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Test Code GTT3 Glucose, 3-Hour Tolerance, Plasma or Serum

Methodology

Hexokinase-Glucose-6-Phosphate Dehydrogenase

Performing Laboratory

Aspen Valley Hospital

Physician Office Specimen Requirements

Call Aspen Valley Hospital Laboratory at 970-544-1570 to obtain glucose tolerance beverage and for procedure for calculating proper dosage of beverage. 
 

Patient Preparation

Patient should be fasting for 12 hours prior to test. A fasting urine specimen is also required and should be collected before patient drinks the glucose tolerance beverage. Timing for blood draw starts when patient finishes drinking the glucose tolerance beverage.

 

Specimen Collection

Plasma or serum and urine are required for this test.

 

Submit only 1 of the following specimens:

 

Plasma

Container/Tube:  Light green-top (lithium heparin gel) tube(s)

Specimen:  2 mL (minimum volume:  0.5 mL) of lithium heparin plasma
Transport Temperature:  Refrigerate
Collection Instructions:  Fasting (12 hour). After fasting specimen is drawn, instruct patient to drink glucose tolerance beverage. A plasma specimen is drawn for each specimen:  1 hour, 2 hours, and 3 hours after ingestion of glucose tolerance beverage. Spin down immediately and send entire tube to laboratory.

Note:  1. Indicate corresponding draw time and as plasma on request form.
2. Label specimen appropriately (corresponding draw time and as plasma).

 

Serum
Container/Tube:
  Gold-top serum gel tube(s) or Plain, red-top tube is also acceptable.

Specimen:  2 mL (minimum volume:  0.5 mL) of serum
Transport Temperature:  Refrigerate

Collection Instructions:  Fasting (12 hour). After fasting specimen is drawn, instruct patient to drink glucose tolerance beverage. A serum specimen is drawn for each specimen:  1 hour, 2 hours, and 3 hours after ingestion of glucose tolerance beverage. Allow specimen to clot for approximately 10 minutes and spin down. If drawing gold-top serum gel tube, send entire tube to laboratory.

Note:  1. Indicate corresponding draw time and as serum on request form.
2. Label specimen appropriately (corresponding draw time and as serum).

 

Urine

10 mL (minimum volume:  1 mL) from a fasting, random urine collection in a plastic urine container. No preservative. Send specimen refrigerated.

Note:  1. Indicate urine on request form.

2. Label specimen appropriately (urine).

Reference Values

Fasting glucose:  70-99 mg/dL

1-Hour glucose:  70-199 mg/dL

2-Hour glucose:  70-139 mg/dL

3-Hour glucose:  55-139 mg/dL

Critical values (automatic call-back) 

0 days-2.5 months:  <35 mg/mL or >120 mg/dL

≥2.5 months:  <50 mg/mL or >500 mg/dL

Fasting urine glucose:  negative

Note:  Reference ranges are for fasting glucose.

Day(s) Test Set Up

Monday through Sunday

Test Classification and CPT Coding

82951 - glucose tolerance test, 3 specimens

82952 x 2 - glucose tolerance test, each additional