GI physiology (digestion, absorption, motility) US Medical PG Practice Questions and MCQs
Practice US Medical PG questions for GI physiology (digestion, absorption, motility). These multiple choice questions (MCQs) cover important concepts and help you prepare for your exams.
GI physiology (digestion, absorption, motility) US Medical PG Question 1: A 25-year-old male presents to his primary care physician for fatigue, abdominal pain, diarrhea, and weight loss. He states that this issue has occurred throughout his life but seems to “flare up” on occasion. He states that his GI pain is relieved with defecation, and his stools are frequent, large, and particularly foul-smelling. The patient has a past medical history of an ACL tear, as well as a car accident that resulted in the patient needing a transfusion and epinephrine to treat transfusion anaphylaxis. His current medications include vitamin D and ibuprofen. He recently returned from a camping trip in the eastern United States. He states that on the trip they cooked packed meats over an open fire and obtained water from local streams. His temperature is 99.5°F (37.5°C), blood pressure is 120/77 mmHg, pulse is 70/min, respirations are 11/min, and oxygen saturation is 98% on room air. Physical exam reveals poor motor control and an ataxic gait on neurologic exam. Cardiac and pulmonary exams are within normal limits. Laboratory studies are ordered and return as below:
Hemoglobin: 9.0 g/dL
Hematocrit: 25%
Haptoglobin: 12 mg/dL
Leukocyte count: 7,500 cells/mm^3 with normal differential
Platelet count: 255,000/mm^3
Serum:
Na+: 140 mEq/L
Cl-: 102 mEq/L
K+: 5.0 mEq/L
HCO3-: 24 mEq/L
BUN: 24 mg/dL
Glucose: 82 mg/dL
Creatinine: 1.0 mg/dL
Ca2+: 9.0 mg/dL
LDH: 457 U/L
AST: 11 U/L
ALT: 11 U/L
Radiography is ordered which reveals a stress fracture in the patient’s left tibia. Which of the following is the best confirmatory test for this patient’s condition?
- A. Stool ELISA
- B. Vitamin B12 and folate level
- C. Vitamin E level (Correct Answer)
- D. Bowel wall biopsy
- E. Iron studies
GI physiology (digestion, absorption, motility) Explanation: ***Vitamin E level***
- The patient's presentation suggests **celiac disease** causing **malabsorption** with secondary **vitamin E deficiency**, which is causing the specific complications seen here.
- The **neurological findings** of **ataxic gait** and **poor motor control** combined with **hemolytic anemia** (low haptoglobin 12 mg/dL, elevated LDH 457 U/L, anemia) are **pathognomonic for vitamin E deficiency**.
- Vitamin E deficiency causes **spinocerebellar degeneration**, **peripheral neuropathy**, and **hemolytic anemia** due to oxidative damage to RBC membranes and neuronal lipids.
- The **stress fracture** suggests bone disease from calcium/vitamin D malabsorption, but the neuro-hematologic picture is most specific for vitamin E.
- **Serum vitamin E level** is the **confirmatory test** for this specific deficiency syndrome causing the patient's neurological and hematological complications.
- While the underlying condition is likely celiac disease, confirming vitamin E deficiency directly explains the constellation of findings and guides immediate treatment.
*Bowel wall biopsy*
- A **small intestine biopsy** would confirm the underlying diagnosis of **celiac disease** (villous atrophy, crypt hyperplasia) causing the malabsorption.
- However, the question asks for confirmation of "this patient's condition" - referring to the specific syndrome presenting with the characteristic triad of **ataxia + hemolysis + malabsorption**.
- This triad is pathognomonic for **vitamin E deficiency**, making direct measurement more confirmatory for the presenting complication than tissue diagnosis of the underlying cause.
*Vitamin B12 and folate level*
- **Vitamin B12 deficiency** can cause **subacute combined degeneration** with ataxia and neurological symptoms, but typically presents with **posterior column signs** (loss of proprioception, vibration) and **peripheral neuropathy**, not primarily cerebellar ataxia.
- **Folate deficiency** causes **megaloblastic anemia** but does **not** cause neurological deficits or the hemolytic pattern seen here (low haptoglobin, elevated LDH with normal liver enzymes).
- The **hemolytic anemia** is specific to vitamin E deficiency, not B12/folate deficiency.
*Stool ELISA*
- Could detect **Giardia lamblia** given the history of drinking stream water during camping, which can cause acute diarrhea and malabsorption.
- However, this does not explain the **lifelong, recurring symptoms**, **neurological deficits**, **hemolytic anemia**, or **stress fracture**.
- The chronic nature points to a primary malabsorption disorder, not acute infection.
*Iron studies*
- **Iron deficiency** commonly occurs with celiac disease due to duodenal malabsorption and could contribute to the **anemia**.
- However, iron deficiency causes **microcytic anemia**, not hemolytic anemia, and does **not** explain the **low haptoglobin**, **elevated LDH**, **ataxic gait**, or **motor control issues**.
- These findings are specific to vitamin E deficiency.
