MSNC 505 WEEK 6: ADVANCED
GASTROINTESTINAL AND RENAL
PATHOPHYSIOLOGY QUESTIONS AND
DETAILED SOLUTIONS JUST
RELEASED
1. A patient presents with Acute Kidney Injury (AKI) and a Fractional Excretion of Sodium
(FeNa) of less than 1%. Which of the following is the most likely etiology?
A. Acute Tubular Necrosis
B. Postrenal Obstruction
C. Intrarenal Glomerulonephritis
D. Prerenal Azotemia
Answer: D
Conceptual Explanation: A FeNa of less than 1% indicates that the renal tubules are still
functioning and attempting to conserve sodium, which is characteristic of prerenal causes
where the primary issue is decreased perfusion.
2. In the development of Barrett’s esophagus, which histological change is observed due to
chronic acid exposure?
A. Columnar metaplasia to squamous epithelium
,B. Squamous metaplasia to columnar epithelium
C. Dysplasia of the goblet cells only
D. Atrophy of the submucosal layer
Answer: B
Conceptual Explanation: Barrett’s esophagus involves the replacement of normal
stratified squamous epithelium with simple columnar epithelium (intestinal metaplasia) as
a protective response to gastric acid.
3. Which mechanism primarily explains the development of anemia in patients with Stage 4
Chronic Kidney Disease?
A. Inadequate production of erythropoietin by peritubular cells
B. Excessive destruction of RBCs in the spleen
C. Iron deficiency from malnutrition
D. Reduced absorption of Vitamin B12 in the ileum
Answer: A
Conceptual Explanation: Erythropoietin is synthesized by peritubular fibroblasts in the
renal cortex; as renal mass decreases in CKD, synthesis drops, leading to normocytic
normochromic anemia.
, 4. A patient with cirrhosis develops hepatic encephalopathy. What is the physiological basis
for using lactulose in this patient?
A. To increase the production of bile salts
B. To reduce the absorption of vitamins
C. To stimulate the urea cycle in the liver
D. To convert ammonia into non-absorbable ammonium ions
Answer: D
Conceptual Explanation: Lactulose is metabolized by gut bacteria into lactic acid, which
lowers the pH of the colon, converting NH3 into NH4+ (ammonium), which is trapped in
the gut and excreted.
5. Which electrolyte abnormality is most characteristic of the ‘oliguric phase’ of Acute Tubular
Necrosis?
A. Hypokalemia
B. Hypophosphatemia
C. Hypernatremia
D. Hyperkalemia
Answer: D
Conceptual Explanation: During the oliguric phase of ATN, the kidneys fail to excrete
potassium, leading to potentially life-threatening hyperkalemia.
GASTROINTESTINAL AND RENAL
PATHOPHYSIOLOGY QUESTIONS AND
DETAILED SOLUTIONS JUST
RELEASED
1. A patient presents with Acute Kidney Injury (AKI) and a Fractional Excretion of Sodium
(FeNa) of less than 1%. Which of the following is the most likely etiology?
A. Acute Tubular Necrosis
B. Postrenal Obstruction
C. Intrarenal Glomerulonephritis
D. Prerenal Azotemia
Answer: D
Conceptual Explanation: A FeNa of less than 1% indicates that the renal tubules are still
functioning and attempting to conserve sodium, which is characteristic of prerenal causes
where the primary issue is decreased perfusion.
2. In the development of Barrett’s esophagus, which histological change is observed due to
chronic acid exposure?
A. Columnar metaplasia to squamous epithelium
,B. Squamous metaplasia to columnar epithelium
C. Dysplasia of the goblet cells only
D. Atrophy of the submucosal layer
Answer: B
Conceptual Explanation: Barrett’s esophagus involves the replacement of normal
stratified squamous epithelium with simple columnar epithelium (intestinal metaplasia) as
a protective response to gastric acid.
3. Which mechanism primarily explains the development of anemia in patients with Stage 4
Chronic Kidney Disease?
A. Inadequate production of erythropoietin by peritubular cells
B. Excessive destruction of RBCs in the spleen
C. Iron deficiency from malnutrition
D. Reduced absorption of Vitamin B12 in the ileum
Answer: A
Conceptual Explanation: Erythropoietin is synthesized by peritubular fibroblasts in the
renal cortex; as renal mass decreases in CKD, synthesis drops, leading to normocytic
normochromic anemia.
, 4. A patient with cirrhosis develops hepatic encephalopathy. What is the physiological basis
for using lactulose in this patient?
A. To increase the production of bile salts
B. To reduce the absorption of vitamins
C. To stimulate the urea cycle in the liver
D. To convert ammonia into non-absorbable ammonium ions
Answer: D
Conceptual Explanation: Lactulose is metabolized by gut bacteria into lactic acid, which
lowers the pH of the colon, converting NH3 into NH4+ (ammonium), which is trapped in
the gut and excreted.
5. Which electrolyte abnormality is most characteristic of the ‘oliguric phase’ of Acute Tubular
Necrosis?
A. Hypokalemia
B. Hypophosphatemia
C. Hypernatremia
D. Hyperkalemia
Answer: D
Conceptual Explanation: During the oliguric phase of ATN, the kidneys fail to excrete
potassium, leading to potentially life-threatening hyperkalemia.
