Pitfalls in diagnostic gastrin measurements.

Area of Science:

• Endocrinology
• Clinical Chemistry
• Oncology

Background:

• Gastrin measurements are vital for diagnosing gastrinomas, tumors causing Zollinger-Ellison syndrome (ZES).
• Gastrin exists in multiple bioactive forms, and patterns differ in gastrinoma patients, necessitating measurement of all forms.
• Immunoassays, particularly radioimmunoassays (RIAs), were historically used, targeting the active C-terminus.

Purpose of the Study:

• To evaluate the diagnostic sensitivity and analytical specificity of commercial gastrin immunoassay kits.
• To identify the limitations of current kits in accurately measuring all gastrin forms.
• To highlight the need for improved gastrin assays for ZES diagnosis.

Main Methods:

• Analysis of commercial gastrin immunoassay kits.
• Assessment of kit performance regarding diagnostic sensitivity and analytical specificity.
• Examination of cross-reactivity with O-sulfated gastrins and plasma proteins.

Main Results:

• Over half of the examined gastrin kits are unsuitable for diagnostics.
• Kits frequently yield falsely low concentrations by measuring only a single gastrin form.
• Falsely high concentrations can occur due to cross-reactivity with O-sulfated gastrins or plasma proteins.

Conclusions:

• Inadequate diagnostic sensitivity of current gastrin kits can delay ZES diagnosis, leading to severe complications.
• Accurate diagnosis requires assays that measure all bioactive gastrin forms.
• Future assays must utilize antibodies that bind the C-terminal epitope without O-sulfation interference.