Which of the following is NOT a negative acute-phase reactant?

• A. Albumin
• B. Transferrin
• C. Ferritin
• D. Antithrombin

Answer: (C)

During an acute inflammatory response, the liver shifts production toward positive acute-phase reactants (which rise) and away from negative acute-phase reactants (which fall). Ferritin behaves as a positive acute-phase reactant; its level increases in inflammation because cytokines like IL-6 stimulate hepatic synthesis and ferritin helps sequester iron to limit bacterial growth. In contrast, albumin, transferrin, and antithrombin are negative acute-phase reactants, meaning their concentrations decrease during this response. So ferritin is not a negative acute-phase reactant, which is why it’s the correct choice in this context. (Note: ferritin can be elevated for other reasons as well, such as iron overload or liver disease, but in the inflammatory setting it acts as a positive acute-phase reactant.)