1 mL serum from a plain red top tube. Allow sample toclot in an upright position for at least 60 minutes, thencentrifuge sample and transfer serum to a plastic transporttube within 2 hours of collection. Clearly label tube asserum from a plain red top tube. Freeze.Note: samples should be collected prior to such prostatemanipulations as digital rectal exam (dre), prostatemassage, transrectal ultrasound (trus) and prostate biopsy.when multiple tests are ordered, submit a separate tube forthis test.