Blood

Question 1

Which of the following statements is FALSE regarding true anemia?
a. Alterations of the mean corpuscular volume are characteristic of anemia.
b. Increased destruction of erythrocytes can lead to anemia.
c. Decreased production of erythrocytes is not a common cause of anemia because the
bone marrow is continuously renewing the red blood cell pool.
d. Reticulocytes will live for a longer period of time in the peripheral blood when a person is anemic.
e. The main parameters in diagnosing anemia are RBC count, hemoglobin concentration, and hematocrit

Answer 1

Correct answer: c.

Explanation: True anemia commonly results from decreased erythrocyte production, despite the bone marrow’s regenerative capacity. Statement c is false because decreased production is a well-known cause of anemia, especially in bone marrow suppression (e.g., aplastic anemia). The other statements correctly describe anemia features or diagnostic considerations

Now let’s explain the other options:

a. Alterations of the mean corpuscular volume (MCV) are characteristic of anemia.
• What it means: MCV is the average size of red blood cells.
• Why it’s true: In anemia, the size of RBCs often changes — they can be small (microcytic), large (macrocytic), or normal (normocytic) depending on the cause. So yes, MCV changes are common in anemia and help classify it.

⸻

b. Increased destruction of erythrocytes can lead to anemia.
• What it means: If your red blood cells are being destroyed faster than they can be replaced (e.g. in hemolytic anemia), it can cause anemia.
• Why it’s true: Conditions like autoimmune hemolytic anemia or sickle cell disease destroy RBCs prematurely, leading to anemia.

⸻

d. Reticulocytes will live for a longer period of time in the peripheral blood when a person is anemic.
• What it means: Reticulocytes are young red blood cells released from the bone marrow.
• Why it’s true: In anemia, the body tries to compensate by releasing more reticulocytes into the bloodstream, and these may persist slightly longer as the body is trying to restore RBC levels.

⸻

e. The main parameters in diagnosing anemia are RBC count, hemoglobin concentration, and hematocrit.
• What it means: These are standard blood tests.
• Why it’s true: They directly measure the amount of red blood cells, hemoglobin (oxygen-carrying protein), and the proportion of blood made up by RBCs. Low values in any of these can indicate anemia.

Question 2

Which of the following types of anemia is properly paired with its cause?
a. iron deficiency anemia—blood loss.
b. sideroblastic anemia—vitamin B12 deficiency.
c. megaloblastic anemia—folate supplementation.
d. aplastic anemia—ethanol.
e. megaloblastic anemia—lead poisoning

Answer 2

Correct answer: a. iron deficiency anemia—blood loss.

Explanation: Iron deficiency anemia is most commonly due to chronic blood loss (e.g., from GI bleeding or heavy menstruation). The other pairs are incorrect:

a. Iron deficiency anemia — blood loss ✅ (Correct Pairing)
• What it is: This is the most common type of anemia.
• Why it happens: Blood loss (from heavy periods, GI bleeding like ulcers or colon cancer) causes a loss of iron, which is essential for making hemoglobin (the oxygen-carrying part of red blood cells).
• Key signs: Microcytic (small cell) anemia, low ferritin, low serum iron, high TIBC.

⸻

b. Sideroblastic anemia — vitamin B12 deficiency ❌
• What it is: Sideroblastic anemia happens when the body has trouble incorporating iron into hemoglobin, even if iron is available.
• Why it’s wrong: It’s not caused by B12 deficiency.
• True causes: Genetic mutations, alcoholism, lead poisoning, or drugs (like isoniazid).
• Key feature: Ringed sideroblasts seen in bone marrow.

⸻

c. Megaloblastic anemia — folate supplementation ❌
• What it is: Megaloblastic anemia is due to folate or B12 deficiency, leading to impaired DNA synthesis and large, immature RBCs.
• Why it’s wrong: Folate deficiency causes megaloblastic anemia, not supplementation. Supplementation treats it.
• Key signs: Macrocytic cells, hypersegmented neutrophils.

⸻

d. Aplastic anemia — ethanol ❌
• What it is: Aplastic anemia means the bone marrow stops making all types of blood cells (RBCs, WBCs, platelets).
• Why it’s wrong: While ethanol can suppress marrow a little, true aplastic anemia is usually caused by:
• Autoimmune destruction,
• Radiation,
• Medications (like chloramphenicol),
• Viral infections (like parvovirus B19).
• Key signs: Pancytopenia (all cell types low), fatty bone marrow.

⸻

e. Megaloblastic anemia — lead poisoning ❌
• What it is: Megaloblastic anemia, as mentioned, is due to folate or B12 deficiency.
• Why it’s wrong: Lead poisoning causes microcytic anemia, not megaloblastic. It interferes with enzymes in heme synthesis.
• Key signs: Basophilic stippling, abdominal pain, neurological symptoms in kids.

Question 3

The inability to synthesize the porphyrin ring of hemoglobin will most likely result in which
of the following?
a. iron deficiency anemia.
b. improper RBC mitosis.
c. inability to synthesize thymidine.
d. accumulation of iron within erythroblasts.
e. bone marrow hypoplasia.

Answer 3

Correct answer: d. accumulation of iron within erythroblasts.

Explanation: This is characteristic of sideroblastic anemia, where the defect in heme synthesis leads to iron accumulation in mitochondria within erythroblasts. Other options relate to different types of anemia or are incorrect pathways.

Hemoglobin = heme (contains porphyrin ring) + globin (protein part).
To make heme, the body must create a porphyrin ring and insert iron into it. If the body can’t make the porphyrin ring, the iron has nowhere to go — so it builds up inside immature red blood cells (erythroblasts) in the bone marrow.

This iron collects in mitochondria, forming a ring around the nucleus, visible under a microscope. These are called ring sideroblasts.

⸻

Now let’s quickly go through the wrong options:
• a. Iron deficiency anemia
• Wrong because iron levels are low in iron deficiency anemia, not high. This question is about iron accumulating, which is the opposite.
• b. Improper RBC mitosis
• That’s more related to megaloblastic anemia, where there’s DNA synthesis problems (like from folate or B12 deficiency), not porphyrin ring issues.
• c. Inability to synthesize thymidine
• This also points to megaloblastic anemia. Thymidine is needed for DNA replication, not heme synthesis.
• e. Bone marrow hypoplasia
• That’s more about aplastic anemia, where the bone marrow stops producing all types of blood cells. It’s not due to porphyrin ring issues.

⸻

Key takeaway for memorization:

Sideroblastic anemia = iron overload in RBC precursors = defective heme synthesis.
Think: “Sidero” = iron, and it’s stuck in the cell because the heme factory is broken.

