Introduction: Rheumatic fever is an inflammatory disease that may develop after an infection with streptococcus pyogenes bacteria, Believed to be caused by antibody cross reactivity that can involve heart, joints, skin and brain. Measurement of Anti Streptolysin O (ASO) antibodies to specific streptococcal antigens is therefore necessary for the diagnosis of the preceding group A streptococcal infection.
Aims and Objectives: To determine the upper limit of normal (ULN) of antistreptolysin O (ASO) titers in normal healthy children in the age group of 5-15 years.
Material and Method: A cross sectional study was done on normal healthy children aged 5 -15 years age group divided into 2 groups, group I (5-10 years) & group II (10-15 years). after taking informed consent from the parents ASO titre was done .
Results: out of 120 children included in the study, 60 children in group I and 60 Children in group II.The mean ASO titers for group I was 121.23 and group II was 138.63 ( Table 3) with a standard deviation of 51.58 and 29.50, respectively. There was a statistical difference (p <0.05). The upper limit of normal in our study group was greater in group I (226.20 IU). But the upper limit of normal for the entire group was 212.25 IU. So the upper limit of normal in school age children in our study population can be considered as 212 IU.
Conclusion: ASO titer of 212 IU of this study can be considered as the upper limit of normal value.