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Glucose, Two-hour Postprandial

CPT: 82950
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Synonyms

  • Postprandial Sugar
  • PP Glucose, Two-hour (After Meal)

Test Includes

Glucose level two hours after meal or glucose drink


Expected Turnaround Time

Within 1 day



Related Documents


Specimen Requirements


Specimen

Serum or plasma


Volume

1 mL


Minimum Volume

0.5 mL serum or 0.5 mL plasma (Note: This volume does not allow for repeat testing.)


Container

Gel-barrier tube (1) or gray-top (sodium fluoride/potassium oxalate plasma) tube (1)


Collection

Collect specimen two hours from the beginning of meal. Separate serum or plasma from cells within 45 minutes of venipuncture. Gray-top tubes only, may be submitted without centrifugation. Label tube with patient's name and collection time.


Storage Instructions

Maintain specimen at room temperature.


Stability Requirements

Temperature

Period

Room temperature

14 days

Refrigerated

14 days

Frozen

14 days

Freeze/thaw cycles

Stable x3


Patient Preparation

Adequate meal or 75-gram glucose load two hours before two-hour postprandial glucose, as specified by the patient's physician. Patient is allowed usual meal (breakfast or lunch). Patient must complete meal within 15 to 20 minutes.


Causes for Rejection

Stressed patients (surgery, infection, corticosteroids) should not have GTT; specimens not labeled with collection time


Test Details


Use

Only a minority of patients with diabetes mellitus have the classic symptoms of polyuria, polyphagia, polydipsia, and weight loss. The two-hour postprandial glucose is extensively used to establish the diagnosis of diabetes mellitus. It may be used along with FBS to follow patients with impaired glucose tolerance.

Follow up women who had gestational diabetes, of whom most revert after delivery to normal glucose tolerance (up to half ultimately become diabetic).

It is used as part of the work-up for hypertriglyceridemia, neuropathy, retinopathy, glycosuria and for certain types of renal diseases. Work-up of vulvovaginitis, blurred vision, fatigue, and some instances of urinary tract infections.

Causes of postprandial hypoglycemia include alimentary type (commonly secondary to prior gastrointestinal surgery); reactive hypoglycemia without prior gastrointestinal surgery—alimentary or spontaneous, functional, idiopathic, indeterminate; some prediabetics; leucine-induced; fructose-induced; galactosemia; indeterminate group.


Methodology

Enzymatic


Contraindications

Stressed patients (surgery, infection, corticosteroids) should not have GTT

Reference Interval

65−139 mg/dL


References

Jacobs D, Kasten BL Jr, DeMott WR. Laboratory Test Handbook With Key Word Index. Hudson, Ohio: Lexi-Comp Inc;1988:128.

LOINC® Map

Order Code Order Code Name Order Loinc Result Code Result Code Name UofM Result LOINC
002022 Glucose, Two-Hour Postprandial 1521-4 002022 Glucose, Two-Hour Postprandial mg/dL 1521-4

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