Falsely increased prostate-specific antigen concentration attributed to heterophilic antibodies.

We describe a 50-year-old man with a serum total prostatic-specific antigen concentration of 67.6 mug/L (reference range 0-4 mug/L) revealed as part of an annual health check programme. Clinical examination failed to identify any prostatic abnormality, and laboratory investigation indicated positive interference due to heterophilic antibodies.