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Newly-diagnosed, unexplained iron deficiency anaemia (NDUIDA)

Warning

Background

Introduction

This pathway is for assessment and investigations of newly diagnosed patients with newly-diagnosed, unexplained iron deficient anaemia (NDUIDA) Iron Deficiency Anaemia (IDA).

Iron deficiency anaemia is anaemia (haemoglobin below local laboratory sex-adjusted range) due to low body iron stores (ferritin). There are multiple causes including physiological causes such as menstruation, pregnancy or low dietary intake of iron. Investigations should be appropriate for the individual patient’s specific circumstances.

Despite national guidelines, variations exist in investigations and management of IDA, leading to over- or under-investigation. Some patients undergo avoidable invasive tests with risk of significant complications. Prioritising endoscopic and non-endoscopic tests is needed to avoid unsafe, unmanageable endoscopy waiting times and preserve timely access.

Gastrointestinal (GI) conditions can cause chronic, insidious blood loss. GI investigations should be considered in proven IDA when the likely benefit outweighs the risks of invasive testing. Oesophagogastroduodenoscopy OGD (upper GI endoscopy) and colonoscopy carry risks including bleeding, perforation, sedation-related cardiopulmonary complications, aspiration pneumonia, hospitalisation, surgery, and mortality.

In some scenarios, GI investigations may be inappropriate because

  • the yield of significant findings is very low, or
  • patients are frail (including where they are not fit for treatment) or asymptomatic and unlikely to benefit.

It is recognised that services operate differently in different health boards. For example the referral route may differ - for example it may be general surgery or gastroenterology in different areas. Furthermore different health boards have different protocols for access to tests such as faecal calprotectin. These guidelines are not meant to dictate a "correct" referral pathway or route to test but should be assessed and implemented by the appropriate teams that are involved in iron deficiency anaemia referrals in each region.

Aims of the guidelines

This pathway helps confirm IDA and decide whether investigations are appropriate on an individualised basis. It supports prioritisation for those most likely to benefit and avoids unnecessary risk from invasive tests where benefit is unlikely. It builds on existing guidance, including use of qFIT to guide lower GI investigation.

Guiding principles

The National Centre for Sustainable Delivery (CfSD) commissioned the IDA Group to develop a Scotland-wide pathway for patient-centred evaluation, investigation and management of newly diagnosed, as-yet unexplained IDA. The group reviewed evidence, aligned it with existing guidance, and produced a pathway that keeps patients central and reflects the ethos of CfSD.

The pathway promotes shared responsibility between referring and receiving teams. It supports timely access to endoscopy for those most likely to benefit and reduces avoidable exposure to invasive procedures where the benefit–risk balance is less favourable. It also clarifies when further secondary care investigation is not routinely indicated and emphasises primary care follow-up and safety-netting in these situations.

Referrals should include key clinical details and results of completed pre-referral tests (noting that these may be available via local electronic results portals). The referring teams must include information around frailty, if relevant to the case. This supports effective secondary care triage, which may include direct-to-test endoscopy, outpatient review, imaging, or watchful waiting with clear safety-netting advice to primary care teams.

Pathway recommendations

All referrals to secondary care should include:

  • Clinical history and findings
  • Coeliac serology
  • Renal function (to ensure investigations can be safely performed)
  • Upper GI symptoms and H. pylori where applicable
  • qFIT result (plus second sample if first less than 20) (qFIT access per local pathways)
  • Frailty score (if appropriate)
  • Patients meeting USC clinical criteria (red boxes) - do not wait for qFIT results

The pathway applies to all clinical settings; if IDA is detected out with primary care (e.g., in-patients), follow the same assessment and referral protocols.

qFIT access and local set-up varies across Scotland: follow local processes.

Click on the image below to view the pathway

IDA Comms Edit Flow Chart 300926 Image

 

Good practice notes

Note 1

  • IDA: haemoglobin below local laboratory thresholds and ferritin less than 30 µg/L.
  • “New” = not investigated within the past 2 years.
  • Start oral iron replacement therapy - do not delay while awaiting investigations
  • IDA can be difficult to diagnose at times. Ferritin may be normal/raised in inflammation (acute phase response). Consider a 2 to 4 week trial of iron therapy and assess haemoglobin response. Alternatively, transferrin more than 3 and low MCV may help. If unsure, seek secondary care advice on need for further investigations.
  • If investigated within 2 years, include details and any prescribed iron therapy so second-line tests can be considered.

