Glucose Tolerance Test, 3 Specimens (75g)

Test Code

23475

CPT Code(s)

82951

CPT Code is subject to a Medicare Limited Coverage Policy and may require a signed ABN when ordering.

Test Code

23475

CPT Code(s)

82951

CPT Code is subject to a Medicare Limited Coverage Policy and may require a signed ABN when ordering.

Not offered in Quest Diagnostics Nichols Institute (IFD) – San Juan Capistrano | Quest Nichols Institute -San Juan Capistrano, CA. Please provide SERVICE AREA INFORMATION to find available tests you can order.

In-home collection is not available in your area through Quest Mobile.

Clinical Significance

Glucose Tolerance Test, 3 Specimens (75g) - 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 body weight, up to 75. The diagnosis of diabetes is made if the fasting glucose is ≥126 mg/dL or if the 2-hour specimen is ≥200 mg/dL.

Test Resources

Clinical Focus

Polycystic Ovary Syndrome (PCOS)

Test Guide

Laboratory Testing for Diabetes Diagnosis and Management

Test Details

Includes

Fasting, 1-Hour, 2-Hour glucose

Patient Preparation

Fasting required. Fasting is defined as no consumption of food or beverage other than water for at least 8 hours before testing.

Methodology

Spectrophotometry (SP)

Reference Range(s)

American Diabetes Association Diagnostic Criteria for Diabetes Mellitus

	Glucose Value (mg/dL)
Interpretation	Fasting	1-Hr Tolerance	2- Hr Tolerance
Normal	<100	Not Established	<140
Impaired Fasting	100-125
Impaired Tolerance			140-199
Diabetes	≥126*		≥200*
*Must be confirmed by testing on a subsequent day.

LOINC® Codes, Performing Laboratory

Service Area must be determined

Includes

Fasting, 1-Hour, 2-Hour glucose

Patient Preparation

Fasting required. Fasting is defined as no consumption of food or beverage other than water for at least 8 hours before testing.

Methodology

Spectrophotometry (SP)

Reference Range(s)

American Diabetes Association Diagnostic Criteria for Diabetes Mellitus

	Glucose Value (mg/dL)
Interpretation	Fasting	1-Hr Tolerance	2- Hr Tolerance
Normal	<100	Not Established	<140
Impaired Fasting	100-125
Impaired Tolerance			140-199
Diabetes	≥126*		≥200*
*Must be confirmed by testing on a subsequent day.

LOINC® Codes, Performing Laboratory

Service Area must be determined

Preferred Specimen(s)

Three - 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 75 g load of glucose. Draw subsequent specimens 1 and 2 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

Setup Schedule

Service Area must be determined

Preferred Specimen(s)

Three - 1 mL plasma specimens collected in fluoride/oxalate (gray-top) tubes

Alternative Specimen(s)

Minimum Volume

0.5 mL for each specimen

Collection Instructions

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

Setup Schedule

Service Area must be determined

In-home collection is not available in your area through Quest Mobile.

Test Details

Clinical Significance

Test Resources

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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