[Dynamic change in vitamin D level in infants/toddlers with severe pneumonia and a correlation analysis].

Objective: To study the correlation of dynamic change in serum 25-hydroxy vitamin D [25(OH)D] level with the disease severity and related laboratory markers in infants/toddlers with severe pneumonia.

Methods: A total of 132 infants/toddlers with severe pneumonia who were hospitalized between March 2017 and March 2018 were enrolled as the severe pneumonia group. According to the disease severity on admission and after one week of treatment, they were further divided into non-critical group (41 children on admission and 78 after one week of treatment), critical group (59 children on admission and 35 after one week of treatment), and extremely critical group (32 children on admission and 19 after one week of treatment). A total of 142 infants/toddlers who underwent physical examination during the same period of time were enrolled as the healthy control group. The serum levels of 25(OH)D, procalcitonin (PCT), and N-terminal pro-brain natriuretic peptide (NT-proBNP) were measured on admission and after one week of treatment for the severe pneumonia group, and the serum level of 25(OH)D was measured on admission for the healthy control group. According to the 25(OH)D level after one week of treatment, the children with severe pneumonia were divided into increased vitamin D (VD) group with 81 children and reduced VD group with 51 children, and a comparative analysis and a correlation analysis were performed.

Results: The severe pneumonia group had a significantly lower mean 25(OH)D level than the healthy control group (P<0.05), and all the three subgroups of different severities had significantly lower 25(OH)D level than the healthy control group (P<0.05). On admission and after one week of treatment, the non-critical group had a significantly higher 25(OH)D level than the critical and extremely critical groups (P<0.01), and the critical group had a significantly higher 25(OH)D level than the extremely critical group (P<0.05). The extremely critical and critical groups had significantly higher serum levels of PCT and NT-proBNP than the non-critical group on admission and after one week of treatment (P<0.05). After one week of treatment, compared with the reduced VD group, the increased VD group had a significantly less serious condition. At discharge, the increased VD group had a significantly better outcome compared with the reduced VD group (P<0.01). In the children with severe pneumonia, the change value of serum 25(OH)D level after treatment was negatively correlated with the change values of PCT and NT-proBNP (r=-0.597 and -0.404 respectively; P<0.01).

Conclusions: The change in VD level is correlated with the severity of severe pneumonia in infants/toddlers and can be used as an index for disease monitoring. VD supplementation may help with disease recovery.