Increased calprotectin levels are regularly found in stool samples from patients with organic (but not functional) gastrointestinal disorders, in particular Crohn's disease, ulcerative colitis, gastric or colorectal cancer and bacterial enteritis.
For determination of calprotectin in feces small samples (about 1-2 grams) can be sent by ordinary mail to the laboratory. The doctor or laboratory can provide patients with plastic boxes with screw caps and envelopes for collection and shipment of samples.
Calprotectin is determined by a simple ELISA in fecal extracts prepared by mixing about 100 mg stool sample with a special extraction buffer in a closed tube for 30 minutes followed by centrifugation.
Faeces sample collection and preparation
1. Collect approx. 1-5g stool and place it in a suitable container.
2. Stool samples is sent or delivered to the laboratory within 4 days.
3. Temperatures during transport should never exceed 30 degre celcius.
4. Store faeces samples at -20 degre celcius.
5. Thaw frozen stool samples at room temperature.
6. Weigh (tare) the empty screw cap tube together with the inoculation loop.
7. take approx. 100 mg (between 40-120 mg) faeces by means of the inoculation loop, and place into a screw-cap-tube.
8. Weigh tube and loop with faeces and calculate net faeces weight (between 40-120 mg).
9. Break of the loop handle, leaving the loop with faeces and a 4-6 cm handle inside the screw cap tube.
10. Add pre-diluted extraction buffer (weight/volume ratio 1:50), e.g. 100mg faeces + 4.9 ml diluted extraction solution (see table in the technical advice and customer service). Close the tube.
11. Shake or mix vigorously for 30 seconds by means of a mixer.
12. Homogenise 25+/- 5 minutes on a shaker or roller. The loop inside the tube will act as an agitator.
13. Transfer the homogenate (1 ml) to an Eppendorf tube and centrifuge for 20 min. at 10.000g at RT using a bench- top centrifuge (e.g. Heraeus Biofuge 13).
14. Transfer 0.5 ml of the clear extract supernatant to new Eppendorf tube.
15. The extracts may be tested immediately. Extracts may be stored (max. 3 months at -20 degre celsius) for later measurement.
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