Question 4

Which of the following will cause a right shift in the oxygen dissociation curve?
a. increased pH.
b. decreased carbon dioxide concentration.
c. decreased body temperature.
d. increased 2,3-BPG concentration.
e. fetal hemoglobin

Answer 4

Correct answer: d. increased 2,3-BPG concentration.

Explanation: A right shift indicates decreased oxygen affinity—allowing more oxygen to be released to tissues. This occurs with increased 2,3-BPG, decreased pH, increased CO2, or increased temperature. The other options (a–c, e) cause a left shift, increasing affinity.

What a “Right Shift” Means:
• Hemoglobin has lower affinity for oxygen.
• It lets go of oxygen more easily, so more oxygen is released to tissues.
• This is helpful during exercise, high altitude, or fever—situations where your body needs more oxygen.

⸻

Key causes of a right shift (think of the conditions when tissues are working hard):

Use the mnemonic CADET face Right:
• C = increased CO₂
• A = increased Acid (↓ pH)
• D = increased 2,3-DPG (another name for 2,3-BPG)
• E = Exercise
• T = increased Temperature

So, increased 2,3-BPG is totally in line with this—it tells hemoglobin: “let go of the oxygen!”

⸻

Let’s look at the wrong answers:
• a. Increased pH
• High pH = more basic = left shift. Hemoglobin holds onto O₂ tighter.
• b. Decreased CO₂
• Less CO₂ = less acid = left shift. Again, tighter O₂ binding.
• c. Decreased body temperature
• Cold conditions = lower metabolic need = left shift. Oxygen is held onto.
• e. Fetal hemoglobin
• Fetal Hb has higher oxygen affinity so it can grab O₂ from mom’s blood = left shift.

What is 2,3-BPG (2,3-bisphosphoglycerate)?

2,3-BPG is a small molecule found inside red blood cells. Its main job is to regulate how tightly hemoglobin holds onto oxygen.

⸻

What it does:
• It binds to hemoglobin and lowers hemoglobin’s affinity for oxygen.
• This means hemoglobin lets go of oxygen more easily, especially in tissues that need it.

⸻

Why it’s important:
• It helps deliver more oxygen to tissues, especially during:
• Exercise
• High altitude
• Chronic hypoxia (low oxygen)
• Anemia

Without 2,3-BPG, hemoglobin would hold onto oxygen too tightly and not release enough to the body’s tissues.

Question 5

All of the following statements regarding erythrocytes are true EXCEPT:
a. Aged erythrocytes are removed by the liver, where the iron is recycled.
b. Erythrocytes have a life span of approximately 120 days.
c. Red blood cells generally lose their nuclei before entering the circulation.
d. Reticulocytes are immature RBCs that still have a little RNA.
e. Persons with anemia have a higher than normal reticulocyte:erythrocyte ratio

Answer 5

Correct Answer: a.

“Aged erythrocytes are removed by the liver, where the iron is recycled.”

⸻

Why this is FALSE:

Old or damaged red blood cells are mostly removed by macrophages in the spleen, not the liver.
• The spleen is like a quality control center — it checks red blood cells as they pass through and removes the old ones.
• The liver does help with recycling iron from those cells, but it’s not the primary place where RBCs are destroyed.

⸻

Now let’s break down the other TRUE statements:

⸻

b. “Erythrocytes have a life span of approximately 120 days.”
• True. RBCs live about 3–4 months in circulation before being removed.

⸻

c. “Red blood cells generally lose their nuclei before entering the circulation.”
• True. Red blood cells in humans are anucleate — they lose their nucleus before they leave the bone marrow. This makes more room for hemoglobin and gives them their biconcave shape.

⸻

d. “Reticulocytes are immature RBCs that still have a little RNA.”
• True. Reticulocytes are like teenage RBCs. They still have some leftover ribosomal RNA, which stains bluish with certain dyes. They usually mature into full RBCs within a day or two.

⸻

e. “Persons with anemia have a higher than normal reticulocyte:erythrocyte ratio.”
• True, in most cases. When the body detects low RBC levels (anemia), it boosts reticulocyte production to compensate. So, there’s a higher ratio of young cells trying to replace the lost ones — unless the bone marrow is damaged and can’t keep up.

⸻

Summary:
• The spleen clears out old RBCs, not the liver.
• Everything else listed is true and helps you understand how RBCs are made, matured, and recycled.

Question 6

All of the following statements regarding oxidative hemolysis are true EXCEPT:
a. Reactive oxygen species are commonly generated by RBC metabolism.
b. Superoxide dismutase and catalase are enzymes that protect against oxidative damage.
c. Reduced glutathione (GSH) increases the likelihood of oxidative injuries to RBCs.
d. Glucose-6-phosphate dehydrogenase deficiency is commonly associated with oxidative hemolysis.
e. Xenobiotics can cause oxidative injury to RBCs by overcoming the protective
mechanisms of the cell.

Answer 6

Correct answer: c. Reduced glutathione (GSH) increases the likelihood of oxidative injuries to RBCs.

Explanation: Reduced GSH protects RBCs from oxidative damage. Its deficiency increases the risk. So this statement is false. The others correctly describe oxidative hemolysis and protection mechanisms.

Correct Answer (False statement):

c. Reduced glutathione (GSH) increases the likelihood of oxidative injuries to RBCs.
• Why it’s FALSE:
Reduced glutathione actually protects RBCs from oxidative damage. It acts like an antioxidant “shield.”
So if you have enough GSH, you’re protected. If it’s low or depleted, then damage increases.
The statement is backward.

⸻

Other statements (all TRUE):

⸻

a. Reactive oxygen species (ROS) are commonly generated by RBC metabolism.
• True!
Even normal metabolism in RBCs produces small amounts of ROS (like superoxide and hydrogen peroxide). The problem starts when the balance tips — too many ROS and not enough antioxidants = oxidative stress.

⸻

b. Superoxide dismutase and catalase are enzymes that protect against oxidative damage.
• True!
These are like cleanup crews:
• Superoxide dismutase (SOD) converts superoxide (a dangerous ROS) into less harmful hydrogen peroxide.
• Catalase then breaks down hydrogen peroxide into water and oxygen.
Together, they help protect RBCs from oxidative stress.

⸻

d. Glucose-6-phosphate dehydrogenase (G6PD) deficiency is commonly associated with oxidative hemolysis.
• True!
G6PD is critical for making NADPH, which keeps glutathione in its reduced (protective) form.
Without enough G6PD → less NADPH → less GSH → oxidative damage builds up → hemolysis.
This is why G6PD deficiency is a classic cause of oxidative anemia.

