OBJECTIVES: Patients who develop cytokine storm while they have coronavirus disease 2019 (COVID-19) experience more severe symptoms. This article aims to evaluate the effect of biochemical parameters on the clinical course of the disease in patients treated with tocilizumab (TCZ) due to cytokine storm. METHODS: Medical documents of patients with COVID-19 were searched retrospectively. Patients who entered cytokine storm were classified as group 1 and divided into two subgroups as patients who were followed up in the ward and in the intensive care unit (ICU). Less severe COVID-19 patients who did not enter cytokine storm were included in the control group as group 2. RESULTS: A total of 522 patients with COVID-19 infection were included in the study. The mean age was 62.0 ± 15.6 years, and the majority were male (64.4%). Hypertension and diabetes mellitus were the two most common diseases, seen in 50.8% and 29.9%, respectively. There were 392 patients with TCZ application (group 1) and 130 patients without TCZ (group 2). Significantly higher serum glucose, magnesium, and sodium and lower calcium levels were present in group 1 than in group 2 (<0.001). Hypocalcemia, hypernatremia, hypermagnesemia, and hyperkalemia were more frequently detected in the ICU compared with the patients treated in the wards ( 0.001, 0.001, 0.039, and 0.001, respectively). CONCLUSIONS: Following up closely electrolyte disturbances may support patient survival and decrease the probability of ICU necessity. This approach should be taken before the development of important disorders to be effective in the treatment process of the main disease.