A systematic review and meta-analysis of routine white blood cell concentrations in people with eating disorders.

INTRODUCTION

Secondary consequences of eating disorders on physical health include alterations in immune parameters, such as white blood cells (WBCs), because of altered eating patterns and compensatory behaviours.

METHODS

This systematic review and meta-analysis examined articles from three databases, reporting concentrations of WBCs or WBC subtypes (e.g., lymphocytes, eosinophils, basophils, monocytes, neutrophils) in people with eating disorders. Random-effects meta-analyses were conducted cross-sectionally for WBCs and available subtypes for anorexia nervosa (AN) versus HC, bulimia nervosa (BN) versus HC, and longitudinally for AN at different stages of weight restoration.

RESULTS

38 studies were included: of these, 27 reported cross-sectional data in AN, eight reported cross-sectional data in BN, and seven reported longitudinal data in AN. Cross-sectionally, concentrations of WBCs, lymphocytes, basophils, monocytes and neutrophils were lower in AN compared with HCs, although eosinophils were unaltered. Meta-regressions showed no association between the age and BMI of the AN group and cross-sectional differences in WBC and lymphocyte concentrations. In BN, concentrations of WBCs and most subtypes were unaltered compared to HC, although basophils were decreased. Longitudinally, concentrations of WBCs were unchanged after short or medium-term weight gain but significantly increased when the BMI approached 18.5 kg/m2 (longer-term weight restoration). Concentrations of lymphocytes were unaltered at all time-points.

DISCUSSION: It is likely that the reduction in WBCs and WBC subtypes seen in AN is a consequence of undernutrition, and that sufficient weight restoration is necessary for normalisation. Concentrations of WBCs are largely unaltered in individuals with BN.