Background/Aims: Hyperammonemia causes severe mortality and morbidity when left unnoticed. We aimed to compare the number of ammonia test requests before and after establishing the Department of Pediatric Metabolism (DPM) in a clinic of pediatrics. Methods: The study was conducted retrospectively between 15/11/2022-16/11/2023. Study data were evaluated before (pre-group) and after (post-group) the establishment of DPM. Results: Two hundred eighty-five admissions were assessed in the study. There were 99 admissions in the pre-group and 186 in the post-group. There were 17 admissions for different reasons in the pre-group and 29 in the post-group. The most common reasons for admission were elevated transaminases, seizures, vomiting and metabolic acidosis. Definitive diagnosis was made in 16 (17.6%) patients admitted in the pre-group and 39 (23.8%) in the post-group. The most common diagnoses were genetic syndromes, mitochondrial diseases and organic acidemias. Twenty-one patients were diagnosed with inherited metabolic diseases (IMDs). Mitochondrial diseases were the most commonly diagnosed IMD (8(38%)). From the 15 pediatric subunits, ammonia test was requested from 8 in the pre-group and 13 in the post-group. In the pre-group, the pediatric subunit where ammonia was requested the most was the Pediatric Neurology Polyclinic (n=25 (25.3%)). In the post-group, the subunit that required the highest number of ammonia tests was the DPM (68(23.9%)). In the ROC analysis conducted for the predictive power of the initial ammonia level in requesting a control ammonia test, the area under the curve is 0.927, and the p-value is 0.001. For the cut-off value of 60.3 µmol/l, the sensitivity was 90.9%, and the specificity was 88.6%. Conclusion: After DPM was established, there was an increase in ammonia test requests, in the diversity of reasons for requesting ammonia testing from admissions, and in IMD diagnosis. DPM had a positive effect on pediatricians’ awareness of hyperammonemia.