Gaspari F, Thakar S, Carrara F, Perna A, Trillini M, Aparicio MC, Diadei O, Ferrari S, Cannata A, Stucchi N, Ruggenenti P, Remuzzi G, Perico N: Safety of Iohexol Administration to Measure Glomerular Filtration Rate in Different Patient Populations: A 25-Year Experience. Nephron 10.1159/000489898
The current estimating equations for glomerular filtration rate (GFR) exhibit consistent inaccuracies (bias and precision) and as a result from time-to-time a measurement of GFR (mGFR) is both necessary and appropriate. The classic, “gold standard” urinary inulin clearance method, pioneered by Homer Smith more than 80 years ago, is too cumbersome for routine clinical use and as a result, various simpler methods of assessing mGFR have evolved. The plasma disappearances of non-radioactive, non-ionic iohexol has been very widely used for this purpose. This method entails multiple collections of venous blood after a single bolus infusion of iohexol. As iohexol contains iodine, concerns have arisen regarding safety and hypersensitivity reactions.
Gaspari and co-workers from Bergamo, Italy, have had extensive experience in using iohexol plasma disappearance as a means of obtaining a mGFR for over 25 years entailing over 15,000 procedures. They are in a very good position to examine these postulated safety concerns. In a detailed survey of their experience, they found an overall rate of iohexol related adverse events to be 0.0066 % or 6.6 / 100,000 procedures. Thus, the safety of the procedure is verified. Other issues remain. Iohexol plasma disappearance requires multiple blood samples (2 – 5) over several hours (even greater numbers in patients with impaired kidney function) rendering the procedure somewhat labor intensive. Although it is more accurate than eGFR in many circumstances, the iohexol plasma disappearance provides mGFR values that are not in perfect agreement with “gold standard” urinary inulin clearance method (for details see [1, 2] ), but these variations are of doubtful clinical significance. Hopefully, simpler, cost-effective and accurate methods of assessing mGFR on a routine clinical basis will evolve in the not too distant future . But it is quite clear that the answer to the Question posed by short essay is that iohexol plasma disappearance is a quite safe procedure.
1. Delanaye P, Ebert N, Melsom T, Gaspari F, Mariat C, Cavalier E, Björk J, Christensson A, Nyman U, Porrini E, Remuzzi G, Ruggenenti P, Schaeffner E, Soveri I, Sterner G, Eriksen BO, Bäck SE. Iohexol plasma clearance for measuring glomerular filtration rate in clinical practice and research: a review. Part 1: How to measure glomerular filtration rate with iohexol? Clin Kidney J. 2016 Oct;9(5):682-99
2. Delanaye P, Melsom T, Ebert N, Bäck SE, Mariat C, Cavalier E, Björk J, Christensson A, Nyman U, Porrini E, Remuzzi G, Ruggenenti P, Schaeffner E, Soveri I, Sterner G, Eriksen BO, Gaspari F. Iohexol plasma clearance for measuring glomerular filtration rate in clinical practice and research: a review. Part 2: Why to measure glomerular filtration rate with iohexol? Clin Kidney J. 2016 Oct;9(5):700-4
3. Wang E, Meier DJ, Sandoval RM, Von Hendy-Willson VE, Pressler BM, Bunch RM, Alloosh M, Sturek MS, Schwartz GJ, Molitoris BA. A portable fiberoptic ratiometric fluorescence analyzer provides rapid point-of-care determination of glomerular filtration rate in large animals. Kidney Int. 2012 Jan;81(1):112-7