Quick answer: "No." I was a Director of Clinical and Anatomical Pathology Laboratory for 20 years. The PSA test is not one where you need to be fasting prior to sample collection. It also does not show what is called diurnal variation: it doesn't vary with time, like - say - Cortisol. "However"...it "can" vary with exercise like bike riding and sexual activity. Six different studies were done with bicycle riders ranging from short 15 minute rides to 4-day long race events. Just two of the studies showed that bicycle riders were found to have PSA values that can be between 3-4-fold higher than non-bicycle riders. But again, the other four studies were inconclusive or did not show any differences with non-bicycle riders. Also, PSA levels can remain higher in men for 24 hours after sexual activity to include ejaculation. Someone who enjoys an active sexual life of 4-5 times per week or more, might perpetually show higher levels of PSA. So, if you are having a blood specimen collected for PSA, I would wait 24-48 hours after your last sexual activity/ejaculation before having the specimen collected.