Vit and Min III

Question 1

name 4 enzmyes that need copper as a coenzyme

Answer 1

• lysyl oxidase
  
  • synthesis of collagen (formation of cross-links in collagen), different from lysyl hydroxylase which needs vit. C
• tyrosinase
  
  • melanin synthesis
• cytochrome c
  
  • part of complex IV of the ETC
• superoxide dismutase

Question 2

describe copper metabolism

Answer 2

• ingested copper is absorbed in the stomach and intestine and transported to the liver bound to albumin
• in hepatocytes, it is used to form ceruloplasmin which is secreted into the plasma (require copper transporting ATPase)
• aged ceruloplasmin is taken up by the liver from the plasma and degraded and copper is secreted into the bile (require copper transporting ATPase)

Question 3

describe the role of ceruloplasmin in iron metabolism

Answer 3

• ceruloplasmin (ferroxidase) converts ferrous iron to the ferric form
  
  • it facilitates the conversion of ferrous (absorbed iron) to the ferric form and incorporates the ferric iron into transferrin for transport of iron
• ceruloplasmin also mobilizes ferric ions from ferritin and hemosiderin
• ceruloplasmin is a serum protein that is an alpha2-globulin and is an acute phase protein

Question 4

describe copper deficiency

Answer 4

• nutritional deficiency usually presents along with malnutrition
• signs and symptoms:
  
  • microcytic anemia (smaller RBCs): as ceruloplasmin (ferroxidase) is required for iron metabolism and mobilization, copper def. affects iron mobilization
  • degradation of vascular tissue: decreased lysyl oxidase activity
  • defects in hair; hypopigmented discolored hair because of low tyrosinase activity

Question 5

describe Menkes syndrome

Answer 5

• X-linked disease
• inherited defect in absorption of copper from the GI tract
• low levels of copper in plasma and most tissues
• copper deficiency can lead to aneurysms and cerebral dysfunction because of reduced lysyl oxidase actvity

Question 6

describe Wilson disease

Answer 6

• autosomal recessive disorder of copper metabolism
• characterized by accumulation of toxic levels of copper in vital organs including liver, brain and eye
• mutation of the copper transporting ATPase in the liver
  
  • this protein is needed to attach copper to ceruloplasmin and also to excrete copper into the bile

Question 7

describe the progression of Wilson disease

Answer 7

Question 8

what is Kayser Fleischer ring?

Answer 8

• deposition of copper in the cornea as seen in Wilson disease

Question 9

descrbie dietary iron uptake

Answer 9

• the dietary iron absorption is tightly regulated by body iron stores
  
  • intestinal mucosal cells have an iron sensing mechanism to regulate iron absorption
• heme iron: absorbed more effectively than inorganic iron
• inorganic iron: needs to be converted from the ferric form to ferrous form (easier to absorb)
• ferric iron is changed to ferrous iron in the stomach (low pH in stomach and dietary vit. C)

Question 10

describe the transport and storage of iron

Answer 10

• ceruloplasmin (ferroxidase) participates in the release of ferrous iron from intestinal cells and forms ferric iron which is needed for transport in the blood
• transferrin is the transport protein for ferric ion in blood plasma
  
  • B-globulin serum protein
• iron is stored in liver and RES as ferritin and hemosiderin (ferric)

Question 11

describe lab tests for iron status

Answer 11

• serum iron
  
  • low serum iron: iron deficiency anemia
  • high serum iron is seen in iron overload (hemochromatosis)
• total iron binding capacity (TIBC)
  
  • TIBC increased in iron deficiency anemia (adaptive)
  • TIBC is decreased in iron overload (adaptive)
• % saturation of transferrin:
  
  • transferrin saturation decreased in iron def. anemia
  • transferrin saturation increased in iron overload

Question 12

describe lab findings for hemochromatosis

Answer 12

• high serum ferritin levels (indicates excessive iron stores)
• high seurm iron levels
• transferrin saturation (>50%)
• TIBC is decreased

Question 13

describe hereditary hemochromatosis

Answer 13

• autosomal recessive disorder
• genetic defect causing excessive absorption of iron, caused by a mutation in the HFE gene
  
  • most frequent mutation is C282Y allele but there is allelic heterogeneity
• delayed age of onset
• males affected earlier than females because of menstrutation in females
• excessive accumulation of iron in the parenchymal organs, most importantly liver and pancreas

Question 14

name clinical features of hemochromatosis

Answer 14

• more common in males; presenting at age 40
• acute synovitis or chronic joint pain (knuckles)
• chornic fatigue
• hepatomegaly; liver damage, cirrhosis
• diabetes due to destruction of beta cells of pancreas
• brownish skin pigmentation

Question 15

describe lab findings in iron deficiency anemia

Answer 15

• low Hb levels; low hematocrit
• low MCV
• low serum ferritin levels (indicate low body iron stores)
• low seurm iron levels
• low % saturation of transferrin
• increased TIBC