Understanding PSA Levels
PSA is measured in nanograms per millilitre (ng/mL). The specific “normal” range can vary, but traditionally, a PSA less than 4.0 ng/mL has been considered normal. However, some doctors now use a threshold of 2.5 or 3.0 ng/mL.
Age-Specific Ranges
PSA levels tend to rise with age. Therefore, age-specific ranges have been developed to interpret PSA levels more accurately:
40-49 years: 0-2.5 ng/mL
50-59 years: 0-3.5 ng/mL
60-69 years: 0-4.5 ng/mL
70 and older: 0-6.5 ng/mL
PSA Velocity
It’s not just the absolute value of the PSA that’s important, but also how quickly it changes. A rapid rise in PSA levels over time, known as PSA velocity, can be indicative of prostate cancer even if the absolute values are not above the traditional threshold.
PSA Density
This considers the size of the prostate. Two men might have the same PSA level, but if one has a larger prostate, the density (PSA level divided by the volume of the prostate) would be lower, which might be less concerning.
Free vs. Bound PSA
PSA exists in two forms in the blood: free (not bound to proteins) and bound (attached to proteins). A lower percentage of free PSA can indicate a higher risk of prostate cancer. Typically, if the PSA is between 4 and 10 ng/mL, a free-to-total PSA ratio is calculated. A ratio below 10-15% means a higher risk of prostate cancer.