Metabolic Effects of Bariatric Surgery — MCQs
Which protein secreted by adipocytes prevents obesity?
Which of the following is true about somatostatin, insulin, and glucagon?
An obese patient undergoes a gastric bypass procedure to lose weight but never returns for follow-up or continuing care. Three years later, he presents to an emergency room with fatigue, a glossy tongue, and a macrocytic and hyperchromic anemia. Which one of the following is deficient or malfunctioning in this patient, leading to this anemia?
In case of LPL deficiency, which of the following will increase after a fat rich diet?
In surgical stress all hormones are increased except:
A patient scheduled for elective inguinal hernia surgery has a history of myocardial infarction (MI) and underwent coronary artery bypass grafting (CABG). What should be included in the preoperative assessment?
Dietary deficiency of which vitamin is considered extremely rare?
The anesthetic agent which can cause massive hepatic necrosis?
What is true about carcinoma of the esophagus?
In patients with osteoarthritis of the knee joint, atrophy occurs most commonly in which muscle?
Metabolic Effects of Bariatric Surgery Indian Medical PG Practice Questions and MCQs
Question 1: Which protein secreted by adipocytes prevents obesity?
- A. Galanin
- B. Neuropeptide Y
- C. Cathepsin
- D. Leptin (Correct Answer)
Explanation: ***Leptin*** - **Leptin** is a hormone secreted by **adipocytes** (fat cells) that plays a crucial role in long-term energy balance and appetite suppression. - It signals the brain about the body's energy stores, leading to decreased food intake and increased energy expenditure, and thus **preventing obesity**. *Galanin* - **Galanin** is a neuropeptide that has been shown to **stimulate food intake**, particularly fat consumption. - It is associated with **increased appetite** and **obesity**, rather than its prevention. *Neuropeptide Y* - **Neuropeptide Y (NPY)** is a potent **orexigenic** (appetite-stimulating) peptide primarily found in the hypothalamus. - Its activation leads to **increased food intake** and **decreased energy expenditure**, promoting weight gain and obesity. *Cathepsin* - **Cathepsins** are a family of **proteolytic enzymes** found in lysosomes. - They are involved in protein degradation and other cellular processes, but they are not directly involved in the prevention of obesity through appetite regulation or energy balance.
Question 2: Which of the following is true about somatostatin, insulin, and glucagon?
- A. Glucagon blocks insulin and Somatostatin release.
- B. Somatostatin blocks release of insulin and glucagon. (Correct Answer)
- C. Insulin increases glucagon release.
- D. Somatostatin stimulates insulin.
Explanation: ***Somatostatin blocks release of insulin and glucagon.*** - **Somatostatin** acts as a paracrine inhibitor within the **islets of Langerhans**, suppressing the secretion of both **insulin** from beta cells and **glucagon** from alpha cells. - This inhibitory action helps to modulate and fine-tune nutrient absorption and utilization following a meal, preventing excessive fluctuations in blood glucose levels. *Glucagon blocks insulin and Somatostatin release.* - **Glucagon's primary role** is to raise blood glucose by stimulating **hepatic glucose production**, not to block the release of insulin or somatostatin. - In fact, glucagon can stimulate **somatostatin release**, which then acts to inhibit glucagon secretion, forming a negative feedback loop. *Insulin increases glucagon release.* - **Insulin and glucagon** have opposing roles in glucose regulation; insulin's main function is to lower blood glucose, while glucagon raises it. - High insulin levels typically **suppress glucagon secretion**, as the body needs to lower glucose, not raise it further. *Somatostatin stimulates insulin.* - **Somatostatin** is a potent **inhibitor** of insulin release, not a stimulator. - This inhibitory effect helps to prevent rapid and excessive insulin secretion, which could lead to hypoglycemia.
Question 3: An obese patient undergoes a gastric bypass procedure to lose weight but never returns for follow-up or continuing care. Three years later, he presents to an emergency room with fatigue, a glossy tongue, and a macrocytic and hyperchromic anemia. Which one of the following is deficient or malfunctioning in this patient, leading to this anemia?
