Investigations

Combining the MCV and RDW results can help define potential causes of the anaemia . ^b  

Note:

MCV and RDW in defining potential causes of anaemia

MCV	RDW	Potential causes b
Low	Normal	Chronic disease
-	-	Heterogenous thalassaemia
Low	High	Iron deficiency
-	-	RBC fragmentation (artificial valve)
-	-	HbH
-	-	S beta-thalassaemia
Normal	Normal	Any chronic disease (including chronic liver disease)
-	-	Haemorrhage
-	-	Haemolysis
-	-	Transfusion
-	-	Hb AS, Hb AC
-	-	Chronic lymphocytic leukaemia with <150 x 10 3 WBC
-	-	Hereditary spherocytosis
Normal	High	Early iron or folate (or both) deficiency
-	-	Hb SS, Hb SC
-	-	Myelofibrosis
-	-	Sideroblastic anaemia
High	Normal	Aplastic anaemia
-	-	Preleukaemia
High	High	Folate or B 12 deficiency
-	-	Immune haemolytic anaemia
-	-	Cold agglutins with >150 x 10 3 WBC