An evaluation of a kinetic acid phosphatase method

Area of Science:

• Clinical Chemistry
• Biochemical Diagnostics
• Urology

Background:

• The diagnostic utility of acid phosphatase assays, particularly for prostate cancer, relies on enzyme specificity.
• Alpha-naphthyl phosphate has been proposed as a substrate for a highly specific assay for prostatic acid phosphatase.
• However, this claimed specificity has been questioned, necessitating further clinical evaluation.

Purpose of the Study:

• To evaluate a new kinetic acid phosphatase method using alpha-naphthyl phosphate as the substrate.
• To assess the specificity of this method across diverse patient populations, including those with and without prostate cancer.

Main Methods:

• A kinetic assay for acid phosphatase was performed using alpha-naphthyl phosphate.
• Patient cohorts included urology clinic attendees, individuals with uremia, multiple myeloma patients, and those who underwent prostatic biopsies.
• A total of 311 patients were evaluated, with 270 confirmed to be free of prostate cancer.

Main Results:

• Seven out of 270 patients without prostate cancer exhibited elevated acid phosphatase values.
• These elevated values were associated with diagnoses such as fibromuscular glandular hyperplasia, multiple myeloma, and uremia.
• Fifteen of 17 patients with metastatic prostate cancer showed elevated acid phosphatase, while one of 24 patients with non-metastatic prostate cancer also had elevated levels.

Conclusions:

• The alpha-naphthyl phosphate method for acid phosphatase is not exclusively specific to the prostatic isozyme.
• Elevated acid phosphatase levels can occur in non-prostatic conditions, impacting diagnostic accuracy.
• Further investigation is needed to refine or validate the use of this substrate in clinical settings for prostate cancer detection.