- A. Intrinsic factor (Correct Answer)
- B. Gastrin
- C. Iron
- D. Lead
Explanation: ***Intrinsic factor*** - This patient's symptoms (fatigue, glossitis, macrocytic, and hyperchromic anemia) strongly suggest **vitamin B12 deficiency**, which often results from insufficient intrinsic factor. [1] - **Gastric bypass surgery** can lead to reduced gastric acid secretion and a decreased production of intrinsic factor, both of which are crucial for vitamin B12 absorption in the terminal ileum. [1] *Gastrin* - **Gastrin** primarily regulates gastric acid secretion and mucosal growth, but its deficiency is not a typical direct cause of macrocytic anemia. - While gastrin production can be altered in certain gastric conditions, it's not the primary factor in **vitamin B12 malabsorption** post-gastric bypass. *Iron* - An **iron deficiency** would typically present as **microcytic, hypochromic anemia**, not macrocytic and hyperchromic anemia. [2] - The symptoms described (glossy tongue, specific type of anemia) are inconsistent with isolated iron deficiency. [3] *Lead* - **Lead poisoning** can cause anemia (often microcytic or normocytic, and sometimes with **basophilic stippling**), but it does not lead to a **glossy tongue** or **macrocytic, hyperchromic anemia**. - The clinical presentation is not suggestive of lead toxicity.
Question 4: In case of LPL deficiency, which of the following will increase after a fat rich diet?
- A. LDL
- B. HDL
- C. Lipoprotein (a)
- D. Chylomicron (Correct Answer)
Explanation: ***Chylomicron*** - **LPL (lipoprotein lipase)** is crucial for the breakdown of **chylomicrons** and VLDL. A deficiency leads to an accumulation of undigested chylomicrons in the bloodstream after a fat-rich meal. - **Chylomicrons** transport dietary triglycerides from the intestines to tissues. Without LPL, these triglycerides remain packaged in chylomicrons. *LDL* - **LDL (low-density lipoprotein)** levels are not directly increased by a short-term fat-rich diet in the context of LPL deficiency. LDL primarily carries cholesterol and is formed from VLDL remnants, a process that is also impaired by LPL deficiency indirectly. - While chronic LPL deficiency can affect overall lipid metabolism, the immediate post-meal increase is not in LDL but in triglyceride-rich lipoproteins. *HDL* - **HDL (high-density lipoprotein)** is involved in reverse cholesterol transport and is generally not directly increased after a fat-rich diet, especially in LPL deficiency. - In fact, severe hypertriglyceridemia, often seen in LPL deficiency, can sometimes lead to lower HDL levels due to altered lipid exchange. *Lipoprotein (a)* - **Lipoprotein (a)**, or Lp(a), is a genetically determined lipoprotein similar to LDL but with an added apolipoprotein (a) and its levels are not acutely affected by dietary fat intake or LPL deficiency. - Lp(a) levels are determined primarily by genetic factors and do not participate in the post-prandial handling of dietary fats.
Question 5: In surgical stress all hormones are increased except:
- A. Insulin (Correct Answer)
- B. Epinephrine
- C. ACTH
- D. Cortisol
Explanation: ***Insulin*** - While other **stress hormones** increase, **insulin** levels typically **decrease** or remain stable due to increased **insulin resistance** during surgical stress. - This physiological response aims to maintain **blood glucose** levels for energy during heightened metabolic demands. *Epinephrine* - **Epinephrine** (adrenaline) is a key **catecholamine** released during surgical stress, leading to a "fight or flight" response. - It increases **heart rate**, **blood pressure**, and promotes **gluconeogenesis** to supply quick energy. *ACTH* - **Adrenocorticotropic hormone (ACTH)** is released from the **pituitary gland** in response to surgical stress. - **ACTH** stimulates the adrenal cortex to produce **cortisol**, a critical stress hormone. *Cortisol* - **Cortisol** levels significantly rise during surgical stress, mediated by **ACTH** release. - It plays a crucial role in **modulating inflammation**, **glucose metabolism**, and maintaining **hemodynamic stability**.
Question 6: A patient scheduled for elective inguinal hernia surgery has a history of myocardial infarction (MI) and underwent coronary artery bypass grafting (CABG). What should be included in the preoperative assessment?
