Reference ranges
Reference ranges were established independently at each institution using samples from 20 to 110 normal individuals, or were verified using samples from at least 20 individuals according to the protocols described in CLSI EP28-A3 [8]. There were ten tests sets with less than 20 samples due to infrequent order. All individuals were presumptively normal and the samples were de-identified prior to use. All studies were conducted in compliance with each institution's IRB policies.