The following is based on the BNF, NICE CKS: Anaemia – iron deficiency (November 2021) and the British Society of Gastroenterology guidelines for the management of iron deficiency anaemia in adults (September 2021)

Do not wait for investigations to be carried out before prescribing iron supplements unless colonoscopy is imminent.

Treatment with an iron preparation is justified only in the presence of a demonstrable iron-deficiency state. It is important to exclude any serious underlying cause of the anaemia (e.g. gastric erosion, gastro-intestinal cancer).

• A dose of 65mg elemental iron once daily (on an empty stomach) is needed to treat iron deficiency anaemia.

Prophylaxis with an iron preparation may be appropriate in malabsorption (i.e. coeliac disease), menorrhagia, pregnancy, after subtotal or total gastrectomy, in haemodialysis patients, in the management of low birth-weight infants such as preterm neonates, people with an iron-poor diet (i.e. vegans), and people with recurring anaemias (i.e. an elderly person) and further investigations are not indicated or appropriate.

• An ongoing prophylactic dose of 65mg elemental iron once daily may be beneficial in these patient groups.

If dietary deficiency of iron is thought to be a contributory cause of iron deficiency anaemia, advise the person to maintain an adequate balanced intake of iron-rich foods (for example dark green vegetables, iron-fortified bread, meat, apricots, prunes, and raisins) and consider referral to a dietitian. Please see bda.uk.com for further details.

Prescribe all people with iron deficiency anaemia one tablet once daily of oral ferrous sulfate or ferrous fumarate, or two tablets once daily of ferrous gluconate.

Monitor to ensure that there is an adequate response to iron treatment. Patients should be monitored in the first 4 weeks for an Hb response to oral iron, and treatment should be continued for a period of around 3 months after normalisation of the Hb level, to ensure adequate repletion of the marrow iron store. Then monitor full blood count periodically — for example, 3-monthly for 12 months and then 6-monthly for 2–3 years.

Patients unable to tolerate, or not responding to, oral iron treatment:

• Assess compliance and whether the iron treatment is tolerated — if an oral iron supplement is not tolerated, address the adverse effects:
  • Offer a laxative to people with constipation.
  • Offer reassurance to people who have black stools.
  • Recommend the person takes iron with or after meals.
  • Reduce the dose to one tablet on alternate days, or consider alternative oral preparations.

Consider parenteral iron if oral iron is contraindicated, ineffective or not tolerated.

Traditionally oral iron salts were taken as split dose, two or three times a day. More recent data suggest that lower doses and more infrequent administration may be just as effective, while probably associated with lower rates of adverse effects. In addition, it may be inconvenient for some people to find three periods during the day to take iron on an empty stomach.

Modified-release preparations of iron are licensed for once-daily dosage but have no therapeutic advantage and should not be used. These preparations are formulated to release iron gradually; the low incidence of side-effects may reflect the small amounts of iron available for absorption as the iron is carried past the first part of the duodenum into an area of the gut where absorption may be poor.

Compound preparations containing iron and folic acid are used during pregnancy in women who are at high risk of developing iron and folic acid deficiency; they should be distinguished from those used for the prevention of neural tube defects in women planning a pregnancy. Low haemoglobin in pregnancy does not mean anaemia and iron should only be prescribed if the mean corpuscular volume (MCV) and ferritin are low.

Referral should be considered if the cause of iron deficiency is not clear or there is an inadequate response to iron treatment. For referral criteria for people with iron deficiency anaemia, see local clinical referral guidelines:

• Iron deficiency anaemia (South Devon & Torbay)
• Iron deficiency anaemia (Western Locality)

9.1.1.1 Oral iron

Iron content of oral iron preparations

Ferrous fumarate

• Tablets 210mg (68mg elemental iron) (£1.33 = 28 tablets)

Indications and dose

• Iron-deficiency anaemia (prophylaxis and treatment):
  • One tablet once daily (off-label dose for treatment)
• Long-term supplementation following gastric bypass or sleeve gastrectomy:
  • One tablet once daily
  • Menstruating women; one tablet twice daily

Ferrous sulfate

• Tablets 200mg (65mg elemental iron) (£1.07 = 28 tablets)

Indications and dose

• Iron-deficiency anaemia (prophylaxis and treatment):
  • One tablet once daily (off-label dose for treatment)
• Long-term supplementation following gastric bypass or sleeve gastrectomy:
  • One tablet once daily
  • Menstruating women; one tablet twice daily

Ferrous gluconate

• Tablets 300mg (35mg elemental iron) (£1.76 = 56 tablets)

Indications and dose

• Iron-deficiency anaemia (prophylaxis and treatment):
  • Two tablets once daily (or one tablet once daily if higher doses are not tolerated) (off-label dose for treatment)
• Long-term supplementation following gastric bypass or sleeve gastrectomy:
  • One tablet once daily

Sodium feredetate

• Oral solution sugar free 190mg/5ml (27.5mg/5ml elemental iron) (£8.37 = 10ml once daily)

Indications and dose

• Iron-deficiency anaemia (prophylaxis and treatment):
  • 10ml once daily (or 5ml if higher doses are not tolerated) (off-label dose for treatment)

9.1.1.2 Parenteral iron

MHRA Drug Safety Update (August 2013): Intravenous (IV) iron and serious hypersensitivity reactions: strengthened recommendations to manage and minimise risk.

