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Flashcards in Vit and Min III Deck (15)
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1

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

2

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)

3

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

4

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

5

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

6

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

7

describe the progression of Wilson disease

8

what is Kayser Fleischer ring?

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

9

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)

10

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)

11

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

12

describe lab findings for hemochromatosis

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

13

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

14

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 

15

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