Objective：To assess the application value of serum lactate dehydrogenase in children with refractory Mycoplasma pneumoniae pneumonia(MPP).

Methods：Fourteen pediatric patients with refractory MPP hospitalized in Erdos Central Hospital from January 2012 to November 2014 were included as the observation group, and 42 pediatric patients with MPP who responded to antibiotics treatment promptly during the same period in Erdos City Central Hospital as the control group. All patients received blood tests on admission，including routine blood test, C-reactive protein, alanine aminotransferase(ALT), aspartate aminotransferase(AST), serum lactate dehydrogenase(LDH), and interleukin(IL)-6 levels. For those who didn't respond to Macrolide antibiotic treatment after 7 days and were considered to be with refractory MPP, the above-mentioned lab tests were performed again, and glucocorticoid combination therapy was used, Sou-medrol 2 mg/(kg·d),for 3 days in a row. The rests were performed again 3 days after treatment and on discharge from hospital, including blood routine, C-reactive protein and biochemical indexes.

Results：The results of laboratory tests were not statistically different between the two groups at admission. Serum LDH, ALT, AST and IL-6 levels were significantly higher in the observation group than in the control group on day 7 before corticosteroid use(P<0.05). Significant positive correlation was found between serum values of IL-6 and LDH. A serum LDH level of 390 IU/L was calculated from receiver operating characteristic curve analysis. The sensitivity, specificity and the area under ROC curve were 78.57%, 100% and 0.81 at this level. The serum levels of LDH in the observation group were decreased to normal range after effective treatment with antibiotics combined with glucocorticoid.

Conclusion：MPP children who have prolonged fever and deterioration of clinical and radiological findings despite administration of Macrolides antibiotics for at least 7 days, with LDH more than 390 IU/L, may receive combined glucocorticoids treatment as early as possible.