Theranos, the high-profile Silicon Valley company that promised to revolutionize blood testing, was warned by federal regulators this week that its Newark, Calif. laboratory has "deficient practices" that "pose immediate jeopardy to patient health and safety," according to a letter sent to the company this week. The letter from the Centers for Medicare and Medicaid Services defines "immediate jeopardy" as "a situation in which immediate corrective action is necessary because the laboratory's non-compliance ... has already caused, is causing, or is likely to cause, at any time, serious injury or harm, or death, to individuals served by the laboratory or the health and safety of the general public."