⸻

e. Xenobiotics can cause oxidative injury to RBCs by overcoming the protective mechanisms of the cell.
• True!
Xenobiotics = foreign chemicals (like drugs, toxins, some foods).
Some can generate too many ROS or deplete GSH, overwhelming the RBC’s antioxidant defenses and causing hemolysis.
Example: Fava beans can trigger hemolysis in people with G6PD deficiency.

Question 7

Which of the following sets of leukocytes is properly characterized as granulocytes because of the appearance of cytoplasmic granules on a blood smear?
a. neutrophils, basophils, and monocytes.
b. basophils, eosinophils, and lymphocytes.
c. eosinophils, neutrophils, and lymphocytes.
d. basophils, eosinophils, and neutrophils.
e. lymphocytes, neutrophils, and basophils

Answer 7

Correct answer: d. basophils, eosinophils, and neutrophils.

Explanation: These are the three types of granulocytes, identifiable by cytoplasmic granules on blood smear. The others include monocytes or lymphocytes, which are not granulocytes.

Which set of leukocytes (white blood cells) are granulocytes, meaning they contain visible granules in their cytoplasm on a blood smear?

Correct Answer: d. Basophils, eosinophils, and neutrophils

⸻

So what are granulocytes?

Granulocytes are a type of white blood cell (WBC) that have visible granules (tiny dots or particles) in their cytoplasm when stained and looked at under a microscope.

There are three main granulocytes, and you can remember them with the mnemonic BEN:
• Basophils
• Eosinophils
• Neutrophils

These cells are part of the innate immune system and each has a unique role:

⸻

1. Neutrophils
   • Most common WBC
   • First responders to infection (especially bacteria)
   • Granules contain enzymes that kill microbes
   • Think: “Neutralize invaders”

⸻

2. Eosinophils
   • Fight parasites and play a role in allergic reactions
   • Bright red-orange granules on staining
   • Think: “E for Eosinophils, E for Eek! Parasite!”

⸻

3. Basophils
   • Least common WBC
   • Involved in allergic responses and inflammation
   • Granules contain histamine and heparin
   • Think: “B for Basophils, B for Bee sting allergy”

⸻

Now, the other types (NOT granulocytes):

⸻

Lymphocytes
• Include B cells, T cells, and NK cells
• Key players in adaptive immunity (targeted response)
• No granules on smear
• Round nucleus, clear cytoplasm

⸻

Monocytes
• Largest WBC
• Become macrophages in tissues (clean up crew)
• No distinct granules
• Big, folded nucleus

⸻

Why the other answer choices are wrong:
• a. Neutrophils, basophils, and monocytes
→ Monocytes are not granulocytes.
• b. Basophils, eosinophils, and lymphocytes
→ Lymphocytes are not granulocytes.
• c. Eosinophils, neutrophils, and lymphocytes
→ Lymphocytes again — not a granulocyte.
• e. Lymphocytes, neutrophils, and basophils
→ Lymphocytes still don’t belong.

Question 8

All of the following statements are true EXCEPT:
a. Xenobiotics can greatly slow down the proliferation of neutrophils and monocytes,
increasing the risk of infection.
b. Ethanol and cortisol decrease phagocytosis and microbe ingestion by the immune system.
c. Agranulocytosis is predictable and can be caused by exposure to a number of environmental toxicants.
d. Heroin and methadone abusers have reduced ability to kill microorganisms due to drug induced reduction in superoxide production.
e. Toxic neutropenia may be mediated by the immune system

Answer 8

Correct Answer: c. “Agranulocytosis is predictable…”

This is the FALSE statement — which is what the question is asking for.

Why it’s false:
• Agranulocytosis is a condition where granulocytes (especially neutrophils) are dangerously low.
• It’s often idiosyncratic, meaning it’s unpredictable and not dose-dependent.
• It can occur suddenly and severely after exposure to certain drugs or chemicals, without warning.

So, saying it’s predictable is incorrect — and that’s why c is the correct “EXCEPT” choice.

⸻

Now let’s explain the TRUE statements:

⸻

a. Xenobiotics can slow proliferation of neutrophils and monocytes.
• True. Xenobiotics (foreign chemicals) like chemo drugs, benzene, and other toxins can suppress bone marrow, reducing white blood cell production and increasing infection risk.

⸻

b. Ethanol and cortisol decrease phagocytosis and microbe ingestion.
• True. Both alcohol and stress hormones (like cortisol) weaken immune responses. They make neutrophils and macrophages less efficient at eating and destroying microbes.

⸻

d. Heroin and methadone abusers have reduced ability to kill microorganisms.
• True. These drugs impair the immune system. Specifically, they reduce superoxide production, which is part of the oxidative burst neutrophils use to kill microbes.

⸻

e. Toxic neutropenia may be immune-mediated.
• True. Some cases of neutropenia (low neutrophils) are due to immune responses, like the body forming antibodies against its own neutrophils, often triggered by a drug.

⸻

Quick Recap:
• Agranulocytosis = unpredictable + dangerous = NOT predictable.
• All the other choices describe real immune system effects caused by toxins or drugs.

Question 9

Leukemias:
a. are often due to cytogenic abnormalities, particularly damage to or loss of chromosomes
8 and 11.
b. are rarely caused by agents used in cancer chemotherapy.
c. originate in circulating blood cells.
d. are characterized as “acute” if their effects are short-lived and severe.
e. have long been associated with exposure to x-ray radiation.

Answer 9

Correct answer: e. have long been associated with exposure to x-ray radiation.

Explanation: X-ray radiation is a well-known risk factor for leukemia, especially acute forms. Other options are true: cytogenic abnormalities, chemotherapy links, and leukemia characteristics.

Why E was chosen as the “best” option:
• The connection between leukemia and ionizing radiation (like X-rays, especially in high or prolonged exposures) is a historically famous and well-established cause.
• After the atomic bomb and in early medical radiation use, leukemia was the first cancer clearly linked to radiation.
• It’s a strong epidemiologic association that has shaped leukemia research and regulation.

⸻

Let’s contrast with the other options:

a. Cytogenetic abnormalities (chromosomes 8 and 11):
• True, and very important in specific subtypes of leukemia.
• But not as universal or historically emphasized as radiation exposure.
• Not all leukemias involve those exact chromosomes.

b. Rarely caused by chemo:
• True, but it’s less frequent and more of a secondary concern (chemo can cause leukemia, but it’s rare compared to radiation).

c. Originate in circulating blood cells:
• Technically inaccurate — leukemia begins in the bone marrow, not the blood.
• The abnormal cells appear in blood, but the origin is marrow.

d. Acute leukemias = short and severe:
• True, but more about classification than causation or hallmark associations.

