Turnaround times
The quoted turnaround time is from sample receipt in the laboratory, to results authorisation in the Laboratory Information Management system. The times do not include transport of specimen to the laboratory or the administrative process to print and post/email reports. Service users must allow for transport and reporting time when ordering tests.
Clinical background:
Prostate-specific antigen (PSA) is a glycoprotein produced exclusively by prostatic tissue. PSA’s absolute tissue specificity makes it valuable as an important tumour marker for prostatic cancer. Prostatic cancer is prevalent in the older male population and is a major cause of death in men. PSA is useful for monitoring therapy, particularly surgical prostatectomy, because complete removal of the prostate gland should result in PSA being undetectable. PSA is not totally prostate specific e.g. small amounts have been found in breast disease and other tissues (e.g. GI tract, salivary glands, pancreas, colon and lymphoma).
Specimen container paediatric:
Serum (SST or plain tube)
Specimen container adult:
Serum (SST or plain tube)
Minimum volume paediatric:
0.5 mL
Minimum volume adult:
1 mL blood
Sample stability:
Unseparated:
24 hours
Separated:
at +15° to +25°C: 7 days
at +2° to +8°C: 30 days
at -20°C: 3 months
Reference ranges:
<50 years – >2.5 ug/L
50 – 59 years – >3.0 ug/L
60 – 69 years – >4.0 ug/L
70 – 79 years – >6.5 ug/L
80 years and over – >20 ug/L
Factors affecting result:
Samples for PSA must be drawn prior to digital rectal examination (DRE) and ultrasonography (TRUS). Levels are affected by ejaculation and exercise. Catheterization, urinary tract infection and urine retention can result in grossly elevated results. Finasteride (5-a reductase inhibitor used in BPH) results in approximately 50% reduction in circulating PSA. Terazosin (a-1 adrenergic antagonist used in LUTS) has no effect
Other info:
lithium heparin plasma sample also acceptable