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399) An asymptomatic 48-year-old patient was screened for HFE gene mutations after a sibling was discovered to have a homozygous mutation in this gene (C282Y/C282Y). The patient’s ferritin level is currently 2200 ng/mL (12 to 300 ng/mL), and there is no evidence of inflammation (e.g., C-reactive protein levels within normal range). If serum hepcidin levels were measured, which one of the following choices is most correct for the expected hepcidin level?

Low hepcidin level as seen in nutritional iron deficiency. High hepcidin level as seen in transfusion-induced iron overload. Normal hepcidin level as seen in an iron-replete male. Low hepcidin level as seen in transfusion-induced iron overload. High hepcidin level as seen in nutritional iron deficiency.

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• The C282Y mutation in the HFE gene is the most common mutation causing hemochromatosis.

• About 1 in 200 northern Europeans carries the C282Y homozygous mutation. However, the disease has variable penetrance, so most cases are asymptomatic.

• Mature hepcidin is a 25–amino acid peptide hormone that regulates iron homeostasis by regulating the amount of iron that enters the circulation from gut enterocytes.

• Hepcidin causes degradation of the iron channel, ferroportin, which resides on the basolateral side of gut enterocytes. Thus, a high hepcidin level decreases iron absorption and a low level enhances iron absorption.

• Although the exact mechanism controlling hepcidin levels has yet to be determined, mutations in the HFE gene result in too low of a hepcidin level for the host’s iron status.

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Clinical Pathology: General Principles, Hematology & Coagulation

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