Is anyone aware of the most accurate tests for deficiencies in vitamins and minerals.  For instance, I heard that urine tests were more accurate than blood tests, and I'm not sure if I heard right that vitamin levels can be checked by a hair sample?  Please tell me the exact names of the tests (for example I've heard that an MMA test is the most accurate for vitamin B-12) but I don't know the names of the tests for all the other vitamins. Thanks!
Vitamin A
Vitamin C
Calcium
Iron
Vitamin D
Vitamin E
Vitamin K
Thiamin
Riboflavin
Niacin
Vitamin B6
Folate
Vitamin B12
Biotin
Pantothenic acid
Phosphorus
Iodine
Magnesium
Zinc
Selenium
Copper
Manganese
Chromium