New BSG guidelines on IDA contain useful reminders of the principles of management for GPs, says Dr Matthew Lockyer
Iron deficiency anaemia (IDA) is commonly discovered and investigated in general practice, but I do not suppose many GPs turn to guidelines on management very often.
The new guidelines for the management of IDA from the British Society of Gastroenterology (BSG)1 outline the principles of investigation, which is a useful exercise for doctors seeing patients with IDA. I find it is sometimes beneficial to revisit the principles of management of common presentations to make sure that new evidence or meta-analyses have not rewritten the accepted wisdom.
The main message of the guidelines is that IDA is a symptom and not a diagnosis. A haemoglobin level below the normal range for your local laboratory, together with a low serum ferritin, are the best diagnostic tests. A microcytic/hypochromic picture is also common.
It is important to bear in mind the uncommon causes of a microcytic/hypochromic anaemia, especially haemoglobinopathies.
I recently had a reminder of another rare cause when the anaemic child of a couple doing up an old property was found to have lead poisoning from the ancient paint.
In men and postmenopausal women the most common cause of IDA is bleeding from the gastrointestinal tract. Unless there is obvious bleeding from another source (check urine microscopy), or an easily correctable factor such as NSAID use, visualisation of the upper and lower bowel is indicated. Malignancy of the gastrointestinal tract is always a possible cause of blood loss.
The guidelines suggest upper gastrointestinal endoscopy followed by colonoscopy as the 'gold standard' investigation.
Barium enema is considered a reasonable alternative for investigating the lower bowel. This is helpful to know, as the availability of services varies greatly across the country. Not all district general hospitals have a one-stop investigation service for anaemia.
The guidelines recommend biopsies of small bowel at gastroscopy because 2–3% of patients with IDA will have coeliac disease. Many GPs are now much more alive to this possibility and are testing iron-deficient patients for IgA and endomysial antibodies before referral. I am now testing for this in persistent IDA at all ages, especially in those with irritable bowel syndrome, as a working diagnosis. Faecal occult blood is not considered to be a particularly helpful test, as it is not sufficiently sensitive.
The treatment recommended for the majority of cases is to correct any treatable underlying cause and to give oral iron as the preferred first-line replacement treatment. Although treatment of underlying causes is definitive, response to iron treatment where no underlying diagnosis is found is often excellent.
Although the guidelines emphasise that taking a dietary history is helpful in diagnosis, diet is not mentioned in treatment. Many patients dislike taking iron because of side-effects, and can supplement their treatment with increased consumption of green vegetables and liver.
The management of IDA is discussed in some depth, but I felt that there were few revelations as the analysis of available evidence largely supports the status quo.
- See also 'BSG guidelines aim to raise awareness of iron deficiency anaemia' in this issue.
- Goddard AF, McIntyre AS, Scott BB, for the British Society of Gastroenterology. Guidelines for the management of IDA. Gut 2000; 46: iv1-iv5