Test Name

Glucose 1h (pregnant) after 50 g
load

Test Code

241

Unit

mg/dL

Station

Chemistry

Synonym Name/Abbreviation

GTT, OGTT, Oral Glucose Tolerance Test, Glucose Challenge
(1h) Test (GCT)

CPT Code

82952

Performing Facility

American Medical Labs, Herzliya
Pituah

Analyzer

Roche cobas 6000

Test Method

 Enzymatic
colorimetric assay

AML Preferred Tube

5 mL SST gel (separate serum within 45 minutes). Alternate
tube: NA-Fl (gray top tube)

Storage Instructions

Refrigerated. Separate serum from cells within 45 minutes.

Stability:

8 hours at 15‑25 �C, 72 hours at 2 to 8�C
Gray top tube whole blood is stable 24 hours.

Min. Volume

1 mL

Comments

A plasma glucose > 140 mg/dL 1h after 50g load indicates
the need for additional testing ( Expert
Committee, American Diabetes Association -ADA- criteria for Diagnosis of
Gestational Diabetes Mellitus- GDM) Presumptive Gestational Diabetes
Mellitus:
 130 mg/dL or
greater (identifies 90%
 of
patients with GDM)
 140
mg/dL or greater (identifies 80%
 of patients with
GDM)

Turn-Around-Time

One day.

Intended Use

The test is the first stage screen for gestational diabetes
mellitus. Also used to test insulin resistance, and sometimes reactive
hypoglycemia. If this test result is abnormal, a 100g glucose load test is
recommended by ADA

Patient Preparation

Fasting is not necessary before collection of specimens.
Patient should drink the glucose and specimen will be drawn 1 hour
later.

Reasons for Rejection

Non fasting patient; stressed patient (surgery, infection,
corticosteroids) should not have GTT; specimen not labeled with hourly
times; gel tubes received unspun; improper specimen labeling

Adult (pregnant) Reference
Ranges

< 140 mg/dL
.

 See
“Comments”