REF-1422 · Dugan et al., 2025 · British Journal of Sports Medicine · Paper · PubMed

Should I get an iron infusion?

In 26 active, non-anaemic iron-deficient women, IV iron refilled stores; VO2peak, threshold and haemoglobin mass did not differ from placebo; economy did; fatigue eased in the iron group. A doctor's call.

Main caveat: Abstract only; the publisher's free PDF returned a bot check and was not tried further.
moderate evidenceMeasured on recreational people

Dugan and colleagues (University of Western Australia, University of East London) randomised 26 recreationally active women of reproductive age with iron deficiency without anaemia to intravenous iron (IRON) or placebo (PLA), double-blind.

Before, 4 days and 4 weeks after the intervention, they measured exercise performance, haemoglobin mass, blood iron status and haematology, fatigue, mood and quality of life. Intravenous iron significantly raised serum ferritin, serum iron and transferrin saturation (p < 0.05), "with a highly variable individual response".

There were no differences between groups in VO2peak, lactate threshold or haemoglobin mass. Running economy improved in the iron group from baseline to 4 weeks and differed from placebo at 4 weeks (p < 0.05), and fatigue scores improved after 4 weeks with iron but not with placebo (p < 0.05); mood and quality of life did not change.

The authors conclude that intravenous iron corrects iron status and improves exercise economy and fatigue scores after 4 weeks.

Our reading: in the population that asks about infusions, IV iron refilled stores fast but did not raise aerobic capacity or red-cell mass within a month; the economy and fatigue findings come from a small trial with several outcomes and need confirming.

Protocol

Participants: n = 26 recreationally active females of reproductive age with iron deficiency without anaemia (definition not in the abstract).
Groups: intravenous iron (IRON) or placebo (PLA), double-blind; product and dose not in the abstract.
Assessments: before, 4 days and 4 weeks after the intervention — exercise performance (VO2peak, lactate threshold, running economy), haemoglobin mass, iron status and haematology, fatigue, mood states, quality of life.
Registration: ACTRN12620001357943.
Competing interests (PubMed, as printed): PJ reports personal fees from Vifor Pharma and Pfizer Australia, outside the submitted work.TR reports grants from UK NIHR HTA, Australian NHMRC, NIHR EME and Australian MRFF; grants, personal fees and non-financial support from Pharmocosmos and from Vifor Pharma; personal fees from Medtronic; conference expenses; work with agencies promoting meetings or healthcare; and is a director of Veincare London Ltd."No funding was provided by these institutions for this research, nor were they involved in any aspects of the research design, data collection, analysis or writing." The remaining authors declare none. (Not printed in the record, our note: Vifor and Pharmacosmos market intravenous iron.)
Funding: the trial's funder is not given in the abstract record.

Key Results

Iron status: serum ferritin, serum iron and transferrin saturation improved with IV iron (p < 0.05), with a highly variable individual response.
Capacity: no differences between groups in VO2peak, lactate threshold or haemoglobin mass.
Economy: running economy improved in IRON from baseline to 4 weeks (p < 0.05) and differed from PLA at 4 weeks (p < 0.05).
Fatigue: improved in IRON but not PLA after 4 weeks (p < 0.05).
Mood and quality of life: unchanged in both groups.
Not in the abstract: effect sizes, ferritin values, the iron preparation and dose, side effects (including phosphate), group sizes.

Mechanisms

Measured: IV iron raised iron markers within days to weeks, without a change in haemoglobin mass or VO2peak by 4 weeks.
Authors' interpretation: correcting iron status in IDNA women improves exercise economy and fatigue.
Inference: an economy gain without a haemoglobin-mass gain would point to a muscle-level effect of iron rather than more oxygen carriers, which is how REF-1420's authors explain efficiency gains; with 26 participants and several outcomes, a chance finding cannot be excluded.

Practical Application

Should I get an iron infusion? In 26 active, non-anaemic iron-deficient women, IV iron refilled stores; VO2peak, threshold and haemoglobin mass did not differ from placebo; economy did; fatigue eased in the iron group. A doctor's call.
What to say about infusions (B+, abstract): IV iron corrects stores faster than tablets (REF-1411) but did not raise aerobic capacity in this trial; tiredness may ease, matching REF-1412. Whether an infusion is indicated is a physician's decision (REF-1410: oral failure, intolerance, concomitant disease, low stores before an altitude camp, in a setting with resuscitation skills; REF-1411: contraindication, failure, intolerance or urgency).
Harms and rules the abstract does not cover: hypophosphataemia is common after ferric carboxymaltose (58% in REF-1411); infusions fall under anti-doping rules (REF-1410 quotes the 2015 wording; the current rule was not checked here).
Not from this paper; the base's own practice: the assistant never suggests IV iron; it reports what trials found and refers to a clinician.

Limitations

Abstract only; the publisher's free PDF returned a bot check and was not tried further.
Small: 26 women; several outcomes at two time points.
Short: 4 weeks; whether haemoglobin mass or VO2peak would change later is not known.
Missing from the abstract: preparation, dose, deficiency definition, effect sizes, adverse events.
Interests: two authors report fees, grants or non-financial support from intravenous-iron companies (Vifor Pharma; Pharmacosmos, printed "Pharmocosmos"), stated as outside the submitted work and not involved in the research; the trial's funder is not in the record.
How this entry was checked and changed
Why this level

(from the abstract) — a parallel RCT with 20-39 participants (rubric B+); the iron product, dose, deficiency definition, group sizes and effect sizes are not in the abstract