A full clinical history and physical examination should be undertaken.
- inquire about
- use of aspirin and other NSAID's
- family history of IDA - may indicate inherited disorders of iron absorption
- haematological disorders e.g. - thalassaemia
- telangiectasia and bleeding disorders
- family history of colorectal carcinoma (1,2)
- consider if patient meets either
- criteria for urgent cancer referral or
- use of faecal immunochemical test (FIT) in symptomatic patients outside urgent cancer referral guidance
- see linked items
In patients with no obvious cause for iron deficiency anaemia (IDA), the following investigations could be carried out (2):
- coeliac serology (presence of anti-endomysial antibody or tissue transglutaminase antibody) - The British Society of Gastroenterology suggests that all patients with IDA should be screened for coeliac disease
- upper and lower GI investigations - in all postmenopausal female and all male patients in whom iron deficiency has been confirmed (except when there is a history of significant overt non GI blood loss)
- urine testing for blood - since around 1% of patients with IDA will have renal tract malignancy
- stool examination - if appropriate to detect parasites
- testing for Helicobacter pylori - H. pylori colonisation may impair iron uptake and increase iron loss
- faecal immunochemical test (FIT):
- FIT in symptomatic patients outside urgenct cancer referral guidance (2 week wait criteria) (3)
- NICE criteria for requesting test for occult blood in faeces (FIT)
- should be offered to adults without rectal bleeding who:
- are aged 50 or over with unexplained:
- abdominal pain or weight loss or
- are aged under 60 with:
- changes in their bowel habit or iron-deficiency anaemia or
- are aged 60 or over and have anaemia without iron deficiency
- the the level of Hb used for an abnormal versus a normal result my vary with respect to implementation of this pathway
- a level of greater than or equal to 10 µg Hb/g faeces for defining an "abnormal result" has been suggested by NICE
- an "abnormal test" meets the criteria for urgent cancer referral (3)
Investigations in IDA include the following:
- full blood count and blood film examination
- recognise the indices of iron deficiency
- reduced haemoglobin - Men <13.5 g/dl, women < 11.5 g/dl
- reduced MCV - <76 fl (76–95 fl )
- reduced MCH - 29.5 ± 2.5 pg (27.0–32.0 pg)
- reduced MCHC - 32.5 ± 2.5 g/dl (32.0–36.0 g/dl) (1)
- blood film
- microcytic, hypochromic cells
- occasional target cells and pencil-shaped poikilocytes
- platelet count may be at or above the upper limit of normal if there is persistent bleeding
- haematinic assays:
- decreased serum ferritin - best biochemical marker (in the absence of inflammation)
- the cut off concentration that is diagnostic varies between 12 and 15 mg/l.
- but in the presence of an inflammatory disease a concentration of 50 mg/l or even more may still be consistent with iron deficiency
- vitamin B12, folate
- increased serum transferrin receptor (sTfR) assay - is a good indicator of iron deficiency in instances where ferritin estimation is likely to be misleading but its value in the clinical setting remains to be proven (1).
- serum iron and total iron binding capacity (TIBC)
The best proof of iron deficiency anaemia is that the anaemia is cured by administration of iron.
Reference: