Presentation on theme: "Hemochromatosis Thomas W. Faust, M.D., M.B.E."— Presentation transcript:
1 Hemochromatosis Thomas W. Faust, M.D., M.B.E. Professor of Clinical MedicineDivision of GastroenterologyThe University of Pennsylvania
2 Hemochromatosis Introduction Classification of iron overload syndromes PathogenesisClinical manifestationsDiagnosisTreatmentScreening
3 Hereditary Hemochromatosis Introduction Inherited disorder of inappropriate dietary iron absorptionPrevalent in 1/250 individualsMost patients are asymptomaticHepatic and extrahepatic manifestationsHFE (autosomal recessive) mutations account for majority of casesNon-HFE mutations are rare causes of iron overloadSecondary iron overload statesC282Y homozygotes account for 80-95% of cases associated with HFE mutations. H63D and S65C account for other HFE mutations. Iron overloading typically with C282Y. Only 70% of C282Y homozygotes will develop iron overload. Modifying genes may account for lack of complete penetrance. Consider repeating TS and ferritin every 5 yrs for non-expressing C282Y homozygotes. C282Y/H63D or H63D/H63D usually have mild to moderate iron overload; most pts with these mutations with severe iron overload have another contributing disease (ETOH, viral hepatitis etc). Likewise, C282Y and H63D heterozygotes usually have normal iron stores; elevated iron associated with another unidentified mutation or another disease. Modifier genes may account for incomplete penetrance. Disease is more common in males. Non-HFE causes of iron overload: hepcidin, hemojuvelin, TR2, ferroportin. Other causes of iron overload: ineffective erythropoiesis, chronic liver disease, parenteral iron administration.Phatak P et al., Ann Intern Med 2008;149:
4 Hemochromatosis Hereditary Causes HFE hemochromatosisC282Y/C282Y (95%)C282Y/H63D (4%)H63D/H63D or C282Y/S65C (1%)Non HFE hemochromatosis (rare)HemojuvelinHepcidinFerroportinTransferrin receptor 2DMT-1Juvenile HH: mutations of hemojuvelin and HAMP. Pts with hemojuvelin mutations have low hepcidin. Inactivating mutations of HAMP that encodes for hepcidin. Inactivating mutations for ferroportin result in iron retained in RE cells rather than hepatocytes; transferrin saturation lower, hepcidin increased. Gain of function mutations of ferroportin result in classic HH phenotype; hepcidin increased.Ferroportin disease: Autosomal dominant. Accumulation of iron in macrophages. Elevated ferritin with mild hypochromic microcytic anemia. TS may be normal or elevated. Liver disease less advanced when compared to HFE dz.1 unit phlebotomy monthlyJuvenile hemochromatosis:Autosomal recessive. Mutations in HJV or HAMP (hepcidin) genes. Severe iron overload in heart, endocrine organs, and liver. Treatment is phlebotomyBeutler E. et al, Lancet 2002;359:
5 Hemochromatosis Non-Hereditary Causes Secondary iron overloadThalassemia majorSideroblastic anemiasLiver disease (ETOH, HCV, HBV, PCT, NAFLD)Excessive iron ingestionParenteral iron overloadRBC transfusionsIron-dextran infusionsLong-term dialysisETOH, HBV, HCV, and NAFLD can have elevation in ferritin and/or TS without iron overload. Bx justified for clarification.
