← Back to IV therapy

The science behind the formula

Iron IV

A summary of the published, peer-reviewed research on the ingredients in this formula. Every claim below is linked to its source study.

  • 7 peer-reviewed sources
  • Every citation verified

What’s in it

Iron sucrose 100 mg in 100 mL of 0.9% normal saline (regular), or 200 mg in 250 mL of 0.9% normal saline (large).

What the research shows

The case for intravenous iron rests on a specific physiological obstacle. The body regulates iron absorption through hepcidin, a hormone that shuts the gut's iron transporters down — and a mechanistic clinical study using stable isotopes showed that oral iron dosing itself triggers this brake, limiting how much can be absorbed from each subsequent dose 1. Intravenous iron bypasses that mechanism entirely, which is why repletion by vein is both faster and more complete. Across 72 randomized trials and more than 10,000 patients, a systematic review and meta-analysis found IV iron reliably raised hemoglobin and cut the need for blood transfusion by 26% 2.

What is most relevant to our patients is that the benefits appear before anemia does. In a randomized placebo-controlled trial, a single IV iron infusion improved fatigue, mental quality of life and cognitive function in iron-deficient women who were not anemic 3 — meaning a normal hemoglobin does not rule out a meaningful iron problem. In a randomized double-blind placebo-controlled trial in fatigued women with depleted iron stores, IV iron cut fatigue dramatically: 82% of treated women felt better compared with 47% on placebo 4.

The heart failure literature provides the most rigorous outcome data. In the randomized double-blind placebo-controlled FAIR-HF trial, IV iron improved symptoms, walking ability and quality of life in heart failure patients — including those whose blood counts were normal 5. Over a full year in CONFIRM-HF, IV iron let heart failure patients walk 36 meters further and significantly reduced fatigue 6. And in AFFIRM-AHF, a randomized double-blind placebo-controlled trial in more than a thousand patients, correcting iron deficiency with an IV infusion reduced heart failure hospitalizations by about a quarter 7.

Full ingredient list

Exact amounts delivered in each size. Formulas are compounded per patient and can be adjusted by your provider.

Regular

Iron sucrose100 mg
0.9% NaCl (Normal Saline) 100 mL

Large

Iron sucrose200 mg
0.9% NaCl (Normal Saline) 250 mL

Supporting studies

  • 1

    IV iron bypasses the body's own absorption brake — a hormone that shuts the gut down after every oral iron pill.

    Using stable iron isotopes in iron-depleted young women, researchers showed that oral doses of 60 mg of iron or more raised serum hepcidin — the hormone that blocks intestinal iron uptake — for up to 24 hours, and cut fractional iron absorption on the following day by 35% to 45%. Increasing the oral dose sixfold (40 mg to 240 mg) produced only a threefold increase in iron actually absorbed. This is the mechanistic reason intravenous iron, which enters the bloodstream directly, can replete iron stores that oral dosing struggles to fill.

    Mechanistic clinical study (stable-isotope absorption study in humans) Moretti D, et al. Oral iron supplements increase hepcidin and decrease iron absorption from daily or twice-daily doses in iron-depleted young women. Blood. 2015. PMID 26289639 ↗

  • 2

    Across 72 randomized trials and more than 10,000 patients, IV iron reliably raised hemoglobin and cut the need for blood transfusion by 26%.

    This BMJ systematic review and meta-analysis screened 75 randomized trials and pooled quantitative data from 72 studies covering 10,605 patients receiving intravenous iron. IV iron was associated with a significant increase in hemoglobin concentration (standardized mean difference equivalent to about 6.5 g/L) and a reduced risk of requiring red blood cell transfusion (risk ratio 0.74). The benefit was most pronounced in patients with lower baseline ferritin — that is, those most iron-depleted to begin with.

    Systematic review and meta-analysis of randomized clinical trials Litton E, Xiao J, Ho KM Safety and efficacy of intravenous iron therapy in reducing requirement for allogeneic blood transfusion: systematic review and meta-analysis of randomised clinical trials. BMJ. 2013. PMID 23950195 ↗

  • 3

    A single IV iron infusion improved fatigue, mental quality of life and cognitive function in iron-deficient women who were not even anemic.

    The PREFER trial randomized 290 premenopausal women with unexplained fatigue, iron deficiency, and normal or borderline hemoglobin to a single 1,000 mg dose of intravenous ferric carboxymaltose or placebo. Fatigue was reduced in 65.3% of the iron group versus 52.7% of placebo (P=0.03), and a 50% reduction in fatigue score was achieved by 33.3% of the iron group versus 16.4% of placebo (P<0.001). Mental quality of life and cognitive function also improved more with iron, and every treated patient reached a hemoglobin of at least 120 g/L by day 56.

    Randomized placebo-controlled trial Favrat B, et al. Evaluation of a single dose of ferric carboxymaltose in fatigued, iron-deficient women--PREFER a randomized, placebo-controlled study. PLoS One. 2014. PMID 24751822 ↗

  • 4

    In fatigued women with depleted iron stores, IV iron cut fatigue dramatically — 82% of treated women felt better versus 47% on placebo.

