Anemia: Biochemical Aspects — MCQs

10 questions

Which is an inhibitor of ferrochelatase ?

Distal ileum was removed in a 20-year-old girl. Which absorption deficiency will be seen?

An adult female presents with pallor and fatigue. Blood investigations show low hemoglobin ( Hb ), low serum iron, low ferritin, low transferrin saturation, and increased total iron-binding capacity (TIBC). What is the likely diagnosis?

The daily production of hydrogen ions from CO2 is primarily buffered by which of the following?

A 65-year-old male presents with fatigue, pallor, and low hemoglobin. Which laboratory finding is most indicative of iron deficiency anemia?

What is/are the characterstics of Iron defficiency Anemaia(IDA)?

Which of the following are blood values of Iron Deficiency Anaemia ? 1. Serum iron is less than 30 mg/100 mL 2. Total iron binding capacity is less than 400 µg/mL 3. Percentage saturation is 10% or less 4. Serum ferritin is below 30 µg/mL Select the correct answer using the code given below :

All are increased in IDA except

Which of the following is a common consequence of gastrectomy?

Q10

Which of the following statements is true regarding anemia of prematurity?

Anemia: Biochemical Aspects Indian Medical PG Practice Questions and MCQs

Question 1: Which is an inhibitor of ferrochelatase ?

A. Lead (Correct Answer)
B. Mercury
C. Iron
D. Arsenic

Explanation: ***Lead*** - **Lead** is a potent environmental toxin that directly inhibits the enzyme **ferrochelatase**, preventing the insertion of **iron** into **protoporphyrin IX** to form heme. - This inhibition leads to the accumulation of **protoporphyrin IX** and can cause **anemia** due to impaired **heme synthesis**. *Mercury* - While **mercury** is a heavy metal and neurotoxin, its primary mechanism of toxicity does not involve direct inhibition of **ferrochelatase**. - Its effects are more commonly associated with protein denaturation and enzyme inactivation through binding with **sulfhydryl groups**. *Iron* - **Iron** is a substrate for **ferrochelatase**, not an inhibitor. **Ferrochelatase** catalyzes the insertion of **iron** into **protoporphyrin IX** to complete the synthesis of **heme**. - Deficiencies or excesses of **iron** can affect **heme synthesis**, but **iron** itself does not inhibit the enzyme in a toxic manner. *Arsenic* - **Arsenic** is a metalloid that is toxic through various mechanisms, including interference with cellular respiration and DNA repair. - However, **arsenic** is not known to be a direct inhibitor of **ferrochelatase** in the same way **lead** is.

Question 2: Distal ileum was removed in a 20-year-old girl. Which absorption deficiency will be seen?

A. Bile salts (Correct Answer)
B. Iron
C. Copper
D. Zinc

Explanation: ***Bile salts*** - The **distal ileum** is the primary site for the active reabsorption of **bile salts** back into the enterohepatic circulation. - Their malabsorption leads to **fat malabsorption** and steatorrhea, and can lead to gallstones due to changes in bile composition. *Iron* - The majority of **iron absorption** primarily occurs in the **duodenum** and proximal jejunum, not the distal ileum. - Iron deficiency would typically result from issues higher up in the small intestine or from chronic blood loss. *Copper* - **Copper absorption** mainly occurs in the **stomach** and **duodenum**. - Deficiency typically arises from dietary inadequacy or specific genetic disorders, not distal ileal resection. *Zinc* - **Zinc absorption** occurs throughout the **small intestine**, with significant absorption in the **jejunum**. - While some zinc is absorbed in the ileum, its primary absorption site is not limited to or predominantly in the distal ileum, making malabsorption less likely with isolated distal ileum removal.

Question 3: An adult female presents with pallor and fatigue. Blood investigations show low hemoglobin ( Hb ), low serum iron, low ferritin, low transferrin saturation, and increased total iron-binding capacity (TIBC). What is the likely diagnosis?

