Procalcitonin as a diagnostic aid in osteomyelitis and septic arthritis.

OBJECTIVES: Plasma procalcitonin (PCT) increases rapidly during bacterial infections but remains low in viral infections and other inflammatory processes. High plasma PCT typically occurs in children with bacterial meningitis, severe bacterial infections, particularly in cases of septic shock or bacteremia, and in renal parenchymal damage. The aim of this study was to test the usefulness of plasma PCT analysis in the diagnosis of osteomyelitis, septic arthritis, and other skeletal inflammatory diseases in pediatric patients admitted because of fever and limping.

METHODS: White blood cell count, erythrocyte sedimentation rate, C-reactive protein, and PCT levels were measured in children admitted to the pediatric department with fever, limping, and suspected osteomyelitis or septic arthritis. PCT levels were measured by an immunochromatography assay, based on monoclonal and polyclonal antibodies against katacalcin.

RESULTS: Forty-four children were evaluated: 12 (27.3%) were diagnosed with osteomyelitis, 11 (25%) had septic arthritis, 5 children (11.4%) were diagnosed as a soft tissue infection, and transient synovitis or reactive arthritis was diagnosed in another 6 children (13.6%). Four children (9.1%) were diagnosed as having juvenile rheumatoid arthritis, and 6 (13.6%) with different diseases. PCT value was elevated in 7 patients (58.3%) with osteomyelitis, and only 3 children (27.2%) with the diagnosis of septic arthritis had a mildly elevated value. Among the children with other diagnosis, there were no positive PCT values (P < 0.001 between skeletal infection and all other diagnosis).

CONCLUSIONS: In this study, PCT was found to be a useful marker in the diagnosis of osteomyelitis and not in septic arthritis. A larger group of patients needed to be studied to confirm our findings.