GI physiology (digestion, absorption, motility) US Medical PG Question 2: A 37-year-old man with Crohn disease is admitted to the hospital because of acute small bowel obstruction. Endoscopy shows a stricture in the terminal ileum. The ileum is surgically resected after endoscopic balloon dilatation fails to relieve the obstruction. Three years later, he returns for a follow-up examination. He takes no medications. This patient is most likely to have which of the following physical exam findings?
- A. Dry skin and keratomalacia
- B. Weakness and ataxia (Correct Answer)
- C. Hyperreflexia with tetany
- D. Gingival swelling and bleeding
- E. Pallor with koilonychia
GI physiology (digestion, absorption, motility) Explanation: ***Weakness and ataxia***
- This patient with a history of **Crohn disease** and significant **ileal resection** is at high risk for **vitamin B12 deficiency** due to the removal of the primary site of absorption in the terminal ileum.
- **Vitamin B12 deficiency** can lead to subacute combined degeneration of the spinal cord, manifesting as **weakness**, **ataxia**, and **paresthesias**.
*Dry skin and keratomalacia*
- This presentation is indicative of **vitamin A deficiency**, which can occur in malabsorption but is less specific to ileal resection than B12 deficiency.
- While fat-soluble vitamins (A, D, E, K) are absorbed in the small intestine, severe isolated vitamin A deficiency causing keratomalacia is not the most likely primary finding after ileal resection.
*Hyperreflexia with tetany*
- These symptoms typically suggest **hypocalcemia** or **hypomagnesemia**, often due to vitamin D deficiency or malabsorption of minerals.
- Although possible with generalized malabsorption, it is not the most characteristic neurological complication following isolated ileal resection compared to vitamin B12 deficiency.
*Gingival swelling and bleeding*
- This is a hallmark of **scurvy**, caused by **vitamin C deficiency**, which is typically absorbed in the small intestine and does not correlate specifically with ileal resection.
- This would be a less likely complication given the specific history compared to micronutrient deficiencies related to terminal ileum function.
*Pallor with koilonychia*
- **Pallor** and **koilonychia (spoon nails)** are characteristic signs of **iron deficiency anemia**.
- While iron is absorbed in the duodenum and proximal jejunum, and anemia is common in Crohn disease, the specific neurological symptoms from B12 deficiency are generally more prominent after ileal resection.
GI physiology (digestion, absorption, motility) US Medical PG Question 3: A 21-year-old woman presents to the clinic complaining of fatigue for the past 2 weeks. She reports that it is difficult for her to do strenuous tasks such as lifting heavy boxes at the bar she works at. She denies any precipitating factors, weight changes, nail changes, dry skin, chest pain, abdominal pain, or urinary changes. She is currently trying out a vegetarian diet for weight loss and overall wellness. Besides heavier than usual periods, the patient is otherwise healthy with no significant medical history. A physical examination demonstrates conjunctival pallor. Where in the gastrointestinal system is the most likely mineral that is deficient in the patient absorbed?
- A. Large intestine
- B. Ileum
- C. Jejunum
- D. Stomach
- E. Duodenum (Correct Answer)
GI physiology (digestion, absorption, motility) Explanation: ***Duodenum***
- The patient's symptoms (fatigue, conjunctival pallor, heavy periods, vegetarian diet) are highly suggestive of **iron deficiency anemia**. The **duodenum** is the primary site for the absorption of dietary iron.
- Iron absorption is tightly regulated here to maintain iron homeostasis, and conditions like a vegetarian diet can reduce bioavailable iron, leading to deficiency.
*Large intestine*
- The large intestine is primarily involved in **water and electrolyte absorption** and the formation of stool.
- It does not play a significant role in the absorption of essential minerals like iron.
*Ileum*
- The ileum is the main site for the absorption of **bile salts** and **vitamin B12**.
- While it absorbs some nutrients, it is not the primary site for iron absorption.
*Jejunum*
- The jejunum is the main site for the absorption of most **nutrients**, including carbohydrates, proteins, and fats.
- While some iron absorption can occur here, the **duodenum** is the specialized and most significant site for this process.
*Stomach*
- The stomach's main roles include **digestion** of proteins and production of **intrinsic factor** for vitamin B12 absorption.
- While **acidic pH** in the stomach aids in converting ferric iron (Fe3+) to ferrous iron (Fe2+), which is more readily absorbed, direct iron absorption in the stomach lining is minimal.
GI physiology (digestion, absorption, motility) US Medical PG Question 4: A 42-year-old man comes to the physician because of severe epigastric pain for a week. The pain is constant and he describes it as 6 out of 10 in intensity. The pain radiates to his back and is worse after meals. He has had several episodes of nausea and vomiting during this period. He has taken ibuprofen for multiple similar episodes of pain during the past 6 months. He also has had a 5.4-kg (12-lb) weight loss over the past 4 months. He has a 12-year history of drinking 3 to 4 pints of rum daily. He has been hospitalized three times for severe abdominal pain in the past 3 years. He appears ill. His temperature is 37°C (98.6°F), pulse is 87/min, and blood pressure is 110/70 mm Hg. There is severe epigastric tenderness to palpation. Bowel sounds are normal. Cardiopulmonary examination shows no abnormalities. Laboratory studies show:
Hemoglobin 13.6 g/dL
Leukocyte count 7,800/mm3
Serum
Glucose 106 mg/dL
Creatinine 1.1 mg/dL
Amylase 150 U/L
A CT of the abdomen is shown. Which of the following is the most appropriate long-term management for this patient?
