Test Catalog

Test Id : HEXP

Iohexol, Plasma

Useful For
Suggests clinical disorders or settings where the test may be helpful

Determining glomerular filtration rate in plasma specimens

Method Name
A short description of the method used to perform the test

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

NY State Available
Indicates the status of NY State approval and if the test is orderable for NY State clients.


Reporting Name
Lists a shorter or abbreviated version of the Published Name for a test

Iohexol, Plasma

Specimen Type
Describes the specimen type validated for testing

Plasma Heparin

Specimen Required
Defines the optimal specimen required to perform the test and the preferred volume to complete testing

Supplies: Sarstedt 5 mL Aliquot Tube (T914)

Collection Container/Tube: Green top (heparin)

Submission Container/Tube: Plastic vial

Specimen Volume: 1 mL


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

Specimen Minimum Volume
Defines the amount of sample necessary to provide a clinically relevant result as determined by the Testing Laboratory

0.5 mL

Reject Due To
Identifies specimen types and conditions that may cause the specimen to be rejected

All specimens will be evaluated at Mayo Clinic Laboratories for test suitability.

Specimen Stability Information
Provides a description of the temperatures required to transport a specimen to the performing laboratory, alternate acceptable temperatures are also included

Specimen Type Temperature Time Special Container
Plasma Heparin Refrigerated (preferred) 7 days
Frozen 35 days

Useful For
Suggests clinical disorders or settings where the test may be helpful

Determining glomerular filtration rate in plasma specimens

Clinical Information
Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test

The assessment of glomerular filtration rate (GFR) is an important parameter of renal function utilized by clinicians in the care of patients with varying renal diseases, and for clinical research when precise assessment of renal 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).

Reference Values
Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.

Not applicable

Provides information to assist in interpretation of the test results

Low glomerular filtration rate (GFR) values indicate abnormal renal function, which may be either reversible/transient or irreversible/permanent. GFR tends to decline with age.

Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances

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
Recommendations for in-depth reading of a clinical nature

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

Method Description
Describes how the test is performed and provides a method-specific reference

Blood 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 HPLC 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 Session at: Renal Week 2010. 43rd Annual Meeting of the American Society of Nephrology. Denver, CO, 2010 Nov 16-21)

PDF Report
Indicates whether the report includes an additional document with charts, images or other enriched information


Day(s) Performed
Outlines the days the test is performed. This field reflects the day that the sample must be in the testing laboratory to begin the testing process and includes any specimen preparation and processing time before the test is performed. Some tests are listed as continuously performed, which means that assays are performed multiple times during the day.

Monday through Friday

Report Available
The interval of time (receipt of sample at Mayo Clinic Laboratories to results available) taking into account standard setup days and weekends. The first day is the time that it typically takes for a result to be available. The last day is the time it might take, accounting for any necessary repeated testing.

3 to 4 days

Specimen Retention Time
Outlines the length of time after testing that a specimen is kept in the laboratory before it is discarded

7 days

Performing Laboratory Location
Indicates the location of the laboratory that performs the test


Several factors determine the fee charged to perform a test. Contact your U.S. or International Regional Manager for information about establishing a fee schedule or to learn more about resources to optimize test selection.

  • Authorized users can sign in to Test Prices for detailed fee information.
  • Clients without access to Test Prices can contact Customer Service 24 hours a day, seven days a week.
  • Prospective clients should contact their Regional Manager. For assistance, contact Customer Service.

Test Classification
Provides information regarding the medical device classification for laboratory test kits and reagents. Tests may be classified as cleared or approved by the US Food and Drug Administration (FDA) and used per manufacturer instructions, or as products that do not undergo full FDA review and approval, and are then labeled as an Analyte Specific Reagent (ASR) product.

This test was developed, and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the US Food and Drug Administration.

CPT Code Information
Provides guidance in determining the appropriate Current Procedural Terminology (CPT) code(s) information for each test or profile. The listed CPT codes reflect Mayo Clinic Laboratories interpretation of CPT coding requirements. It is the responsibility of each laboratory to determine correct CPT codes to use for billing.

CPT codes are provided by the performing laboratory.


LOINC® Information
Provides guidance in determining the Logical Observation Identifiers Names and Codes (LOINC) values for the order and results codes of this test. LOINC values are provided by the performing laboratory.

Test Id Test Order Name Order LOINC Value
HEXP Iohexol, Plasma 93974-4
Result Id Test Result Name Result LOINC Value
Applies only to results expressed in units of measure originally reported by the performing laboratory. These values do not apply to results that are converted to other units of measure.
61713 Iohexol, P 93974-4

Test Setup Resources

Setup Files
Test setup information contains test file definition details to support order and result interfacing between Mayo Clinic Laboratories and your Laboratory Information System.

Excel | Pdf

Sample Reports
Normal and Abnormal sample reports are provided as references for report appearance.

Normal Reports | Abnormal Reports

SI Sample Reports
International System (SI) of Unit reports are provided for a limited number of tests. These reports are intended for international account use and are only available through MayoLINK accounts that have been defined to receive them.

SI Normal Reports | SI Abnormal Reports