Endocrinology — MCQs

Endocrinology Indian Medical PG Practice Questions and MCQs

Question 521: A 45-year-old female patient, known diabetic on insulin therapy, presents for a routine general checkup. On examination, truncal obesity is noted. The sensitivity of the agent used in the treatment of this patient is enhanced by which of the following?

A. Leptin
B. Adiponectin (Correct Answer)
C. Glucagon
D. Insulin

Explanation: The patient described is a diabetic on **insulin therapy**. The question asks which factor enhances the sensitivity of insulin. **1. Why Adiponectin is Correct:** Adiponectin is an adipokine secreted by adipose tissue [2]. It acts as a potent **insulin sensitizer**. It enhances insulin sensitivity by [1]: * Increasing fatty acid oxidation via activation of **AMP-activated protein kinase (AMPK)** in skeletal muscle and the liver. * Decreasing hepatic gluconeogenesis. * Increasing glucose uptake in muscles. In patients with truncal obesity (as seen in this case), adiponectin levels are typically **decreased**, contributing to insulin resistance [1]. Therefore, higher levels of adiponectin directly enhance the sensitivity of the insulin the patient is receiving. **2. Why Other Options are Incorrect:** * **Leptin:** While also an adipokine, its primary role is regulating energy balance and appetite (satiety signal) [2]. In obesity, "leptin resistance" occurs. It does not directly enhance insulin sensitivity in the same potent manner as adiponectin. * **Glucagon:** This is a counter-regulatory hormone. It opposes insulin action by promoting glycogenolysis and gluconeogenesis, thereby **decreasing** insulin effectiveness and raising blood glucose. * **Insulin:** Insulin does not enhance its own sensitivity; chronic high levels of insulin (hyperinflation) actually lead to the downregulation of receptors and **increased** insulin resistance. **Clinical Pearls for NEET-PG:** * **Adiponectin Paradox:** Unlike other adipokines (like Resistin or TNF-α), adiponectin levels are **inversely** correlated with body fat percentage (lower in obesity). * **Thiazolidinediones (TZDs):** Drugs like Pioglitazone work partly by increasing the expression and secretion of adiponectin. * **AMPK Activation:** This is the common pathway for both Adiponectin and Metformin to improve insulin sensitivity.

Question 522: Which of the following features is/are suggestive of nephrogenic diabetes insipidus in comparison to central diabetes insipidus?

A. Desmopressin nasal spray restores urine output to a normal level.
B. Basal vasopressin level is greater than 1 pg/ml. (Correct Answer)
C. The normal posterior pituitary bright spot is not visible on MRI scan.
D. Change in water loss during a fluid deprivation test.

Explanation: **Explanation:** Diabetes Insipidus (DI) is characterized by the inability to concentrate urine, leading to polyuria and polydipsia [3]. The primary distinction between Central and Nephrogenic DI lies in the **production versus the action** of Arginine Vasopressin (AVP) [2]. **1. Why Option B is Correct:** In **Nephrogenic DI**, the posterior pituitary functions normally and secretes AVP, but the kidneys are resistant to its effects (due to V2 receptor mutations or drugs like Lithium) [3]. Consequently, the body attempts to compensate for high serum osmolality by secreting more hormone. Therefore, the **basal plasma AVP level is typically elevated (>1–2 pg/ml)** [1]. In contrast, Central DI is characterized by a deficiency of AVP, resulting in low or undetectable levels (<1 pg/ml). **2. Why the Other Options are Incorrect:** * **Option A:** Response to Desmopressin (dDAVP) is the gold standard for differentiation [2]. In **Central DI**, exogenous dDAVP restores urine concentration. In Nephrogenic DI, the kidneys remain unresponsive, and urine output does not normalize. * **Option C:** The "Posterior Pituitary Bright Spot" on T1-weighted MRI represents stored oxytocin and vasopressin. Its **absence** is a classic sign of **Central DI**. In Nephrogenic DI, the bright spot is usually present because hormone synthesis and storage are intact. * **Option D:** Both types of DI show a similar lack of urine concentration during a fluid deprivation test [2]. The test only confirms the diagnosis of DI; it does not reliably distinguish between the two types until dDAVP is administered. **Clinical Pearls for NEET-PG:** * **Most common cause of Nephrogenic DI (Acquired):** Lithium therapy. * **Most common cause of Nephrogenic DI (Inherited):** X-linked recessive mutation in the **V2 receptor gene** [3]. * **Diagnostic Cut-off:** After dDAVP administration, a >50% increase in urine osmolality indicates Central DI, while a <10% increase indicates Nephrogenic DI [2].

