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Recognising and managing iron deficiency anaemia

Recognising and managing iron deficiency anaemia

 - Iron deficiency anaemia (IDA) is one of the most common mineral deficiencies in the population and can lead to significant morbidity

- It is best to try and get adequate iron from the diet but in some individuals it may be necessary to use supplement at a controlled dose

 - Iron supplementation should not be overprescribed as it can cause a number of negative symptoms
Iron is an essential mineral required in the diet, mainly as haemoglobin for the transport of oxygen and cell respiration, but also essential in myoglobin for oxygen storage in muscles. In iron deficiency anaemia (IDA) the red blood cells are unusually small (microcytic) and pale (hypochromic). Iron is also a component of several enzymes including those involved in immune functions and in the cytochromes as part of energy production systems. Iron is stored as ferritin in the blood.  
IDA has a prevalence of 2-5% among adult men and post-menopausal women in the developed world. Between 4-13% of referrals to gastroenterologists are because of IDA.1
Premenopausal women have a higher incidence of IDA because of heavy menstrual blood losses and pregnancy.2 
Outline of the condition
Signs and Symptoms
Signs of iron deficiency anaemia include pallor of fingernails and of the mucous membranes in the mouth and under the eyelids. Nails can become spoon shaped (called koilonychia). Tachycardia is common, or oedema in severe cases. General fatigue is the most well-known symptom but there can also be breathlessness on exertion, insomnia, giddiness and anorexia. There can also be a lessening of resistance to infection, and thermoregulation can be affected. Work capacity, behaviour and intellectual performance are affected.
Who is most at risk?
The National Diet and Nutrition Survey (NDNS) showed that 46% of girls aged 11 to 18 years had intakes below the lower reference nutrient intake (LRNI) for iron for this age group, ie. below the level which is sufficient for only a few individuals, set at 8mg. Iron intakes were below the LRNI for 23% of women aged 19 to 64 years, again set at 8mg.3,4 This is worrying as poor intake coupled with heavy menstrual losses can lead to IDA. Table 1 lists other groups who are at risk of iron deficiency and the reasons for this higher risk.
Iron requirements
Iron requirements in adults are 14.8mg a day for women aged 19-50. This goes down to 8.7mg a day after 50, assuming menstruation has stopped. Men have a requirement of 8.7mg a day for the age of 19-50+. Newborns have a reserve of iron.
when first born (unless premature) but start to require more iron around the time of weaning at 4-6 months, when intake should be around 4.3mg a day. Weaning food should therefore include some iron rich foods. This article will not consider paediatric iron deficiency in detail.
Non-meat (non-haeme) sources of iron require a source of vitamin C (for example orange juice/tomatoes) to be consumed with the iron source or it will not be adequately absorbed.
Vulnerable groups with signs and symptoms of IDA should have a blood test to confirm whether iron deficiency is present. Because of the potential harmful effects of iron therapy, it should not be given without the confirmation of a blood test.
 - Haemoglobin (Hb) <13g/dL in men over 15 years old.
 - Hb <12g/dL in nonpregnant women over 15 years old.
 - Hb <12g/dL in children aged 12-14 years.
Serum ferritin should be measured to confirm iron deficiency (except during pregnancy) as this correlates with total body iron stores. However, ferritin levels can be raised if infection or inflammation is present, even if iron stores are low. A cut-off ferritin level varies between 12-15mcg/L to confirm iron deficiency. If there is co-existing chronic inflammatory disease, then the patient should be referred to a specialist about using other measures of iron status.
Treatment and management
Treatment initially is by the use of iron supplements, but a firm diagnosis of iron deficiency anaemia should be established and iron supplements should not be taken ‘just in case’. With iron coming from the diet, the body is more able to control iron levels in the blood. However, with supplementation it is easier to overdose which can lead to gastrointestinal symptoms, especially constipation. Many minerals share the same carrier mechanism which actively transports the mineral from the GI tract to the blood. So if the body is ‘flooded’ with one mineral, it can prevent adequate other minerals being absorbed, eg. zinc absorption is reduced by high dose iron supplementation. Iron supplements can ‘feed’ some pathogens so giving to patients with HIV and children with diarrhoea should be cautioned.8
The Manual of Dietetic Practice8 suggests that taking over 17mg/day of iron can lead to constipation, nausea and abdominal pain.
Dietary sources of iron
It is also important to look at iron intake from the diet, as vulnerable individuals (those at risk of iron deficiency as outlined above) can easily slip back into deficiency unless they try and improve their iron intake. Some may need to remain on iron tablets but ensuring dietary intakes are adequate will mean less supplementation is necessary. Table 2 outlines very good and good sources of iron.
Factors affecting iron absorption
As well as physiological and various disease states affecting iron absorption, uptake of iron to the body can be inhibited or enhanced by substances and nutrients that may be eaten with iron (see Table 3).
Iron deficiency anaemia is common and needs to be treated usually with iron supplements. However, the dangers of excessive iron consumption and the realisation that iron supplements can have untoward effects are being realised more and more. For this reason emphasis should be placed on preventing its development, particularly in individuals known to be at risk. It is also worth considering the wider diet when advising on iron, such as whether many phytate containing foods are eaten or adequate vitamin C. Patients with chronic diseases such as those with chronic kidney disease, coeliac disease should have their iron status checked as their wellbeing can be improved just by correcting their iron status.  
2. Goddarda A, McIntyreb A, Scott B. Original article Guidelines for the management of iron deficiency anaemia for the British Society of Gastroenterology. Gut 2000;46:iv1-iv5 doi:10.1136/gut.46.suppl_4.iv1 
4. Department of Health. Report on Health and Social Subjects. Dietary Reference Values and Nutrients for the United Kingdom. Report of the Panel on dietary Reference Values of the Committee on medial Aspects of Food Policy. London: HMSO; 1991.
5. Cases-Amenós A, Martínez-Castelao A, Fort-Ros J, Bonal-Bastons J, Ruiz MP, Vallés-Prats M, Coll-Piera E, Galcerán-Gui JM; Investigadores del Estudio Micenas Prevalence of anaemia and its clinical management in patients with stages 3-5 chronic kidney disease not on dialysis in Catalonia: MICENAS I study. [Article in English, Spanish] I. Nefrologia. 2014;34(2):189-98. 
6. Smukalla S, Lebwohl B, Mears J, Leslie L, Green P. How often do hematologists consider celiac disease in iron-deficiency anaemia? Results of a national survey Clin Adv Hematol Oncol. 2014;12(2):100-5.
8. Gandy J. Manual of Dietetic Practice Fifth Edition. London: BDA/Wiley Blackwell; 2014. 
10. Hurrell R, Egli I. Iron bioavailability and dietary reference values. Am J Clin Nutr. 2010;91(5):1461S-1467S. doi: 10.3945/ajcn.2010.28674F. Epub 2010 Mar 3.

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