Though she now faces harsh criticism from the outside, she is still surrounded largely by true believers. Her younger brother, Christian Holmes V, is an executive at Theranos, as is her former Stanford professor, Channing Robertson. Her board of advisers, despite their impressive names, have had little say about how the company operates. Ms. Holmes persuaded George P. Shultz, the former secretary of state, whom she met at a conference, to join in 2011. He then contacted people he knew, like Henry Kissinger and Dr. Frist.

“These were all just friends of George,” said Mr. Kovacevich, who was also introduced to Ms. Holmes by Mr. Shultz.

At this point, her investors and the advisers seem willing to be patient. Elizabeth “will make sacrifices to go slow,” Mr. Kovacevich said. “She knows she has to make money. She wants to change the world in health care.”

But that patience may be wearing thin. After more than 10 years, Ms. Holmes is talking about ways she can remain private — getting new investors to buy out the old ones. The company declined to provide financial information, but she was adamant that Theranos does not currently need more money. “We’re not in a position in which we need to raise equity capital,” she said. “We’re in a position where we will continue to grow from operations.”

While Ms. Holmes argues that Theranos invited the F.D.A. review, the company seems to have been caught off guard after the F.D.A. unexpectedly inspected its manufacturing facilities, where it makes its proprietary equipment, in August and September. The agency told Theranos that it had to comply with its rules, rather than those of other regulatory agencies. According to correspondence made available through a Freedom of Information Act request, Theranos complained of “a fundamental policy shift that is uniquely and highly prejudicial to Theranos.”

Now the company must get approval for all of its equipment — including the devices that are used to analyze and perform tests as well as its so-called nanotainers that are used to collect blood from finger pricks. Ms. Holmes insists, however, that the company can still rely on some of its technology, which she won’t specify.

She is now trying to take back control of the Theranos story. She talks about publishing the company’s internal data, and the company has plans to hold a session with outside experts even sooner to try to convince the doubters. The Cleveland Clinic says it has not reached a final agreement to study the technology.

And there is the matter of the black turtlenecks.

She claims her mother dressed her and her brother in black turtlenecks when they were young and now she finds them comfortable. Moreover, she wanted to deflect attention from what she might be wearing. But now she admits she is frustrated about how to handle the media fascination they seem to have created. Perhaps, she joked, “I should bring them with me and give them to people as gifts.”