Advertisement
Feature Article

Iron deficiency: how to detect it, how to correct it

JOCK SIMPSON, BRYONY ROSS, Jillian de Malmanche
OPEN ACCESS

Treatment of infants and children

Although iron deficiency in children cannot be corrected solely by dietary change, dietary advice should be given to parents and carers. Cows’ milk is low in iron compared with breast milk and infant formula, and enteropathy caused by hypersensitivity to cows’ milk protein can lead to occult gastrointestinal blood loss.31 Excess cows’ milk intake (in lieu of iron-rich solid foods) is the most common cause of iron deficiency in young children.31 Other risk factors for dietary iron deficiency include late introduction of or insufficient iron-rich foods, prolonged exclusive breastfeeding and early introduction of cows’ milk. 

Adult doses of iron can be toxic to children, and paediatric-specific protocols on iron supplementation should be followed. The usual paediatric oral iron dosage is 3 to 6mg/kg elemental iron daily.32 If oral iron is ineffective or not tolerated then consider other causes of anaemia, referral to a specialist paediatrician and use of IV iron.32

Pregnant women

Pregnancy places a significant demand on maternal iron stores. The increase in red blood cell mass during pregnancy, along with fetal growth, the placenta, haemorrhage and lactation increase iron requirements.33 The maternal haemoglobin concentration declines in pregnancy because of haemodilution. The definition of a normal haemoglobin concentration in pregnancy varies between studies. However, most guidelines define anaemia in pregnancy as:

  • a haemoglobin concentration less than 110g/L in the first trimester 
  • a haemoglobin concentration less than 105 g/L in the second and third trimesters.33-35 

By the third trimester, when iron requirements are maximal at 7.5mg per day, dietary absorption is generally insufficient, and maternal stores will be used.36 It has been shown that without supplementation, 80% of women at term have no detectable bone marrow iron stores.37 

Recommendations about iron supplementation in pregnancy conflict. Iron supplementation in pregnancy is recommended by the US Centers for Disease Control and Prevention and the WHO.38 However, in Australia the routine administration of iron supplements to all pregnant women is not recommended by the National Blood Authority.39 A number of commercially available pregnancy multivitamins contain iron.

Diagnosis in pregnancy

The MCV may increase in normal pregnancy, and thus microcytosis should not be relied on as a marker of iron deficiency at this time. Indeed, any microcytosis in pregnancy requires prompt exclusion of underlying or coexisting haemoglobinopathy (and where relevant, paternal evaluation) to evaluate the risk of clinically significant haemoglobinopathy and hydrops fetalis. The ferritin level declines during pregnancy, to a nadir of 15mcg/L without, and 20mcg/L with, iron supplementation.38

Advertisement
Advertisement

In addition to clinical monitoring, screening for anaemia with a full blood count is recommended at the first antenatal appointment, 28 weeks of pregnancy and when there is a clinical concern about anaemia. 

Treatment in pregnancy

The treatment of iron deficiency in pregnancy varies depending on its severity and the stage of pregnancy, as follows.

  • Iron deficiency without anaemia can be managed with low-dose oral therapy (20 to 80mg elemental iron per day)
  • Iron deficiency anaemia in the first trimester of pregnancy should be managed with therapeutic-dose oral iron (100 to 200mg elemental iron daily)
  • Intravenous iron is recommended for:

 – women in the second or third trimester of pregnancy with moderate or severe 

    anaemia (haemoglobin level less than 80g/L) 

 – those in whom oral therapy has failed because of poor tolerance, adherence or 

Advertisement
Advertisement

    absorption

 – women in late pregnancy (over 34 weeks) who require more rapid haemoglobin 

    correction.33 

In these groups the advantages of IV iron generally outweigh the risks. Nonetheless, patients should be advised of the potential for reactions to parenteral therapy. 

Pages

Dr Simpson is a Haematology Fellow at Calvary Mater Newcastle. Dr Ross is a Staff Specialist Haematologist at Calvary Mater Newcastle and Pathology North, Newcastle. Dr De Malmanche is a Staff Specialist Haematologist at Calvary Mater Newcastle and Pathology North, Newcastle, NSW.