Multicystic Dysplastic Kidney: clinical course and prognosis of the contralateral kidney

Introduction: The multicystic dysplastic kidney (MDK) is a frequent malformation discovered in obstetrical ultrasound. In Colombia, there are no publications on clinical characteristics and follow up studies suggesting initial evaluation and follow up in these children. Objectives: To describe the clinical characteristics of 40 patients with unilateral MDK, with emphasis in the evaluation of the contra-lateral kidney (CK) regarding function, size, and associated urological malformations. Methodology: A review of cases of patients under 18 years of age with prenatal or postnatal diagnosis of unilateral MDK that attended the Pediatric Nephrology outpatient clinic at Hospital Infantil Club Noel in the city of Cali from July 1997 to December 2007. Results: A total of 40 patients were found. In 88% of these, diagnosis of unilateral MDK was done prenatally; of these, 55% were males with a mean age of 2 months of age (range 1 to 42 months). Evaluation of contra-lateral kidney showed: hydronephrosis (HN) in 2 cases (5%), vesicouretheral reflux (VUR) grades I and II in 3 cases (9%). Glomerular filtration fluctuated between 81 ml/min/1.73 and 193 ml/min/1.73 (mean 105). Radioisotope renography was performed in 38 patients and only one patient was reported with renal scar. Follow up with renal ultrasound revealed that renal cysts disappeared in 13 patients and persisted in 18 with a media of 60 months (range 15 to 132 months). Conclusions: In this group of patients, a good prognosis of the CK was found: none presented decline of the glomerular filtration rate and frequency of urological malformations as HN and VUR was very low. Renal ultrasound is mandatory in the initial evaluation and follow up of these cases. Renography with 99mTc-DMSA is recommended in the initial evaluation of these patients to demonstrate no function of the MDK and to assess morphology and function of CK. A voiding cystogram should be reserved to patients with hydronephrosis in CK and/or anomalies in the renography. The periodic calculation of the glomerular filtration is important to detect hyperfiltration that can compromise a single functional kidney.