Deficient practices at a lab operated by blood-testing startup Theranos pose "immediate jeopardy to patient health and safety," the U.S. government's Centers for Medicare & Medicaid Services said in a letter to the company released on Wednesday.
Theranos, founded and led by Elizabeth Holmes, has been in the spotlight after reports in the Wall Street Journal suggested that the company's blood-testing devices were flawed and had problems with accuracy.
The CMS, in a letter to the company dated Jan. 25, told Theranos it had 10 days to provide evidence that it had corrected the issues causing concern.
Theranos, which is based on Palo Alto, California, said the CMS report did not reflect the current state of its lab in Newark, California.
"We are still reviewing the report, but we addressed many of the observations during the survey and are actively continuing to take corrective action," the company said. "A full plan of correction will be submitted to CMS within days."
The company said the CMS's findings did not apply to the whole lab and did not relate to the company's lab in Arizona, where Theranos processes more than 90 percent of its tests.
Theranos, valued at about $9 billion, has promised to shake up medical testing by conducting a wide range of tests with just one drop of blood collected using a tiny vial, rather than the large vial typically used.
(Reporting by Rosmi Shaji in Bengaluru; Editing by Ted Kerr)