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Lactose Tolerance Test, 5 Specimens
Test Code7675
CPT Codes
82951, 82952 (x2)
Includes
Fasting specimen, 1/2-hour, 1-hour, 2-hour, and 3-hour specimens
Preferred Specimen
1 mL plasma (x5) collected in each of five fluoride/oxalate (gray-top) tubes
Patient Preparation
Note: This test cannot be performed at a patient service center because of the preparation step required for the lactol solution.
Fasting required. Fasting is defined as no consumption of food or beverage other than water for at least 8 hours before testing.
Minimum Volume
0.5 mL (x5)
Other Acceptable Specimens
Plasma collected in (x5): Sodium or lithium heparin (green-top) tubes • Serum (separated from cells immediately) collected in a plastic screw-cap vials or spun SST • Whole blood collected in fluoride/oxalate (gray-top) tube
Instructions
Immediately after a fasting specimen is obtained, have patient ingest a 50 g dose of lactose (supplied by the laboratory). Draw subsequent specimens 1/2, 1, 2 and 3 hours later. Label each with the specific draw time.
Note: Children should receive 1.75g lactose per kg ideal body weight, up to 50g.
Serum and plasma submissions must be separated from cells.
Transport Temperature
Room temperature
Specimen Stability
Fluoride/oxalate plasma
Room temperature: 7 days
Refrigerated: 7 days
Frozen: 28 days
Heparinized plasma
Room temperature: 48 hours
Refrigerated: 7 days
Frozen: 28 days
Serum
Room temperature: 4 days
Refrigerated: 7 days
Frozen: 28 days
Whole blood
Room temperature: 24 hours
Refrigerated: 72 hours
Frozen: Unacceptable
Room temperature: 7 days
Refrigerated: 7 days
Frozen: 28 days
Heparinized plasma
Room temperature: 48 hours
Refrigerated: 7 days
Frozen: 28 days
Serum
Room temperature: 4 days
Refrigerated: 7 days
Frozen: 28 days
Whole blood
Room temperature: 24 hours
Refrigerated: 72 hours
Frozen: Unacceptable
Reject Criteria (Eg, hemolysis? Lipemia? Thaw/Other?)
Unspun serum separator tube • Anticoagulants other than lithium or sodium heparin or fluoride/oxalate • (Red-top) or non-plasma separator (green-top) tubes
Methodology
Spectrophotometry (SP)
Setup Schedule
Set up: Daily; Report available: Next day
Reference Range
See Laboratory Report
Clinical Significance
Results may be used to evaluate deficiency of small bowel mucosal lactase, which may be associated with intolerance to lactose, manifested by diarrhea and other symptoms following ingestion of milk.