Acid Phosphatase

Function

Acid Phosphatase (ACP) is an enzyme found in various tissues, including the bone, liver, spleen, and red blood cells, but its highest concentration is found in the prostate gland. It functions best in acidic environments and is responsible for breaking down phosphate esters.

Why it is Ordered

Historically, this test was the primary marker for diagnosing and monitoring prostate cancer. However, it has largely been superseded by the more sensitive Prostate-Specific Antigen (PSA) test. Today, it is ordered to:

• Monitor the progression of advanced prostate cancer, especially when it has metastasized to the bone.
• Investigate certain bone diseases (e.g., Paget's disease).
• Assist in forensic investigations, as it is found in high concentrations in seminal fluid.

Associated Conditions

• Prostate Cancer: Specifically metastatic stages where the enzyme leaks into the bloodstream.
• Bone Disorders: Conditions like Gaucher's disease or metastatic bone lesions can elevate the non-prostatic fraction of the enzyme.
• Blood Disorders: Hemolytic anemia or thrombocytosis can cause elevations due to enzyme release from damaged blood cells.
• Prostatitis: Inflammation or trauma to the prostate can cause temporary spikes.

While ACP is less specific than PSA, it remains a valuable tool in specific clinical contexts and as part of a comprehensive oncology panel.