Significance of serum ferritin level in hemophagocytic lymphohistiocytosis diagnosis

摘要

Abstract Introduction The threshold of serum ferritin (SF) level listed in diagnostic guidelines for hemophagocytic lymphohistiocytosis (HLH) of HLH‐2004 has a low specificity. The goal of this research was to evaluate the role of admission SF in HLH diagnostic procedure and to find an appropriate threshold for a HLH suspected cohort with fever. Methods All patients admitted to Beijing Children's Hospital during the period of September 1, 2015 and July 31, 2016 with fever and SF tested at admission were included in this study. The significance of SF in HLH diagnosis and its relationships with HLH‐relevant clinical characteristics were studied. Results Among 357 patients, 39 HLH cases were diagnosed (24 EBV‐related HLH, 13 unknown etiologies triggered HLH, and two familial HLH). The best cutoff value of admission SF was 934?ng/mL, with sensitivity, specificity, positive predictive values (PPV), and negative predictive values (NPV) being 87.2%, 88.4%, 47.9%, and 98.3%, respectively. Compared to 500?ng/mL, specificity and PPV of the new SF standard in HLH diagnose increased by 11.7% and 14.0%, which indicated improvements in diagnostic ability of “non‐HLH” and in veracity of “HLH” identification. Among four HLH patients whose admission SF was between 500?ng/mL and 934?ng/mL, HLH diagnosis was guaranteed by other laboratory results in two patients; however, possible misdiagnosis was made in the rest two patients. Conclusion Elevated cutoff value of admission SF level seems to be more appropriate for distinguishing HLH in patients with fever. The exact cutoff value of SF level at diagnosis needs to be determined.