The new year is off to a rough start for embattled blood-testing company Theranos, as more reports are surfacing of deficiencies at one of its laboratories, the Wall Street Journal reported. 

Although a report has not yet been made public, “people familiar with the matter,” told the Journal health inspectors from the Centers for Medicare and Medicaid Services, the chief federal regulator of clinical labs, found “serious deficiencies” at the facility. According to the unnamed individuals cited by the Journal, the concerns raised by inspectors are more egregious than those raised in a report from more than a year ago. The issues are severe enough to put Theranos’ relationship with Medicare in jeopardy, the Journal said. 

A Theranos spokesperson told the Journal the company has not seen the alleged report and could not comment. 

This is not the first time Theranos, a $9 billion company, has been criticized for its laboratories. Following an inspection of its labs earlier this summer by the U.S. Food and Drug Administration, federal regulators called the company’s proprietary Nanotainer tubes an uncleared medical device. Regulators were critical of some of the practices its inspectors observed, including improper classification for its proprietary Nanotainer tubes used for blood specimens. The FDA said Theranos’ Nanotainer blood specimen tubes are not properly filed as a Class II medical device, but are instead being identified as a Class I medical exempt device. As a result, the FDA said Theranos is “currently shipping this uncleared medical device in interstate commerce between California, Arizona and Pennsylvania.” Other observations made by FDA inspectors include a criticism that a method for addressing complaints regarding a possible failure of the device to meet its specifications were not “reviewed, evaluated, and investigated where necessary.” 

In a letter submitted to the Wall Street Journal in the latter days of 2015, Theranos challenged the veracity of the unnamed sources the Wall Street Journal has relied on for its stories about the company. 

“The Journal has relied almost entirely on anonymous sources—without disclosing those sources’ qualifications, biases, affiliations, motives, or even how recently they were employed. Theranos has not only made its top scientists and engineers available to the Journal, but has provided exhaustive information and on-the-record statements to address every allegation raised by the Journal,” Brooke Buchanan, Theranos’ vice president of communications said in the letter posted on the company’s website. “By continually relying on mostly anonymous sources, while dismissing concrete facts, documents, and expert scientists and engineers in the field provided by Theranos, the Journal denies its readers the ability to scrutinize and weigh the sources’ identities, motives, and the veracity of their statements.” 

Theranos has been under scrutiny since a scathing Journal report alleging the company only performs 10 percent of its blood tests on its proprietary technology. In the article, the Journal cited several former Theranos employees, as well as the medical records of patients who had used the Theranos blood test. According to the article, the former employees allege the company split testing between its own proprietary Edison machines and technology acquired from other companies. The use of the two separate technologies yielded different results “when testing for vitamin D, two thyroid hormones and prostate cancer.” 

In July, the FDA approved Theranos’ systems and test for herpes simplex 1 virus. The FDA clearance includes the use of Theranos’ Nanotainer tubes for tests run by this method, which allow samples to be collected from just a few drops of blood from a virtually painless prick of a patient’s finger.