Prostate-specific antigen (PSA) is a protein produced primarily by the cells of the prostate gland. While most PSA remains in the semen, a small amount naturally leaks into the bloodstream, where its level can be measured with a simple blood test. This test serves as a widely used screening tool to assess the risk of prostate cancer, although elevated levels can be caused by various non-cancerous conditions. Because the prostate is susceptible to many influences, the amount of PSA released into the blood can fluctuate significantly, making interpreting a single test result challenging. Understanding the factors that cause these changes is important for accurately evaluating prostate health over time.
Temporary Physiological and Lifestyle Influences
Several common daily activities and natural bodily changes can cause temporary spikes in PSA levels that are not indicative of serious disease. Ejaculation, for instance, can cause a transient increase in PSA, as the prostate contracts vigorously to release the protein into the seminal fluid. Experts generally advise abstaining from ejaculation for at least 48 hours before a PSA test to ensure a more accurate baseline reading. This temporary rise can be enough to push a borderline result into a concerning range.
Intense physical activities that put direct pressure on the perineum, the area between the anus and the scrotum, can also momentarily elevate PSA. Prolonged cycling or horseback riding are the most common culprits, as the sustained pressure can mechanically irritate the prostate. Men are typically advised to avoid such strenuous activities for 48 hours before their blood draw to minimize this external influence.
A slow, steady increase in PSA levels is also a natural consequence of the aging process. As men age, the prostate gland tends to gradually increase in size, meaning there is simply more tissue present to produce the PSA protein. This age-related rise is considered normal, which is why age-adjusted PSA reference ranges are sometimes used to interpret a result.
Chronic Conditions Causing Sustained Elevation
The most frequent causes of sustained PSA elevation unrelated to cancer are two common prostate conditions: Benign Prostatic Hyperplasia (BPH) and Prostatitis. BPH, often called an enlarged prostate, affects many older men and causes the prostate gland to grow larger over time. The increased volume of glandular tissue produces a proportionally higher amount of PSA, leading to a chronically elevated baseline level.
Prostatitis, which is inflammation or infection of the prostate, is another major cause of elevated PSA. When the prostate tissue becomes inflamed, the protective barrier between the gland and the bloodstream breaks down, allowing large amounts of PSA to leak into the blood. Acute bacterial prostatitis can cause dramatic non-cancerous spikes, sometimes pushing PSA levels temporarily above 20 or 30 ng/mL.
Chronic forms of prostatitis or urinary tract infections can also cause moderate but persistent elevations. Unlike the temporary spikes from exercise, the elevation from these conditions is sustained until the underlying inflammation or infection is resolved, often requiring treatment with antibiotics or anti-inflammatory medications. Once the inflammation subsides, the PSA level is expected to drop back toward its individual baseline.
Influence of Medical Procedures and Treatments
Various medical interventions involving the prostate can cause either a sharp, temporary spike or a sustained, intentional reduction in PSA levels. Procedures that physically manipulate the prostate, such as a recent prostate biopsy, cystoscopy, or the insertion of a urinary catheter, can directly cause the release of PSA into the blood. A prostate biopsy causes significant trauma and can dramatically elevate the reading, necessitating a waiting period of at least six weeks before a reliable PSA test can be performed. Even a routine digital rectal exam (DRE) can cause a small, transient rise, which is why the blood draw is generally taken before the physical examination.
Conversely, certain medications are designed to significantly lower PSA levels. Drugs known as 5-alpha reductase inhibitors (5-ARIs), such as finasteride and dutasteride, are often prescribed to treat BPH or male pattern baldness. These medications work by shrinking the prostate tissue, which in turn reduces the amount of PSA produced. Hormonal treatments used to manage prostate cancer also suppress PSA to very low or undetectable levels, using the protein as a marker for treatment effectiveness.
Clinical Interpretation of PSA Changes
Because PSA levels fluctuate for so many reasons, clinicians rarely rely on a single elevated number for assessment; instead, they focus on the pattern of change over time. One method is calculating the PSA velocity, which measures the rate at which the level rises over a series of tests, usually taken over an 18 to 24-month period. A rapid rise is often considered more suspicious than a single high reading.
Doctors also use a secondary test called the Free vs. Total PSA Ratio when the total PSA level is in the ambiguous range of 4 to 10 ng/mL. PSA in the blood exists in two forms: bound to other proteins or unbound, referred to as “free” PSA. Benign conditions tend to produce more free PSA, resulting in a higher ratio of free-to-total PSA.
A lower free PSA ratio suggests that a larger proportion of the protein is bound, which is more commonly associated with prostate cancer. This ratio, combined with age and the size of the prostate gland, provides context that helps the physician manage the uncertainty of a fluctuating PSA result. These advanced measures allow for a more nuanced risk assessment.