AboutNeha Dahiya MD Expertise I can help patients understand their lab report results, help them with queries regarding what pretest preparation is required. How often a follow up test needs to be done. What does a particular tissue biopsy report mean in everyday English. I can explain the biopsy or cytology procedure. I can deal with Histopathology / cytology / clinical pathology and clinical chemistry queries. Helping in this manner will be my contribution to the community.
Experience I am a pathologist and director of clinical laboratory services. I have been a practicing pathologist for last 9 years in a 350 bed multi specialty hospital laboratory.
Organizations Indian association of pathologists and microbiologists.
MIAC - Member International Academy of Cytology
International association of Pathologists - indian division
Indian association of Cytology
Question This is a question about the method used to report results from a Bayer Chemiluminescent test. Basically, what is the standard error of measure for this test? And two related questions: a) is a reported difference of 0.02 mg/ml statistically significant? b) by custom and normal usage is there a minimum amount of PSA reported instead of a descriptive phrase such as "no measurable amount"?
Thank you for your attention.
Answer Hello Robert:
PSA is a screening test to assess the prostrate. PSA levels below 4.0ng/ml are considered normal. However there have been reports of cancer with PSA levels below 4.0 ng/ml
There is no specific normal or abnormal PSA level. Various factors, such as inflammation (e.g., prostatitis), physical activity etc can cause a man’s PSA level to fluctuate. PSA values can also vary somewhat from laboratory to laboratory. All equipment do not detect below the given normal range.
I am not sure what is the exact standard error in Bayer's method, but all labs report with upto 80 to 85% accuracy. This is because of systemic error introduced due to number of factors like - condition / service of equipment, type of reagents used, lot number of reagents, temp of reagents etc.
0.02ng/ml difference is not very significant. Every time you will be tested the value will be different. The value obtained is reported with a normal range or margin of error. What is more important is that is there a persistent increase in value. In addition it has to be correlated with age and clinical features
I hope I havent confused to with such a lengthy answer.