6 Duodenal Iron Absorption Crypt cellsHFE-transferrin receptor complex senses body iron storesUpregulation or downregulation of DMT-1 based upon body iron storesVillous cellsDietary iron absorption occurs via DMT-1 and ferroportinTransporter expression based upon body iron stores sensed by crypt cellsHFE-TFR-1 complex senses iron stores in crypts.Bacon B et al, Gastroenterology. 1999;116:
7 Regulation of Iron Absorption Crypt Cell Model HFE-transferrin receptor acts as sensor of iron stores in CryptDMT-1 synthesized based upon iron storesIron absorbed at villus tipCrypt cell model — The findings noted above have led to the postulate that the role of the HFE protein is to modulate the uptake of transferrin-bound iron into crypt cells, allowing the complex to act as a sensor of body iron stores [59-62]. (See "Regulation of iron balance".)In this proposed model of the regulation of iron absorption, the following steps would occur (figure 2). Increased body iron stores and the accompanying rise in transferrin-bound iron lead to enhanced uptake of iron into crypt cells. As a result of the ensuing increase in intracellular iron, the differentiating enterocytes migrating up to the villus tip downregulate the production of the iron transporter DMT1, reducing the absorption of dietary iron. This process is reversed in iron deficiency as iron transporters in the developing villus cells and iron absorption are increased.In hereditary hemochromatosis, mutations in HFE may impair TfR-mediated uptake of transferrin-bound iron into crypt cells, providing a false signal that iron stores are low. Ferric iron converted to ferrous form. Ferrous iron transported by DMT-1 across apical membrane. Iron in enterocyte stored as ferritin and sloughed with enterocyte or transferred to plasma via ferroportin. Basolateral transfer requires oxidation to ferric form via hephaestin.Zoller H. et al, Lancet. 1999;353:
8 Regulation of Iron Stores Influence of Hepcidin Regulation of ferroportin-mediated iron export from enterocyteRegulation of ferroportin-mediated iron export from macrophagesHepcidin is a hepatic peptide that may be the key regulator of iron metabolism. Hepcidin deficiency in knockout mice results in severe iron overload. Hepcidin may also have a direct effect on the uptake of iron by intestinal epithelia. Conversely, a relative deficiency of hepcidin can result in increased iron efflux from macrophages. After hepcidin binds ferroportin, ferroportin is internalized and degraded.Fig. 64-2 Schematic representation of the HFE protein, a class 1 MHC protein that is involved in iron metabolism with a cascade of other iron proteins. Typical hemochromatosis patients are homozygous for the C282Y mutation of HFE, which cause conformational changes in the protein that impair intracellular trafficking. BMP, bone morphogenetic protein; Fe, iron; HJV, juvenile hemochromatosis geneHepcidin is a hepatic peptide that may be the key regulator of iron metabolism. Hepcidin deficiency in knockout mice results in severe iron overload. Hepcidin may also have a direct effect on the uptake of iron by intestinal epithelia. Conversely, a relative deficiency of hepcidin can result in increased iron efflux from macrophages. This is consistent with the paradoxical observation in HFE-related hemochromatosis of relative iron deficiency in the spleen and within macrophages. Hepcidin expression in liver tissue, serum, and urine has suggested a relative deficiency in HFE-linked hemochromatosis. However, at the present time it is unclear whether the defect in hepcidin is the primary abnormality in hemochromatosis, or a downstream effect of abnormalities in the HFE protein. The control of hepcidin may be related to a cellular iron-sensing mechanism that includes bone morphogenetic protein-6 (BMP6), transferrin receptors 1 and 2, HFE protein, hemojuvelin, and Smad proteins (Fig. 64-2).[13-16] It is intriguing to speculate whether alterations in non-HFE iron proteins could explain the wide range of clinical expression seen in hemochromatosis. The concept is that the most severe cases of HFE-related hemochromatosis may be heterozygotes for a mutation in another iron-related protein. These mutations would need to be very common to fit this hypothesis. A tantalizing theory has been suggested that the hemochromatosis gene has not been found yet and that the HFE gene is only a modifying gene.Ganz T. Cell Metab 2008;7:
9 Regulation of Iron Stores Normal Hepcidin regulates ferroportin-mediated iron export from duodenum, macrophages, and liverBMP, HJV, HFE, and TFR2 sense body iron stores and regulates release of hepcidinLoss of appropriate hepcidin expression is the central pathogenic mechanism in hereditary hemochromatosis. (A) In normal humans, iron is sensed by the liver and regulates hepcidin secretion, which in turn interacts with and downregulates ferroportin (FPN) expressed on the surfaces of macrophages and duodenal enterocytes, and hepatocytes to regulate the release of iron into the blood stream. Hepatic bone morphogenetic protein (BMP, BMP6 in mice), hemojuvelin (HJV), HFE, and transferrin receptor 2 (TFR2) are all important for sensing serum iron levels and adjusting the expression of hepcidin appropriately to maintain iron balance. (B) Inherited mutations in any one of these hepcidin regulators leads to the inability of the liver to properly sense iron levels, and consequently to inappropriately low expression of hepcidin, unregulated ferroportin activity, and excess export of iron into the bloodstream. The excess iron can deposit into parenchymal tissues where it causes end organ damage that is characteristic of hemochromatosis.Nemeth E. et al, Science 2004;306:2090–2093
