Diagnostic challenge: Discordant alpha-fetoprotein levels in a patient with hepatoblastoma

Hepatoblastoma is a rare malignant tumor which occurs in childhood. Most of the hepatoblastomas secrete large amounts of alpha-fetoprotein (AFP). Accurate measurement of AFP is crucial for the diagnosis and follow-up of hepatoblastoma. Hook effect is a well-recognized problem that occurs in the automated immunoassay methods for the measurement of tumor markers, especially in the case of AFP. We present a case of a 9-month-old baby, whose diagnosis was delayed because of an unrecognized hook effect, due to which a falsely low value was reported. In the subsequent sample, the test was performed in dilution, and the correct value was obtained. The laboratory staff and clinicians should be alert to the possibility of the Hook effect resulting in falsely low levels.