⸻

So, the logic behind picking E:

It reflects a major public health and historical connection between radiation and leukemia, more so than the others reflect core or distinguishing characteristics of the disease as a whole.

⸻

TL;DR:

All the options are factually correct, but E was chosen because the association between radiation and leukemia is one of the earliest and strongest-known links in leukemia causation — a defining feature in its history.

Question 10

Regarding platelets and thrombocytopenia, which of the following statements is FALSE?
a. Platelets can be removed from the circulation through a hapten-mediated pathway that is induced by drugs or chemicals.
b. Cortisol decreases platelet activity by inhibiting thromboxane prostaglandin synthesis.
c. Toxicants can induce a change in a platelet membrane glycoprotein, leading to
recognition and removal of the platelet by phagocytes.
d. Heparin administration can result in platelet aggregation and cause thrombocytopenia.
e. Thrombotic thrombocytopenic purpura is most commonly caused by infectious disease,
but can also be associated with administration of pharmacologic agents

Answer 10

Correct answer: b. Cortisol decreases platelet activity.

Explanation: Cortisol does not decrease platelet activity; in fact, it can increase it indirectly. The rest are accurate descriptions of mechanisms related to thrombocytopenia.

Let’s break this down so it’s clear why option B is FALSE and the others are true when discussing platelets and thrombocytopenia (low platelet count).

⸻

Question: Which statement is FALSE?

Correct answer: b. Cortisol decreases platelet activity by inhibiting thromboxane prostaglandin synthesis.

⸻

Why B is FALSE:
• Cortisol (a glucocorticoid) actually tends to increase platelet count and does not significantly inhibit thromboxane synthesis.
• Thromboxane A2 is a product of platelet activation that promotes aggregation (clumping).
• Drugs that inhibit thromboxane = aspirin and NSAIDs, not cortisol.
• In fact, cortisol is sometimes used to treat autoimmune thrombocytopenia because it suppresses immune destruction of platelets.

⸻

Let’s explain the TRUE statements:

⸻

a. Platelets can be removed via a hapten-mediated pathway from drug exposure.
• True. Some drugs (like quinine, sulfa drugs) can bind to platelets and act as haptens, forming a complex that triggers the immune system to destroy the platelet.

⸻

c. Toxicants can alter platelet glycoproteins, making them targets for phagocytes.
• True. Certain chemicals can change the structure of platelet surface proteins (like GPIIb/IIIa), causing the immune system to think the platelets are foreign and phagocytose (eat) them.

⸻

d. Heparin can cause platelet aggregation and thrombocytopenia.
• True. This refers to Heparin-Induced Thrombocytopenia (HIT) — an immune reaction where antibodies form against heparin-platelet factor 4 complexes, causing clumping and paradoxical clotting and low platelet count.

⸻

e. Thrombotic Thrombocytopenic Purpura (TTP) can be drug-associated.
• True. TTP is often triggered by:
• Infections
• Drugs like ticlopidine, clopidogrel, and some chemotherapy agents
It involves platelet microthrombi formation and low platelet count.

⸻

Quick Recap Mnemonic for Platelet Issues:

“HITT” the platelets:
• Haptens (drug-bound platelets destroyed)
• Immune-mediated reactions (like HIT or ITP)
• Toxicants alter surface proteins
• TTP forms microthrombi

Common causes of thrombocytopenia:
1. Increased destruction
• Autoimmune (e.g., ITP)
• Drugs (e.g., heparin → HIT)
• Infections
• Toxins
2. Decreased production
• Bone marrow failure (e.g., leukemia, chemo)
• Aplastic anemia
• Certain infections (like HIV)
3. Sequestration
• Enlarged spleen can “trap” platelets

⸻

Quick summary:

Thrombocytopenia = low platelets = higher bleeding risk
It can be caused by immune reactions, drugs, infections, or bone marrow problems.

Question 11

Which of the following is NOT a mechanism of drug-induced immune hemolytic anemia?

A. Hapten
B. Conformational change in erythrocyte membrane
C. Schistocyte formation
D. Drug-induced autoantibody

⸻

Answer 11

Correct Answer:

C. Schistocyte formation

⸻

Explanation:

Drug-induced immune hemolytic anemia occurs when certain drugs trigger the immune system to destroy red blood cells. The major mechanisms include:
• Hapten mechanism: A drug binds to the surface of RBCs and acts as a “hapten,” causing the immune system to target the drug-RBC complex.
• Conformational change: The drug causes a change in the RBC membrane structure, exposing antigens and making them look foreign to the immune system.
• Autoantibody induction: Some drugs stimulate the immune system to produce antibodies that attack RBCs, even without being directly attached to the cell.

However, schistocyte formation is not a mechanism of immune hemolysis.
• Schistocytes (fragmented red cells) are typically seen in mechanical hemolysis, like in microangiopathic hemolytic anemia (MAHA), such as TTP, DIC, or HUS — not immune-mediated cases.

Question 12

Which enzyme shows a marked increase in the blood serum following hemolysis?

A. Alkaline phosphatase
B. Creatine phosphokinase
C. Acid phosphatase
D. Lactate dehydrogenase

Answer 12

⸻

Correct Answer:

D. Lactate dehydrogenase (LDH)

⸻

Explanation:

Lactate dehydrogenase (LDH) is a key enzyme found inside red blood cells (RBCs). When hemolysis (destruction of RBCs) occurs, LDH is released into the bloodstream, leading to markedly elevated LDH levels in serum.

This is why high LDH is one of the lab signs used to support a diagnosis of hemolytic anemia.

⸻

Why the others are incorrect:
• A. Alkaline phosphatase
• Associated with liver, bone, and bile ducts, not red blood cells.
• B. Creatine phosphokinase (CPK or CK)
• Found in muscle tissue, especially used to detect muscle injury (e.g., rhabdomyolysis, heart attacks).
• C. Acid phosphatase
• Found in prostate and lysosomes, not a key marker of hemolysis.

Question 13

All of the following are associated with warfarin except…

A. Hepatitis
B. Congenital abnormalities
C. Bone demineralization
D. Skin necrosis

Answer 13

Correct Answer: A. Hepatitis

Explanation:

Warfarin is a blood thinner that interferes with vitamin K. It does not cause hepatitis (which is liver inflammation).

