Free Prostate Specific Antigen (FPSA)

The free Prostate Specific Antigen (FPSA) ratio is a measurement used when the total Prostate Specific Antigen (TPSA) level is in a borderline range. It helps to provide more information about the prostate.

What it is

Prostate Specific Antigen (PSA) is a protein produced by cells in the prostate gland, a small gland in men that sits below the bladder and surrounds the urethra. PSA is normally found in small amounts in the blood.

There are two forms of PSA circulating in the blood:

• Total PSA (TPSA): This is the overall amount of PSA in the blood, including both free and bound forms.
• Free PSA (FPSA): This is PSA that is not attached to other proteins in the blood.

The FPSA ratio is calculated by dividing the amount of free PSA by the total PSA. This ratio is expressed as a percentage.

Why it matters

When a TPSA test result falls into a 'grey area' or borderline range, it can be difficult for doctors to determine the cause. Elevated TPSA levels can be due to several factors, including an enlarged prostate (benign prostatic hyperplasia or BPH), inflammation of the prostate (prostatitis), or prostate cancer.

The FPSA ratio can help to distinguish between these possibilities. Generally, a higher percentage of free PSA (a higher FPSA ratio) is more often associated with non-cancerous prostate conditions like BPH or prostatitis. Conversely, a lower percentage of free PSA (a lower FPSA ratio) may be more suggestive of prostate cancer.

This is because in prostate cancer, a larger proportion of PSA may be bound to other proteins, leading to a lower free PSA level and thus a lower ratio.

What can cause it to be high or low

The FPSA ratio itself is a percentage, so it's not typically described as 'high' or 'low' in isolation, but rather as a percentage that might be considered more or less indicative of certain conditions.

A lower FPSA ratio (meaning a smaller proportion of free PSA compared to total PSA) can be associated with:

• Prostate cancer.

A higher FPSA ratio (meaning a larger proportion of free PSA compared to total PSA) can be associated with:

• Benign prostatic hyperplasia (BPH) – a non-cancerous enlargement of the prostate.
• Prostatitis – inflammation or infection of the prostate.
• Recent prostate procedures or examinations (though this usually affects TPSA more directly, it can influence the ratio).

It's important to remember that the FPSA ratio is just one piece of information. It's used in conjunction with other factors, including your TPSA level, your age, your medical history, and the results of a physical examination (like a digital rectal examination or DRE), to help guide further investigations.

Lifestyle factors that may help

While the FPSA ratio is a laboratory measurement, certain lifestyle factors can influence prostate health and potentially affect PSA levels. Discussing these with your GP might be beneficial:

• Diet: A diet rich in fruits, vegetables, and whole grains, and lower in red meat and processed foods, is generally considered beneficial for overall health, including prostate health. Some research has explored the role of specific nutrients like lycopene (found in tomatoes) and selenium, but evidence for a direct impact on PSA levels or cancer prevention is not conclusive.
• Weight management: Maintaining a healthy weight can contribute to better overall health. Obesity has been linked to various health issues, and its impact on prostate health is an area of ongoing research.
• Exercise: Regular physical activity is important for general well-being and may play a role in maintaining prostate health.
• Smoking and alcohol: Limiting alcohol intake and avoiding smoking are advisable for overall health and may have implications for prostate health.

Questions to discuss with your GP

If you have had a borderline TPSA result and an FPSA ratio has been discussed, here are some questions you might consider asking your GP:

• What does my specific FPSA ratio mean in the context of my TPSA level and my overall health?
• What are the next steps in assessing my prostate health based on these results?
• Are there any other tests or investigations that might be helpful?
• What are the potential causes for my PSA results, and how likely are they?
• Are there any lifestyle changes you would recommend for my prostate health?
• How often should I have my PSA levels monitored in the future?