Iron, Folate and B12 Metabolism

Question 1

R protein

Answer 1

Binds to B12 in the mouth

Question 2

Parietal Cells

Answer 2

Release intrinsic factor which aids in intestinal B12 absorption

Question 3

B12 is absorbed in the ….?

Answer 3

ILEUM!@!@

Question 4

Iron is naturally Fe__+

Answer 4

Fe3+

Question 5

What makes iron become Fe2+?

Answer 5

Vitamin C. It must be in this state to be absorbed.

Question 6

How is iron metabolized?

Answer 6

Its not. Duh. It is lost through bleeding and menstrual periods. Gross.

Question 7

Recommended Iron intake per day?

Answer 7

Males: 10mg/day
Females: 18mg/day

Question 8

How much iron do we absorb per day?

Answer 8

About 1 mg.

Question 9

What does Iron do?

Answer 9

Oxygen carriers: Hemoglobin
Oxygen storage: Myoglobin
Energy Production: Cytochromes, krebs enzymes
Liver detoxification

Question 10

Hemochromatosis

Answer 10

Iron overload.
Can take years to build up
Hemosiderin: extra iron in ferritin
Possibly related to cancers, cardiac toxicity.

Question 11

Iron overload symptoms

Answer 11

Same symptoms as iron deficiency.
Being tired all the time
Lack of menstrual period

Question 12

Blood tests for iron

Answer 12

Serum iron
TIBC - Total iron binding capacity
Transferrin saturation

Question 13

Total average iron in adult male body

Answer 13

35 - 45 mg/kg or approximately 4g total

Question 14

Distribution of Iron

Answer 14

Red cell mass:  50%
Muscles as myoglobin:  7%
Storage as ferritin:  30%  mostly in liver
Other heme proteins:  5%
In serum:  0.1%

Question 15

Where is transferrin made?

Answer 15

In the liver.
Transports iron between body locations
Iron taken up into cells by transferrin receptors

Question 16

How many molecules can each transferrin bind?

Answer 16

Two Fe3 molecules.

Question 17

In iron overload, what happens to transferrin production?

Answer 17

Production is decreased in iron overload, and increased in iron deficiency.

Question 18

Serum transferrin + Serum Iron =

Answer 18

Transferrin saturation.

95% of serum iron is bound to transferrin.

Question 19

How many iron molecules can a Ferritin bind?

Answer 19

4,500 atoms.

Question 20

What is ferritin’s role?

Answer 20

Stores iron and releases it in a controlled fashion.

Question 21

Reasons for iron loss?

Answer 21

Cell Loss (gut, desquamation)
Menstruation
Pregnancy, lactation
Bleeding (trauma)

Question 22

Iron scavenging

Answer 22

Free hemoglobin –> hemopexin —> liver
Free heme –> Hemopexin —> liver
Heme passing through kidney is reabsorbed

Question 23

Where is iron absorbed?

Answer 23

Duodenum

Question 24

Only ___% of dietary iron is absorbed.

Answer 24

10%

Question 25

Hepcidin

Answer 25

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

Question 26

Decreased Hepcidin production leads to?

Answer 26

Iron retention. Caused by low iron levels, low hemoglobin, low oxygen content.

Question 27

Increased Hepcidin Production

Answer 27

Increased Iron Loss. Caused by systemic inflammation (too much iron)

Question 28

Ferroportin

Answer 28

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

Question 29

Iron deficiency

Answer 29

- Extremely common. due to decreased intake, increased demands and increased loss. - Stores reduced before deficiency is seen.

Question 30

Is "Iron Deficiency" an adequate diagnosis?

Answer 30

No, the cause must be identified.

Question 31

Vitamin B12 (Cobalamin)

Answer 31

- 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.

Question 32

T or F: B12 is fat-soluble.

Answer 32

False. B12 is water soluble. Get your shit in order.

Question 33

B12 plays a role in the recycling of ______? What do ______ do?

Answer 33

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.

Question 34

B12 plays a role in methionine synthesis. What does methionine do?

Answer 34

It is an essential amino acid. Comes from meat, fish and dairy products. May treat depression, liver disease, inflammation and muscle pains.

Question 35

______ and ______ deficiencies show the same symptoms.

Answer 35

Vitamin B12 and Folate

Question 36

Megaloblastic Anemia

Answer 36

A vitamin B12 or Folate deficiency. Anemia with larger than normal RBC's. Hypersegmented Neutrophils on CBC

Question 37

Neurologic Disorder

Answer 37

Probably secondary deficiency of methionine. Deprivation of the nerves Parasthesias

Question 38

Homocystenuria

Answer 38

Kyphosis Lens subluxation Atherosclerosis

Question 39

B12 and Folate must be given ______.

Answer 39

Together. Just giving one along may aggravate the disease.

Question 40

2 phases of B12 absorption

Answer 40

Gastric: Intrinsic factor binds B12 Intestinal: IF-B12 is absorbed in illeum

Question 41

Which deficiency is most commonly seen with B12 deficiency?

Answer 41

``` Pernicious anemia (a form of megaloblastic anemia) Failure to secrete intrinsic factor ```

Question 42

Folate (Folic acid)

Answer 42

Vitamin B9. Related to B12, need a good balance between folate and B12.

Question 43

Folate deficiency

Answer 43

Hyperhomocysteiemia: A risk factor for CVD. | Megaloblastic anemia

Question 44

Causes of folate deficiency

Answer 44

Inadequate intake Impaired metabolism/absorption Increased demand (pregnancy/lactation) Elderly (poor diet/absorption)

Question 45

Medications that cause folate deficiency

Answer 45

Omeprazole (used for gerd) OTC H2 blockers (Tagamet) - reduce absorption or iron, folate, B12

Question 46

Microcytes

Answer 46

Drastically smaller RBC's indicative or iron deficiency.

Question 47

Macrocytes

Answer 47

Larger RBC's indicative of megaloblastic anemias and aplastic anemias.

Question 48

Polychromasia

Answer 48

Young RBC's seen in severe anemia

Question 49

Basophilic Stippling

Answer 49

Pernicious anemia, seen in alcoholics and lead poisoning.

Question 50

Hypochromasia

Answer 50

Cells have decreased hemoglobin content, central pallor. indicative of iron deficiency anemia.

Question 51

Spherocytes

Answer 51

Hemolytic anemia

Question 52

Target cells

Answer 52

Chronic liver disease

Question 53

Helmet cells (Schistocyte)

Answer 53

Fragment of cell. indicative of hemolytic anemia or acute leukemia.

Question 54

Burr cells

Answer 54

Hemolytic anemias, iron deficiencies, or acute blood loss.