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HelpTest Code HEXU Iohexol, Timed Collection, Urine
Reporting Name
Iohexol, UUseful For
Determining glomerular filtration rate in urine specimens
Method Name
Liquid Chromatography Tandem Mass Spectrometry (LC-MS/MS)
Performing Laboratory
Mayo Clinic Laboratories in Rochester
Specimen Type
UrineSpecimen Required
Supplies: Sarstedt Aliquot Tube, 5 mL (T914)
Container/Tube: Plastic vial
Specimen Volume: 5 mL
Collection Instructions: Collect a timed urine specimen. Timing may be variable and patient dependent.
Specimen Minimum Volume
0.5 mL
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Urine | Refrigerated (preferred) | 7 days | |
| Frozen | 35 days | ||
| Ambient | 7 days |
Reject Due To
All specimens will be evaluated at Mayo Clinic Laboratories for test suitability.Reference Values
Not applicable
Day(s) Performed
Monday through Friday
CPT Code Information
82542
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| HEXU | Iohexol, U | 93973-6 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| 61712 | Iohexol, U | 93973-6 |
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.
Urine concentrations of iohexol can be used for measurement of GFR following a subcutaneous injection of iohexol (plasma disappearance), or during a continuous infusion of iohexol when used in conjunction with plasma iohexol determinations (HEXP / Iohexol, Plasma). The results can be used to determine the clearance of iohexol, which is a measure of GFR.
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.
Method Description
Timed urine specimens are obtained after subcutaneous injection of nonradiolabeled 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)