Question 523: Which is the hallmark feature of Conn's syndrome?

A. Hypertension with hyperkalemia
B. Hypertension with hypokalemia (Correct Answer)
C. Hypotension with hyperkalemia
D. Hypotension with hypokalemia

Explanation: **Explanation:** **Conn’s Syndrome** (Primary Hyperaldosteronism) is caused by an aldosterone-secreting adenoma of the adrenal cortex. The hallmark clinical presentation is **Hypertension with Hypokalemia**. [2] **1. Why Option B is correct:** Aldosterone acts on the principal cells of the distal convoluted tubule and collecting duct. It promotes the reabsorption of **Sodium (Na+)** and water, which increases plasma volume and leads to **hypertension**. Simultaneously, it promotes the excretion of **Potassium (K+)** and Hydrogen ions (H+), leading to **hypokalemia** and metabolic alkalosis [2]. Notably, the hypertension in Conn’s is often resistant to standard therapy, and the hypokalemia may be spontaneous or easily induced by low-dose diuretics. **2. Why other options are incorrect:** * **Option A:** Hyperkalemia is seen in conditions of aldosterone deficiency (e.g., Addison’s disease) or resistance, not excess. [2] * **Options C & D:** Hypotension is characteristic of adrenal insufficiency. In Conn’s syndrome, the mineralocorticoid excess causes volume expansion, ensuring blood pressure is elevated. **Clinical Pearls for NEET-PG:** * **Screening Test:** Plasma Aldosterone Concentration (PAC) to Plasma Renin Activity (PRA) ratio. A **PAC:PRA ratio > 20-30** is highly suggestive. * **Confirmatory Test:** Saline infusion test (failure to suppress aldosterone) or Oral Salt Loading test. * **Aldosterone Escape:** Patients with Conn’s syndrome do not develop massive edema despite sodium retention because of "atrial natriuretic peptide (ANP) escape," which limits volume expansion. [1] * **Treatment:** Surgical excision for unilateral adenoma; **Spironolactone** (aldosterone antagonist) for bilateral adrenal hyperplasia.

Question 524: A 29-year-old male on oral hypoglycemic drugs has never experienced ketonuria. His BMI is 20.5. His grandfather had diabetes, but his father, who is his grandfather's only son, did not have the disease. Which type of diabetes mellitus is this person most likely to have?

A. Pancreatic diabetes
B. Maturity-Onset Diabetes of the Young (MODY)
C. Type 1 diabetes
D. Type 2 diabetes (Correct Answer)

Explanation: The correct answer is **Type 2 Diabetes (D)**. **1. Why Type 2 Diabetes is correct:** The diagnosis is reached through a process of elimination and clinical pattern recognition. While the patient is young (29 years) and lean (BMI 20.5), the absence of ketonuria and the fact that he is managed on oral hypoglycemic drugs (OHAs) strongly point away from Type 1 Diabetes [1]. The key to this question lies in the **inheritance pattern**. The patient’s grandfather had diabetes, but his father did not. This represents **"skipped generation" inheritance**, which is characteristic of autosomal recessive or polygenic inheritance patterns often seen in Type 2 Diabetes [2]. **2. Why other options are incorrect:** * **MODY (B):** This is the most common distractor. MODY is characterized by **autosomal dominant** inheritance, meaning it typically presents in **every generation** (strong vertical transmission) [3]. Since the father was unaffected, MODY is statistically less likely than Type 2 DM. * **Type 1 Diabetes (C):** The patient is on OHAs and has **never experienced ketonuria**, which is the hallmark of absolute insulin deficiency [5]. Type 1 DM patients are ketosis-prone and insulin-dependent [1]. * **Pancreatic Diabetes (A):** This usually presents with a history of chronic pancreatitis (abdominal pain, steatorrhea) or pancreatic calcification on imaging [1]. There is no such clinical history provided. **3. NEET-PG High-Yield Pearls:** * **MODY:** Look for onset <25 years, non-obese, and **3 consecutive generations** affected (Autosomal Dominant) [3]. MODY 3 (HNF-1ʹ) is the most common subtype. * **Type 2 DM in Lean Individuals:** Common in the South Asian phenotype ("Thin-fat Indians") where visceral adiposity exists despite a low BMI. * **Ketonuria:** Its absence is a strong clinical indicator of residual beta-cell function, favoring Type 2 DM over Type 1 DM [4].