10 Hemochromatosis Non-Ferroportin Mutations Mutations of BMP, HJV, HFE, and TFR2 alter ability of liver to sense body iron storesInappropriately low level of hepcidinExcess ferroportin-mediated export of iron from duodenum, macrophages, and liverLoss of appropriate hepcidin expression is the central pathogenic mechanism in hereditary hemochromatosis. (A) In normal humans, iron is sensed by the liver and regulates hepcidin secretion, which in turn interacts with and downregulates ferroportin (FPN) expressed on the surfaces of macrophages and duodenal enterocytes, and hepatocytes to regulate the release of iron into the blood stream. Hepatic bone morphogenetic protein (BMP, BMP6 in mice), hemojuvelin (HJV), HFE, and transferrin receptor 2 (TFR2) are all important for sensing serum iron levels and adjusting the expression of hepcidin appropriately to maintain iron balance. (B) Inherited mutations in any one of these hepcidin regulators leads to the inability of the liver to properly sense iron levels, and consequently to inappropriately low expression of hepcidin, unregulated ferroportin activity, and excess export of iron into the bloodstream. The excess iron can deposit into parenchymal tissues where it causes end organ damage that is characteristic of hemochromatosis.Nemeth E. et al, Science 2004;306:2090–2093
11 Hemochromatosis Ferroportin Mutations Loss of functionLimited ability to export ironAccumulation of iron in macrophagesHepcidin increasedGain of functionResistant to inhibitory effects of hepcidinPhenotypically similar to classic hemochromatosisSome mutations produce a molecule which either does not traffic appropriately to the cell surface or which has limited ability to export iron, as in panel D of the figure (figure 3). These "loss of function" mutations result in excess accumulation of iron in macrophages, with resulting high serum ferritin, normal to reduced transferrin iron saturation, and a mild anemia. Other mutations produce a ferroportin resistant to inhibition by the iron regulatory molecule hepcidin, retaining full iron export capability, as in panel E of the figure (figure 3) [ ]. These "gain of function" mutations allow iron to be absorbed in excess of need, with patients manifesting high levels of ferritin and hepcidin, increased transferrin saturations, and typical deposition of iron in the hepatic parenchyma.Letocart E. et al, Br J Haematol. 2009;147(3):379
12 Hemochromatosis Overview of Clinical Manifestations Asymptomatic state (majority)Abnormal iron studies and liver function testsNon-specific systemic symptomsWeakness, fatigue, lethargy, apathy, weight loss, abdominal painOrgan-related diseaseHepatic manifestationsExtrahepatic manifestations
14 Hemochromatosis Physical Examination Physical findings in patients with progressive liver diseaseFindings not specific to hemochromatosis
15 Hemochromatosis Hepatocellular Carcinoma Patients with cirrhosis at risk for HCC.All patients with cirrhosis should be screened per AASLD guidelinesOLT considered for cirrhotic patients with HCCNetter’s Gastroenterology, 2nd ed., Elsevier Inc., 2010, all rights reserved
16 Hemochromatosis Extrahepatic Manifestations CardiacRestrictive/dilated cardiomyopathyArrhythmiasRheumatologicArthalgias/arthritisChondrocalcinosisOsteoporosisDermatologicHyperpigmentationPorphyria cutanea tardaEndocrinologicDiabetesLoss of libido/impotenceAmenorrheaHypothyroidismInfectiousYersinia, pasteurella, vibrio vulnificus, listeriaJoint involvement: PIP joints, shoulders, wrists, knees, feet. Hyperpigmentation usually melanin, not iron. Endocrine abnormalities may be associated with low FSH, LH, and testosterone. Iron deposited in parenchymal cells of liver, pancreas, heart, endocrine glands, skin, joints.
17 Hemochromatosis Systemic Disorder Multiple organs involved with progressive iron overloadTherapeutic phlebotomy may correct some of the clinical manifestationsNetter’s Gastroenterology, 2nd ed., Elsevier Inc., 2010, all rights reserved
19 Diagnosis of Hemochromatosis Iron Studies Transferrin SaturationFerritinValue ≥ 45% most common early phenotypic markerSensitivity > 90%Fasting value preferableF/U with genetic testingRises with progressive iron overloadF/U with genetic testingOther diseasesETOH, NAFLD, viral hepatitis, inflammatory disorders, neoplasmsPredicts fibrosisNormal ferritin in combination with TS < 45% has NPV of 97%. Iron overload may be present in patients with elevated ferritin and normal TS particularly in non-HFE or C282y/H63D iron overload states. Ferritin > 1000 in combination with AST/ALT elevation predicts cirrhosis in 80% of C282Y homozygotes. Ferritin < 1000 in combination with normal AST/ALT an accurate predictor for absence of fibrosis/cirrhosis. If either TS > 45% or ferritin above ULN, get HFE mutation analysis.Beutler E. et al, Lancet 2002;359:
