ESR levels in OA can be influenced by which conditions?

• A. Pregnancy
• B. Both pregnancy and infection
• C. Infection
• D. Neither

Answer: (B)

ESR is a nonspecific marker of inflammation. In OA, inflammation is usually minimal, so ESR tends to be normal or only mildly elevated. But ESR can be influenced by other conditions that change plasma proteins or blood properties. Pregnancy raises ESR, especially in later trimesters, due to increases in fibrinogen and other acute-phase reactants and changes in blood volume that promote quicker red cell settling. Infections also raise ESR because the body increases acute-phase proteins like fibrinogen, promoting rouleaux formation and faster sedimentation. Because of its non-specific nature, ESR can be elevated in both pregnancy and infection even if OA is not driving the rise.