Ordering Recommendation

Detect lactase deficiency.


Quantitative Enzymatic




Within 24 hours

New York DOH Approval Status
This test is New York DOH approved.
Specimen Required
Patient Preparation

Recommend drawing specimens for baseline (fasting), 30 minutes, 60 minutes, 120 minutes, and 180 minutes after lactose load (lactose may be obtained from a hospital pharmacy). Fasting patient should be given 50 g lactose in 200-300 mL water consumed in 5 to 10 minutes. Note: If severe lactase deficiency is suspected, the dose should be lowered.


Gray (sodium fluoride/potassium oxalate). Collect separate tube for each timed point.

Specimen Preparation

Separate plasma from cells ASAP or within 2 hours of collection. Transfer 1 mL plasma for each time point to individual ARUP Standard Transport Tubes. (Min: 0.5 mL per timed determination)

Storage/Transport Temperature


Unacceptable Conditions

After separation from cells: Ambient: 24 hours; Refrigerated: 72 hours; Frozen: 1 year

Reference Interval

Fasting glucose: 64-128 mg/dL
Normal lactose tolerance: 20-30 mg/dL elevation in glucose over fasting level after 50 g lactose load.

Interpretive Data

A less than 20 mg/dL increase in glucose over the fasting level, with gastrointestinal symptoms after a lactose load is considered abnormal and consistent with lactase deficiency.

No compliance statements are in use for this test.


Glucose in whole blood at room temperature undergoes glycolysis at a rate of approximately 7 percent each hour.

Hotline History
CPT Codes

82951; 82952 x2

Component Test Code* Component Chart Name LOINC
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  • Disaccharide Absorption Test
  • Oral Lactose Tolerance
Lactose Tolerance