A Revised Classification of Primary Iron Overload Syndromes

Background and Aims

The clinical introduction of hepcidin25 (Hep25) has led to a more detailed understanding of its relationship with ferroportin (FP) and divalent metal transporter1 in primary iron overload syndromes (PIOSs). In 2012, we proposed a classification of PIOSs based on the Hep25/FP system, which consists of prehepatic aceruloplasminemia, hepatic hemochromatosis (HC), and posthepatic FP disease (FP-D). However, in consideration of accumulated evidence on PIOSs, we aimed to renew the classification.

Methods

We reviewed the 2012 classification and retrospectively renewed it according to new information on PIOSs.

Results

Iron-loading anemia was included in PIOSs as a prehepatic form because of the newly discovered erythroferrone-induced suppression of Hep25, and the state of traditional FP-D was remodeled as the BIOIRON proposal. The key molecules responsible for prehepatic PIOSs are low transferrin saturation in aceruloplasminemia and increased erythroferrone production by erythroblasts in iron-loading anemia. Hepatic PIOSs comprise four genotypes of HC, in each of which the synthesis of Hep25 is inappropriately reduced in the liver. Hepatic Hep25 synthesis is adequate in posthepatic PIOSs; however, two mutant FP molecules may resist Hep25 differently, resulting in SLC40A1-HC and FP-D, respectively. PIOS phenotypes are diagnosed using laboratory tests, including circulating Hep25, followed by suitable treatments. Direct sequencing of the candidate genes may be outsourced to gene centers when needed. Laboratory kits for the prevalent mutations, such as C282Y, may be the first choice for a genetic analysis of HC in Caucasians.

Conclusions

The revised classification may be useful worldwide.

Autoimmune Hepatitis: Diagnostic Dilemma When It Is Disguised as Iron Overload Syndrome

Elevated serum ferritin level is a common finding in iron overload syndrome, autoimmune and viral hepatitis, alcoholic and nonalcoholic fatty liver diseases. High transferrin saturation is not a common finding in above diseases except for iron overload syndrome. We encountered a challenging case of 73-year-old female who presented with yellowish discoloration of skin, dark color urine and dull abdominal pain. Initial laboratory tests reported mild anemia; elevated bilirubin, liver enzymes, and transferrin saturation. We came to the final diagnosis of autoimmune hepatitis after extensive workups. Autoimmune hepatitis is a rare disease, and the diagnosis can be further complicated by a similar presentation of iron overload syndrome. Markedly elevated transferrin saturation can simulate iron overload syndrome, but a liver biopsy can guide physicians to navigate the diagnosis.