Having one functioning kidney insufficient to determine reduced renal reserve in boys with PUV

Boys with posterior urethral valves (PUV) may find it difficult to address decreased renal reserve with only one functioning kidney on a dimercaptosuccinic acid (DMSA) scan, suggests a study.

Researchers accessed the CIRCUP randomized controlled trial database, which included only patients with prenatally suspected, postnatally confirmed PUV. An early DMSA scan performed between 1 and 6 months of age was included in standardized follow-up.

Midterm eGFR (>5 years of age) was retrospectively confirmed between patients with or without findings of solitary functioning renal unit (<10 percent differential function of a renal unit). The update Schwartz formula was used to calculate the eGFR. Finally, the research team performed further comparisons between groups using the Mann-Whitney U test.

Of the 68 PUV patients identified, 20 had only one functioning kidney. No differences were observed in baseline characteristics between both groups or in the timing of DMSA scans or latest follow-up. The median follow-up was 7 years, and the median eGFR was 82.5 in the solitary functioning kidney group vs 94.5 in the group with two functioning kidneys.

Midterm eGFR did not significantly differ between the two groups, as did the proportion of boys with midterm eGFR <90 or <60 between groups. However, nadir creatinine was much greater in boys with a midterm eGFR <90 than those with a midterm eGFR >90 (p<0.01).

"In boys with PUV, having only one functioning kidney on a DMSA study is insufficient to determine decreased renal reserve,” the researchers said.