Validity of G1-cells in the differentiation between glomerular and non-glomerular haematuria in children

Urine samples from 100 children and adolescents with micro- or macrohaematuria were investigated using phase contrast microscopy to establish the percentage of G1-cells that could differentiate glomerular from non-glomerular haematuria. The G1-cell is a special form of dysmorphic erythrocyte which seems to be specific for glomerular haematuria. Glomerular haematuria, defined by clinical criteria from biopsy, physical examination, standard laboratory evaluation and family history, was observed in 51 patients (group 1). Non-glomerular haematuria was found in 49 patients (group 2). The latter group had urinary tract infections, urolithiasis, hypercalciuria or haematuria caused by urological operation or diagnostic procedure. The percentage of dysmorphic erythrocytes differed significantly between the two groups studied (42 +/- 3% in group 1 vs. 6 +/- 1% in group 2, mean +/- SEM, P < 0.01); there was also a significant difference in G1-cells (19.4 +/- 1.7% in group 1 vs. 0.6 +/- 0.2% in group 2, mean +/- SEM, P < 0.01). When glomerular haematuria was defined on the basis of > or = 30% dysmorphic erythrocytes by phase contrast microscopy, sensitivity, specificity and efficiency were 71%, 100% and 85%, respectively. When glomerular haematuria was defined on the basis of > or = 5% G1-cells, sensitivity, specificity and efficiency were 100%, 100% and 100%, respectively. The differentiation of glomerular and non-glomerular haematuria in children by determination of G1-cells appears to be more sensitive and efficient than the determination of the percentage of dysmorphic erythrocytes by phase contrast microscopy.