Test Code GDUCR Gadolinium/Creatinine Ratio, Random, Urine
Specimen Required
Patient Preparation: High concentrations of gadolinium and iodine are known to interfere with most metal tests. If either gadolinium- or iodine-containing contrast media has been administered, a specimen should not be collected for 96 hours.
Supplies: Urine Tubes, 10 mL (T068)
Collection Container/Tube: Clean, plastic urine collection container
Submission Container/Tube: Plastic, 10-mL urine tube or clean, plastic aliquot container with no metal cap or glued insert
Specimen Volume: 3 mL
Collection Instructions:
1. Collect a random urine specimen.
2. See Metals Analysis Specimen Collection and Transport for complete instructions.
Useful For
Assessing chronic exposure and monitoring effectiveness of dialysis in a random urine collection
Profile Information
Test ID | Reporting Name | Available Separately | Always Performed |
---|---|---|---|
GDCU | Gadolinium/Creat Ratio, U | No | Yes |
CRETR | Creatinine, Random, U | No | Yes |
Special Instructions
Method Name
GDCU: Inductively Coupled Plasma-Mass Spectrometry (ICP-MS)
CRETR: Enzymatic Colorimetric Assay
Reporting Name
Gadolinium/Creat Ratio, Random, USpecimen Type
UrineSpecimen Minimum Volume
1.5 mL
Specimen Stability Information
Specimen Type | Temperature | Time | Special Container |
---|---|---|---|
Urine | Refrigerated (preferred) | 28 days | |
Frozen | 28 days | ||
Ambient | 14 days |
Reject Due To
All specimens will be evaluated at Mayo Clinic Laboratories for test suitability.Clinical Information
Gadolinium is a member of the lanthanide series of the periodic table of elements and is considered a nonessential element. Due to its paramagnetic properties, chelated gadolinium is commonly employed as contrast media (gadolinium-based contrast agents: GBCA) for magnetic resonance imaging and computer tomography scanning.
Gadolinium is primarily eliminated via the kidneys, so exposure can be prolonged in patients with renal insufficiency. Patients with reduced kidney function and some patients with normal kidney function may exhibit a prolonged gadolinium elimination half-life.
To date the only known adverse health effect related to gadolinium retention is a rare condition called nephrogenic systemic fibrosis (NSF). NSF is a relatively uncommon condition in which fibrous plaques develop in the dermis and often in deeper connective tissues. Reported cases have occurred almost exclusively in patients with severe kidney disease, and almost all have been associated with prior use of GBCA. NSF is a painful skin disease characterized by thickening of the skin, which can involve the joints and cause significant limitation of motion within weeks to months. Over the past decade, changes in clinical practice guidelines have almost completely eliminated the incidence of NSF. However, the association of NSF and observed elevated gadolinium concentrations is still not fully understood.
Reference Values
0-17 years: Not established
≥18 years: <0.8 mcg/g creatinine
Interpretation
Although much of the gadolinium associated with the administration of gadolinium-based contrast agents (GBCA) is cleared in the urine in the first 96 hours, lower concentrations of gadolinium may persist in the urine for months after GBCA exposure. Elevated urine gadolinium results collected after administration of a GBCA confirm past exposure, prolonged elimination of gadolinium, and/or continued exposure through anthropogenic sources. Gadolinium also has been shown to be present in some municipal water sources, which may contribute to the observation of low concentrations of gadolinium in patients who never have been exposed to GBCA.
Elevated gadolinium in a specimen collected more than 96 hours after contrast media infusion does not indicate risk of nephrogenic systemic fibrosis.
Cautions
Urine gadolinium concentration will be elevated if the specimen is collected less than 96 hours after administration of gadolinium-based contrast agents. This elevation is due to the residual gadolinium present from contrast media infusion. An elevated gadolinium in a specimen collected more than 96 hours after contrast media infusion does not definitively indicate risk of nephrogenic systemic fibrosis or gadolinium toxicity. Ultimately, individuals should consult with their healthcare providers to interpret any test results.
Gadolinium may also be present in the effluent of metropolitan sewage treatment plants and in the rivers near metropolitan areas. Sewage treatment does not remove gadolinium. Anthropogenic sources of gadolinium could contribute to low concentrations of gadolinium excreted in the urine.
Method Description
The metal of interest is analyzed by inductively coupled plasma mass spectrometry.(Unpublished Mayo method)
Day(s) Performed
Thursday
Report Available
2 to 8 daysSpecimen Retention Time
14 daysPerforming Laboratory
Mayo Clinic Laboratories in RochesterTest 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
83018
82570
LOINC Code Information
Test ID | Test Order Name | Order LOINC Value |
---|---|---|
GDUCR | Gadolinium/Creat Ratio, Random, U | 93854-8 |
Result ID | Test Result Name | Result LOINC Value |
---|---|---|
CRETR | Creatinine, Random, U | 2161-8 |
615339 | Gadolinium/Creat Ratio, U | 93854-8 |
Forms
If not ordering electronically, complete, print, and send a Renal Diagnostics Test Request (T830) with the specimen.