Back in 1979, a book called Don’t Buy a Car Made on Monday came out, using a humorous title to introduce the idea that what auto workers did over the weekend impacted their work quality on Monday. There was never hard data to support the assertion, but the idea became accepted folklore.
Let’s explore how the same principle may apply to PSA testing.
What the Prostate Does
The prostate secretes prostatic fluid, an integral part of the male reproductive system. This fluid provides the environment for semen to do its job: It serves as an energy source for spermatozoa, helps balance pH during intercourse, and creates the correct viscosity for reproduction.
Prostatic fluid contains a protein called prostate-specific antigen, or PSA. To know what to avoid before a PSA test, you first need to know how PSA gets into your bloodstream.
The Jelly Donut: Prostate Anatomy Explained
Think of the prostate as a prostatic fluid factory, made up of multiple coils of tiny tubes. The inside of each tube produces prostatic fluid, including PSA. These tubes are surrounded by the blood supply, with capillaries running alongside them.
The diagram below shows a cross-section of one of these tubes.
Think of each tiny tube as a miniature jelly donut. The interior jelly is the prostatic fluid (containing PSA), and the donut itself is the layer of cells that produce and contain it.
Anything that disturbs that little miniature donut and allows the jelly to leak out into the bloodstream will raise your PSA.
Why PSA Is Used for Cancer Screening
We use PSA to screen for prostate cancer because abnormal growth within the prostate disturbs the anatomy of those jelly donuts lined up inside it.
Cancer causes the donuts to leak their interior into the bloodstream, elevating PSA.
That’s why elevated PSA can signal a problem worth investigating.
The Problem: PSA Is Not Specific
Any single PSA that comes back abnormally elevated is a false positive 70–80% of the time.
Why so many false positives? Because there are many ways to disturb that jelly donut other than cancer.
What Can Disturb the Prostate (and Raise Your PSA)
Benign Prostatic Hypertrophy (BPH)
As men age, the prostate enlarges. This age-related growth is called benign prostatic hypertrophy. As everything expands and compresses, the jelly donuts become more prone to leaking.
This growth isn’t dangerous, just the normal wear and tear of aging, but your PSA can rise as a result.
Inflammation
If there’s inflammation in the prostate, whether from a bacterial infection or other causes, it creates disturbance in the jelly donut structure. Inflammation makes the junctions between cells more porous, and the jelly (PSA) leaks out.
This is called prostatitis, and it’ll elevate your PSA.
Trauma
Direct trauma to the prostate, whether from medical procedures in that area or from injury, can disturb the anatomy and cause PSA to enter the bloodstream.
Pressure From Cycling
Given the anatomy of sitting on a bicycle, particularly a road bicycle, force is applied to the perineal area. Over a number of hours, this external pressure from the bike seat transmits to the prostate, disturbing those jelly donuts.
Literature documents that a bike ride of several hours can cause a measurable elevation in PSA. So, how long do you need to avoid exercise before a PSA test? At a minimum, 48 hours after any extended cycling.
Sexual Activity
Ejaculation creates leakiness within the prostate’s epithelial cells and basement membrane. The process of secreting and ejaculating prostatic fluid disturbs the jelly donut structure, causing PSA to rise and enter the bloodstream.
How long before a PSA test should you not ejaculate? The same rule applies: at least 48 hours.
What to Avoid Before a PSA Test
For the most accurate PSA result, you need to be at least 48 hours removed from:
- Extended bike riding (especially road cycling)
- Sexual activity
If you have an ongoing prostatitis or infection in the genitourinary tract, you don’t get your PSA tested. Wait until the infection has resolved.
General Principles About PSA Testing
Because false positives outnumber true positives by a three-to-one or four-to-one ratio, the first thing to do when you see an abnormal PSA is repeat it.
Before you freak out, pursue further workup, or move to more sophisticated blood testing, anatomical imaging, or urine testing, push the pause button. Think through all the causes for false positives, make sure none of them apply, and then repeat the test.
I learned this adage in medical school: “A single abnormal test does not a disease make.”
When confronted with an elevated PSA, both the doctor and the patient become alarmed and want to move to the next steps immediately. Resist that urge. A careful, repeated test under the right conditions is the appropriate first response.
Today’s Takeaways
Who gets tested for PSA? Middle-aged men. If you’re too young, you don’t get tested. Too old, you don’t get tested.
And what do a lot of middle-aged guys do on the weekends? They go on long bike rides and have sex.
That artificially elevates their PSA on Monday.
Think about what to avoid before your PSA test: no cycling and no sexual activity for at least 48 hours beforehand. And if you do get an elevated result, don’t panic. Repeat the test under optimal conditions before pursuing further workup.
At Banner Peak Health, we take the time to think through the nuances of testing like this. A thoughtful approach to PSA screening can save you from unnecessary anxiety and invasive follow-up procedures.
