Hyperferritinemia in Hemophagocytic Lymphohistiocytosis: A Single Institution Experience in Pediatric Patients.

Hemophagocytic lymphohistiocytosis (HLH) is an inflammatory condition that may run a rapid fatal course and calls for prompt diagnosis. Early intervention with steroids and other immunosuppressive drugs can contain the disease process and favours positive outcome. Ferritin ≥500 ng/ml is a HLH diagnostic criterion. We evaluated the diagnostic potential of admission ferritin, in children with HLH. Pediatric patients of a referral teaching hospital from Feb 2010-Oct 2013 having been investigated for ferritin on admission were included. HLH was confirmed when patients had clinical features and met 5/8 diagnostic criteria of the revised 2004 HLH guidelines. Ferritin was estimated on Cobas e411 by electrochemiluminiscence, with a measuring range of 0.5-2000 ng/ml. Dilutions were made when linearity exceeded and absolute values were reported. 905 on-admission ferritin investigations were reviewed out of which 346 values ≥500 ng/ml. Hyperferritinemia was seen in HLH/MAS (macrophage activation syndrome) [HLH group, median age 4 year 4 month, 59% male] and in systemic lupus erythematosus, sepsis, juvenile idiopathic arthritis, impending HLH, haemolytic anemias and malignancy [non-HLH group, median age 4 year 6 month, 60% male]. Of 346, 72 cases of hyperferritinemia were diagnosed with secondary HLH while one patient had primary HLH. 13/73 patients expired. The median ferritin level of the HLH group was significantly higher [6556 (2402-11,734) ng/ml] compared to non-HLH group [median 1175 (943-2000) ng/ml] (p < 0.0001). Receiver operator characteristics curve analysis revealed optimal admission ferritin of 3120 ng/ml as the cut-off with sensitivity of 70% and specificity of 88.9% for HLH diagnosis, exceeding the currently prescribed cut-off of 500 ng/ml. Hyperferritinemia below 3120 ng/ml has higher negative predictive value to rule out secondary HLH on admission in the study population of children predominantly diagnosed with infection associated HLH than the prescribed cut-off as per the 2004 guidelines. This may prove to be beneficial to alert physicians for prompt intervention which considerably decreases mortality in this often fatal condition.