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Test Code LACTOL Lactose Tolerance, LAB2571

Performing Laboratory

St. Luke's Hospital Cedar Rapids

Specimen Requirements

Container/Tube:

Preferred: Green-top (lithium heparin) tube

Acceptable: Gold-top serum gel tube or plain red-top tube, lavender-top EDTA, grey-top sodium fluoride.
Specimen Volume: 0.1 mL of plasma or serum

Collection Instructions: Patient must be fasting (however, water may be taken) and refrain from smoking during test. A fasting specimen will be drawn, then a 50 g lactose dose given. Additional specimens will be drawn at 30 minutes, 60 minutes, 90 minutes, and 120 minutes post dose.

Note: Label specimen appropriately (plasma and fasting, 30 minutes, 60 minutes, 90 minutes, or 120 minutes post dose).

Transport:  Spun or separated from cells at room temperature for 8 hours or 72 hours at 2-8 ⁰C

Reference Values

A peak maximal rise of 25 mg/dL in the blood glucose signifies normal lactase activity. A peak rise below 20 mg/dL strongly suggests lactase deficiency.

False-positive reactions may occur in the presence of vomiting, gastric stasis, or severe diarrhea. False-negative reactions may occur in the presence of diabetes.

Day(s) Test Set Up

Monday through Friday

Useful For

Evalulating the presence of lactase.

Methodology

Hexokinase/Ultraviolet

Test Classification and CPT Coding

82951-3 Specimens

82952-Each additional specimen

Report Available

Within 3 hours upon beginning testing