T Nation

Total, LC/MS/MS vs Total Immunoassay


This isn’t a ‘case’ post. It a question about the reference ranges Quest Diagnostics.

For years the test ordered by my endo was “Testosterone, Total, LC/MS/MS” with a ref range of 250-1100 ng/dL. This last test (that was ordered by a PA) was “Testosterone, Total, Males (Adult), Immunoassay” with a ref range 250-827 ng/dL.

With the latter test, my results were 831 ng/dL so now she want to reduce the dose.

Anyway I was curious to know if anyone knows the difference between these tests and has an opinion on the most appropriate test for TRT.

Thanks in advance for your reply.


Don’t know about the different tests only that insurance companies don’t want patients in the 800 ranges. When I scored 829 ng/dL back in Nov my treatment was canceled until I could show a reduction in levels below 800 ng/dL 90 days later.