Oral contraceptive agents have many diverse and important extragenital effects, as manifested by alterations in laboratory test results. Drug therapy, as with oral contraceptive agents, is only one of many variables that must be considered in the knowledgeable interpretation and application of laboratory-generated data.
(JAMA 229:1762-1768, 1974)
Weindling H, Henry JB. Laboratory Test Results Altered by "The Pill". JAMA. 1974;229(13):1762-1768. doi:10.1001/jama.1974.03230510036019