Neutrophil hypersegmentation in iron deficiency anaemia: a case-control study

Neutrophil hypersegmentation (NH) is an important haematological feature of cobalamin or folate deficiency. As iron deficiency and folate deficiency o ften occur in the same target groups it is important to establish whether i ron deficiency alone is a cause of NH. We report a case-control study which addresses this issue. Two groups of hospital patients were studied. Group 1 comprised 50 patients with iron deficiency anaemia (IDA). Group ii compri sed 50 control age- and sex-matched patients who were haematologically norm al without evidence of iron deficiency from the iron studies. Patients with other factors which could affect the degree of neutrophil segmentation (co balamin/folate deficiency, renal failure, infection and drug exposures) wer e excluded from the study, A total of 10 000 neutrophils were examined, 100 from each patient. NH was defined as the presence of five or more five-lob ed neutrophils per 100, or any neutrophils with six or more lobes. The resu lts were as follows: IDA, mean neutrophil lobe count 3.36: number of patien ts with NH 31/50 (62%): controls, mean neutrophil lobe count 2.96, number o f patients with NH 2/50 (4%). These differences were statistically signific ant. We conclude that NH is common in IDA. The mechanism whereby iron defic iency results in NH is not clear.