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Theranos uses key technology in just one test: WSJ

Theranos: A hot company takes fire
Theranos: A hot company takes fire

Diagnostics company Theranos has cut back use of its key finger-prick technology to just one lab test after pressure from regulators, The Wall Street Journal reported, citing a person familiar with the matter.

That followed a recent unannounced visit from Food and Drug Administration inspectors due to concerns about data the company had submitted to the agency to win approval for its testing methods, the person said, according to the WSJ report late Thursday. Theranos has submitted approval requests for almost 130 tests. The Journal reported that the FDA has approved just one, for herpes.

Theranos didn't immediately respond to an emailed request for comment sent outside of regular office hours.

Read More Theranos CEO fires back at WSJ: I was shocked

Theranos has been a Silicon Valley darling after developing a finger-prick blood-testing technology that competes with the traditional use of arm-drawn blood. It was valued at as much at $9 billion in its most recent round of fundraising

The company's founder, Elizabeth Holmes, told CNBC earlier Thursday that Theranos' "nanotainers" for collecting finger-pricked blood were only used for FDA-cleared assays.

Holmes' comments to CNBC followed an an earlier report by the Journal that cited several former Theranos employees as saying that the company may have exaggerated the accuracy of lab tests conducted on its own machines, and that Theranos largely used blood-testing equipment bought by external suppliers, not its own technology.

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The Journal reported that David Boies, Theranos' outside lawyer, and Heather King, Theranos' general counsel, both denied the claims. King added the company has been "upfront and transparent with regulators" about its procedures.

Read More Theranos under fire over lab test accuracy

Theranos later said in a statement that the initial Journal report was "factually and scientifically erroneous and grounded in baseless assertions by inexperienced and disgruntled former employees and industry incumbents."

The company said it sent more than 1,000 pages of documentation to the Journal to demonstrate the tests' accuracy and refute the allegations.

The Journal reported that Theranos declined to allow the newspaper to visit the company's offices to view its technology; Holmes told CNBC that the company had offered to come to the Journal's offices to demonstrate its technology.

A Journal spokesperson later told CNBC the newspaper "fully stands by [writer] John Carreyrou's article about Theranos, which was richly sourced and thoroughly researched."

Abigail Stevenson and Fred Imbert contributed to this report.