Hemochromatosis


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Hemochromatosis

 

Definition

Hemochromatosis is an inherited blood disorder that causes the body to retain excessive amounts of iron. This iron overload can lead to serious health consequences, most notably cirrhosis of the liver.

Description

Hemochromatosis is also known as iron overload, bronze diabetes, hereditary hemochromatosis and familial hemochromatosis. The inherited disorder causes increased absorption of intestinal iron, well beyond that needed to replace the body's loss of iron. Iron overload diseases afflict as many as 1.5 million persons in the United States. The most common of these, as well as one of the most common genetic disorders in the United States, is hereditary hemochromatosis. Men and women are equally affected by hemochromatosis, but women are diagnosed later in life because of blood loss from menstruation and childbirth. It most commonly appears in patients between the ages of 40-60 years, since it takes many years for the body to accumulate excessive iron. Symptoms appear later in females than in males—usually after menopause.
Hemochromatosis causes excess iron storage in several organs of the body including the liver, pancreas, endocrine glands, heart, skin, joints, and intestinal lining. The buildup of iron in these organs can lead to serious complications, including heart failure, liver cancer, and cirrhosis of the liver. It is estimated that about 5% of cirrhosis cases are caused by hereditary hemochromatosis.
Idiopathic pulmonary hemosiderosis, a disorder afflicting children and young adults, is a similar overload disorder characterized by abnormal accumulation of hemosiderin. Hemosiderin is a protein found in most tissues, especially the liver. It is produced by digestion of hematin, an iron-related substance.
Hemochromatosis is one of the most common genetic disorders in the United States. Approximately one in nine individuals have one abnormal hemochromatosis gene (11% of the population). Since everyone has two copies of each gene, these individuals have an abnormal HFE gene and a normal gene. They are called carriers. Between 1/200-1/400 individuals have two abnormal genes for hemochromatosis and no normal gene.
With most autosomal recessive conditions, an affected person's parents are carriers. If more than one family member has the condition, they are siblings. Hemochromatosis is so common, however, that families are seen in which both parents are affected, or one parent is affected and the other parent is a carrier. More than one generation may be affected, which is not usually seen in rare autosomal recessive conditions.

Causes and symptoms

Hereditary hemochromatosis is an autosomal recessive condition. This means that individuals with hemochromatosis have inherited an altered (mutated) gene from both of their parents. Affected individuals have two abnormal hemochromatosis genes and no normal hemochromatosis gene.
The gene that causes hemochromatosis has been identified, and the most common abnormalities of the gene have been described. The gene is on chromosome 6; it is called HFE. Scientists have not confirmed the function of the normal gene product; they do know that it interacts with the cell receptor for transferrin. Transferrin binds and transports iron in the blood.
Because it is an autosomal recessive condition, siblings of individuals who have hemochromatosis are at a 25% risk to also be affected. However, the likelihood that an individual will develop symptoms depends on which gene mutation he or she has as well as environmental factors. The two most common changes in the HFE gene are C282Y and H63D. The age at which symptoms begin is variable, even within the same family.
The symptoms of hemochromatosis include fatigue, weight loss, weakness, shortness of breath, heart palpitations, chronic abdominal pain, and impaired sexual performance. The patient may also show symptoms commonly connected with heart failure, diabetes or cirrhosis of the liver. Changes in the pigment of the skin may appear, such as grayness in certain areas, or a tanned or yellow (jaundice) appearance. The age of onset and initial symptoms vary.
Idiopathic pulmonary hemosiderosis may first, and only, appear as paleness of the skin. Sometimes, the patient will experience spitting of blood from the lungs or bronchial tubes.

