Multicystic Dysplastic Kidney: Better Understanding of Natural History and Complications, and Improving Follow-Up

In the past, patients with multicystic dysplastic kidney (MCDK) underwent nephrectomy due to an expectation of increased incidence of urinary tract infection (UTI), kidney scarring, hypertension (HTN), and Wilms tumor. Later observation did not show these associations, and did show a tendency for involution of the MCDK. More recent studies of single functioning kidney (SFK) including MCDK, showed that there was higher incidence of HTN and kidney injury. The objectives of this study were to describe the natural history of MCDK, and assess the incidence of associated conditions (eGFR, HTN, UTI).

In a retrospective study, data were collected from files of patients with sonographic diagnosis of MCDK at the Institute of Pediatric Nephrology in Schneider Children`s Medical Center. Of 59 patients 55 (93%) were diagnosed prenatally; for 50 (85%), MCDK was a solitary finding. Complete involution was found in 62.5%, another 29.5% showed involution process. 12% underwent nephrectomy, 60.5% had compensatory hypertrophy of contralateral kidney, 42% hyperfiltration, and 12.5% kidney injury. Blood pressure measurements were high in 18%, but none were consistent with the definitions of pre-HTN or HTN. Episodes of UTI were noted for 22% of the patients; with 15% episodes of pyelonephritis, mostly under age 1 year.

Considering the above, nephrectomy is not warranted. We recommend initial evaluation with US and DMSA scan, and annual clinical follow-up with US and laboratory examination. The relation between MCDK and UTI should be further investigated; currently, a high index of suspicion is needed, especially under age 1 year.