Natural History of Contralateral Hypertrophy in Patients with Multicystic Dysplastic Kidneys.

PURPOSE

We evaluated predictive factors for compensatory hypertrophy and renal outcomes in a large cohort of patients with multicystic dysplastic kidneys.

MATERIALS AND METHODS

We conducted a retrospective review from 1997 to 2016. Contralateral kidney and multicystic dysplastic kidney length were recorded from all ultrasounds as well as creatinine when available. We used generalized estimating equations to determine predictors of contralateral kidney length.

RESULTS

A total of 443 children with multicystic dysplastic kidneys were identified based on sonographic findings and lack of function on nuclear scan. Average followup was 3.2 years (IQR 1.5 to 5.7). Median time to involution in patients diagnosed before age 2 years was 5.5 years (95% CI 3.8-7.0). In all patients the median time to contralateral hypertrophy was 2.7 years (95% CI 2.2-3.3), and 90% of patients manifested contralateral hypertrophy by 10 years. After adjusting for age, gender, multicystic dysplastic kidney side and cohort status for each year of involution after age 2 years, the contralateral kidney grows 0.35 cm longer (95% CI 0.01-0.68, p = 0.04) compared to cases without involution. Patients with contralateral hypertrophy had greater creatinine clearance at followup (83 vs 61 ml per minute, p = 0.07), although this finding was not statistically significant due to limited data.

CONCLUSIONS

The majority of children with multicystic dysplastic kidneys will have contralateral hypertrophy by age 3 years. Multicystic dysplastic kidney involution predicts contralateral kidney growth rate after age 2 years. A small cohort of patients with multicystic dysplastic kidneys will not exhibit contralateral hypertrophy and may be at risk for renal insufficiency.