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Lactose Tolerance Test (Outpatient Only)

Test Codes

EPIC: LAB8521

Department

Chemistry

Instructions

This test must be scheduled through the Beaumont Appointment Center at 800-328-8542.

Patient Preparation
The patient should be on a high carbohydrate diet for three days. The patient should be instructed to fast and abstain from liquids other than water for a period of 8-12 hours prior to the start of the test.

Specimen Collection Criteria

• The patient should fast and abstain from liquids other than water for a period of 8-12 hours prior to the start of the test.
• The test should be performed early in the morning and must be scheduled.

Collect: One Gray-top Potassium Oxalate / Sodium Fluoride tube prior to the administration of the Lac-Test solution which is the fasting glucose specimen. A minimum volume of 0.5 mL of specimen is requied for anlysis. An ideal volume is above 1.0 mL.

• Administer Dose: The selected amount of Lac-Test is given orally with the appropriate amount of water. 
• If the patient is not an adult, refer to the following directions:

Weight	Lac-Test Soln		Added Water
lbs.	oz.	ml.	oz.	ml.
14–21	3	75	5	175
22–28	4	120	4	130
29–35	5	150	3	100
36–42	6	180	2	70
43–49	7	210	1	40
50+	8	250	0	0

EXAMPLE:  weight = 36 lbs. Take the Lac-Test solution (2 packages diluted with 240 ml water). Measure out 6 oz. (180 ml) and then add 70 ml. of water to bring total volume to 250 ml. 

• If the patient is greater than 50 lbs., administer 50 gms of Lac-Test.
• After the patient has finished ingesting the Lac-Test beverage, set a timer and glucose specimens should be drawn at ½ hour, 1 hour, and 2 hours. Record the exact time of collection on the tube. Specify if specimen is fasting, ½ hour, 1 hour, 2 hour.

Physician Office/Draw Specimen Preparation

Maintain Gray-top tubes refrigerated (2-8°C or 36-46°F) prior to and during courier transport. (Minimum: 0.5 mL per tube)

Rejection Criteria

• Specimens collected in any tube other than a Gray-top tube.
• Specimens not collected and processed as indicated.
• Specimens less than 0.5 mL.

Storage

Specimen Stability for Testing:

Gray-top Tubes
Room Temperature (20-26°C or 68-78.8°F): 2 – 4 hours
Refrigerated (2-8°C or 36-46°F): 7 days
Frozen (-20°C/-4°F or below): 7 days

Specimen Storage in Department Prior to Disposal:

Refrigerated (2-8°C or 36-46°F): 7 days

Laboratory

Dearborn Chemistry Laboratory

Performed

Monday – Friday.
Results available within 24 hours of receipt in the Laboratory.

Test Methodology

Enzymatic.

Interpretation

This test is utilized to determine lactose intolerance. The normal for each individual is different and is subject to individual interpretation. A less than 20 mL/dL increase in glucose over the fasting level, with gastrointestinal symptoms after a lactose load, is considered abnormal and consistent with lactose deficiency.

Reference

A. Peternel, W.W., Lactose tolerance in relation to intestinal lactase activity. Gastroenterol. 48/3:299-306, 1966.

CPT Codes

CPT and LOINC Codes
Glucose Fasting                      82951     12638-3
Glucose ½ Hour Post-dose     82951     26777-3
Glucose 1 Hour Post-dose      82951     26778-1
Glucose 2 Hour Post-dose      82952     26780-7

Contacts

Last Updated

10/7/2023