Decreasing the variability observed in urine analysis

Urine analysis is affected significantly by biological variability. The obj ective of this study was to study the feasibility of reducing the biologica l variability of excretion of various analytes in urine, especially albumin in children with diabetes, by mixing small volumes of early morning sample s. Twenty-two male children with type 1 diabetes collected early morning al iquots of approximately 10 ml of urine on 3 consecutive days and kept them refrigerated in sealed containers. The urine collection was repeated every 4-6 months in the diabetic children. Ten normal children and 10 normal adul ts participated as controls. The specimens were analyzed individually and a s mixed samples for each subject. Mixing the 3 urine samples before analysi s decreased the biological variability of all urine assays (albumin, glucos e, creatinine, total protein, potassium). The diabetic children had 3 times higher variability of urine albumin (as a ratio to creatinine) compared to normal children, when the urine samples were collected individually (61% v s 19%, respectively). The variability in the diabetic children decreased wh en the 3 specimens were analyzed as a single sample after mixing, especiall y when urine albumin was expressed as a ratio to creatinine. Blood glycated hemoglobin levels correlated better with urine glucose levels when 3 urine samples were mixed before analysis.