Diagnosis

The most common diagnostic methods for hemochromatosis are blood studies of iron, genetic blood studies, magnetic resonance imaging (MRI), and liver biopsy. Blood studies of transferrin-iron saturation and ferritin concentration are often used to screen for iron overload. Ferritin is a protein that transports iron and liver enzymes. Additional studies are performed to confirm the diagnosis.
Blood studies used to confirm the diagnosis include additional iron studies and/or genetic blood studies. Genetic blood studies became available in the late 1990s. Genetic testing is a reliable method of diagnosis. However, in the year 2001 scientists and physicians are studying how accurately having a hemochromatosis mutation predicts whether a person will develop symptoms. Most individuals affected with hemochromatosis (87%) have two identifiable gene mutations; that is, genetic testing will confirm the diagnosis in most individuals. Genetic studies are also be used to determine whether the affected person's family members are at risk for hemochromatosis. The results of genetic testing are the same whether or not a person has developed symptoms.
MRI scans and/or liver biopsy may be necessary to confirm the diagnosis. MRI studies of the liver (or other iron absorbing organs), with quantitative assessment of iron concentration, may reveal abnormal iron deposits. For the liver biopsy, a thin needle is inserted into the liver while the patient is under local anesthesia. The needle will extract a small amount of liver tissue, which can be analyzed microscopically to measure its iron content and other signs of hemochromatosis. Diagnosis of idiopathic pulmonary hemosiderosis begins with blood tests and x-ray studies of the chest.

Treatment

Patients who show signs of iron overload will often be treated with phlebotomy. Phlebotomy is a procedure that involves drawing blood from the patient, just like blood donation. Its purpose as a treatment is to rid the body of excess iron storage. Patients may need these procedures one or two times a week for a year or more. Less frequent phlebotomy may be continued in subsequent years to keep excess iron from accumulating. Patients who cannot tolerate phlebotomy due to other medical problems can be treated with Desferal (desferrioxamine). Diet restrictions may also be prescribed to limit the amount of iron ingested. Complications from hemochromatosis, such as cirrhosis or diabetes, may also require treatment. Treatment for idiopathic pulmonary hemosiderosis is based on symptoms.
Diet restrictions may help lower the amount of iron in the body, but do not prevent or treat hemochromatosis. Individuals who are affected or who know they have two C282Y and/or H63D genes may reduce iron intake by avoiding iron and mineral supplements, excess vitamin C, and uncooked seafood. If a patient is symptomatic, he/she may be advised to abstain from drinking alcohol.

Prognosis

With early detection and treatment, the prognosis is usually good. All potential symptoms are prevented if iron levels are kept within the normal range, which is possible if the diagnosis is made before an individual is symptomatic. If a patient is symptomatic but treated successfully before he/she develops liver cirrhosis, the patient's life expectancy is near normal. However, if left untreated, complications may arise which can be fatal. These include liver cancer, liver cirrhosis, diabetes mellitus, congestive heart failure, and difficulty depleting iron overload through phlebotomy. Liver biopsy can be helpful in determining prognosis of more severely affected individuals. Genetic testing may also be helpful, as variable severity has been noted in patients who have two C282Y genes compared to patients with two H63D genes or one of each. Men are two times more likely than women to develop severe complications. The prognosis for patients with idiopathic pulmonary hemosiderosis is fair, depending on detection and complications.

Key terms

Autosomal — Relating to any chromosome besides the X and Y sex chromosomes. Human cells contain 22 pairs of autosomes and one pair of sex chromosomes.
Cirrhosis — A chronic degenerative disease of the liver, in which normal cells are replaced by fibrous tissue. Cirrhosis is a major risk factor for the later development of liver cancer.
Diabetes mellitus — The clinical name for common diabetes. It is a chronic disease characterized by inadequate production or use of insulin.
Phlebotomy — The taking of blood from the body through an incision in the vein, usually in the treatment of disease.

Prevention

Screening for hemochromatosis is cost effective, particularly for certain groups of people. Relatives of patients with hemochromatosis—including children, siblings, and parents—should be tested by the most appropriate method. The best screening method may be iron and ferritin studies or genetic testing. If the affected person's diagnosis has been confirmed by genetic testing, relatives may have genetic testing to determine whether or not they have the genetic changes present in the affected individual. Many medical groups oppose genetic testing of children. Relatives who are affected but do not have symptoms can reduce iron intake and/or begin phlebotomy prior to the onset of symptoms, possibly preventing ever becoming symptomatic.
In the winter of 2000, population screening for hereditary hemochromatosis is being widely debated. Many doctors and scientists want population screening because hemochromatosis is easily and cheaply treated, and quite common. Arguments against treatment include the range of symptoms seen (and not seen) with certain gene mutations, and the risk of discrimination in health and life insurance. Whether or not population screening becomes favored by a majority, the publicity is beneficial. Hemochromatisis is a common, easily and effectively treated condition. However, diagnosis may be difficult because the presenting symptoms are the same as those seen with many other medical problems. The screening debate has the positive effect of increasing awareness and suspicion of hemochromatisis. Increased knowledge leads to earlier diagnosis and treatment of symptomatic individuals, and increased testing of their asymptomatic at-risk relatives.

