Hereditary Hemochroamtosis - Essay Example

Hereditary Hemochromatosis (HH). HH is the most common form of iron overload disease. It is an inherited disorder that causes the body to absorb and store too much iron. Iron is an essential nutrient found in many foods. In the body, iron becomes part of hemoglobin, a molecule in the blood that transports oxygen from the lungs to all body tissues. Healthy people usually absorb about 10 percent of the iron contained in the food they eat to meet the body needs. People with hemochromatosis absorb more than the body needs (Vautier, Murray, Olynyk, 2001). Graphic 1 shows the normal distribution of body iron stores. As iron loading progresses many organs and tissues can be damaged, leading to serious problems such as arthritis, liver disease, cirrhosis, cancer, and liver failure, damage to the pancreas, heart abnormalities, impotence, early menopause, abnormal (gray or bronze) pigmentation of the skin, thyroid deficiency, damage to the adrenal gland (Guidelines, 1996; McDonnell, Preston, Jewell, Barton, Edwards, Adams, et al, 1999). The disease was first described by Armand Trousseau in an article on diabetes in 1865. However, he did not make the link with iron accumulation. This was done by Daniel von Recklinghausen in 1889. Traditionally, hereditary haemochromatosis has been viewed as a rare inherited disorder, primarily of older men, that presents with life threatening complications such as "bronzed diabetes" (skin pigmentation, diabetes, and cirrhosis), primary liver cancer, or heart failure (Guidelines, 1996). Causes Genetic or hereditary hemochromatosis is mainly associated with a defect in a gene called HFE, which helps regulate the amount of iron absorbed from food. There are two known important mutations in HFE, named C282Y and H63D. C282Y is the most important. When C282Y is inherited from both parents, iron is overabsorbed from the diet and hemochromatosis can result. H63D usually causes little increase in iron absorption, but a person with H63D from one parent and C282Y from the other may rarely develop hemochromatosis. The genetic defect of hemochromatosis is present at birth, but symptoms rarely appear before adulthood. A person who inherits the defective gene from both parents may develop hemochromatosis. A person who inherits the defective gene from only one parent is a carrier for the disease but usually does not develop it. However, carriers might have a slight increase in iron absorption. Risk Factors Hereditary hemochromatosis is one of the most common genetic disorders in the United States. It most often affects Caucasians of Northern European descent, although other ethnic groups are also affected. About 5 people in 1,000 (0.5 percent) of the U.S. Caucasian population carry two copies of the hemochromatosis gene and are susceptible to developing the disease. One person in 8 to 12 is a carrier of the abnormal gene. Hemochromatosis is less common in African Americans, Asian Americans, Hispanic Americans, and American Indians. Although both men and women can inherit the gene defect, men are about five times more likely to be diagnosed with the effects of hereditary hemochromatosis than women. Men also tend to develop problems from the excess iron at a younger age (Steinberg, Cogswell, Chang, et al, 2001). Symptoms Joint pain is the most common complaint of people with hemochromatosis. Other common symptoms include fatigue, lack of energy, abdominal pain, loss of sex drive, and heart problems. Symptoms tend to occur in men between the ages of 30 and 50 and in women over age 50. Also, doctors may focus on the conditions caused by hemochromatosis - arthritis, liver disease, heart disease, or diabetes - rather than on the underlying iron overload. At the same time, many people have no symptoms when they are diagnosed. However, if the iron overload caused by hemochromatosis is diagnosed and treated before organ damage has occurred, a person can live a normal, healthy life (Fleming, Sly, 2002). Diagnosis A thorough medical history, a physical examination, and routine blood tests help rule out other conditions that could be causing the symptoms. This information often provides helpful clues, such as a family history of arthritis or unexplained liver disease. Blood tests can determine whether the amount of iron stored in the body is too high. The transferrin saturation test determines how much iron is bound to the protein that carries iron in the blood. The total iron binding capacity (TIBC) test measures how well your blood can transport iron. The serum ferritin test shows the level of iron in the liver. If either of these tests shows higher than normal levels of iron in the body, doctors can order a special blood test to detect the HFE mutation, which will help confirm the diagnosis. A liver biopsy may be needed - it will show how much iron has accumulated in the liver and whether the liver is damaged (Vautier, Murray, Olynyk, 2001). These trials identified 2-5in 1000people as having biochemical evidence of iron overload.3 In most white populations of northern European heritage about 85% of people with clinically diagnosed hereditary haemochromatosis are homozygous for the C282Y mutation (Bradley, Johnson, Palomaki, Haddow, Robertson, Ferrie., 1998). Graphic 2 represents relationship between total body iron stores and clinical manifestations of hereditary hemochromatosis over time (Riely 297). Treatment Treatment is simple, inexpensive, and safe. The first step is to rid the body of excess iron. The process is called phlebotomy, which means removing blood the same way it is drawn from donors at blood banks. Blood ferritin levels will be tested periodically to monitor iron levels. The goal is to bring blood ferritin levels to the low end of normal and keep them there. Once iron levels return to normal, maintenance therapy, which involves giving a pint of blood every 2 to 4 months for life, begins. The earlier hemochromatosis is diagnosed and treated in appropriate cases, the better. If treatment begins before any organs are damaged, associated conditions-such as liver disease, heart disease, arthritis, and diabetes-can be prevented. However, for instance, if cirrhosis has developed, the person's risk of developing liver cancer increases, even if iron stores are reduced to