- A. History + c/e + routine labs + V/Q scan
- B. History + c/e + routine labs
- C. History + c/e + routine labs + stress test (Correct Answer)
- D. History + c/e + routine labs + angiography to assess graft patency
Explanation: ***History + c/e + routine labs + stress test*** - A **stress test** is crucial in patients with a history of MI and CABG to assess **myocardial ischemia** and functional capacity, guiding perioperative management. - This evaluation helps determine the patient's **cardiac risk** for non-cardiac surgery and the need for further cardiac optimization. *History + c/e + routine labs + angiography to assess graft patency* - **Coronary angiography** is an invasive procedure and is generally not indicated as a routine preoperative assessment unless there are new, significant cardiac symptoms or signs of **graft dysfunction**. - Assessing graft patency through angiography carries risks and would only be justified if there were strong clinical indications suggesting acute or severe **cardiac ischemia**. *History + c/e + routine labs* - While critical for any preoperative assessment, **routine history, physical examination, and basic laboratory tests** are insufficient for a patient with a significant cardiac history like MI and CABG. - This approach would **underestimate the cardiac risk** and might miss undetected ischemia, leading to adverse perioperative cardiac events. *History + c/e + routine labs + V/Q scan* - A **ventilation-perfusion (V/Q) scan** is primarily used to diagnose **pulmonary embolism** or assess regional lung function. - It does not provide information about myocardial ischemia or cardiac functional capacity, making it **irrelevant** for assessing cardiac risk in this clinical scenario.
Question 7: Dietary deficiency of which vitamin is considered extremely rare?
- A. Thiamine
- B. Vitamin B6
- C. Vitamin E (Correct Answer)
- D. Vitamin D
Explanation: ***Vitamin E*** - **Vitamin E deficiency** is exceptionally rare because it is a **fat-soluble vitamin** stored in the body and is widely available in many common foods. - Symptoms of deficiency, when they do occur, are usually seen in individuals with severe **malabsorption syndromes** or genetic abnormalities affecting its metabolism. *Vitamin B6* - **Vitamin B6 deficiency** can occur, especially in individuals with **alcoholism**, those taking certain medications, or with certain chronic diseases. - It can manifest with neurological symptoms, such as **neuropathy** and **seizures**, as well as dermatological issues. *Thiamine* - **Thiamine (Vitamin B1) deficiency** is a known problem in regions with poor nutrition and in chronic alcoholics. - It leads to conditions like **beriberi** (wet and dry) and **Wernicke-Korsakoff syndrome**, affecting the cardiovascular and nervous systems. *Vitamin D* - **Vitamin D deficiency** is common globally, particularly in populations with limited sun exposure or inadequate dietary intake. - It can cause **rickets** in children and **osteomalacia** in adults, impacting bone health.
Question 8: The anesthetic agent which can cause massive hepatic necrosis?
- A. N 2 O
- B. Halothane (Correct Answer)
- C. Methoxyflurane
- D. Isoflurane
Explanation: ***Halothane*** - Halothane can be metabolized into toxic intermediates through oxidative pathways, leading to **halothane hepatitis** or fulminant hepatic necrosis. - This idiosyncratic reaction is more likely after repeated exposures and presents as severe liver injury, possibly due to **immune-mediated mechanisms** triggered by trifluoroacetylated proteins. *N 2 O* - **Nitrous oxide** (N2O) is generally considered very safe regarding hepatic effects and does not cause massive hepatic necrosis. - Its primary metabolism involves no significant liver pathways that would generate toxic metabolites affecting hepatocytes. *Methoxyflurane* - Methoxyflurane is known to cause **nephrotoxicity** due to its metabolism to fluoride ions, which can impair renal concentrating ability. - While it can be hepatotoxic, its effects are generally less severe and less common than halothane-induced necrosis, with **renal toxicity** being its most prominent adverse effect. *Isoflurane* - Isoflurane is a commonly used volatile anesthetic with a **very low incidence of hepatotoxicity** compared to halothane. - It undergoes minimal metabolism, reducing the likelihood of producing toxic metabolites that could harm the liver.
