Introduction: This study is designed to study clinical symptoms in children with elevated lactate: pyruvate ratio to understand the magnitude of respiratory chain disorder. Materials and Method: Children attending pediatric outpatient department in our center who showed clinical symptoms suggestive of inherited metabolic disorder were enrolled into the study. Arterial blood gas, lactate and lactate: pyruvate ratio were analysed by collecting arterial blood from selected children. Clinical symptoms of those children with elevated lactate: pyruvate ratio was evaluated. Result: 304 patients who showed clinical symptoms of either developmental delay without asphyxia, seizures, vomiting, poor suck or weak cry at birth were evaluated. Of them 147 showed one or more of positive biochemical findings such as metabolic acidosis, elevated lactate or lactate: pyruvate ratios which were the basic laboratory data to suspect energy metabolic disorder. Elevated lactate: pyruvate ratio was found in 81 patients, which is one of the biochemical markers to narrow down diagnosis of respiratory chain disorder. Conclusion: Our study showed that suspected energy metabolic disorders are not uncommon. Clinical suspicion is crucial to start further diagnostic profile. Children with delay in attaining milestones despite being born at term without asphyxia need to be referred for metabolic work up. There is a need to create awareness in primary health care providers about this in order to initiate further diagnosis and intervention. Elevated lactate: pyruvate ratio suggests this and warrants further work up. Serum alanine and beta-hydroxy butyrate: acetoacetate ratio may help us to know more about energy metabolic disorders like respiratory chain disorders.
