Well so now I have an enigma on my hands. Some weeks back you may recall that I blogged about the great Vitamin D Project by Grassrootshealth. That was Feb 27th and within a few days I had my test kit, punctured my finger, blotted blood, and sent it off.
Roughly two weeks later, a couple of days ago, I had blood drawn for my various series of tests and one I requested was a vitamin D test (25-hydroxy vitamin D). Coincidentally, I got both results today, one from blood taken two weeks ago and one from a current sample.
2 weeks ago: 120 ng/mL
Current: 85 ng/mL
That's quite a difference (the magnitude being greater than the average total vitamin D level for most people). One possibility is lab error, of course. Another is that the first test was at only a week back from spending hours per day in the Puerto Vallarta sun (I continued my 6k IU per day). But it's hard to imagine it could dissipate so rapidly in such a short time, so is something fishy somewhere?
I'm hoping it's the latter one that's fine, as 85 is exactly where I want to be; as well it must be noted that it was an actual blood draw; whereas, the former was a drop on blotter paper. I have no idea of the comparative difference in terms of test quality.
Anyone have any ideas?