A. Iron Deficiency Anemia (IDA) (Correct Answer)
B. Anemia of Chronic Disease
C. Hemolytic Anemia
D. Thalassemia
E. Sideroblastic Anemia

Explanation: ***Iron Deficiency Anemia (IDA)*** - The unique constellation of **low hemoglobin**, **low serum iron**, **low ferritin**, **low transferrin saturation**, and **increased total iron-binding capacity (TIBC)** is the hallmark of Iron Deficiency Anemia. - **Ferritin** is a direct measure of iron stores, and its low level confirms depletion, while **increased TIBC** signifies the body's attempt to absorb more iron due to deficiency. *Anemia of Chronic Disease* - While also presenting with **low hemoglobin** and often **low serum iron**, Anemia of Chronic Disease is characterized by **normal or increased ferritin** (as ferritin is an acute phase reactant) and **decreased TIBC**. - There is a functional iron deficiency, but iron stores are typically adequate, and inflammation plays a central role. *Hemolytic Anemia* - Hemolytic anemia is characterized by the premature destruction of red blood cells, leading to **low hemoglobin** but typically **normal or elevated serum iron** and ferritin due to iron release from lysed red cells. - Key indicators, such as **elevated bilirubin**, **lactate dehydrogenase (LDH)**, and **reticulocytosis**, are absent in the given scenario. *Thalassemia* - Thalassemia is a genetic disorder causing defective hemoglobin synthesis, resulting in **microcytic hypochromic anemia** with **low hemoglobin**. - However, thalassemia typically presents with **normal to high serum iron** and ferritin levels, as iron absorption may be increased, and there's no primary iron deficiency. *Sideroblastic Anemia* - Sideroblastic anemia is characterized by defective heme synthesis with iron accumulation in mitochondria, forming characteristic ring sideroblasts on bone marrow examination. - Laboratory findings typically show **normal to increased serum iron**, **increased ferritin**, and **increased transferrin saturation**, distinguishing it from iron deficiency anemia.

Question 4: The daily production of hydrogen ions from CO2 is primarily buffered by which of the following?

A. Red blood cell bicarbonate
B. Extracellular bicarbonate
C. Plasma proteins
D. Red blood cell hemoglobin (Correct Answer)

Explanation: ***Red blood cell hemoglobin*** - **Hemoglobin is the primary buffer** for the massive daily acid load from CO2 (approximately 12,500 mEq H+ per day). - CO2 diffuses into RBCs where **carbonic anhydrase** rapidly catalyzes: CO2 + H2O → H2CO3 → H+ + HCO3-. - **Deoxygenated hemoglobin** has a higher affinity for H+ than oxygenated hemoglobin (reduced hemoglobin is a weaker acid, thus better H+ acceptor). - This buffering is crucial for CO2 transport: **Hb + H+ → HHb**, preventing significant pH changes despite huge CO2 production. - The bicarbonate produced is then transported out via the **chloride shift** to maintain electrical neutrality. *Extracellular bicarbonate* - While the bicarbonate buffer system is quantitatively the largest extracellular buffer, it is **NOT the primary buffer for CO2-derived H+**. - The extracellular HCO3-/CO2 system primarily buffers **metabolic (non-volatile) acids** produced from dietary and metabolic sources (~50-100 mEq/day). - For CO2-derived acid, the buffering occurs **intracellularly in RBCs** via hemoglobin before bicarbonate enters the plasma. *Red blood cell bicarbonate* - Bicarbonate is produced within RBCs from the dissociation of carbonic acid, but it is **not the buffer itself**. - The bicarbonate is a **product** of the buffering reaction, not the buffering agent. - Most RBC-produced HCO3- is transported to plasma via the **anion exchanger (Band 3 protein)** in exchange for Cl-. *Plasma proteins* - Plasma proteins like **albumin** have buffering capacity due to ionizable groups (imidazole groups of histidine residues). - They contribute only about **1-5%** of total blood buffering capacity. - Far less important than hemoglobin for buffering the large CO2-derived acid load.

Question 5: A 65-year-old male presents with fatigue, pallor, and low hemoglobin. Which laboratory finding is most indicative of iron deficiency anemia?

