Abnormalities of liver function or iron tests suggest hemochromatosis in asymptomatic patients. Increased transaminase and γglutamyltranspeptidase levels are common signs of initial liver damage. While the clinical penetrance is low, the biochemical penetrance (i.e., abnormalities of iron tests) is much higher. High transferrin saturation is the hallmark of recessive hemochromatosis and an isolated finding in the early phases when ferritin is still normal. Transferrin saturation > 50 % is present in almost all males and > 45 % in about 50% of women. Progressive iron accumulation is paralleled by increased serum ferritin with levels > 200 μg/L in women and > 300 μg/L in males. Since ferritin concentration prevalently reflects the amount of macrophage iron the increase may be late, always accompanied by high transferrin saturation levels. An exception is ferroportin disease: owing to the early iron accumulation in macrophages ferritin is usually high, while, because of reduced recycling, transferrin saturation is normal/low; dominant inheritance may suggest the correct diagnosis. In non-HFE hemochromatosis, increased transferrin saturation and serum ferritin may appear during the first decade of life in both juvenile and TFR2 diseases. In all types of hemochromatosis the complete blood count is normal; in a few cases Hb and MCV may be at the upper normal limits. Variable microcytic anemia and iron overload characterize the rare atypical microcytic anemias like atransferrinemia, DMT1 deficiency, and aceruloplasminemia.

Genetic testing for HFE (or other gene) mutations confirms the diagnosis of hemochromatosis in the presence of clinical or biochemical signs of iron overload. Genetic testing is recommended in family members of patients, except in children unless a juvenile form is suspected. An HFE C282Y homozygous genotype identified in an individual with normal iron tests (e.g., in a family member of the index case) does not diagnose hemochromatosis, but only a susceptibility to develop iron overload that should be monitored over time.

LIC provides important diagnostic information in all types of iron overload since it indirectly estimates total body iron content. Once measured by liver biopsy, nowadays it is non-invasively assessed by magnetic resonance imaging (MRI). Indications for liver biopsy persist only for prognostic purposes in C282Y homozygotes with ferritin concentration > 1000 μg/L, who have high risk of liver fibrosis. Besides directly assessing the histological damage, liver biopsy allows Perls’ staining, information about iron distribution (Fig. 1), and LIC measurement on a dried specimen. Normal LIC ranges between 0.17 and 1.8 mg/g dry weight (or 3 to 33 μmol/g); its determination is useful to monitor iron excess. Studies in thalassemia major have clearly shown that LIC > 3.0 mg/g indicates significant iron overload and levels > 7.0 mg/g associate with clinical complications. Non-invasive tests combining LIC measurement by MRI and evaluation of liver fibrosis by fibroscan now replace liver biopsy in most cases of both genetic and acquired iron overload.29 MRI may provide quantitative iron concentration also in spleen, pancreas, and heart and is an important tool for diagnosis, and monitoring both iron overload progression and regression after iron chelation in transfusion dependent thalassemia. Assessment of cardiac function, glucose tolerance, and hormonal function is necessary in hemochromatosis patients with ferritin > 1000 μg/L at diagnosis as well as during follow-up of chronically transfused patients.

Fig1. LIVER BIOPSY SAMPLE FROM A PATIENT WITH HFE HEMOCHROMATOSIS. Hematoxylin and eosin stain of the liver (A) shows intact hepatic architecture. Iron stain (B, C) shows marked diffuse iron deposits in the hepatocytes throughout the lobules. A normal liver would show essentially no iron in the hepatocytes.

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Biochemical Assays for Metabolic Diseases

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