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HelpTest Code HEXP Iohexol, Plasma
Reporting Name
Iohexol, PUseful For
Determining glomerular filtration rate in plasma specimens
Performing Laboratory
Mayo Clinic Laboratories in Rochester
Specimen Type
Plasma HeparinSpecimen Required
Supplies: Sarstedt Aliquot Tube, 5 mL (T914)
Collection Container/Tube: Green top (heparin)
Submission Container/Tube: Plastic vial
Specimen Volume: 1 mL
Collection Instructions: Centrifuge and aliquot plasma into a plastic vial.
Specimen Minimum Volume
0.5 mL
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Plasma Heparin | Refrigerated (preferred) | 7 days | |
| Frozen | 35 days | ||
| Ambient | 7 days |
Reference Values
Not applicable
Day(s) Performed
Monday through Friday
Test Classification
This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. It has not been cleared or approved by the US Food and Drug Administration.CPT Code Information
82542
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| HEXP | Iohexol, P | 93974-4 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| 61713 | Iohexol, P | 93974-4 |
Clinical Information
The assessment of glomerular filtration rate (GFR) is an important parameter of kidney function utilized by clinicians in the care of patients with varying kidney diseases, and for clinical research when precise assessment of kidney function is necessary. The GFR is the sum of all the filtration rates of the individual nephrons within the kidney and, as such, reflects the number of functioning nephrons.
Plasma concentrations of iohexol can be used for measurement of GFR through multiple plasma iohexol determinations following an intravenous bolus injection of iohexol (plasma disappearance) or following a continuous infusion (or subcutaneous injection) of iohexol when used in conjunction with urine iohexol determinations (urinary clearance; HEXU / Iohexol, Timed Collection, Urine).
Interpretation
Low glomerular filtration rate (GFR) values indicate abnormal kidney function, which may be either reversible/transient or irreversible/permanent. GFR tends to decline with age.
Cautions
A theoretical complication to injection of iodinated contrast media (one that has not been observed clinically to date) is the transient suppression of thyroid function in premature and newborn infants. Therefore, a sensitive thyrotropin test is suggested approximately 2 to 3 weeks after an iohexol clearance in that age group.
Clinical Reference
1. Brown SC, O'Reilly PH. Iohexol clearance for the determination of glomerular filtration rate in clinical practice: evidence for a new gold standard. J Urol. 1991;146:675-679
2. Gaspari F, Perico N, Ruggenenti P, et al. Plasma clearance of nonradioactive iohexol as a measure of glomerular filtration rate. J Am Soc Nephrol. 1995;6:257-263
3. Schwartz GJ, Abraham AG, Furth SL, et al. Optimizing iohexol plasma disappearance curves to measure the glomerular filtration rate in children with chronic kidney disease. Kidney Int. 2010;77:65-71
4. Schmit DJ, Carroll LJ, Eckfeldt JH, Seegmiller JC. Verification of separate measurement procedures where analytical determinations influence the clinical interpretation of GFR: Iohexol quantitation by HPLC and LC-MS/MS. Clin Biochem. 2019;67:16-23
5. Seegmiller JC, Burns BE, Schinstock CA, Lieske JC, Larson TS. Discordance between iothalamate and iohexol urinary clearances. Am J Kid Dis. 2016;67(1):49-55
Method Description
Blood specimens are obtained after subcutaneous injection of non-radiolabeled iohexol. Iohexol results are acquired via a liquid chromatography tandem mass spectrometry (LC-MS/MS) system. A ThermoFisher LX-2 Cohesive high-performance liquid chromatography system and an ABSciex 5500 MS/MS are used for analysis.(Seegmiller JC, Burns BE, Lieske JC, et al. Discordant glomerular filtration rate determinations between iothalamate and iohexol renal clearances. Poster presented at: Renal Week 2010. 43rd Annual Meeting of the American Society of Nephrology; November 16-21, 2010; Denver, CO)
Report Available
3 to 4 daysSpecimen Retention Time
7 daysReject Due To
All specimens will be evaluated at Mayo Clinic Laboratories for test suitability.Method Name
Liquid Chromatography Tandem Mass Spectrometry (LC-MS/MS)
Forms
If not ordering electronically, complete, print, and send a Renal Diagnostics Test Request (T830) with the specimen.