GP · haematological-presentations
Iron deficiency and iron deficiency anaemia
Also known as Iron deficiency anaemia · IDA · Low iron · Sideropenia
GP-fellowship guide to iron deficiency and iron deficiency anaemia: ferritin thresholds with the inflammation caveat, transferrin saturation in borderline cases, the coeliac-screen-plus-GI-investigation mandate in men and postmenopausal women, menstrual quantification, once-daily and alternate-day oral iron built on hepcidin physiology, response expectations and total treatment duration, the structured non-response workup, IV iron indications with hypophosphataemia risk of newer formulations, suspected-cancer referral pathways and pregnancy management.
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Red flags
- Iron deficiency anaemia in any man or postmenopausal woman is gastrointestinal disease until proven otherwise — bidirectional endoscopy plus coeliac serology is mandatory unless there is overt non-GI blood loss; the lower the haemoglobin, the more urgent the investigation
- A normal-range ferritin does not exclude iron deficiency — endoscopic yield remains significant at ferritin 40–100 ng/ml even without GI symptoms
- Never treat anaemia with iron alone and close the episode at a normal haemoglobin — continue therapy after normalisation to replete stores, and recheck that stores are full
- Ferric carboxymaltose causes hypophosphataemia in about half of recipients — check phosphate after dosing and prefer alternatives when repeated dosing is anticipated
- Failure of haemoglobin to rise on oral iron is a diagnosis still outstanding: adherence, coeliac disease, H. pylori, ongoing loss — not simply 'more iron'
Overview
Iron deficiency is the commonest deficiency state worldwide. Iron deficiency anaemia affects 2–5% of adult men and postmenopausal women in the developed world, and it is one of general practice's highest-stakes presentations: most cases are benign, but among them hide colonic and gastric cancers and coeliac disease.[5] Non-anaemic iron deficiency is also not benign trivia — in older adults its prevalence runs near 9% (11% of women) and it carries measurable excess mortality over 14 years.[13]
The GP's tasks: recognise deficiency early using ferritin interpreted against inflammation; find the cause — always, in the mandated groups; replace effectively using dosing schedules that respect iron biology; and follow up until stores, not just haemoglobin, are replete.[5]
References15ShowHide
- [1]Stoffel NU et al. Iron absorption from oral iron supplements given on consecutive versus alternate days and as single morning doses versus twice-daily split dosing in iron-depleted women: two open-label, randomised controlled trials. Lancet Haematol, 2017.PMID 29032957
- [2]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
- [3]Stoffel NU et al. Iron absorption from supplements is greater with alternate day than with consecutive day dosing in iron-deficient anemic women. Haematologica, 2020.PMID 31413088
- [4]Shepshelovich D et al. Intravenous Versus Oral Iron Supplementation for the Treatment of Anemia in CKD: An Updated Systematic Review and Meta-analysis. Am J Kidney Dis, 2016.PMID 27321965
- [5]Goddard AF et al. Guidelines for the management of iron deficiency anaemia. Gut, 2011.PMID 21561874
- [6]Pavord S et al. UK guidelines on the management of iron deficiency in pregnancy. Br J Haematol, 2012.PMID 22512001
- [7]Mahadev S et al. Prevalence of Celiac Disease in Patients With Iron Deficiency Anemia-A Systematic Review With Meta-analysis. Gastroenterology, 2018.PMID 29689265
- [8]Zoller H et al. Hypophosphataemia following ferric derisomaltose and ferric carboxymaltose in patients with iron deficiency anaemia due to inflammatory bowel disease (PHOSPHARE-IBD): a randomised clinical trial. Gut, 2023.PMID 36343979
- [9]Wang SA et al. Gastrointestinal endoscopic findings in men with unexplained anemia and low normal ferritin values. Am J Hematol, 2006.PMID 16628728
- [10]Ganz T et al. Hepcidin and iron homeostasis. Biochim Biophys Acta, 2012.PMID 22306005
- [11]Ching V et al. Diagnostic yield of upper gastrointestinal tract endoscopy and colonoscopy in patients with iron deficiency anaemia while on direct oral anticoagulants. Intern Med J, 2025.PMID 39718804
- [12]Hudak L et al. An updated systematic review and meta-analysis on the association between Helicobacter pylori infection and iron deficiency anemia. Helicobacter, 2017.PMID 27411077
- [13]Philip KEJ et al. The prevalence and associated mortality of non-anaemic iron deficiency in older adults: a 14 years observational cohort study. Br J Haematol, 2020.PMID 32072619
- [14]Guyatt GH et al. Diagnosis of iron-deficiency anemia in the elderly. Am J Med, 1990.PMID 2178409
- [15]Miles LF et al. Associations between non-anaemic iron deficiency and outcomes following elective cardiac surgery (IDOCS): a prospective cohort study. Lancet Haematol, 2022.PMID 35772430