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Test Code GTT3HR 3 Hour Glucose Tolerance Test (Gestational)

Specimen Requirements

Container/Tube: GRN/SST/GREY
Preferred: Plasma
Acceptable: Serum
Specimen Volume: 1.0 mL

Specimen Requirements: Fasting required. Fasting is defined as no consumption of food or beverage other than water for at least 8 hours before testing. If patient specimens are not to be collected at a Willis-Knighton patient service center, collect specimens in Grey-top tube (Sodium Floride). Immediately after a fasting specimen is obtained, have patient (pregnant woman)ingest a 100 g load of glucose. Draw subsequent specimen 1 hours later. Draw 2 hour specimen 1 hour after the 1 hour specimen. Draw 3 hour specimen 1 hour after the 2 hour specimen. Label each specimen with the specific draw time.

SPECIMEN PROCESSING and HANDLING

Complete clot formation should take place before centrifugation. Serum or plasma should be physically separated from cells as soon as possible with a maximum limit of two hours from the time of collection.

TRANSPORT TEMPERATURE

Glycolysis decreases serum glucose by approximately 5% to 7% per hour in normal uncentrifuged, coagulated blood at room temperature. In separated, nonhemolyzed sterile serum, the glucose concentration is generally stable as long as 8 hours at 25 °C and up to 72 hours at 4 °C; variable stability is observed with longer storage conditions. Glycolysis can be inhibited and glucose stabilized for as long as 3 days at room temperature by addition of sodium iodoacetate or sodium fluoride (NaF) to the specimen.

PERFORMING LAB

WKMC, WKB, WKP, WKS