• IV iron products are indicated in the treatment of iron deficiency and anaemia when iron supplements cannot be given or have not worked.
• Hypersensitivity reactions are well known to occur rarely with IV iron products, and may be life-threatening or fatal. These reactions can occur even when a previous administration has been tolerated (including a negative test dose), therefore, an initial test dose on first use of an IV iron product for a patient is no longer recommended.
• Intravenous iron products should only be administered when appropriately trained staff and resuscitation facilities are immediately available; patients should be closely monitored for signs of hypersensitivity during and for at least 30 minutes after every administration. In the event of a hypersensitivity reaction, treatment should be stopped immediately and appropriate management initiated.
• The risk of hypersensitivity is increased in patients with known allergies, immune or inflammatory conditions, or those with a history of severe asthma, eczema, or other atopic allergy; in these patients, intravenous iron should only be used if the benefits outweigh the risks.
• The prescribing, dosing, administration, and safety information differs between IV iron product formulations, and the individual product information should be consulted before and during use.
• Further information is also detailed in the MHRA safety update.

The dose of all parenteral iron preparations requires calculation on an individual basis (See drug entries below).

The only valid reasons for administering iron parenterally are failure of oral therapy due to lack of patient co-operation, severe gastro-intestinal side effects, continuing severe blood loss or malabsorption and for patients with severe renal failure receiving haemodialysis.

Ferinject

(Ferric carboxymaltose)

• Solution for injection 50mg/ml, 2 ml ampoule, 10ml vial

Notes

1. Prescribe by brand (to aid identification where products contain multiple ingredients, or to prevent confusion where multiple brands contain similar ingredients)
2. See the Ferinject Summary of Product Characteristics for dose calculations
3. The absorption of oral iron is reduced when administered concomitantly with parenteral iron preparations. Therefore, if required, oral iron therapy should not be started for at least 5 days after the last administration.
4. MHRA Drug Safety Update (November 2020): Ferric carboxymaltose (Ferinject): risk of symptomatic hypophosphataemia leading to osteomalacia and fractures
   • ferric carboxymaltose is known to be commonly associated with hypophosphatemia
   • cases have been reported of symptomatic hypophosphataemia leading to infrequent reports of hypophosphataemic osteomalacia and fractures in patients with existing risk factors and following prolonged exposure to high doses – some cases required clinical intervention, including surgery
   • monitor serum phosphate levels in patients:
     • requiring multiple administrations of ferric carboxymaltose at higher doses
     • on long-term treatment with ferric carboxymaltose
     • with pre-existing risk factors for hypophosphataemia such as vitamin D deficiency, calcium and phosphate malabsorption, secondary hyperparathyroidism, inflammatory bowel disease, and osteoporosis
   • advise patients to seek medical advice if they experience symptoms indicative of hypophosphataemia, including new musculoskeletal symptoms or worsening of tiredness – be aware these symptoms may be confused with those of iron deficiency anaemia
   • if hypophosphataemia persists, re-evaluate treatment with ferric carboxymaltose

CosmoFer

(Iron dextran)

• Solution for injection 50mg/ml for slow intravenous injection or intravenous infusion

Notes

1. Prescribe by brand (to aid identification where products contain multiple ingredients, or to prevent confusion where multiple brands contain similar ingredients)
2. See the CosmoFer Summary of Product Characteristics for dose calculations
3. The absorption of oral iron is reduced when administered concomitantly with parenteral iron preparations. Therefore, if required, oral iron therapy should not be started for at least 5 days after the last administration.

Ferric derisomaltose

• Pharmacosmos 100mg/ml solution for injection/infusion vials

Notes

1. Prescribe by brand (to aid identification where products contain multiple ingredients, or to prevent confusion where multiple brands contain similar ingredients)
   
2. See the Pharmacosmos Summary of Product Characteristics for dose calculations
   
3. The absorption of oral iron is reduced when administered concomitantly with parenteral iron preparations. Therefore, if required, oral iron therapy should not be started for at least 5 days after the last administration
4. Ferric derisomaltose was formerly known as Monofer

Venofer

(Iron sucrose)

• Solution for injection 100mg in 5ml for slow intravenous injection or intravenous infusion

Notes

1. Prescribe by brand (to aid identification where products contain multiple ingredients, or to prevent confusion where multiple brands contain similar ingredients)
2. See the Venofer Summary of Product Characteristics for dose calculations
3. The absorption of oral iron is reduced when administered concomitantly with parenteral iron preparations. Therefore, if required, oral iron therapy should not be started for at least 5 days after the last administration.