Once upon a time, there were two major functional/specialty diagnostic laboratories. They each offered some unique test profiles, but there was also a lot of overlap between the two. The overlap, however, was not perfect duplication – for example, both labs claimed to offer amino acids testing, but one analyzed urinary output, while the other took a direct blood measurement.
The most pivotal test offered between the two labs is the comprehensive stool analysis. Both labs offered a similar panel, but their methods differed greatly. One utilized the DNA-based PCR method, which is highly superior, while the other utilized the standard culture method, which misses a lot.