Your Dad is a lucky man to have a daughter like yourself. Since your Dad had his prostate removed his PSA should be < 0.1. It sounds like your Dad had been getting the Ultra sensitive PSA tests at the prior lab. He needs to verify if the new lab processed as an Ultra sensitive test or standard test. The low limit on a standard PSA test is 0.1. Most labs only run the standard test so it's definitely possible that your Dad's last blood test went to a standard lab from the new PCP. Also, the less than sign, < , is important. The lab results hopefully read < 0.1. If that's the case your Dad is fine. I would contact the PCP and definitively find out what type of PSA test was performed. Frankly, the new PCP should have asked your Dad if he wanted to have the ultra sensitive test or the standard test. If your Dad's test result was actually 0.1 on the nose (in either the ultra or standard test) I would request the PSA be ran again in a month or two not six. Even if his test is actually 0.1 most likely a follow up PSMA test will show nothing and radiation to the prostate bed and surrounding area will be recommended. I think his blood test went to a lab that only runs the standard test. In any case he'll be fine.