Getting a clearer picture of how to slow or stop kidney disease in children
Two-year-old Marley Martinac has a serious chronic kidney disease, but she’s going to have a better shot at a healthy life than kids born just a decade earlier.
KANSAS CITY — Two-year-old Marley Martinac has a serious chronic kidney disease, but she's going to have a better shot at a healthy life than kids born just a decade earlier.
Thanks largely to an ongoing national study with leadership at Children's Mercy Hospital in Kansas City, doctors now have a clearer picture of the best ways to stop or slow the progression of kidney disease in children like Marley.
The goal is to keep the children growing and thriving for as long as possible, preventing, or at least postponing, the need for kidney dialysis or a transplant.
"Thank God, we're not at that point at all," said Marley's mother, Katie Martinacof Bates City, Mo. "She's pretty spunky. She hasn't lost that."
About 16 percent of the U.S. population has chronic kidney disease, a gradual loss of kidney function caused by high blood pressure, diabetes and a variety of other conditions. How many children have these conditions isn't known, but 2,500 children nationwide are on dialysis and more than 5,000 have received kidney transplants.
"We're aiming to head things off in childhood," said Children's Mercy kidney specialist Bradley Warady, "to prevent children from requiring dialysis or a kidney transplant, or maybe delay it to give children more chance to grow and for their minds to develop."
Warady, along with researchers at Children's Hospital of Philadelphia, is coordinating the Chronic Kidney Disease in Children (CKiD) Cohort, a study that since 2003 has been following close to 900 children with mild to moderate kidney disease recruited from medical centers across the United States and Canada. Their research, funded by the National Institutes of Health, is now the largest long-term study in North America of any chronic childhood disease.
Research by the CKiD group, published recently in the American Journal of Kidney Diseases, shows that the severity of three common conditions in children with kidney disease — high blood pressure, anemia and protein loss through urine — predict how quickly their disease will worsen. For example, when urine has high protein levels, kidneys deteriorate twice as fast.
Because these conditions are all treatable, Warady said, the study offers doctors guidance for improving their patients' care.
"We want to detect it when it's mild and easier to intervene," he said. "We have the tools to treat these things. But the treatment hasn't been done yet in a consistent way. This emphasizes the importance of these factors. It raises awareness of how significant they are."
Doctors have not had much data on childhood kidney disease, said Joseph Vassalotti, chief medical officer of the National Kidney Foundation. This research "really advances our understanding of the natural history of chronic kidney disease in children."
These diseases include birth defects, such as abnormally developed kidneys that don't work well or blockages in the kidney's plumbing; genetic conditions such as polycystic kidney disease, in which fluid-filled cysts destroy kidney tissue; and a variety of diseases that attack the hundreds of thousands of tiny clusters of blood vessels that filter the blood.
"There's a lot to childhood kidney disease," Warady said. "It's a lot more complicated than 'I just don't pee.'"
Marley has a condition called nephrotic syndrome that causes her kidney damage. Doctors at Children's Mercy aren't sure what is responsible, but they've been able to keep the condition under control.
Marley's mother remembers that it was Christmas Eve of 2013 when her daughter's eyes began to redden and swell. As Marley was taken from pediatrician to pediatrician who said she had allergies, her condition worsened. "Her body was so swollen, and her skin was splotchy and white," Martinac said.
At the Children's Mercy emergency room in April, doctors discovered that protein was spilling into her urine. Healthy kidneys don't let much protein pass through their filters. But when those filters are damaged, protein can leak through. And the protein release itself can lead to more kidney damage.
Marley finally was diagnosed with kidney problems that she and her family will have to deal with for a lifetime.
"It was very shocking," Martinac said. "We never thought we'd have to deal with something like that. No one ever does."
Marley spent four nights at Children's Mercy. Fluid from her abdomen was drained, and she was placed on steroids to control her kidney condition. "It didn't take long for the steroids to get going and working for her," Martinac said.
Marley still takes the steroid prednisone. In October, she started taking a chemotherapy drug that has made it possible to lower her steroid dose and may wean her off prednisone entirely.
Martinac uses test strips twice a week to check for protein in Marley's urine. Marley gets regular blood pressure checks. And she's on a low-sodium diet to keep her blood pressure down.
"It's not just one easy fix," Martinac said.
Care for children like Marley has already made great strides, Warady said. A sign of the improvement so far is that in 1980, doctors considered it ethically questionable to even treat infants with advanced kidney disease because they had so little hope for survival.
"Even the most seriously ill child now has a chance at a good outcome," Warady said. "That is an absolute change over 30 years."
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