The rate of change in serum PSA levels may serve as an early indicator for prostate carcinoma.
PSA velocity in ng/mL/year =
= ((PSA at time 2 in ng/mL) - (PSA at time 1 in ng/mL)) / (period between time 1 and time 2 in years)
If a series of data is available, then the slope of the line through the data will be the PSA velocity.
Interpretation:
• A velocity of 0.75 ng/mL/year in a testing series of at least 3 tests performed with an adequate interval between is considered an indication for further workup.
Limitations:
• If the PSA measurements are performed too closely together, then a high velocity can be seen with even a minimal increase in the PSA due to test variability.
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