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Anaemia - iron deficiency - draft

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Overview

Definition

Anaemia is defined as haemoglobin concentration below the lower limit of normal for relevant population and laboratory performing test:

  • In men aged over 15 years - Hb below 130 g/L.
  • In non-pregnant women aged over 15 years - Hb below 120 g/L.
  • In pregnant women - Hb below 110 g/L throughout pregnancy. An Hb level of 110 g/L or more appears adequate in the first trimester, and a level of 105 g/L appears adequate in the second and third trimesters.
  • Postpartum - below 100 g/L.

Guidelines

Please see the Anaemia page  in the haematology section which includes advice on assessment of anaemia and how to confirm iron deficiency.

The following guidelines are also available:

The following sections address iron deficiency anaemia and iron deficiency without anaemia and how to investigate and manage in primary care and when to refer.

Confirming Iron Deficiency Anaemia

If Hb is below the defined threshold then haematinics including ferritin should be checked.

Further advice on how to classify anaemia can be found on the Anaemia page in the haematology page - including interpretation of ferritin results.

The important thing not to miss is an underlying iron deficiency as iron deficiency anaemia may be normocytic in some elderly patients and sometimes the ferritin is spuriously raised and so appears to be “normal”. Any inflammatory condition can falsely raise the ferritin even in the presence of iron deficiency anaemia, as can chronic kidney disease, liver disease, malignancy, hyperthyroidism and heavy alcohol intake.

To help clarify the situation, it may be worth also checking the patient’s iron status:

  • NBT - available on ICE as 'iron status' under haematology panel
  • UHB - there is no iron studies box to tick, so please request Transferrin saturation and Ferritin.

The finding of a low serum iron and/or low transferrin saturation would point towards an iron deficiency. Dr Charlotte Bradbury (Consultant Haematologist at BRI) has previously advised us on this and recommends the following:

'If microcytic anaemia/possible iron deficiency, it may be worth checking another marker of iron status – if transferrin saturation <20%, and ferritin <200, a trial of iron is reasonable.'

Investigation of cause

A good history including systemic enquiry and physical examination may help direct appropriate investigations.

Other than blood tests, a urine dip should also be checked to exclude haematuria.

If there is no obvious benign cause of anaemia then investigation of IDA should initially prioritise exclusion of lower GI causes (unless symptoms suggest an upper GI cause) and a step wise approach is usually required.

Step 1 - Lower GI Investigation

Please see guidelines on when to do a FIT in patients with iron deficiency anaemia (or non-iron deficiency anaemia).

Please see the Lower GI - USC (2WW) page for advice on appropriate investigation of patients with iron deficiency anaemia with positive FIT and/or suspected colorectal cancer

Step 2 - Upper GI Investigation

An upper GI endoscopy outside the USC(2WW) pathway is recommended in people over 55 with upper abdominal pain and low haemoglobin levels. (NICE - Referral for suspected stomach cancer). For red flags for upper GI cancer see the Upper GI USC (2WW) page.

Otherwise upper GI endoscopy outside of 2WW should be considered only if lower GI investigations are negative (simultaneous referral for upper and lower GI scopes is not advised).

The quickest way to organise an upper GI endoscopy is from InHealth (Prime Endoscopy) or PPG (Emersons Green Treatment Centre) - see the Endoscopy page for details. If patients do not meet criteria for direct access endoscopy then please refer to your local trusts upper GI team via eRS.

Step 3 - Further investigation if negative lower and upper GI investigation

If a GI cause for iron deficiency anaemia is not apparent from initial upper and lower GI investigations, then please consider the following:

  1. Medication - culprit drugs (e.g. NSAIDs, aspirin, anticoagulants, bisphosphonates) should be reviewed. 
  2. Ensure the picture is true iron deficiency (you would be surprised how often patients are investigated in whom it isn’t true iron deficiency….)
  3. Dip the urine for blood - consider urological investigations if positive. See Haematuria page.
  4. Check the patient has had upper and lower GI endoscopy within the recent past (certainly within 12 months) and ensure that the quality of the endoscopic investigations are good (e.g. sometimes there is very poor bowel prep, incomplete colonoscopy etc) and consider repeating if concerned.
  5. Check coeliac serology – if positive then see Coeliac disease page.

Step 4 - Consider referral for capsule endoscopy

Proceeding directly to small bowel investigations is only indicated when there is ongoing Melaena with normal investigations – these patients tend to be under secondary care already.

For iron-deficient anaemia, small bowel investigation is only indicated for cases that fail to correct with iron replacement (or maybe if they need transfusion), or sometimes when there is recurrent IDA. This is because the pathology yield from small bowel investigation is relatively low.*

If referral is indicated, then please refer to gastroenterology via eRS (UHBW or NBT) initially where a decision on further investigation can be made (including onward referral for capsule endoscopy if this is necessary).

If you are uncertain about appropriateness of referral, then consider requesting gastroenterology A and G.

*The above advice is based on BSG guidelines (1) with local guidance provided by Dr Ana Terlovich (Consultant gastroenterologist at NBT).

Iron Replacement

See the BNSSG formulary for the Treatment of Iron Deficiency in Adults Pathway. for advice on iron preparations and next steps if oral iron is not tolerated.

Oral Iron

In all patients, consider oral iron supplements which can be started prior to endoscopy (although if 2ww colonoscopy is requested it would be best to advise patient to not start taking the iron until the colonoscopy has been performed, but they can be given the prescription).

If a patient is struggling with side effects then consider alternative salts, alternate day dosing, taking with food. If still not tolerated then consider Ferric maltol (Feraccru) 30mg BD for 12 weeks (added to BNSSG formulary in August 2023)

Parenteral Iron

Follow the BNSSG Treatment of Iron Deficiency in Adults Pathway prior to consideration of iron infusion. If oral iron is still not tolerated consider referral for iron infusion - see the Blood Transfusions & Iron infusions page for referral criteria and pathway:

Follow up

Monitor Hb and if it drops again or fails to increment adequately with iron replacement then refer to secondary care for consideration of small bowel investigation.

Iron deficiency without anaemia

The British Society of Gastroenterology Guidelines on Management of IDA (2011) has advice on how to manage patients with low iron and normal Hb as well as iron deficiency anaemia - summary as below:

'Iron deficiency without anaemia  is three times as common as IDA, but there is no consensus on whether these patients should be investigated, and further research is needed. The largest study shows very low prevalence of GI malignancy in patients with iron deficiency alone (0.9% of postmenopausal women and men, and 0% of premenopausal women)(2). Higher rates have been reported only in more selected groups. In the absence of firm evidence, we tentatively recommend coeliac serology in all these patients but that other investigation be reserved for those with higher-risk profiles (eg, age >50 years) after discussion of the risks and potential benefits of upper and lower GI investigation. All others should be treated empirically with oral iron replacement for 3 months and investigated if iron deficiency recurs within the next 12 months.

(2) Ioannou GN, Rockey DC, Bryson CL, et al. Iron deficiency and gastrointestinal malignancy: a population-based cohort study. Am J Med 2002;113:276e80.'

Resources

(1) Guidelines for the Management of Iron Deficiency Anaemia in Adults - The British Society of Gastroenterology (bsg.org.uk)

(2) Treatment of iron deficiency in Adults Pathway - BNSSG Formulary



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