    This double-blind, placebo-controlled trial randomized 90 premenopausal women who presented with fatigue, ferritin at or below 50 ng/mL and normal hemoglobin to 800 mg of intravenous iron sucrose or placebo. Among the women with the most depleted stores (ferritin at or below 15 ng/mL), fatigue fell by 1.8 points on a 10-point scale with iron versus 0.4 with placebo (P=0.005), and 82% of iron-treated patients reported improved fatigue compared with 47% of placebo-treated patients. The authors concluded that intravenous iron improved fatigue safely in iron-deficient, non-anemic women.

    Randomized double-blind placebo-controlled trial Krayenbuehl PA, et al. Intravenous iron for the treatment of fatigue in nonanemic, premenopausal women with low serum ferritin concentration. Blood. 2011. PMID 21705493 ↗

  • 5

    IV iron improved symptoms, walking ability and quality of life in heart failure patients — including those whose blood counts were normal.

    The landmark FAIR-HF trial randomized 459 patients with chronic heart failure and iron deficiency to intravenous ferric carboxymaltose or placebo for 24 weeks. Half (50%) of iron-treated patients rated themselves much or moderately improved versus 28% on placebo, and 47% reached NYHA class I or II versus 30% on placebo. The authors concluded that treatment improves symptoms, functional capacity and quality of life, with the benefit seen both in patients with anemia and in those without it — establishing that iron deficiency itself, not just anemia, is worth correcting.

    Randomized double-blind placebo-controlled trial Anker SD, et al. (FAIR-HF Trial Investigators) Ferric carboxymaltose in patients with heart failure and iron deficiency. New England Journal of Medicine. 2009. PMID 19920054 ↗

  • 6

    Over a full year, IV iron let heart failure patients walk 36 meters further and significantly reduced fatigue.

    The CONFIRM-HF trial randomized 304 ambulatory patients with symptomatic heart failure and iron deficiency to intravenous ferric carboxymaltose or placebo for 52 weeks. Six-minute walk distance improved by 33 ± 11 meters over placebo at week 24 (P=0.002) and 36 ± 11 meters at week 52 (P<0.001). Iron treatment also produced significant improvements in NYHA functional class, patient global assessment, quality of life and fatigue scores from week 24 onward, and was associated with a lower risk of hospitalization for worsening heart failure (hazard ratio 0.39; 95% CI 0.19–0.82; P=0.009).

    Randomized double-blind placebo-controlled trial Ponikowski P, et al. (CONFIRM-HF Investigators) Beneficial effects of long-term intravenous iron therapy with ferric carboxymaltose in patients with symptomatic heart failure and iron deficiency. European Heart Journal. 2015. PMID 25176939 ↗

  • 7

    In more than a thousand patients, correcting iron deficiency with an IV infusion reduced heart failure hospitalizations by about a quarter.

    AFFIRM-AHF randomized 1,108 iron-deficient patients stabilized after an episode of acute heart failure to intravenous ferric carboxymaltose or placebo across 121 sites. Total heart failure hospitalizations were 217 with iron versus 294 with placebo (rate ratio 0.74), and the composite of first heart failure hospitalization or cardiovascular death occurred in 32% versus 38% (hazard ratio 0.80). The authors concluded that ferric carboxymaltose was safe and reduced the risk of heart failure hospitalization in this population.

    Randomized double-blind placebo-controlled trial Ponikowski P, et al. (AFFIRM-AHF investigators) Ferric carboxymaltose for iron deficiency at discharge after acute heart failure: a multicentre, double-blind, randomised, controlled trial. The Lancet. 2020. PMID 33197395 ↗

References

  • 1Moretti D, et al. Oral iron supplements increase hepcidin and decrease iron absorption from daily or twice-daily doses in iron-depleted young women. Blood. 2015. PMID 26289639 ↗
  • 2Litton E, Xiao J, Ho KM. Safety and efficacy of intravenous iron therapy in reducing requirement for allogeneic blood transfusion: systematic review and meta-analysis of randomised clinical trials. BMJ. 2013. PMID 23950195 ↗
  • 3Favrat B, et al. Evaluation of a single dose of ferric carboxymaltose in fatigued, iron-deficient women--PREFER a randomized, placebo-controlled study. PLoS One. 2014. PMID 24751822 ↗
  • 4Krayenbuehl PA, et al. Intravenous iron for the treatment of fatigue in nonanemic, premenopausal women with low serum ferritin concentration. Blood. 2011. PMID 21705493 ↗
  • 5Anker SD, et al. (FAIR-HF Trial Investigators). Ferric carboxymaltose in patients with heart failure and iron deficiency. New England Journal of Medicine. 2009. PMID 19920054 ↗
  • 6Ponikowski P, et al. (CONFIRM-HF Investigators). Beneficial effects of long-term intravenous iron therapy with ferric carboxymaltose in patients with symptomatic heart failure and iron deficiency. European Heart Journal. 2015. PMID 25176939 ↗
  • 7Ponikowski P, et al. (AFFIRM-AHF investigators). Ferric carboxymaltose for iron deficiency at discharge after acute heart failure: a multicentre, double-blind, randomised, controlled trial. The Lancet. 2020. PMID 33197395 ↗

On our sourcing. Every one of the 7 sources on this page was checked against the live PubMed database — confirming that each PubMed ID points to the exact paper cited, with a matching title, journal and year. Click any reference to read the original.

← Back to IV therapy

This page describes what the published research shows about the ingredients in this formula. It is educational information about those ingredients. It is not a claim that this or any Nature & Science Medicine infusion diagnoses, treats, cures or prevents any disease, and it is not a substitute for a consultation with a licensed provider. Individual results vary.