ABSTRACT
Antistreptolysin O [ASO] levels vary with age group of the study population and geographical location. The aim of the present work was to measure the upper limit of normal [ASO] titer as a referent value among healthy children of age up to 12 years living in El-Behera governorate and near areas. It was undertaken to 300 normal children of age 0-12 years, with no history of recent sore throat infection, they were attending the pediatric and ENT outpatient clinics of Damanhour Medical National Institute [DMNI] during the period from February 2004 to January 2005. The modified Randall method was used for estimating ASO titers. The results showed that the upper limit of normal [ULN] ASO level for the children of age 0 - < 2 years was 147 IU. The ULN, ASO level for the children of age 2- < 6 years was 336.8 IU and that for children of age 6-12 years was 353.2 IU. There were statistically significant difference among the three groups [ANOVA, F=160, P = 0.00]. By multiple comparison, the least significant difference [LSD] showed that the mean difference between children of age group 2 to < 6 years and those of 2 months to < 2 years was 138.6 IU [p= 0.000 and 95% confidence interval was ranging from 120.4 IU to 156.8 IU], and the mean difference between children of age group 6 to 12 years and those of 2 months to < 2 years was 148.2 IU [p= 0.000 and 95% confidence interval was ranging from 129.9 IU to 166.4 IU]. On the other hand the mean difference between children of age group 6 to 12 years and those of 2 to < 6 years was 9.6 IU [p = 0.301 and 95% confidence interval was ranging from] -8.6 [0] IU to 27.8 IU]