Inron kinetics

c

What percentage of total body iron is contained within hemoglobin in red blood cells?

A. 10%

B. 25%

C. 65%

D. 50%

E. 85%

b

Which iron compartment includes hemoglobin, myoglobin, and cytochromes?

A. Transport compartment

B. Functional compartment

C. Storage compartment

D. Free iron compartment

E. Excretory compartment

c

What is the daily dietary requirement range for iron intake?

A. 1 to 2 mg

B. 5 to 8 mg

C. 10 to 20 mg

D. 25 to 30 mg

E. 50 to 100 mg

a

How much iron is typically absorbed daily by the body from the diet?

A. 1 to 2 mg

B. 5 to 10 mg

C. 10 to 20 mg

D. 0.1 to 0.5 mg

E. 25 to 30 mg

d

What percentage more dietary iron requirement do women have compared to men?

A. 10%

B. 25%

C. 33%

D. 50%

E. 75%

b

Which specific cell layer of the small intestine is responsible for absorbing dietary iron?

A. Hepatocytes

B. Enterocytes

C. Splenic macrophages

D. Erythroblasts

E. Reticulocytes

b

Which form of iron is absorbable by intestinal enterocytes?
A. Ferric iron (Fe^{3+})
B. Ferrous iron (Fe^{2+})
C. Hemoglobin-bound ferric iron
D. Ferritin-bound ferric iron
E. Transferrin-bound iron

c

What protein facilitates the transport of ferrous iron across the apical membrane into enterocytes?

A. Ferroportin

B. Transferrin Receptor 1

C. Divalent Metal Transporter 1 (DMT1)

D. Ceruloplasmin

E. Hepcidin

b

What is the primary export protein that allows iron to leave the enterocyte into the circulation?

A. Transferrin

B. Ferroportin

C. Ferritin

D. DMT1

E. Hemosiderin

c

Which copper-containing enzyme oxidizes Fe^{2+} to Fe^{3+} in the bloodstream so it can bind to transferrin?
A. Ferrochelatase
B. Hepcidin
C. Ceruloplasmin
D. Transferrin receptor
E. Alkaline phosphatase

c

What key regulatory peptide produced by the liver regulates the action of ferroportin and controls systemic iron flow?

A. Erythropoietin

B. Ferritin

C. Hepcidin

D. Transferrin

E. Ferrozine

c

Where is surplus iron stored primary as iron-ferritin complexes?

A. Spleen sinusoids

B. Bone marrow matrix

C. Liver parenchyma

D. Muscle sarcoplasm

E. Plasma membrane

e

What cell type ingests senescent red blood cells in the spleen to recycle iron?

A. Splenic macrophages

B. Enterocytes

C. Hepatocytes

D. Neutrophils

E. Erythroblasts

a

What is the standard reference range for serum iron?

A. 10 to 50 ug/dL

B. 50 to 160 ug/dL

C. 250 to 400 ug/dL

D. 100 to 250 ug/dL

E. 500 to 800 ug/dL

c

What reagent is used in the serum iron colorimetric assay to produce a measurable color reaction?

A. Magnesium carbonate

B. Acidic potassium ferrocyanide

C. Ferrozine

D. Zinc protoporphyrin

E. Prussian blue

a

Why are early morning fasting specimens required for serum iron testing?

A. Hepcidin levels fluctuate due to diurnal variation

B. Red blood cells hemolyze rapidly in the afternoon

C. Transferrin degrades after meals

D. Ferritin precipitates at midday

E. Intestinal motility alters iron clearance

c

What is the normal reference range for Total Iron Binding Capacity (TIBC)?

A. 50 to 160 ug/dL

B. 100 to 200 ug/dL

C. 250 to 400 ug/dL

D. 450 to 600 ug/dL

E. 10 to 50 ug/dL

c

What substance is added in the TIBC procedure to precipitate unbound iron?

A. Ferrozine

B. Potassium ferrocyanide

C. Magnesium carbonate

D. Hydrochloric acid

E. Ammonium sulfate

c

Approximately what fraction of transferrin binding sites are normally saturated with iron?