Resources

Books

Barton, James C., and Corwin Q. Edwards, editors. Hemochromatosis: Genetics, Pathophysiology, Diagnosis and Treatment. Cambridge: Cambridge University Press, 2000.

Periodicals

Motulsky, A.G., and E. Beutler. "Population Screening for Hemochromatosis." Annual Review of Public Health 21 (2000): 65-79.

Organizations

American Hemochromatosis Society, Inc. 777 E. Atlantic Ave., PMB Z-363, Delray Beach, FL 33483-5352. (561) 266-9037 or (888) 655-IRON (4766). ahs@emi.net. http://www.americanhs.org.
American Liver Foundation. 1425 Pompton Ave., Cedar Grove, NJ 07009. (800) 223-0179. http://www.liverfoundation.org.
Hemochromatosis Foundation, Inc. PO Box 8569, Albany, NY 12208-0569. (518) 489-0972. s.kleiner@shiva.hunter.cuny.edu. http://www.hemochromatosis.org.
Iron Disorders Institute, Inc. PO Box 3021, Greenville, SC 29602. (864) 241-0111. irondis@aol.com. http://www.irondisorders.org.
Iron Overload Diseases Association, Inc. 433 Westwind Dr., North Palm Beach, FL 33408. (561) 840-8512. iod@ironoverload.org.

Other

Hemochromatosis Information Sheet. National Institute of Diabetes & Digestive & Kidney Diseases (NIDDK). http://www.niddk.nih.gov/health/digest/pubs/hemochrom/hemochromatosis.htm.
Hereditary Hemochromatosis. Lecture by Richard Fass, MD, hematologist, Advanced Oncology Associates, given April 25, 1999. http://www.advancedoncology.org/listen.htm.

hemochromatosis

/he·mo·chro·ma·to·sis/ (-kro″mah-to?sis) a disorder of iron metabolism with excess deposition of iron in the tissues, bronze skin pigmentation, cirrhosis, and diabetes mellitus.hemochromatot?ic

he·mo·chro·ma·to·sis

(hē′mə-krō′mə-tō′sĭs)
n.
A hereditary disorder of iron metabolism characterized by excessive accumulation of iron in tissues, diabetes mellitus, liver dysfunction, and a bronze skin pigmentation. Also called bronzed disease.

hemochromatosis

[hē′mōkrō′mətō′sis, hem′-]
Etymology: Gk, haima, blood, chroma, color, osis, condition
a rare disease of iron metabolism, characterized by excess iron deposits throughout the body. Hepatomegaly, skin pigmentation, diabetes mellitus, and cardiac failure may occur. The disease most often develops as a complication of a hemolytic anemia such as sickle cell anemia. Multiple phlebotomies are required to deplete excess iron, with maintenance phlebotomy being performed once iron has been sufficiently depleted. Also spelled haemochromatosis. Compare hemosiderosis. See also iron metabolism, siderosis, thalassemia.

hemochromatosis

 [he″mo-kro″mah-to´sis]
a disorder of iron metabolism with excess deposition of iron in the tissues, bronze skin pigmentation, cirrhosis of the liver, and diabetes mellitus; see also hemosiderosis and siderosis. Called also bronze diabetes and iron storage disease. adj., adj hemochromatot´ic.

hemochromatosis (hēˈ·m·krōˈ·m·tōˑ·sis),

n a rare metabolic condition in which excess iron is deposited throughout the body. May lead to skin pigmentation, hepatomegaly, cardiac failure, or diabetes mellitus. Related to sickle-cell anemia and other hemolytic anemias.
Enlarge picture
Hemochromatosis.

hemochromatosis (hē´mōkrō´mə-tō´sis),

n an uncommon disorder, usually a complication of hemolytic anemia, that results in a surplus of iron deposits throughout the body. See also hemosiderosis; iron metabolism; siderosis; and thalassemia.

