Objective: To examine the association of serum 25-hydroxyvitamin D [25(OH)D] concentrations with critical and severe hand, foot and mouth disease (HFMD) and assess the clinical significance and prognostic effect of 25(OH)D concentrations in children with HFMD. Methods: This is a prospective observational study. The 138 children with HFMD were divided into common (49 cases), severe (52 cases), and critical (37 cases) HFMD groups. Another 59 healthy children undergoing outpatient medical examinations during the same period were chosen as the control group. Serum 25(OH)D concentrations were measured in all the subjects, and each group was subdivided by serum 25(OH)D concentration into 25(OH)D normal (≥30 ng/mL); insufficiency (20–29.9 ng/mL), and deficiency (<20 ng/mL) groups. The pediatric critical illness score (PCIS) was recorded for the critical and severe HFMD group upon admission to the pediatric intensive care unit (PICU). Children with critical and severe HFMD were also monitored for blood lactate (LAC), serum calcium ions (Ca++), D-dimer (DD), lactate dehydrogenase (LDH), and creatine kinase-MB (CK-MB) levels; the incidences of brainstem encephalitis, neurogenic pulmonary edema, and circulatory failure; and the 14-day mortality rate. Results: Serum 25(OH)D concentrations were generally low in all groups. The critical HFMD group showed a significantly lower serum 25(OH)D mean concentration (20.0 ± 8.4 ng/mL) and a higher proportion of deficiency (18%) compared with the control group (28.1 ± 6.6 ng/mL, 8%), common (29.5 ± 8.1 ng/mL, 10%) and severe (31.9 ± 9.7 ng/mL, 8%) HFMD groups (p
< 0.05). In the critical and severe HFMD groups, the 25(OH)D deficiency group had lower PCISs than the 25(OH)D normal and insufficiency groups (p
< 0.05); and had higher values than the latter two groups for LAC, LDH, CK-MB and DD; and the incidences of brainstem encephalitis, neurogenic pulmonary edema, circulatory failure, and mortality (p
< 0.05). The death group showed significantly lower serum 25(OH)D concentrations and PCISs than the survival group (p
< 0.05) and had higher LAC, LDH, CK-MB and DD levels and higher incidences of brainstem encephalitis, neurogenic pulmonary edema, and circulatory failure (p
< 0.05). Logistic regression analysis revealed that the serum 25(OH)D concentration was an independent factor that influenced mortality in children with critical and severe HFMD. Conclusions: In this study, we find the serum 25(OH)D concentrations are substantially reduced in children with critical and severe HFMD and are associated with the severity of HFMD. The serum 25(OH)D concentrations may have clinical value for determining the progression of critical HFMD and predicting the risk of death. Further evidence is needed before it can be stated that 25(OH)D concentrations have clinical value in HMFD diagnosis.
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