Abstract:

Objective To investigate the clinical utility of krebs von den lungen-6 （KL-6）， a sialoglycan antigen， in the auxiliary diagnosis of idiopathic pulmonary hemosiderosis （IPH） in children. Methods A total of 140 children admitted to the First Affiliated Hospital of Guangzhou Medical University from June 2014 to July 2024 were categorized into a case group and a control group. The case group was further subdivided into four subgroups based on disease type： IPH group （n = 32）， interstitial lung disease （ILD） group （n = 22）， pneumonia （PN） group （n = 60）， and non-pulmonary disease （NPD） group （n = 26）. Serum KL-6 levels were measured for all children across these groups， and the differences in KL-6 expression between children with IPH and those without IPH （including the ILD， PN， and NPD groups） were analyzed. Results The positive rates of KL-6 in each group of children， from highest to lowest， were as follows： IPH （68.75%）， ILD （45.45%）， PN （1.69%）， and NPD （0.00%）. The differences in positive rates between groups were statistically significant （χ2 = 66.10， P < 0.001）. The mean serum level of KL-6 in the IPH group was significantly higher than that in the PN group （Z = -6.92， P < 0.001）. Diagnostic test results indicated that the area under the ROC curve was 0.940 （95%CI： 0.89 to 1.00， P < 0.001）， with a cut off value of 392.00 U/mL， sensitivity of 81.30%， and specificity of 95.00%. Conclusions KL-6 demonstrates significant diagnostic value in distinguishing IPH children from those with PN and NPD， making it a promising blood biomarker for aiding in the diagnosis of IPH.

Key words: krebs von den lungen-6, idiopathic pulmonary hemosiderosis, pediatric pneumonia, biomarkers