U4 LEC: IRON KINETICS AND METABOLISM Flashcards
Iron kinetics happen in the?
intestinal lumen
T/F: Iron is not endogenouslly produced.
True
Forms of Iron from our diet
- heme form
- ionic form (ferric form)
If Iron is in heme form, to where does it get transported and by what?
Enterocyte, Heme transporter
This degrades the heme for release of Iron from Protoporphyrin IX.
Heme Oxygenase
This reduces the ferric Iron to ferrous Iron.
Duodenal Cytochrome B
Ferrous iron can be absorbed in enterocyte through the?
Divalent Metal Transporter 1 (DMT1)
Excess iron can be stored as?
Ferritin
Stored Iron
Ferritin
Iron released from the enterocyte then in to the circulation is through the?
Ferroportin
Aside from enterocytes, these cells also have Ferroportin.
- hepatocytes
- macrophages
Protein produced by the liver responsible for transporting ferric Iron
Transferrin
T/F: Before Transferrin transports the Iron, it must be in Ferrous form
False
must be reoxidized back to ferric state
This is responsible for the reoxidation of ferrous to ferric state so it can bind to Transferrin.
Hephaestin
Transferrin will carry Iron to ________ for heme synthesis to occur on developing eryhthroblasts.
Bone Marrow
Excessive iron leads to?
iron toxicity and damage to the heart, liver, internal organs
This is responsible to maintain iron homeostasis, produced in the liver that blocks Ferroportin.
Hepcidin
Hepcidin blocks Ferroportin to?
prevent absorption and release of Iron in the circulation
Increased Serum Fe, _______ Hepcidin
Increased
Iron is also excreted through?
enterocyte (sloughed off)
Absorption of excessive iron, can lead to iron toxicity
Primary Hemochromatosis
Overdose of Iron due to medical treatments, drugs, supplements
Secondary Hemochromatosis
Protein of hepatic origin that inhibits Ferroportin from transporting iron out of the enterocyte
Hepcidin
T/F: All cells except the mature RBC can store Ferritin.
True
Mature RBC is the end receiver of iron used to synthesize Hgb
1 Ferritin is equal to?
4000 Iron Ion Reserve
Partially degraded Ferritin, less metabolically active and available
Hemosiderin
These are found in RTE cells.
Hemosiderin granules
These are cells that line the convoluted tubules.
Renal Tubular Epithelial Cells (RTE Cells)
If patient has Intravascular Hemolysis (rupture of RBC in circulation), it will rseult to?
Hemoglobinuria
In Hemoglobinuria, RTE tries to reabsorb the excessive Hgb and will deposit to RTE as?
iron as Hemosiderin granules
Iron is stained by?
Prussian Blue
Screening Tests for defects in Iron/Hgb Metabolism added to CBC
- Serum Fe
- TIBC
- % Transferrin Saturation
- Serum Ferritin
If results are not yet definite for diagnosis or not matching , it is termed as?
equivocal
If results are equivocal, these additional tests can be done:
- Prussian blue staining
- Hgb content of Reticulocytes
- Soluble Transferrin Receptor
- sTfR/log ferritin
- ZPP
This is the Iron present in the circulation, or an indicator of available transport Iron.
Serum Iron Level (Serum Fe2+)
Decreased (↓) Iron due to lack of dietary intake, increased need of Iron in pregnant women or developing children, chronic bleeding
Iron Deficiency Anemia (depletion of Ferritin)
This refers to profused bleeding due to traumatic condition (surgery, gunshot, stab)
Acute Bleeding (↓ Decreased blood volume, abrupt losing)
This refers to slowly losing small amounts of blood due to GI bleeding, heavy menstruation
Chronic bleeding (Normal blood volume but losing Iron)
IDA
What is depleted first?
Ferritin
Genetic condition in which patient has increased absorption of iron (abnormal iron overload)
Primary Hemochromatosis
This is an acquired condition due to taking of iron supplements, medicine.
Secondary Hemochromatosis
This conditions stems from malignant conditions such as cancer, TB, systemic lupus erythematosus, rheumatoid arthritis.
Anemia of Chronic Inflammation (Affected ferrokinetics)
ACI
In presence of inflammation, liver will produce?
more Hepcidin (depleted serum iron)
Hepcidin and C-reactive proteins are called?
Acute Phase Reactants (Elevated in inflammation)
Requirements for Serum Iron Level testing
- fasting (intake will cause false elevated iron)
- early morning specimen (high in the morning, low in afternoon)
Serum Iron Level
Reference Value
50-160 ug/dL
Serum Iron Level
Conditions
IDA: Decreased (↓)
HEMO: Increased (↑)
ACI: Decreased (↓)
