Prostate Health Index (PHI) Calculator

Formula

p2PSA (%[-2]proPSA isoform) in pg/mL; fPSA (free PSA) and tPSA (total PSA) in ng/mL. Values must come from the Beckman Coulter Access Hybritech assays for the interpretation table below to apply.

Enter Laboratory Values

Result

Interpretation Table (tPSA 4–10 ng/mL)

Source: Beckman Coulter manufacturer risk categories, derived from men with tPSA 4–10 ng/mL undergoing biopsy.

How PHI Helps in Detecting Prostate Cancer

• The problem: Total PSA is organ-specific but not cancer-specific. In the 4–10 ng/mL "gray zone" only about 25% of biopsied men have cancer, so most biopsies in this range are negative. BPH and prostatitis also raise PSA.
• p2PSA: [-2]proPSA is an isoform of free PSA found in higher proportion in prostate cancer tissue. Combining it with fPSA and tPSA gives better specificity than tPSA or %fPSA alone.
• Reducing unnecessary biopsy: A low PHI (below 27) identifies men with a low probability of cancer, in whom biopsy can be deferred with structured follow-up. This is most relevant in men with tPSA in the gray zone and a normal DRE.
• Clinically significant cancer: Higher PHI values are associated with a greater likelihood of higher-grade disease (Gleason score 7 or above), which helps prioritise men who need biopsy or MRI-guided evaluation.

Applicability and Limitations

• Labelled use: men aged 50 years or older, tPSA 4–10 ng/mL, and a non-suspicious digital rectal examination. The published risk table is derived from this range.
• tPSA 2–4 ng/mL: Several studies have evaluated PHI in the 2–10 ng/mL range, and the score is calculated the same way. The probabilities above were not derived from this sub-range, so interpret them with caution.
• Use results from the Beckman Coulter Access Hybritech PSA, free PSA and p2PSA assays only. Values from other assays are not interchangeable.
• PHI does not replace clinical judgement. Consider age, family history, DRE, prostate volume, PSA density, prior biopsy, multiparametric MRI, and the effect of 5-alpha-reductase inhibitors, recent infection or instrumentation on PSA.
• PHI is not absolute evidence for or against cancer. Benign conditions can raise PHI, and a low PHI does not exclude cancer.