- A. Pancreatic enzyme therapy (Correct Answer)
- B. Whipple procedure
- C. Endoscopic stent placement
- D. Celiac ganglion block
- E. Gluten-free diet
GI physiology (digestion, absorption, motility) Explanation: ***Pancreatic enzyme therapy***
- This patient likely has **chronic pancreatitis** due to long-term alcohol abuse, presenting with severe epigastric pain, weight loss, and recurrent episodes. **Pancreatic enzyme replacement therapy (PERT)** helps in managing malabsorption and pain by reducing pancreatic stimulation.
- While amylase is only slightly elevated (150 U/L), this is typical in chronic pancreatitis where extensive glandular destruction prevents dramatic enzyme elevation seen in acute pancreatitis. The abdominal CT would likely show calcifications or ductal dilation, further supporting the diagnosis and the need for enzyme support due to **exocrine insufficiency.**
*Whipple procedure*
- The **Whipple procedure** (pancreaticoduodenectomy) is a complex surgical intervention primarily performed for **pancreatic head tumors** or severe, intractable chronic pancreatitis not amenable to less invasive treatments.
- This patient's symptoms, while severe, do not immediately indicate a need for such aggressive surgery, and other medical managements should be attempted first.
*Endoscopic stent placement*
- **Endoscopic stent placement** is typically used to relieve **biliary obstruction** or **pancreatic duct strictures** that cause pain or cholangitis in chronic pancreatitis.
- While it might be considered for specific ductal complications, it is not the initial long-term management for the diverse symptoms of chronic pancreatitis, especially **exocrine insufficiency**.
*Celiac ganglion block*
- A **celiac ganglion block** provides temporary pain relief for severe abdominal pain, particularly in conditions like **chronic pancreatitis** or **pancreatic cancer**, by interrupting nerve signals.
- It is a **palliative measure** for pain control and does not address the underlying **exocrine insufficiency** or disease progression, making it not a long-term comprehensive management strategy.
*Gluten-free diet*
- A **gluten-free diet** is the primary treatment for **celiac disease**, an autoimmune disorder affecting the small intestine.
- There is no clinical indication or laboratory finding in this patient's presentation (e.g., diarrhea, positive celiac serology) to suggest celiac disease as the cause of his symptoms or to warrant a gluten-free diet.
GI physiology (digestion, absorption, motility) US Medical PG Question 5: An 82-year-old woman presents with 2 months of foul-smelling, greasy diarrhea. She says that she also has felt very tired recently and has had some associated bloating and flatus. She denies any recent abdominal pain, nausea, melena, hematochezia, or vomiting. She also denies any history of recent travel and states that her home has city water. Which of the following tests would be most appropriate to initially work up the most likely diagnosis in this patient?
- A. Fecal fat test (Correct Answer)
- B. Tissue transglutaminase antibody test
- C. Stool O&P
- D. Stool guaiac test
- E. CT of the abdomen with oral contrast
GI physiology (digestion, absorption, motility) Explanation: ***Fecal fat test***
- The patient's symptoms of **foul-smelling, greasy diarrhea**, along with **fatigue, bloating, and flatus**, strongly suggest **malabsorption**, specifically **steatorrhea** (excess fat in stool).
- A **fecal fat test** (e.g., Sudan stain or 72-hour quantitative stool fat collection) directly assesses fat malabsorption and would be the most appropriate initial diagnostic test.
*Tissue transglutaminase antibody test*
- This test is used to screen for **celiac disease**, which can cause malabsorption symptoms.
- While celiac disease is a possibility, a fecal fat test is a more general and appropriate initial step to confirm fat malabsorption before looking for specific causes.
*Stool O&P*
- Stands for **Stool Ova and Parasites**, used to detect parasitic infections like **Giardia** or **Cryptosporidium**, which can cause diarrhea.
- However, the absence of recent travel, city water, and the prominent greasy nature of the stool make this less likely as the primary initial investigation compared to confirming malabsorption.
*Stool guaiac test*
- This test detects **occult blood in stool**.
- The patient denies **melena or hematochezia**, and there are no signs pointing to gastrointestinal bleeding, making this test irrelevant for her presenting symptoms.
*CT of the abdomen with oral contrast*
- A CT scan with contrast might be used to investigate structural abnormalities or inflammation if other tests confirm malabsorption or point to a specific organ pathology (e.g., pancreatitis, Crohn's disease).
- It's an imaging study and generally not the most appropriate *initial* test for evaluating the described symptoms of malabsorption.
More GI physiology (digestion, absorption, motility) US Medical PG questions available in the OnCourse app. Practice MCQs, flashcards, and get detailed explanations.