Question 525: Which of the following is NOT a symptom of endemic goitre?

A. Cold intolerance
B. Hoarseness
C. Dysphagia
D. None of the above (Correct Answer)

Explanation: **Explanation:** Endemic goitre is primarily caused by **iodine deficiency**, leading to a compensatory enlargement of the thyroid gland to maintain euthyroidism. However, as the condition progresses, it can manifest through two distinct mechanisms: **mechanical compression** and **hypothyroidism**. [1] 1. **Why "None of the above" is correct:** All the listed options (A, B, and C) are recognized clinical features of endemic goitre. Since the question asks which is *NOT* a symptom, and all are possible symptoms, "None of the above" is the correct choice. 2. **Analysis of Options:** * **Cold Intolerance (Option A):** Chronic iodine deficiency often leads to **hypothyroidism** because iodine is a critical substrate for T3 and T4 synthesis [1]. Cold intolerance is a classic constitutional symptom of a low metabolic state associated with hypothyroidism. * **Hoarseness (Option B):** A significantly enlarged thyroid gland (goitre) can exert pressure on the **recurrent laryngeal nerve**, leading to vocal cord paresis and hoarseness of voice. * **Dysphagia (Option C):** This is a **mechanical/obstructive symptom**. A large retrosternal or multinodular goitre can compress the esophagus, making swallowing difficult [1]. **High-Yield Clinical Pearls for NEET-PG:** * **Definition:** A goitre is considered "endemic" if it affects >5% of the population (or >10% of children). * **Pemberton’s Sign:** Used to detect superior vena cava syndrome caused by a large retrosternal goitre; look for facial flushing and inspiratory stridor when the patient raises both arms. * **Wolff-Chaikoff Effect:** Transient inhibition of thyroid hormone synthesis following a large iodine load. * **Jod-Basedow Phenomenon:** Iodine-induced hyperthyroidism, often seen when iodine is replaced in a deficient population.

Question 526: A 30-year-old woman presents with prominent cervical and dorsal fat pads, hirsutism, acne, purple abdominal striae, unexplained hypokalemia, and diabetes mellitus. What is the most likely disease process causing these clinical syndromes?

A. Acromegaly
B. Exogenous human growth hormone (HGH) use
C. Empty sella syndrome
D. Cushing disease (Correct Answer)

Explanation: ### Explanation **Correct Answer: D. Cushing disease** **1. Why Cushing Disease is Correct:** The patient presents with the classic constellation of **Cushing Syndrome**: centripetal obesity (cervical/dorsal fat pads), androgen excess (hirsutism, acne), and skin changes (purple striae) [1]. The presence of **hypokalemia** and **diabetes mellitus** (secondary to insulin resistance) indicates severe hypercortisolism. * **Medical Concept:** Cushing *Disease* specifically refers to a pituitary adenoma secreting excess ACTH [1]. While "Cushing Syndrome" is the clinical state, in NEET-PG contexts, when classic features are paired with metabolic derangements like hypokalemia (often seen in high ACTH states due to mineralocorticoid cross-reactivity), Cushing disease is the most likely endogenous cause in a young female. **2. Why the Other Options are Incorrect:** * **A & B (Acromegaly/Exogenous HGH):** While GH excess causes diabetes and some soft tissue swelling, it does **not** cause purple striae, hirsutism, or dorsal fat pads. Acromegaly typically presents with frontal bossing, macroglossia, and spade-like hands. * **C (Empty Sella Syndrome):** This is usually an incidental radiological finding where the pituitary is flattened. It typically presents with headaches or is asymptomatic; it does not cause a hypercortisolic state unless associated with a specific functional microadenoma (rare). **3. NEET-PG High-Yield Pearls:** * **Screening Test:** Overnight Dexamethasone Suppression Test (ONDST) or 24-hour urinary free cortisol [2]. * **Gold Standard for Localization:** Inferior Petrosal Sinus Sampling (IPSS) to differentiate a pituitary source (Cushing Disease) from ectopic ACTH. * **Hypokalemia Hint:** If hypokalemia is profound, suspect **Ectopic ACTH secretion** (e.g., Small Cell Lung Cancer), as the very high cortisol levels overwhelm the 11β-HSD2 enzyme in the kidney [1]. * **Striae:** To be clinically significant for Cushing’s, striae must be **>1 cm wide** and violaceous.

