Reviews/Iron Status/Oral iron corrects iron-deficiency anaemia
Ida · IRON-IDA-01 · v2
Borderline: within 4 points of the Established/Likely boundary, so a re-grade could land either side.
The evidence shows that oral iron reliably raises haemoglobin in people with iron-deficiency anaemia. Two trials that compared oral iron against a dummy pill both found bigger haemoglobin gains on iron [3][6], and many other trials across adults, pregnant women and children saw the same rise [1][2][5][8][12]. Because anaemia is defined by low haemoglobin, raising haemoglobin is the correction itself, not a stand-in measure. The panel landed high because the direction of effect is consistent everywhere in the corpus. It stopped short of the ceiling because a minority of patients do not respond [10] and iron stores are often not fully refilled even when haemoglobin improves [8].
Across the corpus oral iron consistently raises haemoglobin in iron-deficiency anaemia. The two placebo-controlled trials are decisive: [3] found 52.1% versus 19.1% of patients reached a ≥1.0 g/dL haemoglobin rise on oral ferric citrate versus placebo, and [6] showed a haemoglobin increase of 0.5 g/dL over placebo (P=0.01). Open comparative and single-arm trials corroborate the absolute rise: +1.36 g/dL at 8 weeks [2], +1.84 to 2.00 g/dL [5], +22 g/L at 12 weeks [8], 69.7% reaching a nonanemic state [1], and 10.10 to 11.61 g/dL within-subject [12]. Correction extends to children [4] and CKD [3][6], though a run-in trial found roughly a third are nonresponders [10]. The contested point: The division is over what 'corrects' means: haemoglobin reliably rises, but repletion is often incomplete — median ferritin was only 27 µg/L at 12 weeks in [8] — and roughly a third of patients are nonresponders in [10]. The panel treated these as bounding the strength of the claim rather than refuting its direction.
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The claim is absolute but response is not universal: [10] shows roughly a third of IDA patients are nonresponders to oral iron, so 'corrects' overstates if read as applying to all patients.
Group-mean Hb rises are often modest and do not equal full repletion — [6] is only +0.5 g/dL over placebo and [8] reports median ferritin just 27 µg/L at 12 weeks, so stores are frequently not replete even when Hb rises.
Where it remains uncertain. Response is not universal (about a third are nonresponders [10]) and iron stores are often not fully replete even when haemoglobin rises (median ferritin 27 µg/L at 12 weeks [8]).
Aleatory
Roughly a third of IDA patients did not respond to oral iron in [10], so individual outcomes vary even where the group mean rises.
Epistemic
Haemoglobin is the reported outcome; ferritin remained low (median 27 µg/L at 12 weeks in [8]), so whether stores are fully refilled is not established by these trials.
The load-bearing papers from a corpus of 14, each classified by what it does to the claim. Every DOI is taken from the corpus the claim was graded on.
Large trial: oral iron alone brought 69.7% of pregnant women to a nonanemic state.
“Achievement of nonanemic state was not improved: intravenous ferric carboxymaltose (relative risk 1.05 [99.95% confidence interval 0.97-1.15]) and intravenous ferric derisomaltose (relative risk 1.06 [99.95% confidence interval 0.98, 1.16]) vs oral (69.7%).”
Panel auditInternal validity: high · scope of inference: Second-trimester pregnant women with moderate IDA (Hb 7.0-9.9 g/dL) in India, all also given folic acid.Key limitations: no untreated control for oral iron · rescue IV iron allowed in oral arm · pregnancy-specific population
Absolute Hb rise on oral iron in adult IDA outpatients.
“Mean change in hemoglobin was + 1.05 ± 1.34 g/dL in alternate day arm and + 1.36 ± 1.51 g/dL in daily arm (p = 0.47) at week 8.”
Panel auditInternal validity: medium · scope of inference: Adults with microcytic hypochromic anaemia and/or ferritin <50 ng/mL, Hb ≤10 g/dL.Key limitations: no placebo comparator · modest ~1 g/dL rise at 8 weeks · authors note larger/longer trials needed
Placebo-controlled RCT proof that oral iron corrects IDA above placebo.
“Significantly more patients randomized to ferric citrate achieved the primary end point (61 [52.1%] versus 22 [19.1%] with placebo;<0.001).”
Panel auditInternal validity: high · scope of inference: Adults with non-dialysis-dependent CKD and IDA.Key limitations: CKD-specific population · ferric citrate not a conventional ferrous salt · still ~48% did not meet endpoint
Bounds the claim: correction occurs in most but not all patients.
“Nonresponse to oral iron therapy does not rule out IDA, since two-thirds of patients subsequently responded to intravenous iron.”
Panel auditInternal validity: medium · scope of inference: IDA patients who failed an initial 14-day oral iron run-in (elevated hepcidin).Key limitations: result confined to selected nonresponders · total sample size not stated in abstract · does not test general first-line oral iron response
4 of 14 papers shown. The full review lists all of them, with the panel’s arbitration →
Claims are graded at each quarterly release, and re-graded between releases only when a pivotal trial lands. Every change is a new version of the claim.
Convergent randomised and placebo-controlled evidence establishes oral iron corrects IDA in most patients, with nonresponse and partial repletion capping confidence just below the ceiling.
Release 2026-q4 re-graded every claim from its corpus under protocol v0.19. An earlier release's grade is shown for the record; it came from an earlier protocol and is not a movement.
Assumptions that carry weight but are not themselves established.
The panel records the gap that would most move the claim, and the study that would close it.
Full iron-store repletion as an endpoint. Haemoglobin rises but ferritin stayed low at 12 weeks [8], leaving unclear whether oral iron corrects the deficiency or only the anaemia. The panel rates this the highest-importance open gap for the claim, and names the study design that would close it: An RCT with a pre-specified ferritin/store-repletion endpoint and extended dosing duration.
Open question: Does oral iron restore iron stores to a defined target, not just raise haemoglobin? Why it is still open: Median ferritin was only 27 µg/L at 12 weeks in [8] and no trial tracks repletion to a store target.
Priors is a sceptical first reader, not peer review, and not medical advice.
Release 2026-q4 · graded 18 Sep 2026 · protocol v0.19