Good thinking Dan. Our team has looked into LabCorp offering a test for actual NAD+ levels, but that test is a little more complicated than usual. They don't yet have a test for actual NAD+ levels (yet). 

Longevitybridge.com expects to offer an NAD+ blood test, "available soon". I understand that Dr. Greg Fahey has developed the test, which gives me quite a bit of confidence. At RAADFest I asked Greg about the accuracy he expected from the test, and his answer gave me further confidence.