The early progression of chronic kidney disease in children and teens is poorly understood, but a national research team led by Johns Hopkins scientists is launching the largest-ever study to learn more about this often-stealthy killer.
"There has never, to our knowledge, been a study designed to systematically assess the changes in kidney function over time in children with early kidney disease and to determine how these changes affect behavior, learning, heart disease risk and growth," says Susan Furth, M.D., Ph.D., a nephrologist at the Johns Hopkins Children's Center, one of the project's three principal investigators and lead author of a report on the study, appearing in the Clinical Journal of the American Society of Nephrology.
This NIH-funded, 57-center study hopes to follow over a period of four years 540 children ages 1 through 16 with mild to moderate kidney disease. The Johns Hopkins Children's Center is one of two clinical coordinating sites, along with the Children's Hospital at the University of Missouri-Kansas City. The Johns Hopkins Bloomberg School of Public Health is the study's data coordinating center.
Researchers will collect blood, urine, fingernail and hair samples and will monitor kidney function, height, weight, blood pressure and heart disease by the use of echocardiograms. Periodic surveys are planned to track everything from quality of life and social and cognitive development to sexual maturation during puberty, which is often delayed in teens with kidney disease. Patients will fill out questionnaires detailing everything from symptoms, to use of medications and dietary supplements, to lifestyle and exercise. Researchers will harvest cell lines to study the genetic elements of kidney disease.
Results will be reported incrementally, but some preliminary findings are already in. For example, using data from the pilot study, researchers have refined an existing method - used mostly in Europe - that measures glomerular filtration rate (GFR). GFR, which measures the kidneys' filtering capacity, is the most precise indicator of kidney function and status.
The new, improved method, which measures how fast the kidneys clear an injected contrast agent from the blood, promises to become the new gold standard for kidney function estimates in clinical trials and will also help researchers refine existing GFR-estimate formulas that doctors use for children. The current methods for estimating GFR yield faulty results in children 25 percent of the time.
Kidney disease in children tends to start and evolve silently. More than one-third (37 percent) of kidney transplant patients in 2001 were between the ages of 20 and 44, and the majority of them likely developed the disease in childhood, researchers say. Researchers estimate that 650,000 Americans will develop end-stage renal disease by 2010, costing the health care system $28 billion a year.