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Flashcards in Vit and Min III Deck (15)
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name 4 enzmyes that need copper as a coenzyme

  • 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


describe copper metabolism

  • 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)


describe the role of ceruloplasmin in iron metabolism

  • 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


describe copper deficiency

  • 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


describe Menkes syndrome 

  • 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


describe Wilson disease

  • 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


describe the progression of Wilson disease


what is Kayser Fleischer ring?

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


descrbie dietary iron uptake

  • 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)


describe the transport and storage of iron

  • 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)


describe lab tests for iron status

  • 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


describe lab findings for hemochromatosis

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


describe hereditary hemochromatosis

  • 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


name clinical features of hemochromatosis

  • 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 


describe lab findings in iron deficiency anemia 

  • 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