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Wednesday, January 07, 2009

Which of the following is not true for Hereditary Hemochromatosis – Desferroxamine not treatment of choice

Question 81
Which of the following is not true for Hereditary Hemochromatosis
a.       Gonadal failure is seen
b.      Desferroxamine is the treatment of choice
c.       Arthropathy is seen
d.      Skin pigmentation is seen
Answer
b. Desferroxamine is the treatment of choice
Reference
Harrison 16th Edition Page 2302
QTDF
Harrion
Quality
Reader
Status
Repeat
Discussion
Hemochromatosis is a common disorder of iron storage in which an appropriate increase in intestinal iron absorption results in deposition of excessive amounts of iron in parenchymal cells with eventual tissue damage and impaired function of organs, especially the liver, pancreas, heart, joints, and pituitary. The disease was termed hemochromatosis and the iron-storage pigment was called hemosiderin because it was believed that the pigment was derived from the blood. The terms hemosiderosis and siderosis are often used to describe the presence of stainable iron in tissues, but tissue iron must be quantified to assess body iron status  Hemochromatosis implies potentially severe progressive iron overload leading to fibrosis and organ failure.
Explanation
Ä     Cirrhosis of the liver, diabetes mellitus, arthritis, cardiomyopathy, and hypogonadotrophic hypogonadism are common manifestations.
Ä     The therapy of hemochromatosis involves removal of the excess body iron and supportive treatment of damaged organs. Iron removal is best begun by weekly or twice-weekly phlebotomy of 500 mL. Although there is an initial modest decline in the volume of packed red blood cells to about 35 mL/dL, the level stabilizes after several weeks. The plasma transferrin saturation remains increased until the available iron stores are depleted. In contrast, the plasma ferritin concentration falls progressively, reflecting the gradual decrease in body iron stores. Since one 500-mL unit of blood contains 200 to 250 mg iron and about 25 g iron should be removed, weekly phlebotomy may be required for 1 or 2 years. When the transferrin saturation and ferritin level become normal, phlebotomies are performed at appropriate intervals to maintain levels within the normal range. The measurements promptly become abnormal with iron reaccumulation. Usually one phlebotomy every 3 months will suffice.
Ä     Chelating agents such as deferoxamine, when given parenterally, remove 10 to 20 mg iron per day, which is much less than that mobilized by once-weekly phlebotomy. Phlebotomy is also less expensive, more convenient, and safer for most patients. However, chelating agents are indicated when anemia or hypoproteinemia is severe enough to preclude phlebotomy. Subcutaneous infusion of deferoxamine using a portable pump is the most effective means of administration.
Comments
The management of hepatic failure, cardiac failure, and diabetes mellitus is similar to conventional therapy for these conditions. Loss of libido and change in secondary sex characteristics are partially relieved by parenteral testosterone or gonadotropin therapy
Tips
Ä     Hereditary or genetic hemochromatosis: This disorder is most often caused by inheritance of a mutant HFE gene, which is tightly linked to the HLA-A locus on chromosome 6p. The genetic disease can be recognized during its early stages when iron overload and organ damage are minimal. At this stage the disease is best referred to as early or precirrhotic hemochromatosis.
Ä     Secondary iron overload: Tissue injury usually occurs secondary to an iron-loading anemia such as thalassemia or sideroblastic anemia, in which increased erythropoiesis is ineffective. In the acquired iron-loading disorders, massive iron deposits in parenchymal tissues can lead to the same clinical and pathologic features as in hemochromatosis

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