The prognostic significance of the ionized calcium value measured at admission in patients with sepsis in the emergency intensive care unit

Calcium plays an essential role in nearly all cellular processes. Therefore, cellular and systemic calcium concentrations are tightly regulated. The serum total calcium concentration is affected by many factors such as hypoalbuminemia. Ionized calcium is more important than corrected calcium for the assessment of calcium metabolism. Derangements in tight regulation of calcium metabolism frequently occur during sepsis. However, the prognostic value of ionized calcium in patients admitted to the intensive care unit (ICU) due to sepsis is not known exactly. The aim of our study is to evaluate the prognostic importance of ionized calcium level in patients admitted to the emergency ICU due to sepsis. Material and methods Between January 2020 and December 2021, within a 24 month period, 228 patients who were admitted to the emergency department of Necmettin Erbakan University Faculty of Medicine and hospitalized with the diagnosis of sepsis in the emergency ICU were included in the study. Sepsis-3 definition was considered in the diagnosis of sepsis. Demographic characteristics, vital signs, Sequential Organ Failure Assessment (SOFA), Quick Sequential Organ Failure Assessment(qSOFA) score, admission ionized calcium and corrected calcium levels, admission blood gas analysis, hemogram and biochemistry parameters, vasopressor requirement and oxygen support requirement in the first 24 hours, length of emergency ICU stay and hospital stay, hospital outcome, 7-day and 28-day mortality were recorded retrospectively and analyzed. Results The mean age of the patients was 72.1 ± 14.6 (20-102 years). The male/female ratio was 1.3/1. The mean ionized calcium level of the cases was 1.07 ± 0.20 mmol/l, and the corrected by albumin calcium level was 9.20 ± 1.06 mg/dl. According to ionized calcium, 57.5% had hypocalcemia, 32% had normocalcemia, and 10.5% had hypercalcemia. These rates were 29.4%, 64% and 6.6%, respectively, according to corrected calcium. In first 24 hours mechanical ventilation and vasopressor treatment were required in 20.2% and 30.3%, respectively. 22.4% of the patients died in the emergency ICU. While the 7-day mortality rate 25.4%, the 28-day mortality rate was 47.8%, the hospital mortality rate was 57.9%. Ionized calcium level did not differ according to 7-day mortality (p=0.136), hospital outcome (p=0.281), and 28-day mortality (p=0.398). In ROC analyses, ionized calcium level was not predictive of 7-day mortality (AUC=0.561, 95% CI 0.494-0.626, p=0.188), hospital outcome (AUC=0.525, 95% CI 0.458-0.591, p=0.517), and 28-day mortality (AUC=0.512, 95% CI 0.445-0.578, p=0.761). Ionized calcium level was not correlated with SOFA, length of ICU stay, and length of hospital stay, which were significant indicators of mortality. Conclusion Ionized calcium can provide more accurate results than corrected total serum calcium in demonstrating calcium levels. The frequency of hypocalcemia is high in patients with sepsis. However, the prognostic value of ionized calcium is limited in patients admitted to the emergency ICU due to sepsis. Key words: Ionized calcium, Corrected calcium, Sepsis, Intensive care unit