From the Research
The Erythrocyte Sedimentation Rate (ESR) typically does not show significant decrease within 24 hours after starting antibiotics. ESR is a non-specific inflammatory marker that tends to change slowly, usually taking several days to weeks to normalize even when appropriate antibiotic therapy has been initiated. While the clinical response to antibiotics may begin within 24 hours (such as fever reduction or symptom improvement), the ESR often lags behind clinical improvement. This delayed response occurs because ESR measures how quickly red blood cells settle in a tube of blood, which is influenced by plasma proteins like fibrinogen and immunoglobulins that remain elevated for longer periods during the inflammatory process. For monitoring response to antibiotic therapy, other markers like C-reactive protein (CRP) may show more rapid changes, often decreasing within 24-48 hours of effective treatment 1. When tracking infection resolution, it's essential to consider both clinical improvement and trends in inflammatory markers over time rather than expecting significant ESR changes within the first 24 hours of antibiotic therapy.
Some key points to consider when interpreting ESR results include:
- ESR is not a useful screening test for asymptomatic persons and is most useful in specific clinical contexts, such as diagnosing temporal arteritis or monitoring disease activity in conditions like rheumatoid arthritis 2, 3.
- An unexplained increase in ESR is generally transitory and seldom due to serious disease, but an ESR value exceeding 100 mm/hr has a high predictive value for serious underlying disease 2.
- The use of ESR should be judicious, considering its limitations and the potential for false-positive results, which can lead to unnecessary additional testing and costs 2, 3.
- Recent studies focus more on the pharmacokinetics and pharmacodynamics of antibiotics rather than the direct effect on ESR, highlighting the importance of adequate antibiotic dosing and monitoring in critically ill patients 4.
Given the information available, it is not expected that ESR would significantly decrease within 24 hours after starting antibiotics, and clinical decisions should be based on a comprehensive assessment of the patient's condition, including clinical improvement, trends in inflammatory markers, and other relevant factors.