In what may lead to a shift in treatment, the largest prospective study of children with chronic kidney disease (CKD) has confirmed some experts’ suspicions that complications occur early. The findings suggest the need for earlier, more aggressive management of blood pressure, anemia and other problems associated with kidney disease, according to Dr. Marva Moxey-Mims, a pediatric kidney specialist at the NIH.
Results of the Chronic Kidney Disease in Children (CKiD) Study are in the September issue of the Clinical Journal of the American Society of Nephrology.
Growth failure, metabolic abnormalities and cardiovascular disease risk factors such as high blood pressure occur even at a glomerular filtration rate (GFR) of 50 milliliters per minute in children with CKD. GFR is a measure of kidney function, and a GFR of 50 is approximately half of normal function. Despite therapy, these complications increased in prevalence two- to four-fold with decreasing GFR, concluded the study, funded primarily by the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) at the National Institutes of Health.
Dr. Moxey-Mims noted that many experts previously thought that complications of kidney disease, such as anemia, acidosis and elevated potassium and phosphate, did not usually happen until kidney function was much worse than a GFR of 50.
“Metabolic abnormalities and cardiovascular disease risk factors have rarely been systematically assessed in children with CKD,” said Dr. Susan Furth, a researcher at The Children’s Hospital of Philadelphia and lead study author. “We sought to identify the point along the GFR spectrum at which various common consequences of CKD become more prevalent.” Metabolic abnormalities include high phosphorus and potassium levels, acidosis (too much acid in the blood), anemia and high cholesterol.
“Considering that a lot of kids may not be diagnosed with kidney disease until they are at that lower level of kidney function, this is important. Even above a GFR of 50, some of the abnormalities are already there,” Dr. Moxey-Mims said. “Indeed, they get worse as kidney function drops, but the study shows that issues start to develop sooner than many thought.”
Moxey-Mims added that the findings support what some in the pediatric nephrology community have known anecdotally. “It’s showing us little snippets of things that are putting kids at risk among those who we previously thought were not at risk for the morbidities of chronic kidney disease,” she said. “Now we know that maybe those who are down to a GFR of 50 are the kids to start watching more closely. That’s the main lesson from these findings.”
CKiD is a multi-center, prospective study of children and teenagers ages 1 to 16 years with mild to moderate impairment of kidney function, defined as an estimated GFR between 90 and 30. Forty-eight sites in the United States and two in Canada are following 586 children. There are two clinical coordinating centers, at Children’s Mercy Hospital at the University of Missouri-Kansas City School of Medicine, and The Children’s Hospital of Philadelphia at the University of Pennsylvania. The central laboratory is at the University of Rochester, N.Y., and the data coordinating center is at the Johns Hopkins Bloomberg School of Public Health, Baltimore. The ongoing CKiD study aims to determine risk factors for declining kidney function and to understand how the decline affects cognitive function, behavior, growth failure and the risk for cardiovascular disease.
For more information on the CKiD Study (NCT00327860) visit www.clinicaltrials.gov. Learn more about kidney disease at http://nkdep.nih.gov. General information about children and clinical studies can be found at: http://www.nhlbi.nih.gov/childrenandclinicalstudies.
Additional support was provided by the National Institute of Neurological Disorders and Stroke, the Eunice Kennedy Shriver National Institute of Child Health and Human Development and the National Heart, Lung, and Blood Institute, all at the NIH.
The NIDDK, a component of the NIH, conducts and supports research on diabetes and other endocrine and metabolic diseases; digestive diseases, nutrition and obesity; and kidney, urologic and hematologic diseases. Spanning the full spectrum of medicine and afflicting people of all ages and ethnic groups, these diseases encompass some of the most common, severe and disabling conditions affecting Americans. For more information about the NIDDK and its programs, see www.niddk.nih.gov.
About the National Institutes of Health (NIH): NIH, the nation’s medical research agency, includes 27 Institutes and Centers and is a component of the U.S. Department of Health and Human Services. NIH is the primary federal agency conducting and supporting basic, clinical, and translational medical research, and is investigating the causes, treatments, and cures for both common and rare diseases. For more information about NIH and its programs, visit www.nih.gov.