Glucose, Fasting and Gestational-140 Cutoff [19834X]

Test Code

19834

CPT Codes
82947, 82950

Preferred Specimen

1 mL timed plasma collected in (x2) fluoride/oxalate (gray-top) tubes

Patient Preparation
Fasting is 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 (x2)

Other Acceptable Specimens

Minimum: (x2) timed full tubes whole blood collected in: fluoride/oxalate (gray-top) tubes, drawn from a fasting patient • 1 mL (x2) timed plasma collected in: sodium or lithium heparin (green-top) tube • 1 mL (x2) timed serum collected in: serum separator tube (SST®)

Instructions

Immediately after a fasting specimen is obtained, have patient ingest a 50 g load of glucose. Draw subsequent specimen 1 hour later. Label each specimen with the specific draw time.

Note: The test should be performed between weeks 24 and 28 of gestation. Serum and plasma submissions must be separated from cells.

Transport Temperature

Serum/Plasma: Room temperature
Whole blood: Refrigerated (cold packs)

Specimen Stability

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

Whole blood (gray-top) tube
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 (PST) green-top tubes • Anticoagulants other than lithium heparin, sodium heparin or fluoride/oxalate

Methodology
Spectrophotometry (SP)

Setup Schedule

Set up: Daily; Report available: Next day

Limitations

Glucose levels may be depressed if sample is left on clot for an excessive length of time.

Reference Range

Glucose, Plasma	65-99 mg/dL
Glucose, Gestational Screen (50g)-140 cutoff	<140 mg/dL

Clinical Significance

A value of 140 mg/dL or greater indicates the need for a full diagnostic, gestational glucose tolerance performed in the fasting state to determine if the patient has gestational diabetes.

Performing Laboratory
Quest Diagnostics Nichols Institute
14225 Newbrook Drive
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.