other notes from hema

Question 1

Master regulatory hormone of systemic iron metabolism

Answer 1

Hepcidin (produced by the liver)

Question 2

Effect of decreased iron stores on plasma iron

Answer 2

Decreases plasma iron, leading to liver alert and hepcidin production stops

Question 3

Effect of decreased hepcidin production

Answer 3

Ferroportin in enterocyte and macrophage membranes becomes active, increasing iron absorption and recycling

Question 4

Effect of increased plasma iron on hepcidin production

Answer 4

Plasma iron increases, iron stores increase, liver alerts and produces hepcidin

Question 5

Effect of hepcidin on ferroportin

Answer 5

Inactivates ferroportin in enterocyte and macrophage membranes, reducing iron absorption and recycling

Question 6

Hemochromatosis protein (HFE)

Answer 6

Hepatocyte membrane

Question 7

Transferrin receptor 2 (TfR2)

Answer 7

Hepatocyte membrane

Question 8

Bone morphogenic protein (BMP)

Answer 8

Secreted product of macrophages

Question 9

Bone morphogenic protein receptor (BMPR)

Answer 9

Hepatocyte (and other cells) membrane

Question 10

Hemojuvelin (HJV)

Answer 10

Hepatocyte membrane

Question 11

SMAD (sons of mothers against decapentaplegic)

Answer 11

Hepatocyte (and other cells) cytoplasm

Question 12

Absorption sites for iron

Answer 12

Duodenum and upper jejunum

Question 13

Foods with high iron levels

Answer 13

Red meats, legumes, dark green leafy vegetables

Question 14

Iron forms for absorption

Answer 14

Ionic iron (Fe+2, ferrous) and heme (nonionic)

Question 15

Most common dietary iron form

Answer 15

Fe+3 (ferric), especially in plant sources, poorly absorbed

Question 16

Factors inhibiting iron absorption

Answer 16

Oxalates, phytates, phosphates, calcium

Question 17

Enhancers of iron absorption

Answer 17

Gastric acid, acidic foods (citrus), DcytB (duodenal cytochrome B)

Question 18

Heme iron absorption

Answer 18

More readily absorbed than ionic iron; found in meat (myoglobin, hemoglobin)

Question 19

Ferrous iron (Fe+2) transport

Answer 19

Carried by DMT1 (divalent metal transporter 1) across enterocyte membrane

Question 20

Transport of absorbed iron

Answer 20

Requires ferroportin; Hephaestin reoxidizes Fe+2 to Fe+3 for transport into blood

Question 21

Hephaestin function

Answer 21

Oxidizes iron as it exits the enterocyte for plasma transport.

Question 22

Iron transport protein

Answer 22

Transferrin, formed when apotransferrin binds ferric (Fe+3) iron.

Question 23

Receptor for transferrin

Answer 23

Transferrin receptor 1 (TfR1) on cell membranes.

Question 24

Iron use in cells

Answer 24

Transferred into mitochondria for cytochrome or heme production, or stored as ferritin.

Question 25

Storage form of iron in cells

Answer 25

Ferritin, stored in cells with excess iron, especially in macrophages and hepatocytes.

Question 26

Ferritin characteristics

Answer 26

Intracellular protein secreted by macrophages, an acute phase reactant (APR) elevated in inflammation.

Question 27

Ferritin degradation

Answer 27

Iron is released from ferritin by degradation in lysosomes.

Question 28

Hemosiderin

Answer 28

Partially degraded ferritin, seen in iron overload, detectable using Prussian blue iron stain.

Question 29

Iron excretion mechanism

Answer 29

Minimal daily loss via exfoliation; no active excretion.

Question 30

Iron's role in cells

Answer 30

Essential for energy production and oxygen transport in hemoglobin.

Question 31

Iron recycling source

Answer 31

Primarily from aging RBCs degraded by splenic macrophages.

Question 32

Macrophage iron storage

Answer 32

Stores iron from hemoglobin as ferritin.

Question 33

Macrophage iron export

Answer 33

Uses ferroportin to export iron to other cells.

Question 34

Plasma proteins in iron recycling

Answer 34

Haptoglobin saves hemoglobin; hemopexin saves heme.

Question 35

Hepatocyte role in recycling

Answer 35

Exports stored iron via ferroportin to transferrin.

