Last time I checked my vitamin D levels (or some precursors/metabolites of) the test was pretty expensive and not covered by my insurance. I asked about the pri

Last time I checked my vitamin D levels (or some precursors/metabolites of) the test was pretty expensive and not covered by my insurance. I asked about the price and was told that the test needs to detect those substances in very low concentrations and thus requires more precise and expensive reagents & equipment.