Low serum calcium and phosphorus and their clinical performance in detecting COVID-19 patients.

Yang, Caiting; Ma, Xiaoxia; Wu, Jili; Han, Jie; Zheng, Zhe; Duan, Huiping; Liu, Qun; Wu, Changxin; Dong, Yongkang; Dong, Li

BACKGROUND This study aimed to evaluate the predictive performance of low serum calcium and phosphorus in discriminative diagnosis of the severity of COVID-19 patients. METHODS We conducted a single-center hospital-based study and consecutively recruited 122 suspected and 104 confirmed COVID-19 patients during January 24 to April 25, 2020. The clinical risk factors of COVID-19 were identified. The discriminative power of low calcium and phosphorus regarding the disease severity was evaluated. RESULTS Low calcium and low phosphorus are more prevalent in severe/critical COVID-19 patients than moderate COVID-19 patients (OR 15.07, 95%CI 1.59 -143.18 for calcium, OR 6.90, 95%CI 2.43 - 19.64 for phosphorus). The specificity in detecting the severe/critical patients among COVID-19 patients reached 98.5% (95%CI 92.0-99.7%) and 84.4% (95%CI 74.3-91.6%) by low calcium and low phosphorus, respectively, albeit with suboptimal sensitivity. Calcium and phosphorus combined with lymphocyte count could obtain the best discriminative performance for the severe COVID-19 patients (area under the curve (AUC) = 0.80), and combined with oxygenation index was promising (AUC = 0.71). Similar discriminative performances of low calcium and low phosphorus were found between suspected and confirmed COVID-19 patients. CONCLUSIONS Low calcium and low phosphorus could indicate the severity of COVID-19 patients, and may be utilized as a promising clinical biomarker for discriminative diagnosis. This article is protected by copyright. All rights reserved.