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Iron Deficiency

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Introduction

Iron deficiency is the most common micro-nutrient deficiency in the world. Around 14% of urban New Zealand (Auckland) children between 6 and 23 months have iron deficiency1.

Iron deficiency results in widespread impairment in body functions. The most important adverse effects of iron deficiency in childhood involve learning, behaviour and cognitive function. Iron deficiency also results in anaemia, abnormalities in weight gain, appetite, gastrointestinal function, exercise tolerance and immune response to infections.

Risk Factors

Anthropometric Dietary

Age 6 - 24 months*

Maori/Pacific/other non-European

Premature infants (from 2 - 3 months of age)

Low birth weight

Maternal iron deficiency anaemia in pregnancy

Increased BMI (or preterm/LBW babies who have then experienced rapid large weight gain during infancy with upward crossing of several centiles)

Blood loss (gastrointestinal, iatrogenic through frequent blood sampling)

Adolescent females with poor diets and/or significant menstrual losses

Daily cows milk

Having no milk formula

Eating fruit only as a snack rather than with the main meal

Handmade first solids only rather than commercial solids**

Drinking tea < 5 years of age

 * Birth stores are typically adequate to maintain normal iron status until 4 months of age; high iron needs, rapid growth and insufficient intake of iron rich foods can lead to deficiency thereafter.

** This does not imply that some homemade first solids are not of excellent nutritional quality.

In children aged 6 to 23 months nutritional and anthropometric risk factors interact with one another so for example the risk of iron deficiency is increased further if there is more than one dietary risk factor or a dietary and an anthropometric risk factor are present2.

Diagnosis

Diagnosis of iron deficiency can be challenging. There is no single laboratory measure that accurately characterises the iron status of a child. For this reason, risk assessment is an important part of the diagnosis (see above). History of prematurity, non-formula cow's milk intake and daily intake of iron rich foods will be helpful. Empiric therapy may be warranted based on the blood count alone in high risk children.

Measure the 3 body iron pools (haem iron, storage iron and transport iron) as below. Iron deficiency is defined by abnormalities in ≥ 2 of these 3 measurements. Other helpful tests can include an elevated Red Cell Distribution Width (RDW) or low reticulocyte haemoglobin (Ret-He) < 27pg.

Cut Off Values For Laboratory Tests Of Iron Status

Age in years Red cell pool  Transport Iron Storage Iron
  Hb (g/L) RDW% MCV (fL) Iron saturation % Serum ferritin μg/L
 1 - <2  <110 >14.0  <73  <10  <10
 2-5  <111 >14.0 <75  <12  <10

Note: these levels vary from local laboratory quoted norms. The cut off values above are reference values based upon normal populations including an ethnically stratified normal sample of children living in Auckland.

Interpretation

  1. Mean cell volume (MCV) is reduced in both iron deficiency and alpha-thalassaemia trait. Approximately 15% of Polynesian New Zealanders have alpha-thalassaemia trait.
  2. A major difficulty in diagnosing iron deficiency in children is the confounding effect of acute infection. Even mild acute infection can make the diagnosis of mild iron deficiency anaemia difficult by causing a decrease in haemoglobin concentration, a decrease in iron saturation and an increase in serum ferritin. Infection should not affect MCV or RDW. While it may be preferable to delay blood testing of iron status until 4-6 weeks after the resolution of the infection, in the context of acute emergency department or inpatient care a practical approach is to attempt to make the diagnosis based upon the parameters that are available from the full blood count.

Management

Management involves:

  • Identification of likely cause
  • Parent education and dietary modification
  • Iron supplementation (oral or IV)
  • Blood transfusion in rare cases
  • A follow-up plan

The type of supplementation is determined based on:

  • Severity of anaemia
  • Severity of symptoms
  • Response to previous supplementation

Treatment is usually provided as an outpatient.  Inpatient management is reserved for severe anaemia and/or symptoms, or due to social factors.

Identifying cause of iron deficiency

By far the most common cause of iron deficiency in children is due to inadequate dietary intake, either in isolation, or along with the risk factors above. Consider other causes including gastrointestinal disease causing poor absorption (e.g. Coeliac Disease) or chronic blood loss (e.g. Inflammatory Bowel Disease, Cow's milk protein-induced colitis).  Consider heavy menstrual loss in post-menarche females.

If inadequate dietary intake is the most likely cause, then further investigation is not usually required unless there is inadequate response to treatment.

Parent education and dietary modification

Encourage Discourage

Exclusive breast feeding for first 4-6 months.

Iron fortified formula until 12 months if not breast fed.

Iron rich foods (pureed meat, iron fortified cereals) with a source of vitamin C (fruit) as part of establishing solids.

Homogenised cows milk < 12 months.

Cows milk > 600mL/day for 1-5 year olds.

Tea for any child < 5 years (tannins bind dietary iron preventing it from being absorbed)

 See the ADHB  'All about Iron' information sheet for families.

Iron supplementation (oral)

See the NZFC (http://www.nzfchildren.org.nz/nzf_4907) for subsidised brands, dosage and adverse effects.

