A modest AFP result beside a bulky mass

A 27-year-old patient has a painless testicular mass on ultrasound and a 9 cm retroperitoneal nodal mass on computed tomography. Pre-orchiectomy serum alpha-fetoprotein, abbreviated AFP, is 38 ng/mL with a local reference interval of less than 8.1 ng/mL. The result is high, but its magnitude is discordant with the imaging burden. A tumor marker is a measurement, not a diagnosis, so the mismatch is the first laboratory finding that needs attention.

Tumor markers can help with a defined clinical question, including surveillance, prognosis, treatment monitoring, or selected diagnostic support. The same marker can be high in benign disease, and a cancer can be present with no marker elevation. A reference interval describes a tested population for a method, whereas a decision threshold is a clinical action construct. Neither number converts an isolated marker result into proof of cancer.

The bench question is whether the low-for-context AFP should be accepted or investigated before release. Imaging, clinical timing, the assay format, and prior results are evidence that can rank explanations. Release the number only after asking whether its pattern fits the specimen, method, and available clinical context.