rawlins02

SPONSORED LINKS BY GOOGLE

Since I am at the same latitude as Rochester, MN, maybe that's why the
sample was sent there, rather than to ARUP. But since vitamin D
testing is so "specialized", I doubt that anyone thought that through.

Now, I'm no MD, but I'd like to think that samples should be evaluated
and compared against what is known about the bodies ability to absorb
calcium. If the body's ability to absorb calcium is severely impared
at < 15 ng/ml, then that value should be listed as such on a reference
range: DEFICIENT. If marginal imparement occurs at less than 30, then
list as such. Since there's likely a non-linear relationship between
vit D level and calcium absorption, and each person's body acts
differently, this all becomes rather difficult. I agree with many of
your arguments in that regard.

But if there's a wealth of data suggesting higher mortality rates for
a number of diseases at higher latitudes (may or may not be true, MF
Holick review says there is), and vitamin D levels are known to be
lower at higher latitudes, then it would seem obvious that reference
ranges should not be different based on location.

Cheers,
Mike

robert

SPONSORED LINKS BY GOOGLE

You are now getting more complicated with calcium absorption which is
multifactoral. The PTH hormone level is always measured as low, normal or
high in relation to ionized calcium and not Vit D.
Very few vitamine assays are in clinical use for various reasons. Acute
injection one day may render a normal or high level whereas a person may
have a chronic low level otherwise. The half-life of the analyte is
important in evaluating status. It may might be more valuable to measure
precursor metabolites rather than the vitamine itself. With B12 it was found
that backed up precursor intermediates are more sensitive in picking up B12
deficiency than the actual measurement of B12. Other Biochemical markers of
deficiency are valid in evaluating one another. If Vit D is below the
reference range then it is evaluated to determine if other markers are
present indicating deficiency. If it is grossly in the abnormal range then
obvious clinical signs and symptoms would be present.
If marginal imparement occurs at less than 30, then


Unfortunately only gross abnormalities correlate more closely with clinical
symptoms in any disease. Borderline values with non specific symptoms makes
for poor science. The answer is to find a better test with less borerline
values or to include a battery of test in which they are taken as a whole
for proper interpretation.

Since there's likely a non-linear relationship between


I agree with you there about ranges. The problem though is evaluating your
single result and how it relates to others in your cohort. Taking vitamins
are not without complications so it's not a simple answer for everyone.
Granted if you live in the higher latitudes then it goes without saying. The
russians even put their children under UV.