Calcium, phosphorus, magnesium levels in frequent respiratory tract infections

It was well documented that calcium (Ca), phosphorus (P), and magnesium (Mg) participate in many physiological processes. We aimed to study the changing trend of serum levels of Ca, P, and Mg in frequent respiratory tract infections (FRTI) in children.

A retrospective study was performed in our centre. A total of 213 FRTI cases and 33 controls were enrolled in our study. We analyzed the correlation between serum Ca/P/Mg levels and inflammatory indexes by using Spearman correlation analysis. Standard mean difference (SMD) was applied to test the differences of serum Ca/P/Mg levels between FRTI subgroups and controls. In terms of the findings of SMD between Ca/P/Mg status between FRTI subgroups and controls, receiver operating characteristics (ROC) curve analysis was further applied to test the association between serum Ca level and bronchitis, parainfluenza virus infection, influenza B virus infection and cytomegalovirus infection.

Serum Ca level was significantly associated with white blood cell (WBC), platelet (PLT) and procalcitonin (PCT) (p = 0.006; p < 10^-4; p = 0.004). Serum P level was markedly associated with eryhtrocyte sedimentation rate (ESR) and PCT (p = 0.018; p < 10^-4). Controls showed significantly lower serum Ca level than that among bronchitis (p = 0.001), parainfluenza virus infection (p = 0.027), influenza B virus infection (p = 0.017), cytomegalovirus infection (p = 0.029), and two pathogens infected (p = 0.020). ROC curve analysis showed that serum Ca level was significantly associated with bronchitis (p = 0.047) and influenza B virus infection (p = 0.049).

Serum levels of Ca and P may reflect the inflammatory status in children with FRTI. Alteration of serum Ca level may predict the risk of bronchitis and influenza B virus infection. Keeping the homeostasis of Ca, P, and Mg may be important for the prevention and treatment of FRTI.