On Friday, a closely watched start-up that promised to bring revolution in e medical testing, Theranos said that the Food and Drug Administration (FDA) has raised some questions due to which it had temporarily stopped its trademark practice of collection of small blood samples from finger pricks.

As per some reports, the privately held Theranos has been valued at over $9 billion, nearly similar to the laboratory giants Quest and LabCorp. That is based on purported ability of Theranos to perform a lot of medical tests with the help of only drops of blood from a finger, and not from the conventional huge vials taken from the crook of the arm.

Elizabeth Holmes is the 31-year-old founder of the company. He dropped out of Stanford for starting the company and now he is among the youngest self-made female billionaires ever. Elizabeth Holmes has been often seen in photographs holding a tiny tube of blood that is called by the company as ‘nanotainer’.

However, on Friday, the company based in Silicon Valley, said that according to FDA the nanotainer is required to have regulatory approval as a medical device. Thus the company said while it applies for approval, it has decided to stop using it for all tests except for one test.

The Wall Street Journal reported the company’s action. The report said that the FDA was concerned regarding the data of the company and had also carried out an unannounced inspection.

The Journal has also given rise to questions about the reliability of Theranos’s tests. According to it, most of the tests ran by the company were done on standard laboratory equipment purchased from other vendors, and not its proprietary system about which it has done promotion as a disruptive technology in the industry.