(Bloomberg) -- Blood-testing startup Theranos Inc. said it sent doctors and patients tens of thousands of corrected test results and voided two years of data from its devices, a devastating blow for the company that has come under scrutiny over the accuracy of its technology.

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The Silicon Valley startup told federal health regulators at the Centers for Medicare and Medicaid Services that it had voided results from 2014 and 2015 generated by its testing devices, the Wall Street Journal reported. Theranos spokeswoman Brooke Buchanan confirmed the report by e-mail.

“Excellence in quality and patient safety is our top priority and we’ve taken comprehensive corrective measures to address the issues CMS raised in their observations,” Buchanan said in an e-mail. “As these matters are currently under review, we have no further comment at this time.”

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Lauren Shaham, a spokeswoman for CMS, declined to comment.

Theranos is developing a technology that, the company has said, can run scores of diagnostic tests using only a few drops of blood. The Palo Alto, California-based startup has faced questions about whether its technology works and has been subject to investigations by the U.S. Securities and Exchange Commission, the U.S. Attorney’s Office in San Francisco, and federal and state health regulators.

President and Chief Operating Officer Sunny Balwani left the company last week, saying he was retiring. At the same time, Theranos reconfigured its board, adding former Amgen Inc. executive Fabrizio Bonanni.

Theranos’s business has grown mainly through its partnership with Walgreens Boots Alliance Inc., with about 40 of its testing centers placed in Walgreens outlets in Arizona. Walgreens spokesman Michael Polzin declined to comment on whether the drugstore chain would continue working with Theranos.

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Theranos corrects tens of thousands of blood-testing results

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