Individual renal clearances determined at renal vein catheterization

Area of Science:

• Nephrology
• Diagnostic Imaging
• Renal Physiology

Background:

• Hypertension and renal diseases necessitate accurate assessment of individual kidney function.
• Ureteral catheterization is invasive and typically required for precise measurement of unilateral renal para-aminohippurate (PAH) clearance.
• Non-invasive or less invasive methods are needed to estimate renal function in patients with renal artery stenosis, pyelonephritis, or obstructive nephropathy.

Purpose of the Study:

• To develop and validate a method for predicting individual left or right kidney para-aminohippurate (PAH) clearance using renal vein catheterization.
• To assess the accuracy of predicted PAH clearance compared to measurements obtained via ureteral catheterization.
• To determine if ureteral catheterization can be avoided for assessing unilateral renal PAH clearance in at-risk patients.

Main Methods:

• Renal para-aminohippurate (PAH) clearances were predicted in 16 kidneys of eight hypertensive patients.
• Predictions utilized roentgenographic renal frontal areas (A), total PAH clearances (CT), and individual PAH extractions (E) measured at renal vein catheterization.
• Predicted values were compared with individual PAH clearances measured during diagnostic ureteral catheterization.

Main Results:

• Predicted and individually measured renal PAH clearances showed close correspondence along a line of identity after correction for total PAH clearance differences.
• The 95% confidence limit for predicted individual PAH clearance was approximately +/- 38 cm3/min.
• Predictions for the percentage of total PAH clearance distributed to the left or right kidney had a confidence limit of +/- 6%.

Conclusions:

• Individual renal PAH clearances can be predicted with acceptable accuracy at the time of renal vein catheterization.
• The substantially invasive procedure of ureteral catheterization is not required to ascertain left and right kidney PAH clearance in patients with renal disease.
• This predictive method offers a less invasive approach to assessing unilateral renal function in hypertensive patients with various renal pathologies.