However, it can:

Cause birth defects (congenital abnormalities) if taken during pregnancy

Lead to bone weakening over time (bone demineralization)

Cause rare skin tissue death (skin necrosis), usually early in treatment

Question 14

Acetaminophen overdose would affect the clotting factor with the shortest half-life, which would be…

A. II
B. VII
C. IX
D. X

Answer 14

Correct Answer: B. VII

Explanation:

Factor VII is a clotting protein made in the liver, and it has the shortest half-life (4–6 hours).

If the liver is damaged (like from too much acetaminophen), Factor VII drops first, making you more likely to bleed.

Other clotting factors (II, IX, X) take longer to be affected.

Question 15

Q3: The hemolytic uremic syndrome (HUS) has been linked to…

A. Endotoxin-producing P. aeruginosa
B. Tetrodotoxin
C. Emetic toxins from B. cereus
D. Verocytotoxin from E. coli

Answer 15

Correct Answer: D. Verocytotoxin from E. coli

Explanation:

HUS is a serious condition that causes:

Hemolysis (RBC destruction)
Kidney failure
Low platelets

It’s most often caused by Shiga-like toxin (verocytotoxin) from E. coli O157:H7 (usually from undercooked beef or contaminated water).

The other toxins listed don’t cause HUS.

Question 16

Correct Answer: D. Verocytotoxin from E. coli

Explanation:

HUS is a serious condition that causes:

Hemolysis (RBC destruction)
Kidney failure
Low platelets

It’s most often caused by Shiga-like toxin (verocytotoxin) from E. coli O157:H7 (usually from undercooked beef or contaminated water).

The other toxins listed don’t cause HUS.

Answer 16

Correct Answer: B. Warfarin

Explanation:

Warfarin is an anticoagulant (blood thinner). It doesn’t cause immune hemolytic anemia.

The other drugs can cause your immune system to attack red blood cells:

Alpha-methyldopa: Triggers autoantibodies against RBCs

Penicillin: Acts like a hapten — sticks to RBCs and triggers destruction

Quinidine: Triggers immune complexes that damage RBCs

Question 17

A chemical causing nonoxidative chemical-induced hemolysis of red blood cells is…

A. Hydrogen sulfide
B. Arsine
C. Ozone
D. Xylene

Answer 17

Correct Answer: B. Arsine

Explanation:

Arsine gas destroys red blood cells without causing oxidative stress.

It breaks down the RBC membrane directly, leading to intravascular hemolysis (RBCs break inside blood vessels).

Other options either aren’t hemolytic or act differently.

Question 18

All of the following are advantages of in vitro bone marrow assays except…

A. Can examine effects on myeloid, erythroid, and platelet precursors
B. Can predict pharmacokinetics in humans
C. Can examine combinations of chemicals
D. Can make interspecies comparisons

Answer 18

Correct Answer: B. Can predict pharmacokinetics in humans

Explanation:

In vitro bone marrow tests (done outside the body, like in dishes) are great for studying:

Blood cell development (myeloid = WBCs, erythroid = RBCs)
Drug interactions
Cross-species effects
But they cannot predict how a drug moves through the body (pharmacokinetics). That requires a whole organism.

Question 19

Serial blood and bone marrow sampling is best done in…

A. Hamster
B. Rat
C. Dog
D. Mouse

Answer 19

Correct Answer: C. Dog

Explanation:

Dogs are big enough to allow frequent blood draws and bone marrow biopsies without harming them.

Small animals like mice or rats have very little blood volume and can’t tolerate frequent sampling safely.

Question 20

A grading system for hematologic toxicity was established in 1979 by…

A. WHO
B. FDA
C. EPA
D. OSHA

Answer 20

Correct Answer: A. WHO

Explanation:

The World Health Organization (WHO) created a system in 1979 to grade bone marrow and blood cell toxic effects.

This helps standardize how doctors and scientists describe side effects in studies and treatments.

Question 21

Q9: A hematologic problem detected through postmarketing surveillance was…

A. Bleeding and urokinase
B. Acute allergy and streptokinase
C. Aplastic anemia and felbamate
D. Leukopenia and transexamic acid

Answer 21

Correct Answer: C. Aplastic anemia and felbamate

Explanation:

Felbamate is an anti-seizure drug. After it was approved, rare cases of aplastic anemia were discovered.

This was found through postmarketing surveillance — monitoring side effects in real-world use after a drug hits the market.

Question 22

To detect one adverse event in a clinical trial that occurs at a frequency of 1% at a 95% confidence level, how many test subjects need to be exposed?

A. 100
B. 300
C. 500
D. 1000

Answer 22

Correct Answer: B. 300

Explanation:

To have a 95% chance of detecting at least one event that happens in 1% of people, you need to test around 300 people.

This is based on a statistical formula using probabilities. It ensures you don’t miss rare but serious side effects.

Question 23

Q: All of the following are true of heparin except…

A. Unfractionated heparin causes a higher incidence of thrombocytopenia
B. It causes osteoporosis
C. It crosses the placenta
D. It causes transaminase elevations

Answer 23

A: C. It crosses the placenta

Explanation:

Heparin does not cross the placenta. That’s why it’s safe to use during pregnancy.

A is true: Unfractionated heparin (UFH) is more likely to cause heparin-induced thrombocytopenia (HIT).

B is true: Long-term heparin use can lead to bone loss (osteoporosis).

D is true: Heparin can mildly increase liver enzymes (transaminases) but this doesn’t mean liver damage.

C is false, so it’s the correct answer—heparin stays in the mother’s circulation.

Question 24

Q: All of the following are true of lupus anticoagulants except…

A. They are antibodies that interfere with coagulation reactions
B. They potentiate procoagulant mechanisms
C. They cause severe bleeding
D. They can be induced by procainamide and hydralazine

Answer 24

A: C. They cause severe bleeding

Explanation:

Lupus anticoagulants sound like they cause bleeding, but they actually make the blood more likely to clot, not bleed.

A is true: They are autoantibodies that interfere with clotting tests.

B is true: Despite messing with test results, they promote clot formation in the body.

D is true: Certain drugs like procainamide and hydralazine can trigger these antibodies.

C is false—these antibodies don’t cause severe bleeding, so it’s the right choice.

Question 25

Q: All of the following will decrease bleeding except… A. Nadolol B. Aprotinin C. Aminocaproic acid D. Tranexamic acid

Answer 25

A: A. Nadolol Explanation: Nadolol is a beta-blocker, used for high blood pressure—not for bleeding. B, C, and D are antifibrinolytics—they stop the breakdown of clots, helping reduce bleeding. So, A is correct because it doesn’t help with bleeding at all.

