Objective: To probe into the significance of blood lactate level on condition and evaluation of prognosis of children with severe hand-foot-mouth disease. Methods: Totally 362 children with severe hand-foot-mouth disease admitted into Hunan Children’s Hospital from Jan. 2012 to Dec. 2013 were extracted as the research objects. According to occurrence of brainstem encephalitis

all patients were divided into 68 cases in the critically ill group and 294 cases in the non-critically ill group. According to different prognosis

all patients were divided into 25 cases in the death group and 337 cases in the non-death group. Blood lactate level was detected after admission. Complications of brainstem encephalitis

pulmonary edema

pulmonary hemorrhage and circulatory failure were observed. Differences of blood lactate level in children with different prognosis were compared

effects of blood lactate level on the diagnosis of various complications were analyzed. Results: The blood lactate level in the critically ill group was (3.97±3.77) mmol/L

and in the non-critically ill group was (1.46±0.80) mmol/L; the blood lactate level in the death group was (5.67±4.10) mmol/L

and in the non-death group was (1.47±0.86) mmol/L; the critically ill group and the death group were significantly higher than the non-critically ill group and the non-death group (P<0.05). Taking the blood lactate level of 3.2 mmol/L as the cut-off value

the incidence and mortality of brainstem encephalitis

pulmonary edema

circulatory failure

pulmonary hemorrhage in the >3.2 mmol/L group were higher than those in the ≤3.2 mmol/L group

and the difference was statistically significant (P<0.05). The area under the ROC curve for the diagnosis of pulmonary hemorrhage

circulatory failure

and prognosis of blood lactate level were 0.81(0.70

0.92)

0.82(0.74

0.94)

and 0.85(0.74

0.96). With the blood lactate level of 3.2 mmol/L as the cut-off value

the maximum Youden index was 1.69

which had higher sensitivity and specificity for predicting the occurrence of pulmonary edema

pulmonary hemorrhage

circulatory failure and death. Conclusion: Blood lactate level can reflect the condition and severity of children with severe hand-foot-mouth disease. Children with severe hand-foot-mouth disease with blood lactate level of > 3.2 mmol/L may develop severe complications such as pulmonary edema

pulmonary hemorrhage

and circulatory failure

and even death.