Erythrocyte deformability and microhematuria in children and adolescents.

The aim of this study was to investigate whether erythrocyte deformability is higher in otherwise healthy children and adolescents with asymptomatic isolated glomerular microhematuria and no clinical or laboratory signs indicating renal disorder. Erythrocyte deformability in 33 children and adolescents with unexplained asymptomatic isolated glomerular microhematuria (study group) was compared with erythrocyte deformability in 133 individuals without urinary tract disease and without microhematuria (control group), 26 patients with microhematuria and IgA nephropathy (IgA nephropathy group), and 31 children and adolescents with benign familial hematuria (benign familial hematuria group). The erythrocyte and buffer filtration time was measured, the erythrocyte-to-buffer filtration time ratio calculated, and, on the basis thereof, erythrocyte deformability was estimated as an inverse proportion of the erythrocyte-to-buffer filtration time ratio in all subjects. The erythrocyte-to-buffer filtration time ratio increased with age in all groups (P<0.001). In the study group, the mean erythrocyte-to-buffer filtration time ratio, corrected for age of subjects, was significantly lower than in the control (P=0.042), IgA nephropathy (P=0.004), and benign familial hematuria groups (P= 0.048). Erythrocytes with higher deformability probably pass more easily through the glomerular basement membrane that is assumed to be normal, in which case the mechanism of asymptomatic isolated glomerular microhematuria could be explained by higher erythrocyte deformability.