Can drug screening labs tell the company they are testing for what meds an employee is taking- like methadone?

I am going in for a pre-employment drug screen and am legally prescribed methadone. I am concerned that the drrug screening agency is going to tell the company I'm applying to that I am on methadone. Especially, BC I would be getting a company car. I thought HiPPA protected me, but I'm not sure.

: http://alcoholdrugstreatment.info/can-drug-screening-labs-tell-the-company-they-are-testing-for-what-meds-an-employee-is-taking-like-methadone