PSA / P30
Definition
Prostate-specific antigen, a kallikrein-family serine protease secreted by prostatic epithelium. Present in seminal plasma at 0.5 to 2 mg/mL. The standard confirmatory immunological marker for semen in forensic casework.
- Full name
- Prostate-specific antigen
- Enzyme family
- Kallikrein-family serine protease
- Concentration in semen
- 0.5 to 2 mg/mL
- Role
- Standard confirmatory marker for semen in casework
Common questions
Why is PSA/p30 used as a confirmatory test rather than only a screening test?+
Unlike presumptive acid phosphatase color tests, immunological detection of PSA/p30 with an antibody-based assay is specific enough to confirm the presence of seminal fluid, including in cases of azoospermia where no sperm cells are present to identify microscopically.
Can PSA/p30 confirm semen even in a vasectomized individual?+
Yes. Because PSA is secreted by the prostate rather than produced in sperm cells, it remains present in seminal plasma after a vasectomy, so PSA/p30 testing still confirms semen when microscopic sperm search would otherwise come back negative.
Related terms
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- Azoospermia
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- Lateral-Flow Immunochromatographic Assay
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