Selenium/Creatinine Ratio, Random, Urine
NY State Approved Indicates the status of NY State approval and if the test is orderable for NY State clients.
Monitoring selenium replacement therapy
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|
|SECR||Selenium/Creat Ratio, U||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
SECR/32489: Dynamic Reaction Cell-Inductively Coupled Plasma-Mass Spectrometry (DRC-ICP-MS)
CDCR/7243: Enzymatic Colorimetric Assay
Reporting Name A shorter/abbreviated version of the Published Name for a test; an abbreviated test name
Selenium/Creat Ratio, Random, U
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: 2 mL
1. Collect a random urine specimen.
2. See Metals Analysis-Collection and Transport in Special Instructions for complete instructions.
Additional Information: High concentrations of barium, gadolinium, and iodine are known to interfere with most metals tests. If barium-, gadolinium-, or iodine-containing contrast media has been administered, a specimen cannot 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.
Specimen Stability Information Provides a description of the temperatures required to transport a specimen to the laboratory. Alternate acceptable temperature(s) are also included.
|Urine||Refrigerated (preferred)||28 days|
Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test
Selenium is an essential element. It is a cofactor required to maintain glutathione peroxidase (GSH-Px) activity, an enzyme that catalyzes the degradation of organic hydroperoxides. The absence of selenium correlates with loss of GSH-Px activity and is associated with damage to cell membranes due to accumulation of free radicals.
In humans, cardiac muscle is the most susceptible to selenium deficiency. With cell membrane damage, normal cells are replaced by fibroblasts. This condition is known as cardiomyopathy and is characterized by an enlarged heart whose muscle is largely replaced by fibrous tissue.
In the United States, deficiency is related to use of total parenteral nutrition. This is therapy administered to patients with no functional bowel, such as after surgical removal of the small and large intestine because of cancer, or because of acute inflammatory bowel disease such as Crohn's disease. Selenium supplementation to raise serum concentration >90 ng/mL is the usual treatment. Serum monitoring done on a semi-annual basis checks the adequacy of supplementation.
Selenium toxicity has been observed in animals when daily intake exceeds 4 parts per million (ppm). Teratogenic effects are frequently noted in the offspring of animals living in regions where soil content is high in selenium such as south-central South Dakota and northern-coastal regions of California. Selenium toxicity in humans is not known to be a significant problem except in acute overdose cases. Selenium is not classified as a human teratogen.
Selenium is found in many over-the-counter vitamin preparations because its antioxidant activity is thought to be anticarcinogenic. There is no supporting evidence that selenium suppresses cancer.
Urine quantitation is used to assess clearance and in balance studies.
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: 15-40 mcg/g creatinine
Reference values have not been established for patients that are less than 16 years of age.
The normal daily intake of selenium is 10 to 35 mcg/day, therefore, the usual daily output should be the same.
Daily excretion of <15 mcg/g creatinine indicates a lack of adequate selenium nutriture. Insufficient selenium intake leads to cardiomyopathy.
Selenium output of >40 mcg/g creatinine indicates excessive intake. There is no known toxicity to humans due to intake of modest excesses.
Grossly excessive intake (daily output >500 mcg/g creatinine) may have a teratogenic impact. This effect has been demonstrated in animals.
Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances
High concentrations of gadolinium, iodine and barium are known to interfere with most metals tests. If gadolinium-, iodine- or barium-containing contrast media has been administered, a specimen cannot be collected for 96 hours.
Clinical Reference Provides recommendations for further in-depth reading of a clinical nature
1. Fleming CR, McCall JT, O'Brien JF, et al: Selenium status in patients receiving home parenteral nutrition. J Parenter Enteral Nutr 1984;8:258-262
2. Chariot P, Bignani O: Skeletal muscle disorders associated with selenium deficiency in humans. Muscle Nerve 2003 Jun;27(6):662-668
3. Kvicala J, Zamrazil V, Nemecek J, Anke M: Intake of selenium by seniors of South Bohemia and urine selenium of seniors in the course of a 1-year supplementation by various selenium species. Tr Element Electro 2008;25:21-24
Method Description Describes how the test is performed and provides a method-specific reference
This assay is performed on an inductively coupled plasma-mass spectrometer in dynamic reaction cell mode. Calibrating standards and blanks are diluted with an aqueous acidic diluent containing internal standard(s). Quality control specimens and patient samples are diluted in an identical manner. In turn, all diluted blanks, calibrating standards, quality control specimens 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. The ionized gases plus neutral species formed in the annular plasma space are aspirated from the plasma through an orifice into a quadrupole mass spectrometer. The mass range from 1 to 263 amu is rapidly scanned multiple times and ion counts tabulated for each mass of interest. Instrument response is defined by the linear relationship of analyte concentration vs. ion count ratio (analyte ion count/internal standard ion count). Analyte concentrations are derived by reading the ion count ratio for each mass of interest and determining the concentration from the response line. (Murray DL, Hanley MM, Moyer TP, et al: Selenium, Copper and Zinc: Group antioxidant metals analysis by ICP-MS [Abstract WS206]. Winter Conference on Plasma Spectrochemistry, Tucson, AZ, January 9-14, 2012)
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.
Monday, 8 a.m. - 6 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
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's instructions, or as products that do not undergo full FDA review and approval, and are then labeled as an Analyte Specific Reagent (ASR), Investigation Use Only (IUO) product, or a Research Use Only (RUO) 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 U.S. 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 Medical Laboratories interpretation of CPT coding requirements. It is the responsibility of each laboratory to determine correct CPT codes to use for billing.
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|
|32868||Selenium/Creat Ratio, U||In Process|
|32883||Se Concentration||In Process|