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Quest vs. Arup

Messages
7
Trying to understand the differences in lab results from Quest directly and ARUP. Specifically relating to Coxsackie. Is it that you may get a negative result from Quest and a positive from ARUP or is it something else?
 

halcyon

Senior Member
Messages
2,482
Trying to understand the differences in lab results from Quest directly and ARUP. Specifically relating to Coxsackie. Is it that you may get a negative result from Quest and a positive from ARUP or is it something else?
These labs use two different testing methods. Quest uses a complement fixation assay to detect antibodies in blood. The problem is that complement fixing antibodies disappear a few weeks after the acute infection from what I understand. The ARUP test is done using a neutralization method. Neutralizing antibodies appear to be present in large concentration (1:320 dilution and above) during acute or chronic infections.

I've had both tests numerous times and can confirm, I was completely negative on the Quest test and highly positive (1:320 to 1:640) 3 times over 2 years and counting on the ARUP test. The Quest test also has a tendency to cross react, so the serotype determination can't even be counted on as reliable. It's really a worthless, out of date test and I don't know why they still offer it.