Low dose aspirin is used due to its antiplatelet effect for the subacute phase of Kawasaki disease(KD). It is usually used for 6-8 weeks, then various hematologic laboratory tests and follow up echocardiography for evaluating coronary abnormalities are performed. Our review investigated the usefulness of various follow up laboratory tests performed at 6 weeks after the onset of KD.

Two hundred eighty-two children diagnosed and hospitalized with KD were identified by reviewing patient's charts. Cases which were diagnosed between January 1997 and December 2004 were included in this study. We reviewed laboratory data including leukocytes, platelet counts, antistreptolysin O(ASO), erythrocyte sedimentation rate(ESR), C-reactive protein(CRP), aspartate aminotransferase( AST), alanine aminotransferase(ALT), urinalysis, and echocardiograms performed at admission and 6 weeks after the onset of KD. Paired t-test and Fisher's exact test, as well as logistic regression tests, were used for the statistical analysis.

At 6th week data, ESR and CRP were still elevated in 35(12.4 percent) and 12(4.3 percent) patients, respectively. Sterile pyuria were all normalized. But, 36 patients(12.8 percent) showed thrombocytosis, 22(7.8 percent) elevated AST, 15(5.3 percent) leukocytosis, and 6(2.1 percent) coronary abnormalities. Coronary abnormalities at the 6th week were only shown in patients with initial abnormalites. Younger age and initial thrombocytosis were risk factors for thrombocytosis at the 6th week.

All children with initial coronary abonormalites should have an echocardiogram at 6 weeks after the onset of fever. In view of case-effectiveness, additional echocardiographic studies are justified only if abnormalities are present at admission. ESR, CRP, and urinalysis performed at the 6 weeks after onset of KD is not significant for clinical information of progression. Platelet count should be estimated at 6th week for a judgement of continuous antiplatelet therapy.