Test ID: FECRU
Iron/Creatinine Ratio, Random, Urine
NY State Approved 
Indicates the status of NY State approval and if the test is orderable for NY State clients.
Useful For Suggests clinical disorders or settings where the test may be helpful
Diagnosis of hemochromatosis, hemolytic anemia, paroxysmal nocturnal hemoglobinemia, and impaired biliary clearance
Profile Information A profile is a group of laboratory tests that are ordered and performed together under a single Mayo Test ID. Profile information lists the test performed, inclusive of the test fee, when a profile is ordered and includes reporting names and individual availability.
| Test ID | Reporting Name | Available Separately | Always Performed |
|---|---|---|---|
| FECR | Iron/Creat Ratio, U | No | Yes |
| CDCR | Creatinine Conc | No | Yes |
Special Instructions and Forms Describes specimen collection and preparation information, test algorithms, and other information pertinent to test. Also includes pertinent information and consent forms to be used when requesting a particular test
Method Name A short description of the method used to perform the test
FECR/32499: Inductively Coupled Plasma-Optical Emission Spectrometry (ICP-OES)
CDCR/7243: Enzymatic Colorimetric Assay
Reporting Name A shorter/abbreviated version of the Published Name for a test; an abbreviated test name
Aliases Lists additional common names for a test, as an aid in searching
Iron (Fe)
Specimen Type Describes the specimen type needed for testing
Specimen Required Defines the optimal specimen. This field describes the type of specimen required to perform the test and the preferred volume to complete testing. The volume allows automated processing, fastest throughput and, when indicated, repeat or reflex testing.
Collection Container/Tube: Clean, plastic urine collection container
Submission Container/Tube: Plastic, 10-mL urine tube (Supply T068) or a 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-Collection and Transport in Special Instructions for complete instructions.
Additional Information: High concentrations of gadolinium and iodine are known to interfere with most metals tests. If either gadolinium- or iodine-containing contrast media has been administered, a specimen should not be collected for 96 hours.
Specimen Minimum Volume Defines the amount of specimen required to perform an assay once, including instrument and container dead space. Submitting the minimum specimen volume makes it impossible to repeat the test or perform confirmatory or perform reflex testing. In some situations, a minimum specimen volume may result in a QNS (quantity not sufficient) result, requiring a second specimen to be collected.
Reject Due To Identifies specimen types and conditions that may cause the specimen to be rejected
| Hemolysis | NA |
| Lipemia | NA |
| Icterus | NA |
| Other | NA |
Specimen Stability Information Provides a description of the temperatures required to transport a specimen to the laboratory. Alternate acceptable temperature(s) are also included.
| Specimen Type | Temperature | Time |
|---|---|---|
| Urine | Refrigerated (preferred) | 7 days |
| Frozen | 7 days |
Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test
Iron is cleared primarily by biliary excretion via the feces. Renal clearance of iron is a secondary and relatively minor route of clearance. Excessive accumulation of iron in iron-overload diseases leads to higher than normal urine concentration of iron, known as hemosiderinuria.
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.
> or =16 years: 100-300 mcg/g Creatinine
Reference values have not been established for patients that are <16 years of age.
Interpretation Provides information to assist in interpretation of the test results
Normal excretion of iron occurs at the rate of approximately 100 mcg/day to 300 mcg/g creatinine. In the event that dietary iron is below minimum daily requirements (<2 mg/g creatinine in females, <1 mg/g creatinine in males), urinary excretion will be less than normal.
Urinary iron is greater than normal in iron overload. It is not uncommon to observe iron excretion >20,000 mcg/g creatinine in a patient with clinically evident hemochromatosis. Daily urine output of iron ranging from 500 mcg to 5,000 mcg suggests active hemolytic anemia, early-stage hemochromatosis, or impaired biliary clearance.
Because iron elimination undergoes extreme diurnal variation (serum levels 10 times higher in am than pm), collection of random specimens can cause very misleading interpretation.
Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances
Because iron elimination undergoes extreme diurnal variation (serum levels 10 times higher in am than pm), results from random urine specimens can be very misleading and are of limited value.
High concentrations of gadolinium and iodine are known to interfere with most metals tests. If either gadolinium- or iodine-containing contrast media has been administered, a specimen must not be collected for 96 hours.
Clinical Reference Provides recommendations for further in-depth reading of a clinical nature
1. Gurzau ES, Neagu C, Gurzau AE: Essential metals--case study on iron. Ecotoxicol Environ Saf 2003 Sep;56(1):190-200
2. Ludwig J, Batts KP, Moyer,TP, Poterucha JJ: Advances in liver biopsy diagnosis. Mayo Clin Proc 1994 Jul;69(7):677-678
Method Description Describes how the test is performed and provides a method-specific reference
Iron concentrations in urine can be determined by inductively coupled plasma-optical emission spectrometry. Aqueous acidic calibrating standards, quality control samples, patient specimens, and blanks are diluted with diluent containing an internal standard. In turn, all diluted blanks, calibrating standards, quality control samples, and patient specimens are aspirated into a pneumatic nebulizer and the resulting aerosol directed to the hot plasma discharge by a flow of argon. In the annular plasma the aerosol is vaporized, atomized, and then ionized. Emission signals from iron and the internal standard are observed radially by the emission spectrometer. Instrumentation response is defined by the linear relationship of analyte concentrations versus the ratio of the iron emission signals ratioed with the internal standard. After reagent blank subtraction, unknown sample iron concentrations are calculated by entering the net unknown intensity ratios into the linear calibration equation. (Nixon DE, Moyer TP, Johnson P, et al: Routine measurement of calcium, magnesium, copper, zinc, and iron in urine and serum by inductively coupled plasma emission spectroscopy. Clin Chem 1986;32:1660-1665)
Creatinine is measured using an enzymatic method based on the determination of sarcosine from creatinine with the aid of creatininase, creatinase, and sarcosine oxidase. The liberated hydrogen peroxide is measured via a modified Trinder reaction using a colorimetric indicator. (Package insert: Roche Diagnostics, Indianapolis IN, 2004)
Day(s) and Time(s) Test Performed Outlines the days and times the test is performed. This field reflects the day and time the sample must be in the testing laboratory to begin the testing process and includes any specimen preparation and processing time required before the test is performed. Some tests are listed as continuously performed, which means assays are performed several times during the day.
Wednesday, Friday; 5 p.m.
Analytic Time Defines the amount of time it takes the laboratory to setup and perform the test. This is defined in number of days. The shortest interval of time expressed is "same day/1 day," which means the results may be available the same day that the sample is received in the testing laboratory. One day means results are available 1 day after the sample is received in the laboratory.
Maximum Laboratory Time Defines the maximum time from specimen receipt at Mayo Medical Laboratories until the release of the test result
Specimen Retention Time Outlines the length of time after testing that a specimen is kept in the laboratory before it is discarded
Performing Laboratory Location The location of the laboratory that performs the test
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 Medical Laboratories interpretation of CPT coding requirements. It is the responsibility of each laboratory to determine correct CPT codes to use for billing.
82570-Creatinine concentration
83540-Iron/creatinine ratio
LOINC® Code Information Provides guidance in determining the Logical Observation Identifiers Names and Codes (LOINC) values for the result codes returned for this test or profile.
| Result ID | Reporting Name | LOINC Code |
|---|---|---|
| CDCR | Creatinine Conc | 35674-1 |
| 32878 | Iron/Creat Ratio, U | In Process |
| 32893 | Fe Concentration | In Process |
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