20 Diagnosis of Hemochromatosis Genetic Testing C282Y/C282YFor all patients with TS ≥ 45%For all patients with elevated ferritinLiver biopsy for ferritin ≥ 1000 μg/L or elevated AST/ALTC282Y/H63D or otherFor all patients with TS ≥ 45%For all patients with elevated ferritinExclude other liver or hematologic diseasesTesting for non-HFE mutations not widely availableConsider liver biopsyOther constitutes C282Y/wt, H63D/wt, H63D/H63D, wt/wt. No difference in prevalence of C282Yor H63D in other liver diseases associated with elevated iron indices (viral hepatitis, NAFLD, PCT etc).Guyader D. et al, Gastroenterology 1998;115:
21 Liver Biopsy Diagnosis of Hemochromatosis or Fibrosis Not requiredC282Y/C282YFerritin < 1000 μg/LNormal AST/ALTRequired or suggestedC282Y/C282Y, ferritin ≥ 1000 μg/L, elevated AST/ALTConsider for C282Y/H63D or otherRoutine histopathologyQualitative and quantitative iron assessmentOther constitutes C282Y/wt, H63D/wt, H63D/H63D, wt/wt. HII not frequently used as it does not adequately discriminate HH from other causes of iron overload. Value of 1.9 for HII used. HII replaced by genetic testing.Adams P et al, J Lab Clin Med 1997;130:
22 Hemochromatosis Liver Histopathology HepatocytesProgressive iron accumulation from periportal (zone 1) to pericentral (zone 3) regionsRoutine H&E and Prussian blue stainsKupffer and biliary epithelial cellsIron accumulation with progressive iron loadingFibrosis and cirrhosisTrichrome stainAssociated with advanced iron overloadHepatocellular carcinomaIron-dependent oxidative damage and lipid peroxidation of hepatocytes with generation of profibrogenic cytokines from Kuppffer cells. Cytokines stimulate stellate cells to lay down collagen.
23 Hepatic Iron Overload Other Diseases ETOH, NAFLD, viral hepatitis, PCT, parenteralPanlobular and patchy iron distributionIron accumulation in hepatocytes and Kupffer cellsIron accumulation is usually mildFerroportin disease associated with iron overload in macrophages and reticuloendothelial cells
24 Hemochromatosis Pathology Progressive hepatic iron overloadMyocardial iron overloadCirrhosis: H&ECirrhosis: Prussian Blue
25 Hemochromatosis Imaging CTMRTaouli B et al, AJR 2009;193:14-27Jensen P, Br J Haematol 2004 Mar;124(6):
26 Hemochromatosis Treatment Weekly or twice weekly phlebotomyRemoval of 2-3 units per week or 0.5 units every other weekCheck Hgb/HCT prior to each phlebotomyFollow TS and ferritin every 3 mo.Endpoints: TS < 50%, ferritin < 50 μg/LMaintenance phlebotomy: 1 unit every 3 mo.Avoid iron deficiencyImaging and AFP every 6 mo. to screen for HCC in cirrhotic patientsOLT for hepatic decompensation or HCC500 cc of whole blood equals 250 mg of iron. Phlebotomy prior to cirrhosis and DM prolongs survival. Survival post OLT comparable to non-HH indications. Chelating agents in combination with phlebotomy may be beneficial for HH with cardiac iron overload.Bacon B. Gastroenterology 2001;120:
27 Hemochromatosis Response to Phlebotomy ImprovementTissue iron storesSurvival in absence of cirrhosis and DMLiver-associated enzymesCardiac function, DM, skin pigmentation, fibrosisNo improvementEstablished cirrhosisArthropathyTesticular atrophy
28 Hemochromatosis Screening Family ScreeningPopulation ScreeningHFE (C282Y, H63D) and iron testing for first degree relativesC282Y/C282Y and C282Y/H63Y relatives with iron overload undergo phlebotomyC282Y/wt, H63D/H63D, H63D/wt not at risk for iron overloadC282Y/C282Y or C282Y/H63D children undergo yearly ferritin assessmentRole for population screening with genetic testing unclearIncomplete penetrance raises questions about clinical utility, cost effectiveness, and genetic discriminationNon HFE hemochromatosis is rare and genetic testing only available in research labsIf iron studies normal, yearly f/u with iron studies warranted in patients with appropriate genetic mutations. Phenotypic expression can vary among patients with genetic mutations. For pts with iron overload and non-HFE hemochromatosis or secondary iron overload, phlebotomy warranted as for typical HH pt.Tavil A. Hepatology 2001;33:
29 Hemochromatosis Algorithm SymptomaticTransferrin saturation/ferritinTS < 45% and normal ferritinNo further evaluationTS ≥ 45% and/or elevated ferritinHFE genotypeAsymptomaticHFE GenotypeAdult 1st degree relative of HHHemochromatosis AlgorithmBacon B et al, Hepatology,2011;54:
30 Hemochromatosis Algorithm HFE genotypeC282Y/H63D, C282Y heterozygote, non-C282YExclude other liver or hematologic diseases. ± liver biopsyTherapeutic phlebotomyC282Y/C282YFerritin < 1000 μg/L and normal liver enzymesFerritin ≥ 1000 μg/L or elevated liver enzymesLiver biopsy for HIC and histopathology+Bacon B et al, Hepatology,2011;54:
31 Hemochromatosis Take Home Points HFE (C282Y/C282Y) mutations account for most cases of hereditary hemochromatosis.Be aware of other non-HFE inherited and secondary causes of iron overload.Interrelationship between duodenal iron absorption and hepcidin is important.Patients can present with a variety of hepatic and extrahepatic manifestations.Diagnosis based upon iron studies, genetic testing, and liver biopsy.Phlebotomy is mainstay of therapyGenetic testing recommended for family members of patients with hereditary hemochromatosis.
