I think it's mainstream vs alternative, for the most part. the mainstream tests are things like MRI, lumbar puncture, visual evoked potentials, nerve conductivity tests, etc etc.
alternative approaches use an assortment of tests for nutrient status, pathogens, etc.
odd sx? no dx? check w/ dietitian
DRI=MINIMUM eg bit.ly/1vgQclQ
99% don't meet these. meds/lifestyle can affect levels
status can be low in ms & other cond'ns
'but my results are normal'. typical panels don't test all
deficits occur in 'normal' range