Regulators for the Food and Drug Administration and Centers for Medicare and Medicaid Services are investigating two separate complaints about the practices of the blood-testing startup Theranos, The Wall Street Journal reported on Sunday.

The first complaint was filed in September to the Centers for Medicare and Medicaid Services by a former Theranos employee. It accused the company of instructing employees to continue to test patients' blood using Theranos' devices even though there was evidence of "major stability, precision, and accuracy" issues.

The second complaint was filed earlier this month to the FDA by another former employee. It said a study submitted by Theranos last year for a herpes test was extremely problematic because of improper research protocols. While the tests were being run, parts of the devices used on the tests were modified, which can change the results to favor the company.

This isn't the first time Theranos has run into trouble in the past few months. The blood-testing company known for its finger-prick testing technology came under fire in October after The Wall Street Journal raised questions about the accuracy of the company's test results. In October, the FDA also released a series of concerns about the company after visiting Theranos' labs.

See more at:

Business Insider / The Wall Street Journal