Test Id : CHOU
Carbohydrate, Urine
Useful For
Suggests clinical disorders or settings where the test may be helpful
Screening for conditions associated with increased excretion of carbohydrates, including inborn errors of fructose and galactose metabolism.
This test is not recommended as a follow up test for abnormal newborn screening for galactosemia.
Testing Algorithm
Delineates situations when tests are added to the initial order. This includes reflex and additional tests.
Qualitative testing for the presence of reducing substances is performed followed by quantitative analysis of carbohydrates including fructose, galactose, xylose, glucose, sucrose, lactose, maltose, and raffinose.
Method Name
A short description of the method used to perform the test
Gas Chromatography Mass Spectrometry (GC-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
Aliases
Lists additional common names for a test, as an aid in searching
Carbohydrate, Urine
Fructose
Reducing Substance
Galactose
Xylose
Sucrose
Lactose
Maltose
Raffinose
Glucose
Disaccharide Screening
Monosaccharide Screening
Saccharides
Sugar
Testing Algorithm
Delineates situations when tests are added to the initial order. This includes reflex and additional tests.
Qualitative testing for the presence of reducing substances is performed followed by quantitative analysis of carbohydrates including fructose, galactose, xylose, glucose, sucrose, lactose, maltose, and raffinose.
Specimen Type
Describes the specimen type validated for testing
Urine
Ordering Guidance
This test is a quantitative analysis of carbohydrate excretion in the urine. It is not appropriate for evaluation of an abnormal newborn screen for galactosemia. For those cases, order GCT / Galactosemia Reflex, Blood and consider GAL1P / Galactose-1-Phosphate, Erythrocytes and GATOL / Galactitol, Quantitative, Urine.
Necessary Information
Patient's age is required.
Specimen Required
Defines the optimal specimen required to perform the test and the preferred volume to complete testing
Supplies: Urine Tubes, 10 mL (T068)
Container/Tube: Plastic, 10-mL urine tube
Specimen Volume: 5 mL
Collection Instructions:
1. Collect an early-morning (preferred) random urine specimen.
2. No preservative.
Special Instructions
Library of PDFs including pertinent information and forms related to the test
Forms
Specimen Minimum Volume
Defines the amount of sample necessary to provide a clinically relevant result as determined by the testing laboratory. The minimum volume is sufficient for one attempt at testing.
1 mL
Reject Due To
Identifies specimen types and conditions that may cause the specimen to be rejected
| Urine containing preservatives | Reject |
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 |
|---|---|---|---|
| Urine | Frozen | 42 days |
Useful For
Suggests clinical disorders or settings where the test may be helpful
Screening for conditions associated with increased excretion of carbohydrates, including inborn errors of fructose and galactose metabolism.
This test is not recommended as a follow up test for abnormal newborn screening for galactosemia.
Testing Algorithm
Delineates situations when tests are added to the initial order. This includes reflex and additional tests.
Qualitative testing for the presence of reducing substances is performed followed by quantitative analysis of carbohydrates including fructose, galactose, xylose, glucose, sucrose, lactose, maltose, and raffinose.
Clinical Information
Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test
Carbohydrates are a group of mono-, di-, and oligosaccharides of endogenous and exogenous sources. Their presence frequently reflects dietary consumption but can indicate specific pathology if either a particular saccharide or a particular excretory pattern is present. Most saccharides (except glucose) have low renal thresholds and are readily excreted in the urine.
The identification and quantitation of carbohydrates, in particular galactose and fructose, is useful to screen for inborn errors of galactose and fructose metabolism such as galactosemia and hereditary fructose intolerance. Additionally, xylose may also be detected in individuals with hereditary pentosuria, a benign trait with high frequency among individuals with Ashkenazi Jewish ancestry.
This test is useful as an initial screen. To establish any diagnosis, abnormal results require confirmation by enzyme assay, molecular genetic analysis, or correlation with other laboratory testing.
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.
