Lactose tolerance test

Measured variable
Glucose

Patient preparation
First blood sampling while fasting

Quantity/material
5 x 3 ml NaF / citrate blood, venous

Test procedure

  1. Basal blood sampling (NaF / citrate blood) after 12 hours of fasting
  2. Administration of 50 g of lactose in 400 ml of tea or water
    (4 g/kg body weight in infants, 2 g/kg body weight for children 2 years and older)
  3. Additional blood samples after 30, 60, 90 and 120 minutes

Assessment
A rise in the blood glucose of > 1.11 mmol/l or > 20 mg/dl and the absence of gastrointestinal symptoms argues against lactose intolerance.

Diagnostic sensitivity: 75 % (with a specificity of 83 %)

To rule out malabsorption, the test can be repeated with 25 g of either glucose or galactose.

Indication
Suspected congenital or acquired lactose intolerance (milk and dairy products)

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