A. 1/10

B. 1/5

C. 1/3

D. 1/2

E. 2/3

b

How is percent transferrin saturation calculated?
A. (TIBC /Serum Iron) x 100
B. (Serum Iron / TIBC) x 100
C. (Ferritin / Serum Iron) x 100
D. (sTfR / Ferritin) x 100
E. (Serum Iron / Ferritin) x 100

c

What method is considered the "Gold Standard" in directly assessing tissue body iron stores?

A. Serum iron colorimetry

B. Total Iron Binding Capacity

C. Prussian blue staining

D. Soluble transferrin receptor assay

E. Reticulocyte hemoglobin content

b

What chemical compound forms the basis of Prussian blue staining (Fe_7(CN)_{18})?
A. Ferrozine reagent
B. Acidic potassium ferrocyanide
C. Magnesium carbonate
D. Sodium nitroprusside
E. Ferrous sulfate

a

Which tissues are typically biopsied for evaluation using Prussian blue staining?

A. Bone marrow aspirate and liver biopsy

B. Spleen and kidney tissue

C. Small intestine and gastric mucosa

D. Peripheral blood and lymph node

E. Skeletal muscle and heart tissue

c

Which intracellular protein reflects total body iron stores and acts as an acute-phase reactant during inflammation?

A. Transferrin

B. Ferroportin

C. Ferritin

D. Ceruloplasmin

E. Myoglobin

b

What happens to intracellular soluble Transferrin Receptor (sTfR) levels when intracellular iron decreases?

A. Decreases

B. Increases

C. Remains unchanged

D. Fluctuates diurnally

E. Precipitates

b

Measuring reticulocyte hemoglobin content provides an evaluation of erythropoiesis over what time frame?

A. 12 hours

B. 24 hours

C. 7 days

D. 30 days

E. 120 days

b

​In the Thomas Plot, what two parameters are plotted against each other?

A. Serum iron vs. TIBC

B. sTfR/ferritin ratio vs. reticulocyte hemoglobin content

C. Ferritin vs. Prussian blue score

D. Transferrin saturation vs. Serum iron

E. Zinc protoporphyrin vs. MCH

d

According to the Thomas Plot diagnostic quadrant criteria, what condition is represented by a low sTfR/ferritin ratio and a low reticulocyte hemoglobin content?

A. Normal iron status

B. Latent iron deficiency

C. True iron deficiency

D. Functional iron deficiency

E. Iron overload / Hemochromatosis

C

According to the Thomas Plot criteria, what condition is indicated by an increased sTfR/ferritin ratio along with low reticulocyte hemoglobin content?

A. Normal iron status

B. Latent iron deficiency

C. Iron deficiency

D. Functional iron deficiency

E. Lead toxicity

b

According to the Thomas Plot criteria, an increased sTfR/ferritin ratio paired with a normal reticulocyte hemoglobin content signifies:

A. Normal iron status

B. Latent iron deficiency

C. Functional iron deficiency

D. Sideroblastic anemia

E. Iron deficiency

c

What substance accumulates inside red blood cells when iron is unavailable to bind to protoprophyrin IX?

A. Ferrozine

B. Hemoglobin A

C. Zinc protoporphyrin

D. Ferritin

E. Hemosiderin

b

Elevated levels of Zinc Protoporphyrin (ZPP) serve as a key indicator of impaired activity of which enzyme?

A. Ceruloplasmin

B. Ferrochelatase

C. Cytochrome oxidase

D. Transaminases

E. Heme synthetase inhibitor

c

Which heavy metal toxicity inhibits ferrochelatase and leads to a marked increase in Zinc Protoporphyrin?

A. Mercury poisoning

B. Cadmium toxicity

C. Lead poisoning

D. Arsenic poisoning

E. Silver toxicity

c

Which iron compartment accounts for approximately 25% of total body iron?

A. Functional compartment

B. Transport compartment

C. Storage compartment

D. Plasma compartment

E. Excretory compartment

C

​Which iron compartment accounts for approximately 10% of body iron and includes muscles, plasma, and intracellular sites?