hemochromatosis

a condition observed in sheep and cattle which have been exposed to high intakes of iron in their rations; the liver is enlarged and brown, the hepatic lymph nodes are brown; large amounts of iron are stored in liver and lymph nodes. Seen also in ostriches.

hemochromatosis

Metabolic disease An AR  excess of GI iron absorption with progressive iron loading in parenchymal organs, the gene for which is linked to the HLA locus on the short arm of chromosome 6 Epidemiology The gene occurs in 10% of the white population, most are unaffected heterozygotes; 5/1000 of US whites are homozygotes Clinical Fatigue, cold intolerance, edema, cardiac arrhythmias, dyspnea, hepatosplenomegaly, ascites, spider telangiectasia, hyperpigmentation, palpitations, joint pain, ↓ ROM, impotence, and amenorrhea related to hypothalamic, cardiac, hepatic and pancreatic dysfunction; cardiomegaly 300-fold ↑, cirrhosis 13-fold ↑–once cirrhosis occurs, there is a 200-fold ↑ in liver cancer, gray-bronze skin pigmentation and a 7-fold ↑ in DM–'bronze diabetes', arthropathy and hypogonadism–impotence, testicular atrophy Associated pathology DM, hypopituitarism, hypogonadism, hypoparathyroidism, certain infections–E coli,K pneumoniae,Listeria monocytogenes,Mucor spp,Rhizopus arrhizus,Salmonella enteritidis serotype typhimurium,V vulnificus,Y enterocolitica Lab Transferrin saturation–TS > 62% warrants workup, ↑ iron, ↑ transferrin saturation, ↑ serum ferritin, ↑ transaminases, hyperglycemia; ↓ TSH, ↓ gonadotropins Diagnosis Screen for iron, TS > 60% ≥ 50% ♀ ≥ 60% ♂; ferritin; liver biopsy. See HFE. Cf Juvenile hemochromatosis, Neonatal hemochromatosis.

he·mo·chro·ma·to·sis

(hē'mō-krō'mă-tō'sis), [MIM*235200]
A disorder of iron metabolism characterized by excessive absorption of ingested iron, saturation of iron-binding protein, and deposition of hemosiderin in tissue, particularly in the liver, pancreas, and skin; cirrhosis of the liver, diabetes (bronze diabetes), bronze pigmentation of the skin, and, eventually heart failure may occur; also can result from administration of large amounts of iron orally, by injection, or in forms of blood transfusion therapy.
[hemo- + G. chrōma, color, + -osis, condition]

he·mo·chro·ma·to·sis

(hē'mō-krō-mă-tō'sis)
A disorder of iron metabolism characterized by excessive absorption of ingested iron, saturation of iron-binding protein, and deposition of hemosiderin in tissue, particularly in the liver, pancreas, and skin; cirrhosis, diabetes mellitus (bronze diabetes), bronze pigmentation of the skin, and, eventually heart failure may occur; also can result from administration of large amounts of iron orally, by injection, or in forms of blood transfusion therapy.
Synonym(s): haemochromatosis.
[hemo- + G. chrōma, color, + -osis, condition]

he·mo·chro·ma·to·sis

(hē'mō-krō-mă-tō'sis) [MIM*235200]
Disorder of iron metabolism characterized by excessive absorption of ingested iron, saturation of iron-binding protein, and deposition of hemosiderin in tissue, particularly in the liver, pancreas, and skin; cirrhosis, diabetes (bronze diabetes), bronze pigmentation of the skin, and, eventually heart failure may occur; can also result from administration of large amounts of iron orally, by injection, or in forms of blood transfusion therapy.
Synonym(s): haemochromatosis.
[hemo- + G. chrōma, color, + -osis, condition]
References in periodicals archive ?
Hemochromatosis is a serious condition that is a result of untreated iron overload.
JUVENILE HEMOCHROMATOSIS: SIGNAL TRANSDUCTION AND IRON METABOLISM Hereditary hemochromatosis is a systemic metabolic disease in which aberrant and excessive iron absorption leads to pathologic accumulation in multiple organs, most commonly the liver, heart, gonads, skin, and pancreas.
This suggests that iron accumulation in people with hemochromatosis may be the result of ferroportin-related loss of control over iron export.