Renal Cysts in Potential Kidney Donors—Are They a Problem?

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Renal cysts are a common finding in potential kidney donors and are associated with markers of early kidney injury, according to a study in the American Journal of Kidney Diseases.

The researchers gathered data on renal cystic and solid lesions detected on contrast-enhanced computed tomography scans performed during evaluation of potential kidney donors. The analysis included 1948 potential donors evaluated from 2000 to 2008 (excluding those with cystic disease—mainly autosomal dominant polycystic kidney disease).

Analysis of cysts measuring 5 mm or larger showed cortical cysts in 12 percent of patients, medullary cysts in 14 percent, and parapelvic cysts in 2.8 percent. Older patients were more likely to have cysts, to have a greater number of cysts, and to have larger cysts. Cortical or medullary cysts 2 mm or larger were present in 39 percent of patients under 50 years versus 63 percent of those aged 50 to 75 years of age. The rates were 22 percent versus 43 percent for cysts 5 mm or larger, 7.9 percent versus 43 percent for cysts 10 mm or larger, and 1.6 percent versus 7.8 percent for cysts 20 mm or larger.

Men also had an increased presence and number of cysts. After adjustment for age and sex, the presence of cortical or medullary cysts 5 mm or larger was associated with increased urinary albumin excretion. In some analyses, cysts were also associated with increased body surface area, high blood pressure, and higher GFR.

Angiomyolipomas were found in 2.2 percent of potential donors, hyperdense cysts in 1.2 percent, and enhancing masses or cysts of concern for malignancy in 0.6 percent. All of these findings were more common in older patients.

A few renal cysts in a healthy adult are generally not regarded as problematic. This study of potential kidney donors undergoing contrast-enhanced computed tomography showed substantial rates of renal cysts, particularly in older men.

Associations with albuminuria, hypertension, and hyperfiltration suggest that these cysts might be a marker of early kidney injury. Inasmuch as potential kidney donors are selected for apparent health, “the associations revealed by this study may be even stronger in the general population,” the researchers write. [Rule AD, et al. Characteristics of renal cystic and solid lesions based on contrast-enhanced computed tomography of potential kidney donors. Am J Kidney Dis 2012; 59:611–618.]