| Name | lactose tolerance test |
| Categories | function test |
| Additional testing | glucose in the plasma |
| Specimen requirements | NaF/citrate blood |
| Collection instructions | Take the first blood sample with the patient fasting. |
| Procedure remarks | 1. Take baseline blood sample (NaF/citrate blood) after 12 hours without food intake 2. Administer 50 g of lactose in 400 ml of tea or water (4 g of lactose/kg body weight for infants, 2 g of lactose/kg body weight for 2 years and up) 3. Take additional blood samples after 30, 60, 90 and 120 min |
| Clinical utility | suspicions of innate or acquired lactose intolerance (milk and dairy products) |
| Methodology | photometry |
| Setup schedule and duration | Mon. - Fri. |
| Reference ranges | See findings report |
| Notes and interpretation | An increase in blood glucose of > 1.11 mmol/l or > 20 mg/dl and the absence of gastrointestinal symptoms speaks against lactose intolerance. Diagnostic sensitivity: 75 % (with a specificity of 83 %). To rule out malabsorption, the test can be repeated with 25 g glucose or galactose each time. |