Question 527: Which of the following is NOT true about nephrogenic diabetes insipidus?

A. Increase in urine output
B. Increased sugar in urine (Correct Answer)
C. No response to ADH
D. No response to vasopressin test

Explanation: **Explanation:** The correct answer is **B (Increased sugar in urine)** because Nephrogenic Diabetes Insipidus (NDI) is a disorder of water homeostasis, not glucose metabolism. The term "Diabetes" refers to polyuria (excessive urination), and "Insipidus" means tasteless, reflecting the lack of glucose in the urine—unlike *Diabetes Mellitus*, where glycosuria is a hallmark feature. **Analysis of Options:** * **A. Increase in urine output:** This is a core feature of NDI. Due to the kidneys' inability to concentrate urine, patients experience massive polyuria (often >3L/day) and compensatory polydipsia [3]. * **C & D. No response to ADH/Vasopressin test:** These are the defining physiological characteristics of NDI. In this condition, the posterior pituitary secretes ADH (Vasopressin) normally [1], but the kidneys are resistant to its action due to defects in the V2 receptors or Aquaporin-2 channels [3]. Therefore, administering exogenous Vasopressin fails to increase urine osmolality, distinguishing it from Central Diabetes Insipidus [2]. **High-Yield Clinical Pearls for NEET-PG:** 1. **Etiology:** The most common electrolyte triggers for NDI are **Hypercalcemia** and **Hypokalemia** [2]. 2. **Drug-Induced:** **Lithium** is the most common pharmacological cause of NDI. 3. **Diagnosis:** The **Water Deprivation Test** followed by Desmopressin administration is the gold standard [2]. In NDI, urine osmolality remains low (<300 mOsm/kg) even after Desmopressin. 4. **Treatment:** Paradoxically, **Thiazide diuretics** are used to treat NDI as they induce mild hypovolemia, increasing proximal tubule water reabsorption. Amiloride is specifically used for Lithium-induced NDI.

Question 528: Which screening test for diabetes has the highest sensitivity?

A. Glycosylated Hb
B. Blood fructosamine
C. 50gms glucose challenge test (Correct Answer)
D. Random blood sugar (RBS)

Explanation: **Explanation:** The **50g Glucose Challenge Test (GCT)** is the correct answer because it is specifically designed as a high-sensitivity screening tool, most notably used in gestational diabetes mellitus (GDM) [2]. Unlike diagnostic tests that prioritize specificity to avoid false positives, a screening test aims to identify as many potential cases as possible. The 50g GCT involves administering a glucose load regardless of the last meal and measuring plasma glucose one hour later; its low threshold for "positivity" ensures that very few cases are missed, giving it the **highest sensitivity** among the listed options. **Analysis of Incorrect Options:** * **Glycosylated Hb (HbA1c):** While convenient and used for diagnosis (threshold ≥6.5%), it has lower sensitivity compared to glucose-based tests. It can be falsely low in conditions with high red cell turnover (e.g., hemolytic anemia, pregnancy). * **Blood Fructosamine:** This reflects glycemic control over the past 2–3 weeks. It is useful when HbA1c is unreliable but is not a standard or highly sensitive screening tool for the general population. * **Random Blood Sugar (RBS):** This is the least sensitive and specific [1]. It is highly dependent on the timing and content of the last meal, making it an unreliable screening tool for early-stage diabetes. **Clinical Pearls for NEET-PG:** * **Gold Standard for Diagnosis:** The 75g Oral Glucose Tolerance Test (OGTT) is the gold standard for diagnosing DM and GDM (Carpenter-Coustan criteria) [3]. * **Screening vs. Diagnosis:** Screening (GCT) uses a 50g load; Diagnosis (OGTT) uses a 75g or 100g load. * **HbA1c Limitations:** HbA1c is not used for the diagnosis of GDM; glucose-based tests are mandatory in pregnancy due to physiological changes in RBC lifespan.

Question 529: Pemberton sign is seen in which condition?

