Methylmalonic acid and neutrophil morphometric index in laboratory diagnosis of cobalamin deficiency without macrocytosis

Summary Introduction This study aimed to investigate the utility of methylmalonic acid(MMA) and neutrophil Cell Population Data, available on the Beckman Coulter LH750 Analyser ( Miami, FL, USA), in laboratory assessment of cobalaminstatus in patients at risk of cobalamindeficiency, without macrocytosisand inflammation. Methods The study group included 189 patients. Neutrophil Cell Population Dataalong with vitamin B12 and homocysteinewere assessed in regard to MMA tertile groups. Results Statistically significant differences were between lower and upper MMA tertile in serum B12 (P ˂ 0.001), homocysteine(P = 0.001) and neutrophil morphometricindex, NeS-DW (P = 0.029). Also, serum B12 concentrations were significantly different between lower and middle MMA tertile, P = 0.005. Receiver operating characteristic analysis of NeS-DW ability to detect MMA˃367 nmol/L revealed a significant area under the curve AUC = 0.761 P ˂ 0.001 95% CI 0.693–0.830. Optimal cut-off value was NeS-DW˃3.51% with sensitivity of 74.19% and specificity of 68.87%. Conclusion In patients at risk of cobalamindeficiency and normal MCV, classification according to MMA revealed cobalaminstatus differences. Neutrophil morphometricindex may be an indicator of early changes in neutrophil nucleus morphology caused by impaired cobalaminstatus.