In medicolegal investigation of a suspected sexual assault, seminal staining on fabric is confirmed. Acid phosphatase activity is detected at a high level (>200 IU). The presence of which substance, secreted exclusively by the prostate gland, is the MOST specific marker for seminal staining?
- A Prostate-specific antigen (PSA / p30) ✓
- B Lactate dehydrogenase isoenzyme LDH-X
- C Choline
- D Fructose
Explanation
Prostate-specific antigen (PSA, also called p30 in forensic contexts) is the most specific biochemical marker for seminal material because it is produced exclusively by prostatic epithelium. It is detectable even in azoospermic males (vasectomy, azoospermia), making it more useful than sperm morphology. PSA can be detected by immunoassay from dry stains up to several years after deposition. Fructose is produced by the seminal vesicles and is a nutritional substrate for spermatozoa but is less specific. Acid phosphatase (>200 IU/mL) is a presumptive test — vaginal secretions contain background levels. LDH-X is a sperm-specific isoenzyme but less routinely used in forensic settings.
Reference: The Essentials of Forensic Medicine and Toxicology (Narayan Reddy), 34th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.