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Glucose Tolerance Test, 2 Specimens (75g) : 35181
Test CodeGTT2AU or 35181
CPT Codes
82947, 82950
Includes
Gucose: Fasting, 2-Hour
Instructions
Patient Preparation: Fasting required. Fasting is defined as no consumption of food or beverage other than water for at least 8 hours before specimen collection
Immediately after a fasting specimen is obtained, have patient ingest a 75 g load of glucose. Draw subsequent specimen 2 hours later. Label each specimen with the specific draw time.
Serum and plasma submissions must be separated from cells.
Immediately after a fasting specimen is obtained, have patient ingest a 75 g load of glucose. Draw subsequent specimen 2 hours later. Label each specimen with the specific draw time.
Serum and plasma submissions must be separated from cells.
Transport Container
Preferred Specimen
Two - 1 mL plasma specimens collected in fluoride/oxalate (gray-top) tubes
Alternative Specimens
Plasma from fluoride/oxalate (gray-top) tube in a plastic screw-cap vial, Serum (separated from cells immediately) in a plastic screw-cap vial, Spun SST®, Plasma from lithium heparin (green-top) tube in a plastic screw-cap vial, Plasma from sodium heparin (green-top) tube in a plastic screw-cap vial
Minimum Volume
0.5 mL for each specimen
Two - 1 mL plasma specimens collected in fluoride/oxalate (gray-top) tubes
Alternative Specimens
Plasma from fluoride/oxalate (gray-top) tube in a plastic screw-cap vial, Serum (separated from cells immediately) in a plastic screw-cap vial, Spun SST®, Plasma from lithium heparin (green-top) tube in a plastic screw-cap vial, Plasma from sodium heparin (green-top) tube in a plastic screw-cap vial
Minimum Volume
0.5 mL for each specimen
Transport Temperature
Room temperature.
Specimen Stability
Serum
Room temperature: 4 days
Refrigerated: 7 days
Frozen: 28 days
Whole blood (gray-top) tube
Room temperature: 24 hours
Refrigerated: 72 hours
Frozen: Unacceptable
Sodium fluoride plasma
Room temperature: 7 days
Refrigerated: 7 days
Frozen: 28 days
Heparinized plasma
Room temperature: 48 hours
Refrigerated: 7 days
Frozen: 28 days
Room temperature: 4 days
Refrigerated: 7 days
Frozen: 28 days
Whole blood (gray-top) tube
Room temperature: 24 hours
Refrigerated: 72 hours
Frozen: Unacceptable
Sodium fluoride plasma
Room temperature: 7 days
Refrigerated: 7 days
Frozen: 28 days
Heparinized plasma
Room temperature: 48 hours
Refrigerated: 7 days
Frozen: 28 days
Reject Criteria (Eg, hemolysis? Lipemia? Thaw/Other?)
Unspun serum or plasma separator tube (SST® or PST); Red-top or green-top tube (serum or heparinized plasma not separated from cells); Anticoagulants other than lithium heparin, sodium heparin or fluoride/oxalate
Methodology
Spectrophotometry
Setup Schedule
Sunday - Saturday
Report Available
1 day
Reference Range
Glucose Value (mg/dL)
Interpretation Fasting 2-Hr Tolerance
Normal <100 <140
Impaired Fasting 100-125
Impaired Tolerance 140-199
Diabetes ≥126* ≥200**Must be confirmed by testing on a subsequent day.
Clinical Significance
This test is used for the routine diagnosis of diabetes in children and the non-pregnant adult. For pregnant females see test "Glucose Tolerance Test, Gestational, 4 Specimens (100 g)". For appropriate interpretation of this test, the patient must fast overnight and ingest a 75 g load of glucose, immediately after, a fasting specimen is obtained. For children, the glucose load is 1.75 g/Kg of ideal body weight, up to 75 g glucose. The diagnosis of diabetes is made if the fasting glucose is ≥126 mg/dL or if the 2-hour specimen is ≥200 mg/dL.
Performing Laboratory
med fusion
