Prostate-specific antigen test

Prostate-specific Antigen Test

The prostate-specific antigen (PSA) test is a blood test primarily used to screen for prostate cancer in men. The test measures the level of prostate-specific antigen, a protein produced by both cancerous and noncancerous tissue in the prostate, a small gland that sits below a man's bladder.

Background

The prostate gland is part of the male reproductive system and is responsible for producing seminal fluid. PSA is a protein that helps liquefy semen, allowing sperm to swim freely. While PSA is mostly found in semen, small amounts are also present in the blood.

Purpose of the Test

The PSA test is used for several purposes:

• Screening for Prostate Cancer: The primary use of the PSA test is to screen for prostate cancer in men, especially those over the age of 50 or those with a family history of the disease.
• Monitoring Prostate Cancer: For men who have been diagnosed with prostate cancer, the PSA test can help monitor the effectiveness of treatment or check for recurrence.
• Diagnosing Prostate Conditions: Elevated PSA levels can also indicate other prostate conditions, such as benign prostatic hyperplasia (BPH) or prostatitis.

Procedure

The PSA test is a simple blood test. A healthcare professional will draw a small amount of blood from a vein in the arm, usually at a clinic or hospital. The blood sample is then sent to a laboratory for analysis.

Interpreting Results

PSA levels are measured in nanograms per milliliter (ng/mL) of blood. Generally, a PSA level below 4 ng/mL is considered normal, while levels above 4 ng/mL may indicate the need for further testing. However, there is no specific normal or abnormal level of PSA in the blood, and levels can vary based on age and other factors.

Factors Affecting PSA Levels

Several factors can affect PSA levels, including:

• Age: PSA levels tend to increase with age.
• Prostate Size: Larger prostates produce more PSA.
• Prostate Infections or Inflammation: Conditions like prostatitis can elevate PSA levels.
• Medical Procedures: Recent procedures on the prostate, such as a biopsy or surgery, can temporarily raise PSA levels.
• Medications: Certain medications, such as those used to treat BPH, can lower PSA levels.

Controversies and Considerations

The use of the PSA test for routine screening is controversial. While it can help detect prostate cancer early, it can also lead to overdiagnosis and overtreatment. Some prostate cancers grow so slowly that they may never cause harm during a man's lifetime, leading to unnecessary treatments that can have significant side effects.

Also see

• Prostate cancer
• Benign prostatic hyperplasia
• Prostatitis
• Digital rectal examination