Note 2

  • Anaemia is common and may not always be due to iron deficiency. There are many possible tests and definitions for iron deficiency in literature but the ones used in this guideline represent our consensus view on the most useful and accurate tests to use. Without concerning symptoms or IDA, GI investigation is unlikely to help
  • Assessment | Diagnosis | Anaemia - iron deficiency | CKS | NICE

Note 3

Young women (premenopausal)

IDA is common in young women; contributors include menstrual loss, pregnancy, and low dietary intake. 

Underlying GI pathology is uncommon. After coeliac disease screening, further investigation is usually only needed if additional concerning features are present.

  • Age more than 50
  • Non-menstruating (for example, post-hysterectomy)
  • Red flag symptoms  
  • Major genetic risk: colorectal cancer in two first-degree relatives, or one first-degree relative aged less than 50
  • Recurrent or persistent IDA disproportionate to other likely causes (for example, menstrual loss)
     

Pregnancy: if GI investigation is needed before delivery, gastroscopy and (after the first trimester) MR enterography are considered safe. 

Post-menopausal bleeding should be managed in line with the appropriate guidance or pathway.  

Note 4

  • Anaemia is common in older people. Without symptoms and/or those living with multi-morbidity or frailty, risks of invasive GI tests may outweigh the benefits. Please note that frailty can be age independent.
  • Use the Rockwood Frailty Scale. Use Realistic Medicine discussions to agree appropriateness of invasive tests for a frailty score >4. This should be undertaken by the referring team. 

How do I assess multimorbidity and agree an individualised plan?

Recommendations | Multimorbidity: clinical assessment and management | Guidance | NICE 

How do I assess frailty using Rockwood Frailty scale? 

Rockwood Frailty Scale

Note 5

  • If upper GI symptoms meet the Scottish referral guidelines for suspected cancer, refer via upper GI USC pathway.

Upper gastrointestinal cancers | Right decisions

  • Colonoscopy may also be needed depending on qFIT level or if OGD is normal. This decision and arrangement will be made by the secondary care teams.

Note 6

  • Abdominal or rectal mass: refer as USC, regardless of other results.  
  • qFIT is not required before referral.  

Note 7

  • qFIT: Colorectal cancer is a key concern in IDA. National guidance supports qFIT to prioritise colonoscopy, but access and local processes vary. Follow local qFIT arrangements.
  • qFIT more than or equal to 20 µg Hb/g: refer as colorectal USC. If colonoscopy normal, secondary care may consider OGD.  
  • qFIT less than 20 µg Hb/g: repeat in 6 weeks.  
  • If 2nd qFIT more than 20 µg Hb/g: Refer as colorectal USC.  
  • If either qFIT result 10 to 20 µg Hb/g: refer as urgent for consideration of colonoscopy. If colonoscopy is normal, secondary care may consider OGD.
  • qFIT less than 10 µg Hb/g: see Notes 8 to 12.
  • If upper GI symptoms are present, OGD is likely to be needed in addition to colonoscopy. USC/urgent/routine priority depends on symptoms and will be set by the secondary care vetting clinician, based on referral information.  

Note 8

  • New IDA with upper GI symptoms that do not meet USC criteria and double qFIT <10 µg Hb/g.
  • If Helicobacter pylori positive, eradicate.
  • If symptoms and anaemia resolve after Helicobacter treatment and iron therapy, GI investigations are not required.  
  • If persistent UGI symptoms remain despite H pylori eradication, refer for OGD (expected to be vetted as routine).  

Note 9 

  • If coeliac serology is positive and other tests (including qFIT) are normal or /negative, follow the local coeliac pathway to confirm whether further investigation is needed.  

Please click here for the link to the coeliac disease pathway

Note 10

  • Double qFIT <10 µg Hb/g, no GI symptoms, and no other concerns = very low pathology risk.  
  • Risk and consideration of risks versus benefits of investigation should be made by referrers and vetters on an individual patient basis.
  • Please consider renal US. 

Note 11

  • IDA outside UGI and colorectal cancer guidelines may be referred to secondary care (with relevant clinical and laboratory information) if clinical concern persists. Appropriate ACRT relies on receiving clear clinical information, including frailty score. 
  • Vetting clinicians should review referrals relating to these concerns.
  • Older age, male sex and more severe anaemia increase the risk of pathology (consider frailty as outlined in Note 4).
  • IDA is uncommon in young men. Use the same algorithm as for older people.
  • Local systems should be in place to stop oral iron before colonoscopy.