Question 26

Q: All of the following are associated with an increased risk of bleeding except… A. Aspirin B. Ibuprofen C. Vitamin B6 D. N-methylthiotetrazole cephalosporins

Answer 26

A: C. Vitamin B6 Explanation: Aspirin and ibuprofen both impair platelet function and increase bleeding risk. D refers to a side group in some cephalosporin antibiotics that interferes with vitamin K metabolism, also increasing bleeding. C Vitamin B6 (pyridoxine) doesn’t affect bleeding, so it’s the correct choice.

Question 27

Q: Thrombotic thrombocytopenic purpura (TTP) has been associated with all of the following except… A. Cocaine B. Hydrochlorothiazide C. Ticlopidine D. Clopidogrel

Answer 27

A: B. Hydrochlorothiazide Explanation: TTP is a rare blood disorder that causes clots and low platelets. Ticlopidine and clopidogrel (antiplatelet drugs) and even cocaine have been linked to TTP. Hydrochlorothiazide is a blood pressure medication—not linked to TTP. So it’s the correct answer.

Question 28

Q: All of the following are associated with heparin-induced thrombocytopenia (HIT) except… A. Formation of an immune complex that binds to platelets B. Retroperitoneal hematomas C. Arterial thrombosis D. Venous thrombosis

Answer 28

A: B. Retroperitoneal hematomas Explanation: HIT is an immune reaction to heparin that causes thrombosis (clots) despite low platelets. A, C, D are all true: HIT causes immune complexes and can lead to arterial and venous clots. B is false: Retroperitoneal hematomas are not a classic feature of HIT. So it’s the right choice.

Question 29

Q: There is evidence that xylene causes… A. CLL B. CML C. ALL D. None of the above

Answer 29

A: D. None of the above Explanation: Xylene is a solvent used in labs and industry. It’s toxic but there’s no strong evidence linking it to specific types of leukemia like CLL, CML, or ALL. So “none of the above” is correct.

Question 30

Q: For which of the following drugs is causation data for AML inconclusive? A. Cyclophosphamide B. Busulfan C. Chlorambucil D. None of the above

Answer 30

A: D. None of the above Explanation: All of these drugs (A–C) do have strong evidence linking them to AML (acute myeloid leukemia). So the answer is D—data is not inconclusive; it’s actually clear.

Question 31

Q: Current theories on the origin of AML suggest… A. It’s a multievent progression B. It is caused by an infectious RNA virus C. In utero exposure to a toxicant is necessary for development D. None of the above

Answer 31

A: A. It’s a multievent progression Explanation: AML (acute myeloid leukemia) usually develops from multiple genetic hits or events over time—not a single cause. B is wrong: It’s not caused by a virus. C is wrong: In utero exposure isn’t required. So A is correct.

Question 32

Q: The two conditions most frequently associated with drug or chemical exposure are… A. AML and CLL B. AML and ALL C. AML and MDS D. AML and CML

Answer 32

C. AML and MDS Explanation: AML (acute myeloid leukemia) and MDS (myelodysplastic syndrome) are most often linked to chemicals or chemotherapy drugs. CLL, ALL, and CML are less strongly associated with exposures. So C is correct.

Question 33

Deletions in chromosomes 5 and 7 occur at a low frequency in… A. AML secondary to alkylating agents B. AML secondary to benzene C. AML secondary to topoisomerase II inhibitors D. Non-toxicant and non-chemotherapy-related AML

Answer 33

Correct Answer: D Explanation: A. AML secondary to alkylating agents – FALSE. These deletions are actually common here. B. AML secondary to benzene – FALSE. Benzene exposure is associated with chromosomal deletions, including chromosomes 5 and 7. C. AML secondary to topoisomerase II inhibitors – FALSE. These drugs are also linked to genetic changes, although not as strongly with 5 and 7 deletions. D. Non-toxicant and non-chemotherapy-related AML – TRUE. These spontaneous cases typically have fewer cytogenetic abnormalities like chromosome 5 and 7 deletions. Definitions: AML (Acute Myeloid Leukemia): A cancer of the blood and bone marrow with rapid growth of abnormal white blood cells. Alkylating agents: Chemotherapy drugs that damage DNA and can cause secondary cancers like AML. Topoisomerase II inhibitors: A class of chemotherapy that interferes with DNA repair and replication.

Question 34

All of the following are true of immune neutropenia except… A. The incidence is considerably higher than immune hemolytic anemia B. Direct antigranulocyte antibodies are difficult to measure C. Antigen-antibody reactions can lead to destruction of peripheral WBCs D. Propylthiouracil causes neutropenia by this mechanism

Answer 34

Correct Answer: A Explanation: A. FALSE – Immune neutropenia is less common than immune hemolytic anemia. B. TRUE – These antibodies are tricky to detect reliably. C. TRUE – The immune system targets neutrophils, leading to their destruction. D. TRUE – Propylthiouracil, a thyroid drug, can trigger this immune-mediated reaction. Definitions: Immune neutropenia: A condition where the body makes antibodies that attack neutrophils. Immune hemolytic anemia: The body destroys its own red blood cells. Propylthiouracil: A drug used to treat hyperthyroidism.

Question 35

Which of the following is true for clozapine-induced agranulocytosis? A. The incidence, even with frequent monitoring is 6% B. A genetic predisposition has been established C. Olanzapine causes agranulocytosis by the same mechanism D. All of the above

Answer 35

Correct Answer: B Explanation: A. FALSE – Incidence is closer to 1–2%, not 6%. B. TRUE – Certain genetic markers (like HLA types) are linked with higher risk. C. FALSE – Olanzapine may cause neutropenia, but not the same severity or mechanism. D. FALSE – Not all are true. Definitions: Clozapine: Antipsychotic medication with a known risk of severe neutropenia (agranulocytosis). Agranulocytosis: Almost complete loss of neutrophils, leading to infection risk.

Question 36

All of the following agents affect stem cells except… A. Aminopyrine B. Gold C. Chloramphenicol D. Phenylbutazone

Answer 36

Correct Answer: A Explanation: A. CORRECT – Aminopyrine affects mature cells more than stem cells. B. FALSE – Gold salts can cause bone marrow suppression. C. FALSE – Chloramphenicol is toxic to bone marrow stem cells. D. FALSE – Phenylbutazone can cause aplastic anemia by damaging stem cells. Definitions: Stem cells: Precursors in bone marrow that give rise to all blood cells. Aplastic anemia: Bone marrow failure to produce enough blood cells.

