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Test Code LTT Lactose Tolerance, Plasma

Performing Laboratory

CCHS-Christiana Care Health Services

Methodology

Glucose Oxidase/Hydrogen Peroxide (Trinder)

Intolerance to milk and other dairy products is caused by a deficiency in the enzyme lactase, which catalyzes the hydrolysis of lactose to glucose and galactose. By measuring glucose levels after a dose of lactose, lactase activity can be evaluated. In the lactose tolerance test, a 50 g dose of lactose is taken orally by patient, and blood levels are drawn for up to 2 hours afterward to monitor physiologic response vs. a fasting specimen.

Specimen Requirements

Container/Tube:  3.5-mL gray-top (potassium oxalate/sodium fluoride) tube

Specimen:  Full tube
Collection Instructions:  See “Lactose Tolerance Test” in “Special Instructions” for specimen collection.

Note: Label tube with patient’s full name and 1 additional unique patient identifier such as date of birth, medical record number, emergency ID number, date and time of draw, collector’s initials, and type of specimen.

Reference Values

Normal:  >20 mg/dL above baseline (peak glucose rise)

Lactose intolerant:  <20 mg/dL above the baseline level, with symptoms (peak glucose rise)

Day(s) Test Set Up

Monday through Sunday

Routine Turnaround Time:  8 hours

STAT Turnaround Time:  1 hour

Special Instructions