The patient
A 70 year old retired barber presented to his general practitioner with breathlessness on walking. A history of gradual onset of fatigue, lethargy, and exertional dyspnoea was elicited.
The patient was a non-smoker who had previously been well, took no medications or supplements, and shared a bottle of wine with his wife at weekends. He was not a vegetarian and took a good mixed diet.
Physical examination showed pallor of the conjunctiva and nail beds and mild oedema of the ankles. There was no hepatosplenomegaly nor were there any signs of iron deficiency (such as glossitis, angular cheilosis, or koilonychia). Anaemia was suspected.
An initial full blood count confirmed this suspicion:
Hb concentration was 76 g/l (normal range 133-167 g/l),
MCV was 110 fl (82-98 fl),
white cell count was 4.7x109/l (3.7-9.5x109/l),
neutrophil count was 1.4x109/l (1.7-6.1x109/l), and
platelet count was 182x109/l (145-350x109/l).
Serum creatinine was 98 µmol/l (60-125 µmol/l) and
serum ferritin was 875 ng/ml (20-200 ng/ml).
What is the next investigation?
The clinical history has already excluded relevant drugs and excessive alcohol intake. The following investigations should be performed:
- A repeat full blood count to confirm the initial count and to establish if the abnormalities are stable or progressive.
- A peripheral blood film.Many laboratories will automatically review a blood film when the blood count is as abnormal as in this patient, but it cannot be assumed that the blood film will have been reviewed.
- Vitamin B-12 and folic acid assays.
- Reticulocyte count—will be raised in haemolysis or bleeding.
- Liver and thyroid biochemistry.
RDW within the normal range indicates uniform red cell size and an elevated RDW indicates dimorphic red cells, as were present in the present case. RDW, although, doesn�t replace the examination of peripheral smear, but often provides important information when combined with mean corpuscular volume (MCV) and gives an important clue and guide further assessment of anaemia. To put it simply, RDW is a �lazy person�s peripheral smear� or in community hospitals where a hematologist or technologist is not available to review of the peripheral film, assessment of RDW along with MCV is important in evaluating suspected anaemia.
ReplyDeleteRBC folate provides information about tissue levels, and takes longer to normalize and not affected by few meals with adequate folic acid content. However, it is important to recognize that B12 deficiency interferes with incorporation of folate into RBCs and B12 deficiency without folate deficiency can result in low RBC folate levels.
RACTICE:
ReplyDeleteJames Uprichard and Barbara J Bain
Investigating suspected anaemia
BMJ 2009; 338: b1644
*Rapid Responses:
RDW and else
Malvinder S. Parmar (29 May 2009)