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HelpOrder Code LABCARBU Carbohydrate, Urine
Reporting Name
Carbohydrate, UUseful 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
UrineOrdering 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
CPT Code Information
84379
Method Description
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mass spectrometry, selected ion monitoring using positive ammonia chemical ionization and stable isotope dilution.(Unpublished Mayo method)
Reject Due To
| Urine containing preservatives | Reject |
Method Name
Gas Chromatography Mass Spectrometry (GC-MS)