Clinical signs and laboratory tests in the differential diagnosis of arthritis in children
I. Kunnamo, P. Kallio, P. Pelkonen and T. Hovi
To develop a scheme for primary diagnosis, we analyzed the clinical
findings and laboratory test results in 278 children with arthritis by
using univariate analysis and multivariate logistic regression analysis. An
elevated C-reactive protein (CRP) value, a temperature above 38.5 degrees
C, and a high white blood cell count were independent predictors for the
diagnosis of septic joint infection in patients with acute monoarthritis.
The presence of either of the first two signs had a sensitivity of 100% and
a specificity of 87% for septic arthritis. Sixty-seven percent of all
patients with arthritis were cured within two weeks from the onset of joint
symptoms. In patients whose disease duration exceeded two weeks, a low CRP
value, the absence of fever, and an elevated IgG value were independent
predictors for the diagnosis of juvenile arthritis. Antinuclear antibodies
had a specificity of 100% and a sensitivity of 25% for juvenile arthritis
or other connective tissue diseases. We recommend that laboratory tests
indicated for all children with joint symptoms include determinations of
the erythrocyte sedimentation rate and the CRP value, both total and
differential leukocyte counts, urinalysis, and a bacterial culture of a
throat smear. When arthritis is prolonged or when enteroarthritis is
suspected, tests for antinuclear antibodies and serum immunoglobulins,
serologic tests for Yersinia and Salmonella, and stool bacterial cultures
should be included.
