Renal water handling at early stages of autosomal dominant polycystic kidney disease

Background Previous publications in children with autosomal dominant polycystic kidney disease (ADPKD) have described that there is an alteration of renal water handling in a large percentage of cases, with a striking reduction in maximum urinary osmolality (UOsm). The aim of the present work is to analyze this kidney function in children and adolescents with ADPKD and describe the evolution at two points of their disease. Patients and methods We included 31 patients (15 man, 16 woman) with bilateral renal cysts and a family history of ADPKD, who had, at least, their urinary volume (V/GFR) quantified and a renal ultrasound performed both in the first period (P1; age 8.9 ± 4.8 years) and in the second (P2; age 16.5 ± 2.7 years). UOsm was determined after desmopressin stimulation and GFR was estimated (eGFR) using creatinine-based equations. Results Significant differences were observed in the the longitudinal diameter of both kidneys at P2 compared to P1. No differences were observed in UOsm, eGFR, V/GFR and albuminuria between both periods. UOsm was reduced in 8/28 cases at P1 and in 5/23 cases at P2. Furthermore, V/GFR values were slightly lower than the mean values normal for age. Conclusions In our series the alterations in UOsm were scarce and of little entity. Excessive kidney growth in ADPKD in the first two decades of life does not seem to be directly influenced by vasopressin since there are no evident pathophysiological reasons for its stimulation.