Question 37

All of the following are true regarding idiosyncratic toxic neutropenia except… A. It may or may not be dose related B. Toxicants that do not affect uncommitted stem cells are associated with better outcome C. It usually persists for months after drug withdrawal D. The immunologic form is more common in women and the elderly

Answer 37

Correct Answer: C Explanation: A. TRUE – Some cases are dose-dependent, others not. B. TRUE – Sparing early stem cells leads to quicker recovery. C. FALSE – Usually resolves quickly after stopping the offending drug. D. TRUE – Women and elderly are more likely to experience immune-mediated reactions. Definitions: Idiosyncratic: Unpredictable, not related to the dose. Uncommitted stem cells: Early stem cells that haven’t specialized yet. Neutropenia: Low neutrophil count.

Question 38

Question: Eosinophilia is seen in all of the following conditions except… A. Toxic oil syndrome B. Contaminated tryptophan preparations C. Megoblastic anemia D. Drug allergic reactions

Answer 38

Correct Answer: C. Megoblastic anemia Explanation: Eosinophilia = elevated eosinophil count in the blood. Eosinophils are a type of white blood cell involved in allergic reactions and parasitic infections. A. Toxic oil syndrome – True. This is a rare condition caused by contaminated rapeseed oil, which can cause eosinophilia among other systemic effects. B. Contaminated tryptophan preparations – True. Linked to eosinophilia-myalgia syndrome, a disorder marked by high eosinophil counts and severe muscle pain. C. Megoblastic anemia – False (correct answer). This type of anemia is due to deficiencies in vitamin B12 or folate, leading to impaired DNA synthesis in red blood cell precursors. It is not associated with eosinophilia. D. Drug allergic reactions – True. Hypersensitivity reactions often involve eosinophils, especially in drug-induced eosinophilia. Key Definitions: Eosinophilia: An increase in eosinophils (usually >500 cells/µL), often in response to allergens, parasites, or certain drugs. Megoblastic anemia: A type of anemia characterized by large, immature, and dysfunctional red blood cells, typically caused by vitamin B12 or folate deficiency. Toxic oil syndrome: A rare systemic illness caused by ingestion of adulterated cooking oil, leading to immune-mediated symptoms. Eosinophilia-myalgia syndrome (EMS): A disease associated with contaminated L-tryptophan supplements causing high eosinophils and muscle pain.

Question 39

Question: All of the following are true of neutrophils except… A. A ‘shift to the right’ occurs during major infection B. Serious infections can occur when counts fall below 500/μL C. G-CSF regulates both PMN production and release from bone marrow D. Bands and metamyelocytes are immature forms that can appear in the peripheral blood during infection

Answer 39

Correct Answer: A. A ‘shift to the right’ occurs during major infection Explanation: A. A ‘shift to the right’ occurs during major infection – False (correct answer). Infections usually cause a “left shift”, which is an increase in immature neutrophils (bands, metamyelocytes) in the blood. A “right shift” refers to more mature forms and is not characteristic of infection. B. Serious infections can occur when counts fall below 500/μL – True. This condition is called neutropenia, and the risk of life-threatening infections increases drastically at <500 neutrophils/μL. C. G-CSF regulates both PMN production and release from bone marrow – True. G-CSF (granulocyte colony-stimulating factor) stimulates the bone marrow to produce and release neutrophils (also known as polymorphonuclear leukocytes, or PMNs). D. Bands and metamyelocytes are immature forms that can appear in the peripheral blood during infection – True. These are precursors to neutrophils and appear in the bloodstream during infections, reflecting a strong demand for neutrophils. Key Definitions: Neutrophils: The most abundant type of white blood cell. They are the first responders to infection and critical to innate immunity. Left shift: Increased number of immature white blood cells (bands, metamyelocytes), usually due to infection or inflammation. G-CSF: A cytokine used therapeutically to boost neutrophil counts, especially after chemotherapy. Neutropenia: A low neutrophil count, defined as <1500 cells/μL, with increased infection risk below 500/μL.

Question 40

Question: Eosinophilia is seen in all of the following conditions except… A. Toxic oil syndrome B. Contaminated tryptophan preparations C. Megoblastic anemia D. Drug allergic reactions

Answer 40

Correct Answer: C. Megoblastic anemia Explanation (ELI5-style): Eosinophilia means having too many eosinophils (a type of white blood cell that fights parasites and is involved in allergic reactions). Option A: Toxic oil syndrome True — This was a strange outbreak in Spain in the 1980s linked to contaminated cooking oil, and eosinophilia was a major symptom. Option B: Contaminated tryptophan preparations True — These caused a disease called eosinophilia-myalgia syndrome (EMS), so eosinophils were high. Option C: Megoblastic anemia False (correct answer) — This type of anemia is due to vitamin B12 or folate deficiency and is not associated with eosinophilia. It affects red blood cells more than white blood cells. Option D: Drug allergic reactions True — Allergic reactions, especially drug-induced ones, often cause eosinophilia. Key Definitions: Eosinophilia: Elevated eosinophils in blood; usually due to allergies, parasites, or some toxins. Megoblastic anemia: A type of anemia where red blood cells are too big and not formed correctly, due to B12 or folate deficiency. Toxic oil syndrome: A mass poisoning from contaminated cooking oil, which caused symptoms like eosinophilia, fever, and muscle pain. Eosinophilia-myalgia syndrome (EMS): A rare condition linked to contaminated tryptophan supplements that causes muscle pain and high eosinophils.

Question 41

An inhibition of CXR-chemokine ligand CXCR4 will be expected to… A. Mobilize stem cells from the bone marrow B. Mobilize mature neutrophils from BM C. Treat the myelotoxicity of cancer chemo D. All of the above

Answer 41

Correct Answer: D. All of the above Explanation (ELI5-style): CXCR4 is a receptor found on many blood cells, especially stem cells and white blood cells. When CXCR4 is inhibited, it causes cells that are normally kept in the bone marrow to be released into the bloodstream. A. Mobilize stem cells from the bone marrow True — Inhibiting CXCR4 loosens the “glue” holding stem cells in the bone marrow, so they move into the blood. This is helpful for stem cell collection before a transplant. B. Mobilize mature neutrophils from BM True — It doesn’t just affect stem cells; mature white cells like neutrophils also get pushed out into the blood. C. Treat the myelotoxicity of cancer chemo True — After chemotherapy damages the bone marrow (myelotoxicity), releasing new cells helps with recovery. CXCR4 inhibitors help boost immune cells back into circulation faster. Key Definitions: CXCR4: A receptor that controls how stem cells and immune cells stay inside the bone marrow. Myelotoxicity: Bone marrow damage, usually from chemotherapy, leading to low blood counts. Stem cell mobilization: Moving stem cells from the bone marrow into the bloodstream for collection or to support recovery.

