Utilizing Estimated Creatinine Excretion to Improve the Performance of Spot Urine Samples for the Determination of Proteinuria in Kidney Transplant Recipients

作者:Wang Michael Ke; White Christine; Akbari Ayub*; Brown Pierre; Hussain Naser; Hiremath Swapnil; Knoll Greg
来源:PLos One, 2016, 11(12): e0166547.
DOI:10.1371/journal.pone.0166547

摘要

Background Agreement between spot and 24-hour urine protein measurements is poor in kidney transplant recipients. We investigated whether using formulae to estimate creatinine excretion rate (eCER), rather than assuming a standard creatinine excretion rate, would improve the estimation of proteinuria from spot urine samples in kidney transplant recipients. Methods We measured 24 hour urine protein and albumin and spot albumin: creatinine (ACR) and spot protein: creatinine (PCR) in 181 Kidney transplant recipients. "We utilized 6 different published formulae (Fotheringham, CKD-EPI, Cockcroft-Gault, Walser, Goldwasser and Rule) to estimate eCER and from it calculated estimated albumin and protein excretion rate (eAER and ePER). Bias, precision and accuracy (within 15%, 30% and 50%) of ACR, PCR, eAER, ePER were compared to 24-hour urine protein and albumin. Results ACR and PCR significantly underestimated 24-hour albumin and protein excretion (ACR Bias (IQR), -5.9 mg/day; p < 0.01; PCR Bias, (IQR), -35.2 mg/day; p < 0.01). None of the formulae used to calculate eAER or ePER had a bias that was significantly different from the 24-hour collection (eAER and ePER bias: Fotheringham -0.3 and 7.2, CKD-EPI 0.3 and 13.5, Cockcroft-Gault -3.2 and -13.9, Walser -1.7 and 3.1, Goldwasser -1.3 and -0.5, Rule -0.6 and 4.2 mg/day respectively. The accuracy for ACR and PCR were lower (within 30% being 38% and 43% respectively) than the corresponding values estimated by utilizing eCER (for eAER 46% to 49% and ePER 46-54%). Conclusion Utilizing estimated creatinine excretion to calculate eAER and ePER improves the estimation of 24-hour albuminuria/proteinuria with spot urine samples in kidney transplant recipients.