A. Functional compartment

B. Storage compartment

C. Myoglobin/plasma compartment

D. Hemoglobin compartment

E. Enterocyte compartment

b

What dietary source contains heme iron bound to myoglobin?

A. Dark green leafy vegetables

B. Meat

C. Legumes and beans

D. Whole grains

E. Citrus fruits

c

Which non-heme food source provides a major portion of dietary iron, although its absorption kinetics differ from meat?

A. Dairy products

B. Poultry

C. Dark green leafy vegetables

D. Fish

E. Processed sugar

b

What is the oxidized state of iron that cannot be directly absorbed by enterocytes until reduced?
A. Ferrous iron (Fe^2+)
B. Ferric iron (Fe^3+)
C. Metallic iron (Fe^0)
D. Zinc-iron complex
E. Ferritin core iron

d

What is the primary carrier protein responsible for transporting ferric iron through the plasma?

A. Albumin

B. Haptoglobin

C. Hemopexin

D. Transferrin

E. Transcobalamin

b

When unbound iron is precipitated by magnesium carbonate during a TIBC assay, what is left in the supernatant to be measured?

A. Free ferrous iron

B. Bound iron released from transferrin

C. Ferritin-bound iron

D. Hemosiderin aggregates

E. Hemoglobin-derived iron

c

In Thomas Plot Quadrant 2, when serum ferritin is elevated due to inflammation while sTfR remains normal, the sTfR/ferritin ratio will be:

A. Increased

B. Decreased

C. Normal

D. Unmeasurable

E. Doubled

c

What happens to serum iron levels in classic uncompensated Iron Deficiency Anemia?

A. Increased

B. Normal

C. Decreased

D. Variable

E. Unaffected

b

What happens to TIBC levels in classic Iron Deficiency Anemia?

A. Decreased

B. Increased

C. Normal

D. Zero

E. Slightly reduced

a

An individual with severe iron deficiency will show which combination of sTfR and Ferritin levels?

A. Increased sTfR and Decreased Ferritin

B. Decreased sTfR and Increased Ferritin

C. Normal sTfR and Normal Ferritin

D. Decreased sTfR and Decreased Ferritin

E. Increased sTfR and Increased Ferritin

e

The lifespan of a normal circulating erythrocyte, after which iron is scavenged by macrophages, is approximately:

A. 24 hours

B. 30 days

C. 60 days

D. 90 days

E. 120 days

b

What type of specimen sample is required for performing Clinical Chemistry tests for Serum Iron and TIBC?

A. Whole blood EDTA

B. Serum sample

C. Citrated plasma

D. Urine sample

E. Bone marrow aspirate

B

What key physiological mechanism does the human body lack regarding iron homeostasis?

A. Capacity to recycle iron from old RBCs

B. Capacity to excrete excess absorbed iron actively

C. Capacity to store iron in hepatocytes

D. Capacity to transport iron via transferrin

E. Capacity to reduce ferric iron in the stomach

b

What diagnostic term describes the state where total body iron stores are depleted but functional hemoglobin production is not yet impaired?

A. Functional Iron Deficiency

B. Latent Iron Deficiency

C. Overt Iron Deficiency Anemia

D. Anemia of Chronic Disease

E. Sideroblastic Anemia

b

Which microscopic findings under Prussian blue staining confirm adequate tissue storage iron in a bone marrow smear?

A. Pink-staining Heinz bodies

B. Dark blue dots/granules in macrophages

C. Ringed sideroblasts with red inclusions

D. Yellow-brown crystal clumps

E. Clear vacuolated cytoplasm

b

What is the clinical significance of measuring the reticulocyte hemoglobin content (CHr / Ret-He) compared to standard red cell indices (MCH)?
A. It evaluates iron availability over 120 days
B. It provides a real-time snapshot of recent iron availability for hemoglobin synthesis
C. It directly measures liver parenchymal ferritin stores
D. It replaces the need for Prussian blue staining in lead poisoning
E. It measures intestinal ferroportin activity