Errors in measurement and reporting of serum markers in patients with germ cell tumors.

Elevation of the serum value of either human chorionic gonadotropin or alpha-fetoprotein in patients with germ cell testicular tumors is often accepted as evidence for persistent malignancy in the absence of histologic confirmation. These laboratory values are not subject to review and confirmation, unlike histologic diagnosis. We report 3 cases in which serum marker values were incorrectly reported to be elevated by commercial laboratories over a thirteen-month period and suggest a method for handling serum samples to avoid errors in diagnosis.