Medication Dose Duration
Oral iron elixir (ferrous sulphate oral solution 30mg/ml = 6mg/ml elemental iron)
Ferrous sulfate is unpalatable to some children and gastrointestinal side effects are common, limiting adherence to daily treatment for several months. Given with meal may reduce frequency of side effects. Potentially fatal toxicity with acute ingestions of > 20mg/kg = 3ml/kg therefore store securely.
3 mg/kg/day of elemental iron (= 0.5ml/kg/day of elixir) once daily with drink containing vitamin C

Up to 6 mg/kg/day of elemental iron (= 1ml/kg/day of elixir in divided doses) - monitor for iron overload

Max 200mg elemental iron (= 33ml) daily
Continue for at least 3 months if anaemic
Alternatives to oral elixir
See http://www.nzfchildren.org.nz/nzf_4907 
Ferrous sulfate tablets (e.g. Ferrogradumet 325mg) contain 105mg elemental iron per tablet and are a controlled release formulation.
Similar side effects to liquid.
Ferrous fumarate is available, not controlled release.
Can sometimes be better tolerated than ferrous sulfate (given 2-3 times per day). One tablet contains 65mg of elemental iron.
Ferrrous gluconate is not currently available in New Zealand.
For a formula fed infant, iron fortified follow-on formula and iron fortified partially modified cow's milk have been shown to effectively treat iron deficiency anaemia in infancy when given in place of any other milk or infant formula3.

Iron supplementation (IV)

Indications for intravenous treatment of iron deficiency anaemia:

  1. Oral therapy is contraindicated
  2. Enteric absorption is defective
  3. Patient non-adherence with oral therapy
  4. Persistent gastrointestinal intolerance on oral therapy
  5. Patient with chronic renal failure on haemodialysis

The preferred intravenous formulation is Ferric Carboxymaltose (Ferinject) 500mg/10mL.

  • Ferric carboxymaltose is UNLICENSED FOR USE < 14 years - parental consent is required, and in ADHB requires application through the Hospital Medicines Committee for each patient.  Link to online application here: http://team.adhb.govt.nz/hmc/default.aspx.
  • This has been used effectively in Starship for iron deficiency anaemia, long-term IV nutrition, renal failure, and inflammatory bowel disease in patients from 1-15 years of age.
  • Hypersensitivity reactions can occur even if a child has tolerated a previous dose therefore test doses are not recommended. Children at increased risk are those with known allergies, immune or inflammatory conditions, or atopy.
  • Facilities for resuscitation and treatment of anaphylaxis must be available.

Dose

Ferric carboxymaltase (Ferinject) 15mg/kg (max 1000mg/dose)

Dilution

Dose of Ferinject Volume of Ferinject (500mg/10mL) Volume of sodium chloride 0.9% to dilute
100-200mg 2-4 mL 50 mL
>200-500mg >4-10 mL 100 mL
>500-1000mg >10-20 mL 250 mL

Give dose over 20 minutes followed by a flush of 30 mL sodium chloride 0.9%.

If repeat doses of Ferric carboxymaltase are required they should be given at least a week apart. Frequency of IV therapy can be judged by persistence of deficiency and patient response to therapy.

Monitoring

Monitor the infusion site for signs of extravasation. Monitor blood pressure. Observe all children for at least 30 minutes following each Ferinject injection. If an allergic reaction of any kind is suspected the infusion should be STOPPED immediately and assistance sought.

Further information can be found at http://www.nzfchildren.org.nz/nzf_4932.

If oral iron is taken regularly and well absorbed, the haemoglobin response to oral and IV iron is similar.

Blood transfusion

Transfusions are rarely required except in the setting of cardiac failure or if urgent surgery is required.  Children often tolerate chronic iron deficiency anaemia, with a very low haemoglobin, with few symptoms.  There is usually a very rapid clinic response to oral or IV iron supplementation with an increase in haemoglobin within days.  There is no fixed cut-off level of haemoglobin when tranfusion is required and all clinical factors should be taken into account when determining whether transfusion is needed.

Follow Up

An adequate response to treatment is defined as a rise in haemoglobin by at least 10 g/L after 4 weeks of oral iron supplementation. Response to treatment (and adherence) is assessed by haemoglobin, reticulocyte response and ferritin at 4 weeks.  This will usually be arranged through the patient's General Practitioner.

Clear documentation of the follow up arrangements is essential, including communication with the GP outlining the plan and recommendations.

Most treatment failure is due to poor adherence rather than inadequate response to iron therapy.  Poor response to treatment is also an opportunity to review the diagnosis.

Information for Families

View or download the ADHB 'All about Iron' information sheet.

References

  1. Grant CC, Wall CR, Brunt D, Crengle S, Scragg R. Population prevalence and risk factors for iron deficiency in Auckland, New Zealand. J Paediatr. Child Health 2007; 43: 531-7.
  2. Brunt DR, Grant CC, Wall CR, Reed PW. Interaction between risk factors for iron deficiency in young children. Nutrition & Dietetics 2012; 69: 285-292. 
  3. Wall CR, Grant CC, Taua N, Wilson C and Thompson JMD. Milk versus medicine for the treatment of iron deficiency anaemia in hospitalized infants. Arch. Dis. Child. 2005; 90: 1033-1038.

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Document Control

  • Date last published: 13 July 2016
  • Document type: Clinical Guideline
  • Services responsible: General Paediatrics
  • Author(s): Cameron Grant, Tim Prestidge, Hannah Noel
  • Owner: Cameron Grant
  • Review frequency: 2 years

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