Reducing Substances: Negative
Quantitative results are reported as mmol/mol creatinine.
| Age range | <12 months | 12 months-18 years | > or =19 years |
| Xylose | < or =13 | < or =38 | < or =9 |
| Fructose | < or =32 | < or =31 | < or =16 |
| Galactose | < or =117 | < or =32 | < or =5 |
| Glucose | < or =139 | < or =15 | < or =22 |
| Sucrose | < or =27 | < or =46 | < or =20 |
| Lactose | < or =160 | < or =18 | < or =5 |
| Maltose | < or =5 | < or =1 | < or =2 |
| Raffinose | < or =1 | < or =1 | < or =1 |
Interpretation
Provides information to assist in interpretation of the test results
When abnormal results are detected, a detailed interpretation is given, including an overview of the results and of their significance, a correlation to available clinical information, elements of differential diagnosis, recommendations, if any, for additional biochemical testing, and a phone number to reach one of the laboratory directors in case the referring physician has additional questions.
Cautions
Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances
Ingestion of sorbose, a naturally occurring ketohexose,(1) will interfere with the quantitation of fructose and an interference comment will be included in the report. Retesting is recommended in these cases.
In some instances, normal carbohydrate values for infants (<12 months) and pediatric patients can result in a positive result for reducing substances. This is due to higher normal excretion of carbohydrates in younger age groups.
Clinical Reference
Recommendations for in-depth reading of a clinical nature
1. Hastings J, Owen G, Dekker A, et al. ChEBI in 2016: Improved services and an expanding collection of metabolites. Nucleic Acids Res. 2016;44(D1):D1214-D1219. doi:10.1093/nar/gkv1031
2. Steinmann B, Gitzelmann R, Van den Berghe G. Disorders of fructose metabolism. In: Valle DL, Antonarakis S, Ballabio A, Beaudet AL, Mitchell GA. eds. The Online Metabolic and Molecular Bases of Inherited Disease. McGraw-Hill Education; 2019. Accessed February 21, 2025. https://ommbid.mhmedical.com/content.aspx?bookid=2709§ionid=225080452
3. OMIM. #260800 Pentosuria; PNTSU. Johns Hopkins University; 1986. Updated July 9, 2016. Accessed February 21, 2025. Available at https://omim.org/entry/260800
4. Gaughan S, Ayres L, Baker P II. Hereditary fructose intolerance. In: Adam MP, Feldman J, Mirzaa GM, et al, eds. GeneReviews [Internet]. University of Washington, Seattle; 2015. Updated February 18, 2021. Accessed February 21, 2025. Available at www.ncbi.nlm.nih.gov/books/NBK333439
Method Description
Describes how the test is performed and provides a method-specific reference
The urine is evaluated for reducing substances using the AimTab tablet (Benedict's test). The tablet is a standardized self-heating method for the determination of the reducing substances by copper reduction.
Urine is spiked with a mixture of labeled internal standards and evaporated. The dry residue is oximated, derivatized, then extracted. Specimens are analyzed by gas chromatography mass spectrometry, selected ion monitoring using positive ammonia chemical ionization and stable isotope dilution.(Unpublished Mayo method)
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.
Tuesday
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.
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
Indicates the location of the laboratory that performs the test
Fees :
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 account representative. 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. It 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.
CPT codes are provided by the performing laboratory.
84379
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 |
|---|---|---|
| CHOU | Carbohydrate, U | 74447-4 |
| 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.
|
|---|---|---|
| 622709 | Reducing Substances | 5809-9 |
| 622710 | Xylose | 75051-3 |
| 622711 | Fructose | 34309-5 |
| 622712 | Galactose | 25102-5 |
| 622713 | Glucose | 34312-9 |
| 622714 | Sucrose | 76132-0 |
| 622715 | Lactose | 74438-3 |
| 622716 | Maltose | 74895-4 |
| 622717 | Raffinose | 48147-3 |
| 622744 | Reviewed By | 18771-6 |
| 622708 | Interpretation | 59462-2 |