normal levels (Fleming, Sly, 2002). Graphic 3 reflects cumulative survival in patients who have hereditary hemochromatosis with and without cirrhosis and diabetes (Niederau, Fischer, Sonnenberg, Stremmel, Trampisch, Strohmeyer, 313). People with hemochromatosis should not take iron supplements. Those who have liver damage should not drink alcoholic beverages because they may further damage the liver. Although treatment cannot cure the conditions associated with established hemochromatosis, it will help most of them. The main exception is arthritis, which does not improve even after excess iron is removed (Fleming, Sly, 2002). Tests for Hemochromatosis Screening for hemochromatosis (testing people who have no symptoms) is not a routine part of medical care or checkups. However, researchers and public health officials do have some suggestions: - Brothers and sisters of people who have hemochromatosis should have their blood tested to see if they have the disease or are carriers. - Parents, children, and other close relatives of people who have the disease should consider testing. - Doctors should consider testing people who have joint disease, severe and continuing fatigue, heart disease, elevated liver enzymes, impotence, and diabetes, because these conditions may result from hemochromatosis. Since the genetic defect is common and early detection and treatment are so effective, some researchers and education and advocacy groups have suggested that widespread screening for hemochromatosis would be cost-effective and should be conducted. However, a simple, inexpensive, and accurate test for routine screening does not yet exist, and the available options have limitations. For example, the genetic test provides a definitive diagnosis, but it is expensive. The blood test for transferrin saturation is widely available and relatively inexpensive, but it may have to be done twice with careful handling to confirm a diagnosis and to show that it is the consequence of iron overload (Vautier, Murray, Olynyk, 2001). Within families affected by hemochromatosis, some individuals have been found with a homozygous C282Y mutation but no demonstrable iron overload; investigations for occult blood loss in such patients have been unrevealing (Adams, Chakrabarti, 1998; Adams, Campion, Gwandon, LeGall, David, Jouanolle, 1997). Canadian population screening studies have also identified asymptomatic young adults who are homozygous for the mutation without iron overload. The value of detecting such cases is controversial. On the one hand, these people may be predisposed to develop iron overload later in life and may therefore benefit from surveillance. Family studies may lead to the discovery of relatives who are homozygous for the mutation and do have iron overload. On the other hand, indiscriminate testing can cause unnecessary anxiety and could lead to discrimination with regard to health or life insurance. (Adams, Kertesz, Barr, Bamford, Chakrabarti, 1998) A relatively high proportion of relatives of clinically diagnosed individuals have typical early symptoms, but fewer have evidence of serious organ damage (Bradley, Haddow, Palomaki II 1996). Studies of family members may overestimate the prevalence of symptoms because relatives may be more aware of, and likely to report, clinical manifestations. Also, those with health problems may be more likely to agree to be evaluated. Genetically predisposed relatives of diagnosed cases may even be more likely to become symptomatic (Bradley, Haddow, Palomaki I 1996). Thus, it is evident that during the past several years hereditary haemochromatosis has risen from relative obscurity to become a topic of intense interest in the health community. Graphic 1. The normal distribution of body iron stores. Graphic 2. Relationship between total body iron stores and clinical manifestations of hereditary hemochromatosis over time. Graphic 3. Cumulative survival in patients who have hereditary hemochromatosis with and without cirrhosis and diabetes. References. 1. Adams PC, Campion ML, Gwandon G, LeGall JY, David V, Jouanolle AM. Clinical and family studies in genetic hemochromatosis: microsatellite and HFE studies in five atypical families. Hepatology, 1997;26:986-90. 2. Adams PC, Chakrabarti S. Genotypic/phenotypic correlations in genetic hemochromatosis: evolution of diagnostic criteria. Gastroenterology, 1998; 114:319-23. 3. Adams PC, Kertesz AE, Barr R, Bamford A, Chakrabarti S. Population screening for hemochromatosis with the unbound iron binding capacity (UIBC) [abstract]. Can J Gastroenterol 1998; 12:86A. 4. Bradley L, Johnson D, Palomaki G, Haddow J, Robertson N, Ferrie R. Hereditary haemochromatosis mutation frequencies in the general population. J Med Screen, 1998; 5: 34-36. 5. Bradley LA, Haddow JE, Palomaki GE, II. Population screening for haemochromatosis: a unifying analysis of published intervention trials. J Med Screen 1996; 3: 178-184. 6. Bradley LA, Haddow JE, Palomaki GE. I, Population screening for hemochromatosis: expectations based on studying relatives of symptomatic probands. J Med Screen, 1996; 3: 171-177 7. Fleming RE, Sly WS. Mechanisms of iron accumulation in hereditary hemochromatosis. Annu Rev Physiol 2002; 64: 663-80. 8. Hereditary Hemochromatosis: Practice Guidelines, Development, Task Force of the College of American Pathologists. Clin Chim Acta, 1996; 245: 139-200. 9. McDonnell SM, Preston BL, Jewell SA, Barton JC, Edwards CQ, Adams PC, et al. A survey of 2,851patients with hemochromatosis: symptoms and response to treatment. Am J Med 1999; 106: 619-624. 10. Niederau C, Fischer R, Sonnenberg A, Stremmel W, Trampisch HJ, Strohmeyer G. Survival and causes of death in cirrhotic and in noncirrhotic patients with primary hemochromatosis. N Engl J Med 1985; 313:1256-62. 11. Riely CA, Vera SR, Burrell MI, Koff RS. Inherited liver diseases. AGA clinical teaching project. Unit 8. Bethesda, Md.: American Gastroenterological Association, 1993. 12. Steinberg KK, Cogswell ME, Chang JC, et al. Prevalence of C282Y and H63D mutations in the hemochromatosis (HFE) gene in the United States. JAMA 2001 May 2; 285(17): 2216-22 (Steinberg, Cogswell, Chang, et al, 2001). 13. Vautier G, Murray M, Olynyk JK. Hereditary haemochromatosis: detection and management. Med J Aust 2001 Oct 15; 175(8): 418-21. Read More