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Lactose Tolerance

Source Blood
Mnemonic LTT
Specimen Requirements

CLS:
By appointment only.

Community patients: contact CLS Patient Appointment Line at 403-770-5136 to book an appointment at any Patient Service Centre.
Hospital patients: nursing unit to book appointment with on-site lab.
Test cannot be collected by Mobile Collection Service (MCS).

CRL:
By appointment only.
Rural community and hospital patients: contact the on-site lab for an appointment.
Test cannot be collected at Okotoks Health and Wellness Centre.

Pediatric patients under 5 years of age:
Due to possible difficulty administering the drink, ordering physician must obtain approval by CLS Medical and Scientific Staff. Contact Laboratory Information Center at 403-770-3600 for Pathologist-on-call information. An alternative non-invasive test is the Hydrogen Breath Test for Lactose Intolerance.

1 x 3 mL or 4.5 mL light green (mint) top PST tube for each timed specimen.  Gold top SST tube also acceptable.

0.2 mL plasma or serum

Minimum Whole Blood Volumes for Microcollections

Requires a fast of at least 8 hours.

This test requires collection of a fasting blood specimen, as well as additional blood specimens 30 minutes, 60 minutes, and 120 minutes after the patient is given a lactose drink.

Specimen Handling Procedure takes 2 hours.
Additional Information

Patient instruction sheet (form CH3002) may be given to patient.

Rural and Extra-regional: Order lactose drink from PSC Support Team by email PSCSupportTeam@cls.ab.ca at least three days before collection.

CLS Collection staff:
For drink preparation and administration instructions, refer to procedure PX-SC740 Timed Interval Tests.  Do not use the dilutions indicated on the lactose package, because they are for breath test, not the required blood test.

The drink provided for Lactose Tolerance test includes the following ingredients:

  • Lactose monohydrate
  • Natural orange flavouring
  • No artificial flavouring or colouring
Testing Location Chemistry-DSC
Testing Frequency Weekdays
Alternate Name(s)
Reference Interval A deficiency in lactase, or a malabsorption problem, is supported by a rise of glucose of 1.0 mmol/L or less from baseline on at least one time point during the lactose tolerance test. If mucosal lactase is deficient, the administrated lactase will not be hydrolyzed to glucose, resulting in an inappropriately low increase in measured plasma glucose.