Gastroesophageal reflux disease (GERD) is a common digestive condition, representing one of the most frequent reasons for medical examination, especially in pediatric gastroenterology departments. GERD could be associated with biochemical alterations representing either its systemic manifestations or markers of complications. The aim of our paper was to evaluate biochemical parameters secondary to GERD in children. Two hundred and sixty-seven children of both genders aged between 1 month and 18 years who displayed suggestive symptoms for this condition were included in the study and were monitored for a period of 5 years. Depending on the range of symptoms and technical possibilities, the following procedures/investigations were performed: esophageal pH monitoring and imagistic or endoscopic examination, besides specific biochemical investigations. The cohort was sub-divided into two groups: one that included 213 children with confirmed GERD who represented the study group and 54 healthy children where GERD had been excluded, the control group. Out of all the investigated children, 39.0% displayed low hemoglobin values, 43.7% displayed low values of erythrocyte indices (MCH), and 68.5% had increased erythrocyte sedimentation rate (ESR) values, while increased eosinophil levels were recorded in 46.9% of the cases. Such parameters were proven to be a biomarker of suspected eosinophilic esophagitis, whereas 32.9% of the cases displayed high blood glucose values that could be correlated with gastroesophageal reflux symptoms. Other measured parameters (such as magnesium, aminotransferases and proteins) remained within the normal limits, without statistically significant differences compared to in the control group. This condition is diagnosed based on invasive investigations, which are often difficult to accept by the patients’ parents. The biochemical modifications correlated to the clinical manifestations can anticipate the progression of the disease, thus limiting the necessity of performing invasive diagnosis tests.