A. Low ferritin level (Correct Answer)
B. High reticulocyte count
C. High TIBC
D. Normal MCV

Explanation: ***Low ferritin level*** - **Ferritin** is the primary storage protein for iron in the body, and its level is the most accurate indicator of the body's iron stores. - A **low ferritin level** directly reflects depleted iron stores, which is characteristic of iron deficiency anemia [2]. *High reticulocyte count* - A **high reticulocyte count** typically indicates that the bone marrow is actively producing red blood cells, which is usually a response to anemia, but not specifically diagnostic of iron deficiency. - In iron deficiency anemia, the bone marrow's ability to produce new red blood cells is impaired due to lack of iron, so the reticulocyte count might be normal or even low, not high. *High TIBC* - **Total iron-binding capacity (TIBC)** measures the blood's capacity to bind to iron and is usually high in iron deficiency anemia due to an increase in transferrin, which tries to capture any available iron [1]. - While a high TIBC is consistent with iron deficiency, a **low ferritin** is a more direct and reliable indicator of iron stores. *Normal MCV* - **Mean corpuscular volume (MCV)** measures the average size of red blood cells. In established iron deficiency anemia, MCV is typically low, indicating **microcytic anemia** [1]. - A normal MCV (normocytic anemia) can occur in the very early stages of iron deficiency or in other types of anemia, making it less specific for iron deficiency than ferritin levels.

Question 6: What is/are the characterstics of Iron defficiency Anemaia(IDA)?

A. Increased TIBC
B. Low serum ferritin
C. All of the options (Correct Answer)
D. Low serum iron
E. Low transferrin saturation

Explanation: ***All of the options*** - **Iron deficiency anemia (IDA)** characteristically presents with a combination of these markers due to a true depletion of the body's iron stores [2]. - A comprehensive evaluation of iron studies, including **TIBC**, **ferritin**, **serum iron**, and **transferrin saturation**, is essential for an accurate diagnosis of IDA [3]. *Increased TIBC* - **Total iron-binding capacity (TIBC)** is typically **elevated in IDA** as the body attempts to maximize iron absorption and transport by increasing the production of transferrin [1]. - Transferrin, the primary iron-binding protein, is less saturated with iron, leading to an **increased capacity to bind more iron**. *Low serum ferritin* - **Serum ferritin** is a direct measure of **iron storage** in the body and is considered the most sensitive and specific marker for iron deficiency. - In IDA, **ferritin levels are markedly decreased**, indicating depleted iron reserves. *Low serum iron* - **Serum iron** measures the amount of iron circulating in the blood, primarily bound to transferrin [4]. - In IDA, the **absolute amount of circulating iron is reduced** due to insufficient iron supply [1]. *Low transferrin saturation* - **Transferrin saturation** represents the percentage of transferrin binding sites occupied by iron. - In IDA, due to **low serum iron** and **high transferrin (indicated by increased TIBC)**, the transferrin saturation is significantly reduced.

Question 7: Which of the following are blood values of Iron Deficiency Anaemia ? 1. Serum iron is less than 30 mg/100 mL 2. Total iron binding capacity is less than 400 µg/mL 3. Percentage saturation is 10% or less 4. Serum ferritin is below 30 µg/mL Select the correct answer using the code given below :

A. 1, 3 and 4 (Correct Answer)
B. 1, 2 and 4
C. 1, 2 and 3
D. 2, 3 and 4

Explanation: ***1, 3 and 4*** - In **iron deficiency anemia**, **serum iron** levels are typically **less than 30 µg/dL** [1] (or 30 mg/100 mL), indicating a reduced iron supply. - The **percentage saturation** of transferrin with iron falls to **10% or less** [1] because there is insufficient iron to bind to the available transferrin. - **Serum ferritin**, which reflects iron stores, is significantly **reduced, usually below 30 ng/mL** (or 30 µg/mL) [1]. *1, 2 and 4* - While options 1 and 4 are correct, option 2 stating **total iron binding capacity (TIBC) less than 400 µg/mL** is incorrect. - In iron deficiency, the body attempts to increase iron absorption by producing more transferrin, leading to an **elevated TIBC** [1] (often >400 µg/dL). *1, 2 and 3* - Although options 1 and 3 are correct for iron deficiency anemia, option 2, which states **TIBC is less than 400 µg/mL**, is false. - **TIBC is elevated** in iron deficiency, reflecting an increased capacity for iron binding due to increased transferrin. *2, 3 and 4* - While options 3 and 4 are correct, option 2, suggesting **TIBC is less than 400 µg/mL**, is inaccurate. - **TIBC** is typically **increased** in iron deficiency anemia as the body tries to maximize any available iron.