A. Retrosternal goiter (Correct Answer)
B. Graves ophthalmopathy
C. Thyroid crisis
D. Addisonian crisis

Explanation: **Explanation:** **Pemberton’s sign** is a clinical maneuver used to demonstrate latent superior vena cava (SVC) syndrome, most commonly caused by a **retrosternal goiter**. **Why Retrosternal Goiter is correct:** When a patient with a large retrosternal goiter raises both arms above their head (Pemberton maneuver) for 30–60 seconds, the thyroid gland is pulled into the narrow thoracic inlet. This leads to mechanical compression of the jugular veins and the superior vena cava against the trachea and sternum. The result is a positive sign characterized by **facial congestion, cyanosis, inspiratory stridor, and distension of neck veins.** [1] **Why other options are incorrect:** * **Graves’ Ophthalmopathy:** This is an autoimmune inflammatory condition of the extraocular muscles and orbital fat. While it causes proptosis and lid lag, it does not involve thoracic inlet obstruction. [2] * **Thyroid Crisis (Storm):** This is a life-threatening state of hypermetabolism. Clinical features include high fever, tachycardia, and delirium, but not mechanical venous obstruction. * **Addisonian Crisis:** This is acute adrenocortical insufficiency presenting with hypotension, hyponatremia, and hyperkalemia. It has no anatomical relationship with the thoracic inlet. **NEET-PG High-Yield Pearls:** * **Definition of Retrosternal Goiter:** A goiter where >50% of the thyroid mass is below the thoracic inlet. [1] * **Most common cause of SVC Syndrome:** Historically syphilis/TB; currently **Malignancy** (Bronchogenic carcinoma and Lymphoma). * **Pemberton Sign components:** Facial flushing (plethora), cyanosis, and increased JVP upon arm elevation.

Question 530: Pheochromocytoma predominantly secretes which hormone?

A. Epinephrine (Correct Answer)
B. Norepinephrine
C. Dopamine
D. DOPA

Explanation: The correct answer is **Epinephrine**. While the normal adrenal medulla secretes approximately 80% epinephrine and 20% norepinephrine, **pheochromocytomas** (tumors arising from chromaffin cells) are unique because they are the only catecholamine-secreting tumors capable of converting norepinephrine to epinephrine [1]. This occurs due to the presence of the enzyme **Phenylethanolamine N-methyltransferase (PNMT)**, which requires high local concentrations of cortisol (from the adjacent adrenal cortex) for induction. Since most pheochromocytomas are intra-adrenal, they have access to this cortisol and thus predominantly secrete epinephrine. **Analysis of Incorrect Options:** * **B. Norepinephrine:** While many extra-adrenal paragangliomas secrete norepinephrine exclusively (as they lack PNMT), the classic adrenal pheochromocytoma predominantly produces epinephrine. However, it is important to note that some tumors may secrete a mixture, but epinephrine remains the hallmark of adrenal origin. * **C. Dopamine:** Secretion of dopamine is rare and usually associated with malignant pheendocrine tumors rather than standard pheochromocytomas. * **D. DOPA:** This is a precursor in the catecholamine synthesis pathway. Elevated DOPA levels are typically markers of poorly differentiated or highly malignant neuroendocrine tumors rather than standard pheochromocytomas. **High-Yield Clinical Pearls for NEET-PG:** * **Rule of 10s:** 10% are bilateral, 10% are malignant, 10% are pediatric, and 10% are extra-adrenal (Paragangliomas). * **Diagnosis:** The most sensitive initial screening test is **plasma free metanephrines**; the most specific is **24-hour urinary metanephrines and VMA**. * **Localization:** **MIBG Scan** (I-131 or I-123) is used for localizing extra-adrenal or metastatic tumors [2]. * **Management:** Always start **Alpha-blockers (Phenoxybenzamine)** before Beta-blockers to prevent a hypertensive crisis (unopposed alpha-stimulation).

Practice by Chapter

Diabetes Mellitus

Practice Questions

Thyroid Disorders

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Adrenal Gland Disorders

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Pituitary Disorders

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Calcium and Bone Metabolism

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Reproductive Endocrinology

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Lipid Disorders

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Endocrine Hypertension

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Multiple Endocrine Neoplasia

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Obesity and Metabolic Syndrome

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Neuroendocrine Tumors

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Endocrine Emergencies

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