Detect lactase deficiency.
Quantitative Enzymatic Assay
Within 24 hours
New York DOH Approval Status
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.
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)
After separation from cells: Ambient: 24 hours; Refrigerated: 72 hours; Frozen: 1 year
Fasting glucose: 64-128 mg/dL
Normal lactose tolerance: 20-30 mg/dL elevation in glucose over fasting level after 50 g lactose load.
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.
Glucose in whole blood at room temperature undergoes glycolysis at a rate of approximately 7 percent each hour.
82951; 82952 x2
|Component Test Code*||Component Chart Name||LOINC|
- Disaccharide Absorption Test
- Oral Lactose Tolerance