Iohexol clearance for GFR-determination in renal failure--single or multiple plasma sampling?

Area of Science:

• Nephrology
• Radiology
• Pharmacology

Background:

• Renal failure necessitates accurate assessment of glomerular filtration rate (GFR).
• Conventional GFR measurement methods can be complex and time-consuming.
• Iohexol, a non-ionic contrast agent, is used for imaging and can be utilized for GFR estimation.

Purpose of the Study:

• To evaluate the agreement between single-sample and multiple-sample plasma clearance of iohexol for GFR estimation in renal insufficiency.
• To determine the optimal timing for single plasma sample collection for accurate GFR assessment.
• To assess the safety of iohexol administration in patients with renal failure.

Main Methods:

• Sixty-five patients with renal insufficiency received an intravenous injection of iohexol.
• Plasma samples were collected at multiple time points (3-24 hours) post-injection.
• Plasma-iodine concentrations were measured using X-ray fluorescence.
• Single-sample clearance was calculated using plasma samples drawn at specific time points based on predicted creatinine clearance (4h, 7h, or 24h).

Main Results:

• Single-sample plasma clearance of iohexol showed good agreement with four-sample slope clearance across varying degrees of renal insufficiency.
• Specific sampling times (4h, 7h, 24h) provided accurate GFR estimates.
• No evidence of nephrotoxicity was observed following iohexol administration.

Conclusions:

• Single-sample plasma clearance of iohexol is a reliable and accurate method for estimating GFR in patients with renal failure.
• This simplified approach offers practical advantages for clinical use.
• Iohexol is a safe contrast agent for GFR assessment in this population.