Volume progression in polycystic kidney disease

Area of Science:

• Nephrology
• Medical Imaging
• Genetics

Background:

• Autosomal dominant polycystic kidney disease (ADPKD) is a genetic disorder characterized by the progressive development of kidney cysts.
• These cysts lead to significant kidney enlargement, often resulting in impaired renal function.

Purpose of the Study:

• To quantify the rates of change in total kidney volume (TKV) and total cyst volume (TCV) in ADPKD patients over three years.
• To investigate the correlation between kidney volume changes and renal function decline (iothalamate clearance).
• To identify factors influencing the rate of kidney enlargement in ADPKD.

Main Methods:

• A three-year longitudinal study involving 241 ADPKD patients (232 without azotemia, aged 15-46 at baseline).
• Magnetic-resonance imaging (MRI) was used to measure TKV and TCV.
• Iothalamate clearance was measured to assess renal function. Statistical analyses included ANOVA, Pearson correlation, and multivariate regression.

Main Results:

• TKV and TCV increased exponentially, indicating continuous growth. Mean TKV increased by 5.27% per year (P<0.001).
• A baseline TKV >1500 ml was associated with a significant decline in glomerular filtration rate (4.33 ml/min/year, P<0.001).
• Patients with PKD1 mutations showed greater TKV increase compared to those with PKD2 mutations (P=0.03).

Conclusions:

• Kidney enlargement in ADPKD is a continuous, quantifiable process driven by cyst expansion.
• The rate of kidney enlargement is directly associated with the rate of renal function decline.
• Baseline TKV is a predictor of future kidney volume increase and functional decline.