Iron, Folate and B12 Metabolism Flashcards
R protein
Binds to B12 in the mouth
Parietal Cells
Release intrinsic factor which aids in intestinal B12 absorption
B12 is absorbed in the ….?
ILEUM!@!@
Iron is naturally Fe__+
Fe3+
What makes iron become Fe2+?
Vitamin C. It must be in this state to be absorbed.
How is iron metabolized?
Its not. Duh. It is lost through bleeding and menstrual periods. Gross.
Recommended Iron intake per day?
Males: 10mg/day
Females: 18mg/day
How much iron do we absorb per day?
About 1 mg.
What does Iron do?
Oxygen carriers: Hemoglobin
Oxygen storage: Myoglobin
Energy Production: Cytochromes, krebs enzymes
Liver detoxification
Hemochromatosis
Iron overload.
Can take years to build up
Hemosiderin: extra iron in ferritin
Possibly related to cancers, cardiac toxicity.
Iron overload symptoms
Same symptoms as iron deficiency.
Being tired all the time
Lack of menstrual period
Blood tests for iron
Serum iron
TIBC - Total iron binding capacity
Transferrin saturation
Total average iron in adult male body
35 - 45 mg/kg or approximately 4g total
Distribution of Iron
Red cell mass: 50% Muscles as myoglobin: 7% Storage as ferritin: 30% mostly in liver Other heme proteins: 5% In serum: 0.1%
Where is transferrin made?
In the liver.
Transports iron between body locations
Iron taken up into cells by transferrin receptors
How many molecules can each transferrin bind?
Two Fe3 molecules.
In iron overload, what happens to transferrin production?
Production is decreased in iron overload, and increased in iron deficiency.
Serum transferrin + Serum Iron =
Transferrin saturation.
95% of serum iron is bound to transferrin.
How many iron molecules can a Ferritin bind?
4,500 atoms.
What is ferritin’s role?
Stores iron and releases it in a controlled fashion.
Reasons for iron loss?
Cell Loss (gut, desquamation)
Menstruation
Pregnancy, lactation
Bleeding (trauma)
Iron scavenging
Free hemoglobin –> hemopexin —> liver
Free heme –> Hemopexin —> liver
Heme passing through kidney is reabsorbed
Where is iron absorbed?
Duodenum
Only ___% of dietary iron is absorbed.
10%
Hepcidin
Synthesized in the liver
Hepatic Bacteriocidal Protein.
Stops iron from getting out of gut cells —> makes it shed and be lost into stool.
Increases Iron loss in the gut
Decreased Hepcidin production leads to?
Iron retention. Caused by low iron levels, low hemoglobin, low oxygen content.
Increased Hepcidin Production
Increased Iron Loss. Caused by systemic inflammation (too much iron)
Ferroportin
Present on the surface of cells to release iron into circulation. Gut cells, liver cells and macrophages.
Requires cofactor to oxidize iron to allow for binding to transferrin.
- Hephestin in gut
- Ceruloplasmin in other cells
Iron deficiency
- Extremely common. due to decreased intake, increased demands and increased loss.
- Stores reduced before deficiency is seen.
Is “Iron Deficiency” an adequate diagnosis?
No, the cause must be identified.
Vitamin B12 (Cobalamin)
- Plays a key role in normal functioning of the brain and nervous system.
- Formation of blood
- DNA synthesis and regulation
- Obtained from diet, and produced by bacteria, stored in liver.
T or F: B12 is fat-soluble.
False. B12 is water soluble. Get your shit in order.
B12 plays a role in the recycling of ______? What do ______ do?
They play a role in recycling of folates.
- Support RBC production
- Help prevent homocysteine build up in blood
- High levels of Homocysteine leads to inflammatory and coronary heart disease.
B12 plays a role in methionine synthesis. What does methionine do?
It is an essential amino acid.
Comes from meat, fish and dairy products.
May treat depression, liver disease, inflammation and muscle pains.
______ and ______ deficiencies show the same symptoms.
Vitamin B12 and Folate
Megaloblastic Anemia
A vitamin B12 or Folate deficiency.
Anemia with larger than normal RBC’s.
Hypersegmented Neutrophils on CBC
Neurologic Disorder
Probably secondary deficiency of methionine.
Deprivation of the nerves
Parasthesias
Homocystenuria
Kyphosis
Lens subluxation
Atherosclerosis
B12 and Folate must be given ______.
Together. Just giving one along may aggravate the disease.
2 phases of B12 absorption
Gastric: Intrinsic factor binds B12
Intestinal: IF-B12 is absorbed in illeum
Which deficiency is most commonly seen with B12 deficiency?
Pernicious anemia (a form of megaloblastic anemia) Failure to secrete intrinsic factor
Folate (Folic acid)
Vitamin B9. Related to B12, need a good balance between folate and B12.
Folate deficiency
Hyperhomocysteiemia: A risk factor for CVD.
Megaloblastic anemia
Causes of folate deficiency
Inadequate intake
Impaired metabolism/absorption
Increased demand (pregnancy/lactation)
Elderly (poor diet/absorption)
Medications that cause folate deficiency
Omeprazole (used for gerd)
OTC H2 blockers (Tagamet)
- reduce absorption or iron, folate, B12
Microcytes
Drastically smaller RBC’s indicative or iron deficiency.
Macrocytes
Larger RBC’s indicative of megaloblastic anemias and aplastic anemias.
Polychromasia
Young RBC’s seen in severe anemia
Basophilic Stippling
Pernicious anemia, seen in alcoholics and lead poisoning.
Hypochromasia
Cells have decreased hemoglobin content, central pallor. indicative of iron deficiency anemia.
Spherocytes
Hemolytic anemia
Target cells
Chronic liver disease
Helmet cells (Schistocyte)
Fragment of cell. indicative of hemolytic anemia or acute leukemia.
Burr cells
Hemolytic anemias, iron deficiencies, or acute blood loss.
