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Test Code CHOU Carbohydrate, Urine

Reporting Name

Carbohydrate, U

Useful For

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

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.

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Specimen Type

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


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.


Specimen Minimum Volume

1 mL

Specimen Stability Information

Specimen Type Temperature Time
Urine Frozen 42 days

Reference Values

Reducing Substances: Negative

 

Quantitative results are reported as mmol/mol creatinine.

Age range

<12 months

12 months-18 years

≥19 years

Xylose

≤13

≤38

≤9

Fructose

≤32

≤31

≤16

Galactose

≤117

≤32

≤5

Glucose

≤139

≤15

≤22

Sucrose

≤27

≤46

≤20

Lactose

≤160

≤18

≤5

Maltose

≤5

≤1

≤2

Raffinose

≤1

≤1

≤1

Day(s) Performed

Tuesday

Test 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

84379

LOINC Code Information

Test ID Test Order Name Order LOINC Value
CHOU Carbohydrate, U 74447-4

 

Result ID Test Result Name Result LOINC Value
622708 Interpretation 59462-2
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

Interpretation

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.

Clinical Reference

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&sectionid=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

Report Available

3 to 9 days

Method Name

Gas Chromatography Mass Spectrometry (GC-MS)