After obtaining his PhD, Shaw spent six years working at the Centers for Disease Control and Prevention, where he was a supervisory research chemist and the chief of the radioimmunoassay laboratory. He then worked at Mercer University in Atlanta for a year as an assistant professor of pharmacy, before beginning a twelve-year stint at Smith Kline Beecham Clinical Laboratories, also in Atlanta. From 1991 until 1996, he worked at Children's Mercy Hospital in Kansas City, Missouri. His laboratory, the Great Plains Laboratory, which he founded in 1996, specializes in metabolic and nutritional testing, particularly as it pertains to autism. The Great Plains Laboratory is fully certified under the federally mandated Clinical Laboratory Improvement Amendments (CLIA) Clinical Laboratory Improvement Amendments (listed CLIA #17D0919496).