Rapid and effective turbidimetric GI testing

August 5, 2021

Faecal tests have been widely used by clinicians as informative, non-invasive tools that contribute to the differential diagnosis and monitoring of a wide range of gastrointestinal (GI) conditions. However, our growth in understanding of the GI tract – both normal and diseased – has created a need for new assays that take advantage of this convenient sample type, and potentially offer more analytes and quicker results. This has been addressed by advances in technology, combined with the application of novel immunochemical techniques, and there are now alternative testing options that are proving invaluable in both the clinic and the labs.


Cheaper and faster diagnostic pointers

The IDK® turbidimetry range is a perfect example of this, offering the rapid and effective detection of three key biomarkers – human calprotectin, haemoglobin and pancreatic elastase – that, from the clinical perspective, are crucial for screening and the differential diagnosis of several of the most common GI diseases. However, a really important added advantage of this test portfolio is that it also addresses some of the key challenges that labs face. A unique sampling tube, the IDK TurbiTUBE – designed exclusively for IDK turbidimetric assays – offers easy, clean and precise preparation of stool extracts, creating a constant dilution of 1:100 that is ready for analysis and can be loaded directly onto an analyser. All three parameters can be determined from just one single sample extract, which simplifies testing and simultaneously saves time and money.


Clear clinical value

The three analytes in question all have well-established clinical utility. Calprotectin (IDK TurbiCAL®) is released into intestinal mucosa and lumen whenever there is structural damage; the more the inflammation, the more calprotectin will be excreted into the stools. Measuring calprotectin can therefore be used primarily for the differential diagnosis between inflammatory bowel disease (IBD) and irritable bowel syndrome (IBS), but also to monitor intestinal inflammation and disease activity in IBD patients. IDK TurbiFIT® addresses another critical bowel screen, this time that of colorectal cancer. Recent studies have reported that multiple rounds of non-invasive faecal immunochemical tests (FIT) detect significantly more advanced neoplasia than once-only, invasive flexible sigmoidoscopy or colonoscopy.1,2 This suggests that FIT would be a much more effective preliminary screening test for colorectal cancer in both asymptomatic patients and those with lower abdominal symptoms. The third assay, IDK TurbiPEL®, determines pancreatic elastase levels, offering rapid and effective identification of exocrine pancreatic insufficiency (EPI), and a way to monitor the levels of digestive enzymes in patients.


Why turbidity?

Particle enhanced turbidimetric immunoassays (PETIAs) offer clinicians a more reliable and faster alternative to ELISAs for the detection of these three key analytes in stool samples. Turbidimetry technology relies on agglutination reactions between antigens and their complementary antibodies coated onto latex particles, and is measured as an increase in light absorbance – using a lab’s existing clinical chemistry analysers – which is proportional to the amount of antigen in the sample. However, best of all, turbidimetry offers significant benefits:

  • Simple, fast and reliable, with short incubation times
  • Results in less than 15 minutes, depending on the analyser
  • Ideal for high throughput workflows, continuous loading and random access
  • Reduced hands-on time and cost using the IDK TurbiTUBE
  • Broad measuring range
  • Good clinical correlation with corresponding ELISAs.


With powerful advantages like these, it’s no wonder that the new IDK assays are attracting a lot of interest from clinicians and laboratories alike.

Lab technician with IDK TurbiCAL

Download our brochure to find out more about BIOHIT’s range of turbidimetric immunoassays


  1. Grobbee EJ et al. Diagnostic yield of one-time colonoscopy vs one-time flexible sigmoidoscopy vs multiple rounds of mailed fecal immunohistochemical tests in colorectal cancer screening. Clin Gastroenterol Hepatol. 2020 Mar;18(3):667-675.e1. doi: 31419575. Epub 2019 Aug 13. PMID: 31419575.
  2. Zorzi M et al. Long-term performance of colorectal cancer screening programmes based on the faecal immunochemical test. Gut. 2018 Dec;67(12):2124-2130. doi: 10.1136/gutjnl-2017-314753. Epub 2017 Nov 3. PMID: 29101260.

About BIOHIT HealthCare

BIOHIT HealthCare is a Finnish biotech company, headquartered in Helsinki, that specialises in the development, manufacture and distribution of kits and assays for the screening, diagnosis and monitoring of digestive diseases. Its core disease focus areas include stomach health and dyspepsia, reflux and acid dysregulation, Inflammatory Bowel Disease (IBD), functional gastrointestinal disorders (FGID), Irritable bowel syndrome (IBS), and gut microbiota dysbiosis. Innovating for Health www.biohithealthcare.co.uk

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