Glucose Tolerance Test, Gestational, 4 Specimens (100g)
Test code
CPT code(s)*
Test resources
Details
Includes
Fasting, 1-Hour, 2-Hour, 3-Hour glucose
Methodology
Spectrophotometry (SP)
Specimen requirements | |
|---|---|
| Patient preparation | Fasting required. Fasting is defined as no consumption of food or beverage other than water for at least 8 hours before testing. |
| Preferred specimen(s) | Four - 1 mL plasma specimens collected in fluoride/oxalate (gray-top) tubes |
| Alternative specimen(s) | 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 |
| Collection instructions | Immediately after a fasting specimen is obtained, have patient ingest a 100 g load of glucose. Draw subsequent specimens 1, 2 and 3 hours later. Label each with the specific draw time. Serum and plasma submissions must be separated from cells. |
| Transport container | Fluoride/oxalate (gray-top) tubes |
| 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 |
| Reject criteria | 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 |
Reference Range(s)
| Glucose, Fasting | 65-94 mg/dL | ||||||
| Glucose, 1-Hour | <180 mg/dL | ||||||
| Glucose, 2-Hour | <155 mg/dL | ||||||
| Glucose, 3-Hour | <140 mg/dL | ||||||
Reference ranges are provided as general guidance only. To interpret test results use the reference range in the laboratory report.
*The CPT codes provided are based on AMA guidance and are for informational purposes only. CPT coding is the sole responsibility of the billing party. Please direct any questions regarding coding to the payer being billed.
This material contains content from LOINC® (http://loinc.org). The LOINC Table, LOINC Table Core are copyright © 1995-2019, Regenstrief Institute, Inc. and the Logical Observation Identifiers Names and Codes (LOINC) Committee and is available at no cost under the license at http://loinc.org/license.
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