Laboratory parameters of the 1st order – obligatory laboratory tests.
- Small blood count
- Differential blood count
- Test for occult (non-visible) blood in stool* (if there is any doubt about the diagnosis).
Laboratory parameters 2nd order – depending on the results of the history, physical examination and the obligatory laboratory parameters – for differential diagnostic clarification.
- Stool examination for enteropathogenic germs, fungi, parasites and worm eggs.
- Examination of biopsies (tissue sample) of colonoscopy (colonoscopy).
- Inflammatory parameters – CRP (C-reactive protein).
- Liver parameters – alanine aminotransferase (ALT, GPT), aspartate aminotransferase (AST, GOT), glutamate dehydrogenase (GLDH) and gamma-glutamyl transferase (gamma-GT, GGT), alkaline phosphatase, bilirubin.
- Renal parameters – urea, creatinine, cystatin C if necessary.
- Coagulation parameters – PTT, Quick
- Tumor markers:
- Esophagus (food pipe): squamous cell carcinoma antigen (SCC), CEA.
- Stomach: CEA, CA 19-9,
- Colon (large intestine): CEA, tissue polypeptide antigen (TPA), Septin9 test.
Test method for the detection of occult blood in stool:
- Haemoccult test (guaiac test) – detection of hemoglobin; sensitivity (percentage of diseased patients in whom the disease is detected by use of the test, i.e., a positive test result occurs) 30-60 %; specificity (probability that actually healthy persons who do not suffer from the disease in question are also detected as healthy in the test) 70-85 %; detection limit circa 100 µg/g stool 3 days before and during the test, a meat-free diet is required! The predictive predictive value is 40-73%, that is, in 40-73% of patients by means of the hemoccult test the colon carcinoma (colon cancer) – secured by a colonoscopy (colonoscopy) – correctly detected.
- Immunological test
- Rapid test – sandwich immunoassay (detection of hemoglobin) sensitivity 76%; specificity 92%; detection limit circa 10 µg/g stool No diet required before testing!
- Immunological stool test – Immunoluminometric assay (detection of hemoglobin) sensitivity 96%; specificity > 99%; detection limit circa 1 µg/g stool No diet required before the test!
Interfering factors
- Proton pump inhibitors (proton pump inhibitors, acid blockers):
- Sensitivity (percentage of diseased patients in whom disease is detected by use of the test, i.e., a positive test result occurs) at 43.0% (PPI) and 65.6% (non-PPI), respectively
- Specificity (probability that actually healthy people who do not suffer from the disease in question are also detected as healthy in the test) at 86.9% (PPI) and 92.3% (non-PPI), respectively
- PPI users also had a 63% increased odds ratio for a false positive stool test result (possibly due to gastric acid-related dysbiosis of the small intestinal mucosa, more undigested hemoglobin from upper sections of the gastrointestinal tract, or NSAID-related small intestinal lesions)
