The correlation between kidney volume and measured glomerular filtration rate in an Asian ADPKD population: a prospective cohort study

BackgroundAutosomal dominant polycystic kidney disease (ADPKD) is the most common hereditary kidney disorder that leads to end stage renal disease (ESRD). Cyst expansion in ADPKD is strongly associated with the decline in renal function. However, the correlation between total kidney volume (TKV) and glomerular filtration rate (GFR) at an early stage has not been well demonstrated. There is growing evidence that utilization of estimated GFR (eGFR) may induce misleading information in a population with near normal renal function. Therefore, a more accurate method is essential.MethodsA prospective cohort of ADPKD patients was conducted with clinical data and laboratory collection. Measured GFR (mGFR) was assessed by iohexol plasma clearance method using ultra performance liquid chromatography. eGFR was calculated using the CKD-EPI equation. Kidney volumes were evaluated using MRI imaging protocol.ResultsThirty two patients completed the study. The mean age was 56 years old. The mean initial mGFR was 83.8 mL/min/1.73m(2). The mean change in mGFR per year was -2.99 mL/min/1.73m(2)/year. The mean initial height-adjusted TKV (htTKV) was 681.0 mL/m. The mean percentage change in htTKV per year (%Delta htTKV/y) was 4.77%/year. mGFR had a better association with clinical parameters than eGFR. Initial mGFR was significantly and inversely correlated with initial htTKV and age. The percentage change in mGFR per year was significantly and inversely correlated with the %Delta htTKV/y and 24-hr urine albumin. The %Delta htTKV/y was significantly correlated with initial htTKV.ConclusionsOur studies demonstrated that mGFR using iohexol is a more reliable and accurate method than eGFR for evaluating GFR changes in the early stages of ADPKD patients. There is a strong inverse correlation between kidney volume and mGFR in an Asian ADPKD population. The initial htTKV is a good predictor of kidney volume progression. The %Delta htTKV/y is a good early surrogate marker for the decline in renal function. 24-hr urine albumin is also a good indicator for renal progression.

Automated summary

Our study showed that measuring GFR with iohexol is a more reliable and accurate method than using eGFR to evaluate changes in kidney function in early-stage ADPKD patients. There is a strong negative correlation between kidney volume and GFR in an Asian ADPKD population. The initial htTKV is a good predictor of kidney volume progression, while %Delta htTKV/y serves as a good early surrogate marker for renal function decline.