Comparison of different methods of clearance determination

Area of Science:

• Nuclear Medicine
• Renal Physiology

Background:

• Accurate determination of renal clearance is crucial for assessing kidney function.
• Conventional methods like para-aminohippuric acid (PAH) clearance and whole-body counting have limitations.
• Hippurate renography is a valuable radioisotopic tool for kidney investigations.

Purpose of the Study:

• To compare the efficacy of compartmental analysis of hippurate renograms with conventional PAH clearance and whole-body counting.
• To evaluate the influence of different radioisotopes (131I-hippurate vs. 123I-hippurate) on the accuracy of clearance determination.
• To assess the utility of compartmental analysis for determining divided renal clearance.

Main Methods:

• Comparative study involving 30 cases.
• Utilized compartmental analysis of hippurate renograms.
• Compared results with conventional para-aminohippuric acid (PAH) clearance and partly shielded whole-body counting.
• Investigated the impact of radioisotope count rates using 131I-hippurate and 123I-hippurate.

Main Results:

• Compartmental analysis showed strong correlations with PAH method (r=0.96) and whole-body technique (r=0.94).
• Correlation between PAH and whole-body methods was less consistent (r=0.85).
• Higher count rates with 123I-hippurate improved correlation coefficients (0.89 for 131I to 0.95 for 123I).
• Determination of divided clearance correlated well (r=0.95).

Conclusions:

• Compartmental analysis of hippurate renograms is a valid and accurate method for renal clearance determination.
• 123I-hippurate enables a comprehensive, single-step radioisotopic kidney investigation.
• This method offers an improved alternative to conventional techniques for assessing kidney function.