Quest vs. Arup

[tntntwins]

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]

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 It's really a worthless, out of date test and I don't know why they still offer it.