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Test Code GTT2 Glucose Tolerance, 2 hour

Additional Codes

Epic: LAB169

Specimen Required

Patient Preparation: 

  • Patient should be fasting for at least eight (8) hours before test and no longer than sixteen (16) hours.  Patient cannot eat or drink during test, but water is permitted before and during the test.
  • Cigarette smoking will affect results and should be avoided.

 

Specimen Type: Plasma

Collection Container/Type

Preferred: Grey top (potassium oxalate/sodium fluoride)

Acceptable: Green top (Lithium heparin)

Submission Container/Tube: Plastic vial

Specimen Volume: 3 mL

Collection Instructions: 

  1. Draw a fasting sample and document collection time on the label.
  2. Administer 75 grams oral glucose solution.  Ingestion should be completed within five (5) minutes.
  3. Draw the second sample one (1) hour after ingestion of oral glucose and document collection time on the label.
  4. Draw the third sample two (2) hours after ingestion of oral glucose and document collection time on the label.
  5. Centrifuge and separate cells after clot formation and within 4 hours of collection. 

 

Specimen Type: Serum

Collection Container/Type

Preferred: Serum gel

Acceptable: Red top

Submission Container/Tube: Plastic vial

Specimen Volume: 3.5mL

Collection Instructions:

  1. Draw a fasting sample and document collection time on the label.
  2. Administer 75 grams oral glucose solution.  Ingestion should be completed within five (5) minutes.
  3. Draw the second sample one (1) hour after ingestion of oral glucose and document collection time on the label.
  4. Draw the third sample two (2) hours after ingestion of oral glucose and document collection time on the label.
  5. Centrifuge and separate cells after clot formation and within 4 hours of collection. 

Specimen Minimum Volume

0.1 mL

Specimen Stability

Room temperature: 2 days

Refrigerated: 7 days

Frozen: 1 day

Clinical Significance

Blood glucose determinations are commonly used as an aide in the diagnosis and treatment of diabetes. Elevated glucose levels (hyperglycemia) may also occur with pancreatic neoplasm, hyperthyroidism, and adrenal cortical hyperfunction as well as other disorders. Decreased glucose levels (hypoglycemia) may result from excessive insulin therapy or various liver diseases.

Reference Range

See laboratory report.

Rejection Due To

Unlabeled, mislabeled, wrong tube type, QNS, hemolyzed.

Day(s) and Time(s) Performed

Daily

Report Available

Same day

Method Name

Hexokinase / G-6-PDH