Testing Locations » Texas » San Antonio TX » Quest Diagnostics – Sonterra – Employer Drug Testing Not Offered Quest Diagnostics – Sonterra – Employer Drug Testing Not Offered Quest Diagnostics – Sonterra – Employer Drug Testing Not Offered1139 E Sonterra BlvdSuite 525San Antonio, TX 78258-4347 United States Located in the medical building next to Methodist Hospital-Stone Oak.