It correlates with glomerular filtration rate in children with mild to moderate CKD, study reveals.
As with adults, proteinuria reflects CKD severity in children, according to researchers. Their study of 213 children with mild to moderate CKD revealed that proteinuria correlates with glomerular filtration rate (GFR), regardless of CKD cause or other factors.
Each log increase in the urine protein to creatinine ratio (Up/c) was associated with a 9% decrease in GFR. The children were participants in the ongoing Chronic Kidney Disease in Children (CKiD) prospective cohort study.
“This is one of the first studies to look at the association between kidney function and proteinuria in children with mild to moderate kidney disease,” said co-investigator Susan Furth, MD, PhD, associate professor of pediatrics and epidemiology at Johns Hopkins Medical Institutions in Baltimore. “These results are quite encouraging because [proteinuria testing] is fast, cheap, and simple and is a really handy tool to help us track disease progression in children with kidney disease.”
Strongly associated with CKD, proteinuria is an indicator of underlying glomerular disease and tubular dysfunction. In addition, it is a well-known risk factor for accelerated CKD progression. The relationship between the magnitude of proteinuria and GFR, however, has not been well described in children with mild to moderate CKD.
The study population included 45 children with glomerular disease and 168 with non-glomerular disease. Compared with children with a Up/c less than 0.2, those with a Up/c of 0.2-2 had a 13% lower GFR and those with a Up/c greater than 2 had a 28% lower GFR.
In addition, the children with glomerular disease were 3.3 times more likely to have nephrotic-range proteinuria than children with non-glomerular disease. In addition, the level of proteinuria was higher in patients not on ACE inhibitors or angiotensin receptor blockers (ARBs).
The mean age of the patients was 10.6 years, and 58.7% (125 patients) were boys. A total of 144 patients (67.6%) were Caucasian and 38 (17.8%) were African American.
Children have different kinds of kidney disease than adults, Dr. Furth said. “In adults, the problems are predominantly hypertension and diabetes. In the majority of our kids, the problem is underlying urologic disease; in other words, they are born with abnormal kidneys. The current guidelines suggest measuring proteinuria in children and looking at microalbuminuria only in kids with diabetes. As we move forward with this study, we should be able to have finer markers of proteinuria in children to really quantify the risk of kidney disease decline in kids.”