Test Overview
Test Methodology

Hexokinase, NADH Endpoint

Test Usage

Determine glucose level, monitor insulin therapy, evaluate carbohydrate metabolism

Reference Range *

American Diabetes Association Reference Ranges:
Gestational Diabetes, 50 g load, 1 hr: <140 mg/dl
Gestational Diabetes, 100 g load: Fasting <95 mg/dl; 1 hr <180 mg/dl; 2 hr <155 mg/dl; 3 hr <140 mg/dl
Fasting <95 mg/dL

* Reference ranges may change over time. Please refer to the original patient report when evaluating results.

Test Details
Days Set Up
Daily, 24 hours
Analytic Time

2 hours

Soft Order Code
MiChart Code
Chemical Pathology
Specimen Requirements
Collection Instructions

Collect blood in an SST tube from a fasting patient. Administer 100 gm Glucola. Instruct patient to finish drinking the Glucola within 5 minutes of the time he or she starts drinking and not to eat anything except a few sips of water after finishing the Glucola. Collect blood in an SST tube exactly 1, 2, and 3 hours after the patient finished drinking the Glucola. Centrifuge within 4 hours of collection, aliquot serum into a plastic vial and refrigerate. If specimen cannot be centrifuged at client site, please arrange for delivery to MLabs within 3 hours of specimen collection. Label vials appropriately (Fasting, 1 HR, 2 HR, and 3HR).

Normal Volume
0.5 mL serum
Minimum Volume
0.25 mL serum
Additional Information

A 3-hour Glucose Tolerance test specifically for Obstetrics. This will not replace the current Glucose 3-hour tolerance test (GLUC3), but will be offered in addition, to provide clarity in the interpretation of the results.
Specimen labels are generated at time intervals appropriate for the collection times to be drawn One label to be used for fasting sample at the beginning of testing (GLF) and additional labels to be used on the samples drawn at 1 hour (GL60), 2 hours (GL120), and 3 hours (GL180) after Glucola administration).

CPT Code
Fee Code
GL3OB Glucose Tolerance, 3 hour, Obstetrics LOINC : 50586-7 OGLF Glucose, Fasting OB GTT LOINC: 1558-6 OG60 Glucose, 1-hour OB GTT LOINC: 20438-8 OG120 Glucose, 2-hour OB GTT LOINC: 25667-7 OG180 Glucose, 3-hour OB GTT LOINC: 20437-0