Glucose Tolerance Test, 5 Specimens

Test Code

10560

CPT Codes
82951, 82952 (x2)

Preferred Specimen

1 mL plasma collected in each of 5 separate fluoride/oxalate (gray-top) tubes

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

Minimum Volume

0.5 mL for each specimen

Other Acceptable Specimens

Plasma collected in each of 5 separate sodium or lithium heparin (green-top) tubes • Whole blood collected in each of 5 separate fluoride/oxalate (gray-top) tubes • Serum collected in each of 5 separate serum separator tubes (SST®)

Instructions

Immediately after a fasting specimen is obtained, have patient ingest a 75 g load of glucose. Draw subsequent specimens per physician's order. If not specificed by the physician, draw specimens 1, 2, 3 and 4 hours later. Label each with the specific draw time.
Note: Serum and plasma submissions must be separated from cells

Transport Temperature

Refrigerated (cold packs)

Specimen Stability

Fluoride/oxalated Plasma
Room temperature: 7 days
Refrigerated: 7 days
Frozen: 28 days

Heparinized plasma
Room temperature: 48 hours
Refrigerated: 7 days
Frozen: 28 days

Whole blood
Room temperature: 24 hours
Refrigerated: 72 hours
Frozen: Unacceptable

Serum
Room temperature: 4 days
Refrigerated: 7 days
Frozen: 28 days

Reject Criteria (Eg, hemolysis? Lipemia? Thaw/Other?)

Unspun serum separator tube • Red-top or non-plasma separator green-top tubes • Anticoagulants other than lithium heparin, sodium heparin or fluoride/oxalate

Methodology
Spectrophotometry (SP)

Setup Schedule

Set up: Mon-Sat; Report available: Next day

Reference Range

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.

Specimen 1: 65-99 mg/dL

Clinical Significance

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 glucose exceeds 200 mg/dL in the 2 hour specimen and in any preceding specimen.

Performing Laboratory
Quest Diagnostics Nichols Institute Chantilly
14225 Newbrook Dr
Chantilly, VA 20153

The CPT Codes provided in this document are based on AMA guidelines and are for informational purposes only. CPT coding is the sole responsibility of the billing party. Please direct any questions regarding coding to the payor being billed. Any Profile/panel component may be ordered separately. Reflex tests are performed at an additional charge.