Question 36

Main functional iron compartment in blood

Answer 36

Hemoglobin iron (~68%).

Question 37

Functional iron in muscles

Answer 37

Myoglobin iron (~10%).

Question 38

Functional iron in cellular enzymes

Answer 38

Peroxidase, catalase, cytochromes (~3%).

Question 39

Primary iron storage forms

Answer 39

Ferritin and hemosiderin in macrophages and hepatocytes (~18%).

Question 40

Iron storage exceptions in cells

Answer 40

Mature RBCs do not store iron.

Question 41

Iron transport mechanism in plasma

Answer 41

Transferrin (<1%).

Question 42

Serum iron reference range and use

Answer 42

50 to 160 μg/dL; used for diagnosing disorders of iron metabolism.

Question 43

Serum iron specimen requirements

Answer 43

Nonhemolyzed serum, collected in the morning after 12-hour fasting.

Question 44

TIBC reference range and purpose

Answer 44

250 to 400 μg/dL; indirectly measures transferrin concentration via iron-binding ability.

Question 45

TIBC specimen requirements

Answer 45

Nonhemolyzed serum, 12-hour fasting; values are time-independent.

Question 46

Transferrin iron saturation range and calculation

Answer 46

20% to 55%; (Serum Iron / TIBC) x 100.

Question 47

Serum ferritin reference range for men and women

Answer 47

40 to 400 ng/mL (men), 12 to 160 ng/mL (women).

Question 48

Significance of serum ferritin test

Answer 48

Reflects tissue iron stores; first indicator of declining iron storage.

Question 49

Test used for direct visualization of tissue iron stores

Answer 49

Prussian Blue staining of bone marrow or liver biopsy.

Question 50

Prussian Blue staining mechanism

Answer 50

Uses acidic potassium ferrocyanide; ferric iron forms visible Fe7(CN)18 (Prussian blue) compound.

Question 51

Prussian Blue stain as a diagnostic tool

Answer 51

Gold standard for assessing tissue iron; detects hemosiderin but not ferritin.

Question 52

Serum iron reference range and use

Answer 52

50 to 160 μg/dL; used for diagnosing disorders of iron metabolism.

Question 53

Serum iron specimen requirements

Answer 53

Nonhemolyzed serum, collected in the morning after 12-hour fasting.

Question 54

TIBC reference range and purpose

Answer 54

250 to 400 μg/dL; indirectly measures transferrin concentration via iron-binding ability.

Question 55

TIBC specimen requirements

Answer 55

Nonhemolyzed serum, 12-hour fasting; values are time-independent.

Question 56

Transferrin iron saturation range and calculation

Answer 56

20% to 55%; (Serum Iron / TIBC) x 100.

Question 57

Serum ferritin reference range for men and women

Answer 57

40 to 400 ng/mL (men), 12 to 160 ng/mL (women).

Question 58

Significance of serum ferritin test

Answer 58

Reflects tissue iron stores; first indicator of declining iron storage.

Question 59

Test used for direct visualization of tissue iron stores

Answer 59

Prussian Blue staining of bone marrow or liver biopsy.

Question 60

Prussian Blue staining mechanism

Answer 60

Uses acidic potassium ferrocyanide; ferric iron forms visible Fe7(CN)18 (Prussian blue) compound.

Question 61

Prussian Blue stain as a diagnostic tool

Answer 61

Gold standard for assessing tissue iron; detects hemosiderin but not ferritin.

Question 62

Increased tissue iron stores without tissue damage; may progress to hemochromatosis.

Answer 62

Hemosiderosis

Question 63

Increased iron accumulation in body tissues causing tissue damage.

Answer 63

Hemochromatosis

Question 64

Most common form of iron overload disease

Answer 64

Hereditary Hemochromatosis (Bronze Diabetes)

Question 65

Genetic cause of Hereditary Hemochromatosis

Answer 65

Mutations in the HFE gene regulating dietary iron absorption

Question 66

Symptoms of Hereditary Hemochromatosis

Answer 66

Arthritis, liver cirrhosis, congestive heart failure, impotence, bronze skin, diabetes, thyroid deficiency

Question 67

Treatment approaches for Hereditary Hemochromatosis

Answer 67

Avoiding iron-rich foods, phlebotomy, Deferoxamine (Desferal)