Question 42

All of the following are true of neutrophils except… A. A ‘shift to the right’ occurs during major infection B. Serious infections can occur when counts fall below 500/μL C. G-CSF regulates both PMN production and release from bone marrow D. Bands and metamyelocytes are immature forms that can appear in the peripheral blood during infection

Answer 42

Correct Answer: A. A ‘shift to the right’ occurs during major infection Explanation (ELI5-style): The trick here is the direction of the “shift”: A. A ‘shift to the right’ occurs during major infection False (correct answer) — Actually, during infection, there is a shift to the left, which means more immature neutrophils (like bands) are being released. A “shift to the right” means older cells, which is not what you see in active infection. B. Serious infections can occur when counts fall below 500/μL True — This is known as neutropenia, and it puts people at high risk for infections because they don’t have enough neutrophils to fight off bacteria. C. G-CSF regulates both PMN production and release from bone marrow True — G-CSF (granulocyte colony-stimulating factor) is like a fertilizer that helps grow neutrophils and pushes them into circulation. D. Bands and metamyelocytes are immature forms that can appear in the peripheral blood during infection True — These immature neutrophils show up in the blood when the body is rapidly trying to fight infection and runs out of mature ones. Key Definitions: Neutrophils: A type of white blood cell essential for fighting bacterial infections. Shift to the left: Increased numbers of immature neutrophils in blood — happens during infection. G-CSF: A drug or natural hormone that boosts neutrophil production and release. Bands/metamyelocytes: Immature neutrophil forms.

Question 43

Which of the following are characteristics of aplastic anemia except… A. Causation by radiation exposure B. Peripheral blood pancytopenia C. Bone marrow hypoplasia D. Reticulocytosis

Answer 43

Correct Answer: D. Reticulocytosis Explanation: Aplastic anemia is a bone marrow failure disorder. It causes pancytopenia: low RBCs, WBCs, and platelets. The marrow is hypoplastic or empty. Radiation can destroy stem cells and is a known cause. Reticulocytosis = increased young RBCs, which happens when the marrow is working. In aplastic anemia, the marrow can’t produce cells, so reticulocytes are low, not high.

Question 44

All of the following are true regarding hematopoiesis except… A. In children, it is confined to the yellow or fatty marrow B. In adults, it is confined to the axial skeleton and proximal humerus/femur C. Under extreme conditions embryonic patterns may occur D. The bone marrow is the only blood cell producing organ at birth

Answer 44

Correct Answer: A. In children, it is confined to the yellow or fatty marrow Explanation: In children, hematopoiesis occurs in red marrow, which is active. Yellow (fatty) marrow becomes more common in adults. Adults: red marrow is mostly in the axial skeleton (pelvis, ribs, sternum). In severe anemia, adults can revert to embryonic sites (like liver/spleen). At birth, bone marrow is the primary hematopoietic site.

Question 45

Pure red cell aplasia is caused by all of the following except… A. Isoniazid B. Acetaminophen C. Phenytoin D. Azathioprine

Answer 45

Correct Answer: B. Acetaminophen Explanation: Pure red cell aplasia = only red cell precursors in marrow are affected. Caused by drugs (isoniazid, phenytoin, azathioprine), parvovirus B19, or autoimmune diseases. Acetaminophen can cause liver toxicity but does not affect red cell production directly.

Question 46

Ringed sideroblasts are characteristic of anemias caused by… A. Alpha methyldopa B. Phenytoin C. Lead D. Folate deficiency

Answer 46

Correct Answer: C. Lead Explanation: Ringed sideroblasts = iron-loaded mitochondria around the nucleus of erythroid precursors. Seen in sideroblastic anemias, especially due to lead poisoning (which blocks enzymes in heme synthesis). Folate deficiency = macrocytic anemia. Methyldopa = can cause autoimmune hemolytic anemia.

Question 47

An imbalance in alpha and beta globin chains is the basis for… A. Iron deficiency anemia B. Congenital thalassemia C. Sideroblastic anemia D. Megaloblastic anemia

Answer 47

Correct Answer: B. Congenital thalassemia Explanation: Thalassemia = inherited disorder of globin chain imbalance. Alpha or beta chains are underproduced. Leads to ineffective erythropoiesis and microcytic anemia.

Question 48

In the human fetus, hematopoiesis occurs in all the following organs except… A. Liver B. Lung C. Spleen D. Thymus

Answer 48

Correct Answer: B. Lung Explanation: Fetal hematopoiesis occurs in yolk sac (early), then liver, spleen, thymus, and finally bone marrow. The lung is not a hematopoietic organ at any developmental stage.

Question 49

Oxidative injury to RBCs is most severe in humans with a deficiency of… A. Glucose-6-phosphate dehydrogenase (G6PD) B. Cytochrome P450 2E1 C. Aspartate transaminase D. Creatine phosphokinase

Answer 49

Correct Answer: A. Glucose-6-phosphate dehydrogenase Explanation: G6PD deficiency = RBCs can’t detoxify reactive oxygen species. Leads to hemolysis, especially after oxidative stress (infection, drugs, fava beans). Cytochrome P450, AST, and CK are unrelated to red cell oxidative defense.

Question 50

Schistocytes on a peripheral smear are indicative of… A. Iron deficiency B. Lead poisoning C. Malaria D. Microangiopathic hemolytic anemia (MAHA)

Answer 50

Correct Answer: D. MAHA Explanation: Schistocytes = fragmented RBCs. Seen in MAHA: RBCs are sheared in small blood vessels (e.g., in TTP, HUS, DIC). Not typical of iron deficiency or malaria.

Question 51

The hemoglobin-oxygen dissociation curve shifts left due to… A. Fever B. Acidosis C. Hypophosphatemia D. 2,3-BPG

Answer 51

Correct Answer: C. Hypophosphatemia Explanation: Left shift = increased oxygen affinity (harder to unload O₂ to tissues). Hypophosphatemia reduces 2,3-BPG → tighter O₂ binding. Fever, acidosis, and 2,3-BPG → right shift (more O₂ released).

Question 52

All are true of methemoglobin except… A. Methylene Blue is not effective in G6PD deficiency B. Main detox pathway involves methemoglobin reductase + NADPH C. Most tolerate low methemoglobin levels D. Aniline dyes are causative agents

Answer 52

Correct Answer: B. The predominant detox pathway involves methemoglobin reductase and NADPH Explanation: This is incorrect because the main detox pathway uses NADH, not NADPH. Methemoglobin = oxidized iron (Fe³⁺) in Hb that can’t carry O₂. Methylene blue helps convert it back to functional Hb, but doesn’t work well in G6PD deficiency. Aniline dyes and nitrates can cause it.