Hemochromatosis overview
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Sunny Kumar MD [2]
Overview
Hemochromatosis is a hereditary disease characterized by improper dietary iron metabolism (making it an iron overload disorder), which causes the accumulation of iron in a number of body tissues. Iron accumulation can eventually cause end organ damage, most importantly in the pancreas manifesting as diabetes, and liver failure. It is estimated that roughly one in every 300-400 people are affected by the disease, primarily of Northern European and Anglo-English descent.
Historical Perspective
The disease was first described in 1865 by Armand Trousseau in an article on diabetes in patients with changing skin color. Trousseau did not connect the diabetes with iron accumulation; instead this was done by Friedrich Daniel von Recklinghausen in 1890. The mutation of human genome to increase iron absorption in people who are exposed to iron deficient diet is evolutionary stand point. Hemocromatosis is also known as Celtic Curse.
Classification
Hemochromatosis is divided on basis of it's etiology. Hereditary hemochromatosis is caused by defect in gene and secondary hemochromatosis is caused by excess absorption of iron, repeated blood transfusions, or excess oral intake, typically in patients with disorders of erythropoiesis.
Pathophysiology
Hemochromatosis is due to the iron transfer into the bloodstream in the absence of increased erythropoietic needs that can be toxic for the parenchymatous organs. The features of hemochromatosis are due to presence of toxic iron in pro-oxidant form in surroundings of parenchymatous tissue cells of the liver and other organs, where it can cause oxidative damage and lead to cirrhosis, hypogonadism, diabetes, cardiomyopathy, arthropathy, and skin pigmentation.
Causes
Hemochromatosis is due to unchecked transfer of iron into the bloodstream in the absence of increased erythropoietic needs and its toxic effects in parenchymatous organs. It can be primary as genetic or it can be secondary iron over load.
Differentiating Hemochromatosis from other Diseases
Haemochromatosis is notoriously protean, i.e., it presents with symptoms that are often initially attributed to other diseases. It is also true that most people with hereditary hemochromatosis genetics never actually show signs or suffer symptoms of clinical iron overload (i.e., is clinically silent).
Epidemiology and Demographics
Prevalence of hemochromatosis is 6 times higher in white persons than in black persons.It is often described as a "Celtic mutation"--originating in a Celtic population in central Europe and spreading west and north by population movement.
Risk Factors
People who inherit the HFE gene mutation from both parents are at the greatest risk for developing hemochromatosis. Although both men and women can inherit the gene defect, men are more likely to be diagnosed with the effects of hemochromatosis than women.
Screening
Routine screening of the general population for hereditary hemochromatosis, that is, by genetic testing, has been evaluated by the US Preventive Services Task Force (USPSTF), among other groups. In case-finding for hereditary hemochromatosis, serum ferritin and transferrin saturation tests should be performed. Genotyping and liver biopsy is suggested in cases which strongly suggest hemochromatosis due to high levels of serum ferritin and transferrin saturation.
Natural History, Complications and Prognosis
Hemochromatosis is due to unchecked transfer of iron into the bloodstream in the absence of increased erythropoietic needs and its toxic effects in parenchymatous organs.The features of Hemochromatosis are due to presence of toxic iron in pro-oxidant form in surroundings of parenchymatous tissue cells of the liver and other organs, where it can cause oxidative damage and lead to cirrhosis, hypogonadism, diabetes, cardiomyopathy, arthropathy, and skin pigmentation.
Diagnosis
History and Symptoms
Symptoms usually begin in age of 30 years. The involvement of specific organ produces subsequent symptoms. Early symptoms are fatigue and weakness; and as the iron builds up in the body organs, infections and loss of body hair happen. After disease progression, hemochromatosis may cause the following more serious problems such as arthritis, and heart failure.
Physical Examination
Physical examination of hemochromatosis disease depends on the involved organ are: fatigue in heart failure, erectile dysfunction and hypogonadism in gonads involvements, amenorrhea in pitutary, arthritis in joints invovment.
Laboratory Findings
In patients with high suspicion first test ordered is transferrin saturation TS. It is followed by serum ferritin levels. In case of strong evidence of familial history and lab findings patient should go through genotyping which save the need of unnecessary biopsy of liver to check iron index and chemical index to confirm the diagnosis.
ECG
Hemochromatosis can lead to deposition of iron in heart and damage its myocardial tissue as well as conduction tissue. It will cause cardiomyopathy and cardiac arrhythmia.
Ultrasound
On ultrasound the Iron deposits in the liver usually do not alter liver echogenicity. If ultrasonographic liver abnormalities are present, they are usually secondary to cirrhosis.
CT Scan
Clinically the disease may be silent, but characteristic radiological features may point to the diagnosis.
MRI
MRI is not only the most sensitive imaging modality for the diagnosis of haemochromatosis but is also able to estimate iron concentration within the liver, thus forestalling the need for repeated biopsies.
Treatment
The treatment of hemochromatosis depends on levels of iron deposition in body tissues, symptoms and complications due to damaged organs secondary to inflammatory response towards deposition.