32 Hemochromatosis Question 1 A 55 yr old man presents with mildly elevated transaminases. His serum ferritin is 3000 mcg/L, with transferrin saturation exceeding 90%. He is homozygous for C282Y. Liver ultrasound is normal and liver biopsy shows bridging fibrosis and markedly elevated hepatocellular iron. Weekly phlebotomy is started. The patient’s wife is heterozygous for C282Y and one normal allele. The patient has 2 sons ages 26 and 18. The older son’s ferritin is 2500 mcg/L, whereas the younger son’s ferritin is 180 mcg/L. At this time you make all of the following recommendations except:DDSEP 6, AGA Press, 2011.
33 Hemochromatosis Question 1 A. The older son should be tested for C282Y mutation of HFE geneB. For the older son, liver biopsy may be justified to R/O cirrhosisC. The younger son should be tested for C282Y mutationD. For the younger son, liver biopsy may be justified to R/O cirrhosisE. The older son should have liver ultrasoundDDSEP 6, AGA Press, 2011.
34 Hemochromatosis Question 2 A baby born to parents of Irish descent (father homozygous for C282Y, mother genetic status unknown) is found to be homozygous for C282Y. What is the lifetime risk of hepatic decompensation and/or hepatocellular carcinoma if the child is carefully followed and undergoes phlebotomy over his/her lifetime?A. ZeroB. 5%C. 20%D. 50%E. 80%DDSEP 6, AGA Press, 2011.
35 Hemochromatosis Question 3 An autosomal dominant form of hemochromatosis accompanied by high levels of hepcidin production is associated with mutations of the gene coding for which of the following?A. HFE proteinB. Transferrin receptor type 2C. HemojuvelinD. HepcidinE. FerroportinDDSEP 6, AGA Press, 2011.
36 Hemochromatosis Question 4 Which one of the following statements about liver biopsy in patients with HFE (C282Y homozygous) hemochromatosis is correct?A. Liver biopsy should be performed in all patients after genetic testing.B. Kupffer cells take up iron before hepatocytes in patients with HFE (C282Y homozygous) hemochromatosis.C. Panlobular patchy iron accumulation in hepatocytes and Kupffer cells is classic for C282Y homozygous disease.D. In patients with C282Y disease, iron is taken up by periportal (zone 1) hepatocytes prior to pericentral (zone 3) hepatocytes.E. Bridging fibrosis is seen in early disease
37 Hemochromatosis Question 5 A 65 yr old male is recently diagnosed with C282Y hemochromatosis and cirrhosis. His transferrin saturation is 95% and his ferritin is 5284 mcg/L. Which one of the following statements is incorrect?A. He will not require surveillance for hepatocellular carcinoma once iron stores have been removed from the liver by phlebotomy.B. Phlebotomy should be initiated to achieve endpoints of T. Sat of < 50% and ferritin < 50 μg/L.C. Phlebotomy may improve cardiac function and glucose intolerance.D. Arthropathy does not usually improve with phlebotomyE. At the beginning of treatment, weekly or twice weekly phlebotomy is necessary to reach desired endpoints.
38 Hemochromatosis Question 6 Which one of the following statements about HFE hemochromatosis is correct?A. C282Y/H63D disease is the most common genetic abnormality.B. H63D/H63D commonly results in iron overload.C. Population-based screening for genetic hemochromatosis is recommended.D. CT and MR of the liver are sensitive tests for diagnosing disease.E. Hepcidin regulates ferroportin-mediated iron export from duodenal enterocytes.
39 Hemochromatosis Answers to Questions 1. D2. A3. E4. D5. A6. E