Question 8: All are increased in IDA except

A. Transferrin saturation (Correct Answer)
B. TIBC
C. Soluble transferrin receptor
D. Erythropoietin

Explanation: ***Transferrin saturation*** - In **iron deficiency anemia (IDA)**, there is insufficient iron to saturate transferrin, leading to a **decreased** transferrin saturation. This is the exception among the given options. - Transferrin saturation is calculated as (serum iron / TIBC) x 100, and both **serum iron** and its percentage saturation are low in IDA. *TIBC* - **Total iron-binding capacity (TIBC)** is typically **increased** in IDA as the liver produces more transferrin in an attempt to capture more iron [1]. - This elevated TIBC reflects the body's compensatory mechanism to maximize available iron uptake. *Soluble transferrin receptor* - **Soluble transferrin receptor (sTfR)** levels are **elevated** in IDA because iron-deficient erythroblasts upregulate the production of transferrin receptors on their surface as they try to scavenge more iron. - The elevated sTfR is a sensitive and specific marker for **iron deficiency**, particularly useful in differentiating IDA from anemia of chronic disease [1]. *Erythropoietin* - **Erythropoietin (EPO)** levels are **increased** in IDA due to the kidney's response to the decreased oxygen-carrying capacity of the blood (anemia) [1]. - EPO stimulates the bone marrow to produce more red blood cells, which exacerbates the demand for iron, often leading to further iron depletion if iron stores are low.

Question 9: Which of the following is a common consequence of gastrectomy?

A. Calcium deficiency
B. Iron deficiency (Correct Answer)
C. Steatorrhoea
D. Fluid loss

Explanation: ***Iron deficiency*** - Gastrectomy often leads to **achlorhydria** or hypochlorhydria, reducing the conversion of **ferric iron** (Fe3+) to its more absorbable ferrous form (Fe2+). - Additionally, bypassing the duodenum, a primary site of iron absorption, further contributes to **iron malabsorption**. *Calcium deficiency* - While gastrectomy can contribute to calcium malabsorption due to reduced gastric acidity and faster transit, **iron deficiency** is typically a more direct and common initial consequence. - **Vitamin D deficiency**, often co-occurring with gastrectomy, is a more direct cause of **calcium malabsorption**. *Steatorrhoea* - **Steatorrhoea** (fat malabsorption) is more commonly associated with conditions affecting the **pancreas** or **small intestine** (e.g., celiac disease, chronic pancreatitis) rather than primarily gastrectomy unless there is significant bile salt malabsorption or rapid gastric emptying affecting nutrient mixing. - Although rapid transit post-gastrectomy can sometimes impair fat digestion, it's not the most common direct consequence compared to iron deficiency. *Fluid loss* - **Fluid loss** is usually an acute post-surgical complication or related to conditions causing vomiting or diarrhea, and not a common long-term consequence of gastrectomy itself. - While **dumping syndrome** can occur after gastrectomy, causing osmotic fluid shifts into the intestine, generalized chronic fluid loss is not a primary recognized long-term sequela.

Question 10: Which of the following statements is true regarding anemia of prematurity?

A. Low reticulocyte response (Correct Answer)
B. Hemoglobin level <10 gm/dL
C. 10 ml/kg packed cell transfusion
D. Microcytic hypochromic type

Explanation: ***Low reticulocyte response*** - Anemia of prematurity results from several factors, including a **blunted erythropoietin response** to anemia, **shortened red blood cell lifespan**, and **rapid growth with increased blood volume requirements**. - The combination of these factors leads to **insufficient red blood cell production** by the bone marrow, reflected by a **low reticulocyte count** despite anemia. - This low reticulocyte response is a **key diagnostic feature** distinguishing it from hemolytic anemias. *Hemoglobin level <10 gm/dL* - While premature infants with anemia of prematurity develop low hemoglobin, a specific cutoff of **<10 gm/dL is not universally definitive** for diagnosis. - Hemoglobin nadirs vary based on **gestational age** (more premature = lower nadir) and occur at different postnatal ages. - Transfusion thresholds are determined by **clinical stability and symptoms**, not just a single Hb value. *10 ml/kg packed cell transfusion* - This describes a **treatment intervention**, not a characteristic of the disease itself. - Transfusion volume is typically **10-15 ml/kg** when indicated, but the decision to transfuse depends on gestational age, postnatal age, clinical stability, and symptoms like apnea or bradycardia. - This is **not a defining feature** of anemia of prematurity. *Microcytic hypochromic type* - Anemia of prematurity is typically **normocytic, normochromic**, not microcytic hypochromic. - **Microcytic hypochromic** anemia suggests **iron deficiency**, which is a different condition. - The red cells in anemia of prematurity have **normal size (MCV) and normal hemoglobin content** per cell.

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