Dextran intravenös: ein therapeutischer und experimenteller Beitrag. Schweiz Med Wochenschr. 1970;100(7):301–303. — original description of the iron deficit equation.
- 2.World Health Organization. Daily iron supplementation in adult women and adolescent girls — Guideline. Geneva: WHO; and WHO antenatal care recommendations on anaemia in pregnancy, including trimester-specific haemoglobin thresholds.
- 3.Kidney Disease: Improving Global Outcomes (KDIGO) Anemia Work Group. KDIGO Clinical Practice Guideline for Anemia in Chronic Kidney Disease. Kidney Int Suppl. 2012;2(4):279–335.
- 4.Federation of Obstetric and Gynaecological Societies of India (FOGSI). Good Clinical Practice Recommendations on Iron Deficiency Anaemia in Pregnancy; and Ministry of Health & Family Welfare, Government of India — Anaemia Mukt Bharat operational guidelines.
- 5.Robinson BM, Larkina M, Bieber B, et al. Evaluating the effectiveness of IV iron dosing for anemia management in common clinical practice: results from DOPPS. BMC Nephrol. 2017;18:330.
- 6.Auerbach M, Macdougall I. The available intravenous iron formulations: history, efficacy, and toxicology. Hemodial Int. 2017;21(Suppl 1):S83–S92. — comparative safety and dosing of iron sucrose, ferric carboxymaltose, and iron dextran.
- 7.National Family Health Survey (NFHS-5), India — prevalence of anaemia among pregnant women.
- 8.Manufacturer prescribing information for iron sucrose (Venofer), ferric carboxymaltose (Injectafer), and iron dextran (Imferon) — for product-specific maximum doses, infusion rates, and contraindications; always confirm against the current label before prescribing.
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Reviewed by Dr. Sharma, MBBS — Medical Officer
Content last reviewed: June 2026. This calculator is a clinical decision-support aid based on the Ganzoni equation and published guidelines; it does not replace individual clinical judgement or product labelling.
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This calculator is intended for use by qualified healthcare professionals as a dosing aid. Confirm iron deficiency with iron studies where the diagnosis is uncertain, do not use in iron overload states, and always cross-check the calculated dose against current product labelling and institutional protocol before administration. Not a substitute for clinical judgement.