Iron Deficiency Anaemia (Haematology)

Anaemia due to Iron deficiency

Please note that this guidance also applies to those with proven iron deficiency without anaemia, but please see below about the need for GI investigations.

Definition: 

Anaemia (haemoglobin below normal range) and evidence of iron deficiency – this is defined by either:

1. low ferritin (diagnostic)
2. normal ferritin in which case further iron studies are required on a fasting blood sample (take sample in morning with nothing to eat and only water to drink since midnight) – low serum iron and transferrin ≥3.0 g/l are then diagnostic of iron deficiency. Please see below for more detail.
3. Ferritin < 30 ug/L and not meeting criteria 1 or 2 may reflect low iron stores – give trial of oral iron and response will guide if there was true deficiency. 

In all other cases of anaemia, please follow separate RefHelp guidance for those with microcytic, normocytic or macrocytic anaemia.

Iron deficiency without anaemia.

Endoscopic investigation rarely detects malignancy in patients with proven iron deficiency (low ferritin or normal ferritin with low serum iron and transferrin ≥3.0 g/l on a fasting blood sample), but without anaemia.  However, men and non-menstruating women aged >50 should be considered for management/referral in accordance with this guideline.

Please note:

• Not all microcytic anaemias are caused by iron deficiency.  It is essential to confirm iron deficiency to avoid unnecessary invasive investigations. Always perform a ferritin (low result is diagnostic of iron deficiency). However, since ferritin is an acute phase reactant, a normal or high ferritin does not exclude iron deficiency.  In such cases, check serum iron and transferrin on a fasting blood sample; a low serum iron and transferrin ≥3.0 g/l are then diagnostic of iron deficiency.
• For microcytic anaemia not proved to be caused by iron deficiency, please see Inherited red cell disorders on RefHelp for appropriate management.

Treatment of Iron Deficiency.

Establish cause of blood loss and prevent its recurrence or the lack of absorption/intake.

In cases of confirmed iron deficiency anaemia, treat with once daily iron supplementation as this is effective and better tolerated. Continue until the haemoglobin normalises and then for an additional 3 months to replenish iron stores. Ferritin levels should be >50 before discontinuation of iron supplementation.

If the patient experiences side effects (often nausea or bowel disturbance), reduce the frequency to alternate day iron supplementation or change the oral iron preparation: please see the East Region Formulary for alternative iron formulations.  GI side effects relate to dose.

Patients should be given information about iron rich foods and diet discussed.

Long term PPI use should be discussed as this can cause iron deficiency due to lack of absorption.

Tea and coffee should not be consumed along with iron supplements as it prevents absorption.

Women with heavy menstrual bleeding causing recurrent iron deficiency should be offered tranexamic acid 1g TDS PO on the heaviest days of flow or hormonal interventions unless contraindicated. Please see the RefHelp page on heavy menstrual bleeding for further detail on management.

There are now a plethora of low dose oral iron supplements available from supermarkets and pharmacies.  Liquid water fortified with iron, oral sprays and liquid preparations can be helpful in people who experience GI symptoms as an alternative to IV iron. These may need to be taken for longer periods of time to fully replace iron stores, but oral iron can improve haemoglobin as effectively as IV iron with good compliance.

If the patient is absolutely unable to tolerate any oral iron preparation and they are anaemic (low Hb) they can be referred for consideration of intravenous iron (see below). If under a parent specialty for bleeding symptoms, or with a clear organ system cause for iron deficiency, referral should be directed to the appropriate specialty.

IV iron infusions are associated with osteomalacia and rickets in some people as per the MHRA warning in the BNF. Anaphylaxis and other systemic symptoms can occur with IV iron administration even when tolerated previously. Permanent skin discolouration can occur if IV iron extravasates. These risks should be discussed with patients prior to referral.

Many patients with historical oral iron intolerance may have received IV iron in the past. Such patients should be offered the lower dose oral iron replacement detailed above before re-referral and should be similarly counselled regarding risks of IV iron, especially as the bone side effects are more commonly seen with people receiving repeat infusions.

C.M & L.W 01-02-24