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Test Code HEXP Iohexol, Plasma

Reporting Name

Iohexol, P

Useful For

Determining glomerular filtration rate in plasma specimens

Method Name

Liquid Chromatography Tandem Mass Spectrometry (LC-MS/MS)

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Specimen Type

Plasma Heparin


Specimen 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

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
HEXP Iohexol, P 93974-4

 

Result ID Test Result Name Result LOINC Value
61713 Iohexol, P 93974-4

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.

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.

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 days

Specimen Retention Time

7 days

Forms

If not ordering electronically, complete, print, and send a Renal Diagnostics Test Request (T830) with the specimen.