Question 9: What is true about carcinoma of the esophagus?
- A. The most common site is the lower end.
- B. Both adenocarcinoma and squamous cell carcinoma occur. (Correct Answer)
- C. The commonest histology is adenocarcinoma.
- D. It is more common in females.
Explanation: **Explanation:** Carcinoma of the esophagus is a significant topic in surgical oncology. The correct answer is **Option B** because esophageal cancer primarily manifests in two distinct histological types: **Squamous Cell Carcinoma (SCC)** and **Adenocarcinoma (EAC)**. While their risk factors and primary locations differ, both are recognized as the major pathological variants of the disease. **Analysis of Options:** * **Option A & C:** Historically, SCC was the most common type globally and typically occurred in the **middle third** of the esophagus. However, in Western countries, the incidence of Adenocarcinoma (usually involving the **lower third**) is rising due to GERD and Barrett’s esophagus. Globally, SCC remains more prevalent, making "Adenocarcinoma" or "Lower end" incorrect as absolute "most common" statements without geographic context. * **Option D:** Esophageal cancer shows a strong **male predominance** (often 3:1 or higher), largely due to higher rates of smoking and alcohol consumption (for SCC) and central obesity/GERD (for EAC) in men. **High-Yield Clinical Pearls for NEET-PG:** * **Most common type (Worldwide/India):** Squamous Cell Carcinoma. * **Most common type (Western world):** Adenocarcinoma. * **Risk Factors:** SCC is associated with smoking, alcohol, and achalasia cardia; EAC is strongly linked to **Barrett’s Esophagus** (metaplasia). * **Investigation of Choice:** Upper GI Endoscopy with biopsy. * **Staging:** Contrast-enhanced CT (CECT) for distant spread; **Endoscopic Ultrasound (EUS)** is the most accurate for T and N staging. * **Lymphatic Spread:** The esophagus lacks a serosa, leading to early mediastinal spread.
Question 10: In patients with osteoarthritis of the knee joint, atrophy occurs most commonly in which muscle?
- A. Quadriceps only (Correct Answer)
- B. Hamstrings only
- C. Both quadriceps and hamstrings
- D. Gastrocnemius
Explanation: In patients with osteoarthritis (OA) of the knee, muscle atrophy is a hallmark clinical finding, and the **Quadriceps femoris** is the most commonly and severely affected muscle group. ### Why Quadriceps only is the correct answer: The primary mechanism is **Arthrogenic Muscle Inhibition (AMI)**. Pain, swelling, and joint laxity associated with OA trigger a presynaptic inhibition of the alpha-motoneurons supplying the quadriceps. This prevents the muscle from being fully activated, leading to disuse atrophy. The quadriceps (specifically the *Vastus Medialis Obliquus*) is highly sensitive to joint effusion; even a small amount of intra-articular fluid can inhibit its contraction. This creates a vicious cycle: weak quadriceps fail to absorb shock during gait, leading to increased joint loading and accelerated cartilage degeneration. ### Why other options are incorrect: * **Hamstrings only:** While hamstrings may show some weakness due to overall decreased activity, they do not undergo the same level of reflex inhibition as the extensors. In fact, hamstrings often become relatively "overactive" to stabilize the joint, which can lead to flexion contractures. * **Both quadriceps and hamstrings:** Although generalized limb wasting can occur in advanced stages, the atrophy is significantly disproportionate. The quadriceps waste earlier and more profoundly than the hamstrings. * **Gastrocnemius:** This muscle is primarily involved in ankle plantarflexion. While it crosses the knee joint, it is not the primary stabilizer affected by the neuro-mechanical changes of knee OA. ### High-Yield Clinical Pearls for NEET-PG: * **Vastus Medialis Obliquus (VMO):** This is the first component of the quadriceps to show visible wasting in knee pathologies. * **Quadriceps Lag:** A clinical sign where the patient can passively straighten the knee but cannot maintain active extension, often due to quadriceps weakness/atrophy. * **Management:** Strengthening the quadriceps is the most effective non-pharmacological intervention to reduce pain and improve function in knee OA.
Want unlimited practice?
Get full access to all questions, explanations, and performance tracking.
Start For Free