Last Updated: 2010-01-14 17:00:07 -0400 (Reuters Health)
NEW YORK (Reuters Health) - Roughly 25% of healthy adults have "silent" abnormalities of the kidney and renal artery, according to a study of potential kidney donors.
However, the majority of these incidentalomas don't preclude kidney donation or require intervention other than monitoring, authors from the Mayo Clinic, Rochester, Minnesota, report in the Clinical Journal of the American Society of Nephrology.
"We reviewed the CT scans of almost 2000 adults" during evaluation for potential kidney donation between 2000 and 2008, Dr. Andrew D. Rule told Reuters Health.
"It was surprising to find out how common abnormalities in the kidneys and renal arteries were," he added.
Subjects had been prescreened to exclude those with comorbidities that would preclude kidney donation. The remaining 1957 potential donors - 58% female, with a mean age of 43 years -- had computed tomography (CT) and urography studies.
The most common vascular finding, present in 43%, was an accessory renal artery. The researchers also saw fibromuscular dysplasia in 2.7%, atherosclerosis or narrowing or other stenosis in 5.3%, and dilations or aneurysms in 0.6%.
Eleven percent had kidney stones. Rates of tubular ectasia (medullary sponge kidney), focal scarring, indeterminate masses, parenchymal calcifications, and upper urinary tract dilation ranged from 1% to 4%. Fewer than 1% had diffuse thinning or kidney atrophy, polycystic kidney disease, chronic inflammatory changes, malrotation, congenital lobulation, solitary or horseshoe or pelvic kidney, or perinephric edema.
"Narrowing of renal arteries due to atherosclerosis or fibromuscular dysplasia, scars in the kidney, and indeterminate masses -- several of which were confirmed to be early cancers -- were more common in older adults," Dr. Rule said. "Scarring or thinning of the kidney and dilatation of the urinary collecting system was more common in women than in men."
Overall, 75% had no radiographic abnormalities other than accessory renal arteries or congenital lobulation.
Only 0.5% had findings that were absolute contraindications to donation (polycystic kidney disease, solitary or horseshoe kidney, and pelvic kidney).
Ultimately, 6.7% were excluded as donors based on their scan results. The main intervention was prescription of new or additional medications for hypertension. Fourteen patients had masses. Of the four who had resection at the authors' institution, 3 had renal cell cancers and one had papillary adenoma. The other 10 were advised to undergo surgical resection or follow-up imaging at other institutions.
"Much of the management of kidney and renal artery abnormalities that are discovered on CT scans is based on professional opinion instead of evidence based medicine," Dr. Rule remarked.
"It would be helpful to know the long-term kidney health, general health, and survival of persons with and without these abnormalities on a CT scan," he continued. "This would clarify what abnormalities should or should not be considered a barrier to kidney donation. There also may be other patient groups where the benefits would outweigh the risks for a contrast CT scan of the renal arteries and kidneys to identify treatable disease."
Concluding, Dr. Rule said, "These findings highlight an interesting challenge implicit with improvements in imaging technology. Physicians are now finding more subtle abnormalities in the kidneys and renal arteries, but lack clear evidence as to whether these findings are benign or harmful to the long-term health of patients."
Clin J Am Soc Nephrol 2010.
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