Note 12

Secondary care should provide a single point of entry and single point of exit through this pathway. 

  • For example, if OGD is done based on initial information and qFIT becomes available and is >20 at the time of OGD, secondary care should arrange colonoscopy (not ask the GP to re-refer via another pathway).
  • Similarly, if OGD is needed after colonoscopy, secondary care should arrange this.
  • Some patients may be better suited to non-invasive investigation (for example, CT). This decision may be made in primary or secondary care using Realistic Medicine principles.
  • Secondary care should communicate a clear outcome, plan and safety-netting advice to patients and to the referrer or primary care team.
  • At closure of the referral episode, clinical communication should go to the patient and the referring team (and GP if the referrer is not the GP).
  • After the episode is closed, any future concerns should trigger a new referral and a new episode

Clinicians may find the following information helpful.
This guidance focuses on new, unexplained IDA. Other situations may need additional measures:

  • If OGD and colonoscopy are negative and anaemia has not responded to iron, consider renal ultrasound to exclude renal pathology.
  • Functional iron deficiency (FID) is common in chronic kidney disease (CKD).
  • Iron deficiency is recognised in heart failure and IHD; iron therapy can improve symptoms and QOL in these settings.
  • Once-daily oral iron is effective, but alternate-day dosing is often better tolerated. Some patients tolerate liquid iron better.
  • IDA is a recognised problem in IBD, especially with active disease. Oral iron may be poorly absorbed or tolerated; parenteral iron is often needed. Please refer to local boards IV Iron policy.
  • If in doubt, seek advice from local secondary care teams.

 

References and resources

References

  1. British Society of Gastroenterology (BSG) 2021. Guidelines for the management of iron deficiency anaemia in adults. Available from: BSG Adult Iron Deficiency Anaemia Care Guidelines
  2. National Institute for Health and Care Excellence (NICE) guideline NG56 2016. Multimorbidity: clinical assessment and management. Available from NICE NG56 Multimorbidity guidance
  3. Rockwood, K and Theou, O. Using the Clinical Frailty Scale in Allocating Scarce Health Care Resources. Canadian Geriatrics Journal, Volume 23, Issue 3, pages 254-259, September 2020
  4. Centre for Sustainable Delivery 2024. Quantitative faecal immunochemical testing (qFIT): guidance. Available from https://www.rightdecisions.scot.nhs.uk/endoscopy/quantitative-faecal-immunochemical-testing-qfit-for-patients-with-new-lower-gastrointestinal-symptoms/
  5. Scottish Referral Guideline for Suspected Cancer 2025. Available from https://www.rightdecisions.scot.nhs.uk/scottish-referral-guidelines-srgs-for-suspected-cancer/lower-gastrointestinal-cancers/
  6. Scottish Referral Guideline for Suspected Cancer 2025. Available from https://www.rightdecisions.scot.nhs.uk/scottish-referral-guidelines-srgs-for-suspected-cancer/upper-gastrointestinal-cancers/
  7. Beaton DR, Sharp L, Lu L, et al: Diagnostic yield from symptomatic gastroscopy in the UK: British Society of Gastroenterology analysis using data from the National Endoscopy Database. Gut 2024;73:1421-1430
  8. Goddard AF, Bhala N, Everett SM, et al. British Society of Gastroenterology (BSG) and Association of Coloproctology of Great Britain and Ireland (ACPGBI) guidelines on the role of faecal immunochemical testing (FIT) in the endoscopic investigation of iron deficiency anaemia (IDA) 2025. Frontline Gastroenterology, Published online first: 14 October 2025. doi: 10.1136/flgastro-2025-103329
  9. Centre for Sustainable Delivery 2026. Coeliac disease pathway. Available from: https://www.rightdecisions.scot.nhs.uk/gastroenterology-pathways/coeliac-disease/

Acknowledgements
This pathway has been extensively peer reviewed by clinical (both primary and secondary care), nursing and managerial colleagues at various groups at CfSD. We are particularly grateful to members of IDA group, Gastroenterology and Endoscopy specialty development groups (SDGs) and Primary Care Secondary Care Interface group at CfSD.

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NDUIDA Front Cover

Editorial Information

Last reviewed: 16/09/2026

Next review date: 01/09/2027

Author email(s): cfsdmppp@nhs.scot.