A child with acute haematogenous osteomyelitis is started on appropriate antibiotics. After two weeks of therapy the ESR remains 70 mm/hr while CRP has fallen from 120 mg/L to 15 mg/L and the child is afebrile and weight bearing. What does this pattern indicate?

• A Treatment failure requiring a change of antibiotic
• B Laboratory error, as ESR and CRP must always parallel each other
• C Development of chronic osteomyelitis
• D Expected response, since CRP falls faster than ESR during recovery ✓

Explanation

CRP rises within hours and normalises within one to two weeks of effective therapy, whereas ESR peaks later and may remain elevated for several weeks because it reflects fibrinogen and immunoglobulin levels that clear slowly. A falling CRP with clinical improvement is the expected trajectory and is the preferred marker for monitoring response. A persistently rising or plateaued CRP, not a lingering ESR, signals treatment failure.

Reference: Tachdjian's Pediatric Orthopaedics, 5th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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