Endocrinology Practice Questions

Q: Medullary thyroid carcinoma is associated with which of the following syndromes?

Multiple Endocrine Neoplasia type II (MEN II). Medullary Thyroid Carcinoma (MTC) is a tumor arising from the parafollicular C-cells of the thyroid, which secrete calcitonin. While most cases are sporadic, approximately 25% are familial and occur as a component of **Multiple Endocrine Neoplasia type 2 (MEN 2)**. **1. Why MEN II is correct:** MEN 2 is an autosomal dominant syndrome caused by a germline mutation in the **RET proto-oncogene**. It is subdivided into: * **MEN 2A (Sipple Syndrome):** MTC (100%), Pheochromocytoma (50%), and Parathyroid hyperplasia (20%). * **MEN 2B:** MTC (100%, more aggressive), Pheochromocytoma, Marfanoid habitus, and Mucosal neuromas. MTC is the most consistent feature and often the presenting manifestation of both subtypes. **2. Why other options are incorrect:** * **MEN I (Wermer Syndrome):** Characterized by the "3 Ps"—**P**arathyroid adenoma, **P**ituitary adenoma, and **P**ancreatic neuroendocrine tumors (e.g., Gastrinoma). It is caused by mutations in the *MEN1* gene (Menin protein) and is not associated with MTC. * **MEN IV:** A rare syndrome caused by *CDKN1B* mutations. It presents similarly to MEN I (primarily parathyroid and pituitary tumors) but does not typically include MTC. **High-Yield Clinical Pearls for NEET-PG:** * **Screening:** In patients with a known *RET* mutation, prophylactic thyroidectomy is often indicated. * **Tumor Marker:** Calcitonin is used for both diagnosis and monitoring recurrence of MTC. Carcinoembryonic antigen (CEA) is also a useful marker. * **Rule of Thumb:** Always exclude a **Pheochromocytoma** (via urinary/plasma metanephrines) before performing surgery on a patient with MEN 2 to prevent a hypertensive crisis during anesthesia.

Q: In Conn's syndrome, which of the following statements are true?

Systolic hypertension without edema. **Explanation:** **Conn’s Syndrome (Primary Hyperaldosteronism)** is characterized by the autonomous overproduction of aldosterone, usually due to an adrenal adenoma [1]. **1. Why the Correct Answer is Right:** Aldosterone acts on the principal cells of the collecting duct to increase sodium and water reabsorption and promote potassium excretion. This leads to volume expansion and **hypertension**. A hallmark of Conn’s syndrome is **Hypertension without edema**. This occurs due to the **"Aldosterone Escape" phenomenon**: the initial volume expansion triggers the release of Atrial Natriuretic Peptide (ANP) and increases pressure natriuresis, leading to the excretion of excess sodium and water [2]. This prevents the formation of overt edema while maintaining a high-pressure state (systolic hypertension). **2. Analysis of Incorrect Options:** * **A. Diastolic hypertension:** While both systolic and diastolic pressures rise, systolic hypertension is the more prominent clinical feature of the volume-expanded state. * **C. Pseudotetany:** While hypokalemia can cause muscle weakness, "pseudotetany" is not a classic or defining feature of Conn’s. True tetany is associated with hypocalcemia. * **D. Hyperkalemia:** This is incorrect. Aldosterone causes **Hypokalemia** due to increased potassium secretion in the distal tubules. **3. NEET-PG High-Yield Pearls:** * **Classic Triad:** Hypertension, Hypokalemia, and Metabolic Alkalosis. * **Screening Test:** Plasma Aldosterone Concentration (PAC) to Plasma Renin Activity (PRA) ratio. A ratio **>20-30** is highly suggestive. * **Confirmatory Test:** Saline infusion test (failure to suppress aldosterone) or Oral Salt Loading test. * **Management:** Surgical excision for adenoma (Conn’s); Spironolactone or Eplerenone (Aldosterone antagonists) for bilateral adrenal hyperplasia [1].

Q: Whipple's triad is seen in which of the following conditions?

Insulinoma. **Explanation:** **Whipple’s Triad** is the classic clinical diagnostic criterion for **Insulinoma**, a neuroendocrine tumor of the pancreatic beta cells that results in the autonomous secretion of insulin. The triad consists of: 1. **Symptoms of hypoglycemia** (e.g., sweating, palpitations, confusion, or seizures) usually triggered by fasting or exercise. 2. **Low plasma glucose levels** (typically <55 mg/dL) measured at the time of symptoms. 3. **Relief of symptoms** promptly after the administration of glucose. **Why the other options are incorrect:** * **Gastrinoma:** Causes Zollinger-Ellison Syndrome, characterized by refractory peptic ulcers and diarrhea due to excessive gastric acid secretion. * **VIPoma:** Causes WDHA syndrome (Watery Diarrhea, Hypokalemia, and Achlorhydria), also known as Verner-Morrison syndrome. * **Somatostatinoma:** Presents with a "inhibitory syndrome" including diabetes mellitus, cholelithiasis, and steatorrhea due to the suppression of multiple gastrointestinal hormones. **High-Yield Clinical Pearls for NEET-PG:** * **Diagnosis:** The gold standard for diagnosing insulinoma is the **72-hour supervised fast**. * **Biochemical Profile:** During a hypoglycemic episode, patients with insulinoma will show **elevated Insulin**, **elevated C-peptide**, and **elevated Pro-insulin** levels, with an absence of sulfonylureas in the urine/blood. * **Localization:** Most insulinomas are small, benign, and solitary. Endoscopic ultrasound (EUS) is highly sensitive for localization. * **Association:** While most are sporadic, insulinomas can be associated with **MEN1 syndrome** (3Ps: Pituitary, Parathyroid, Pancreas).

Q: Chovstek's sign is seen in which of the following conditions?

Hypocalcemia. **Explanation:** **Chvostek’s sign** is a clinical indicator of **latent tetany** caused by **hypocalcemia** [1]. It is elicited by tapping the facial nerve at the angle of the jaw (anterior to the external auditory meatus). A positive sign is characterized by twitching of the facial muscles (ipsilateral) due to neuromuscular irritability. **Why Hypocalcemia is the correct answer:** Calcium ions normally stabilize neuronal membranes by inhibiting sodium channels. In hypocalcemia, the threshold for depolarization is lowered, making the nerve membranes "hyperexcitable." Even minor mechanical stimulation (like tapping) triggers spontaneous action potentials, leading to muscle contraction. **Why other options are incorrect:** * **Hypercalcemia:** This leads to decreased neuromuscular excitability, typically presenting with muscle weakness, constipation, and "moans, stones, and groans," rather than twitching. * **Hypokalemia:** Usually presents with muscle weakness, paralysis, or U-waves on ECG, but does not cause Chvostek’s sign. * **Hyperkalemia:** Primarily affects cardiac conduction (peaked T-waves) and can cause muscle weakness, but not tetany. **High-Yield Clinical Pearls for NEET-PG:** 1. **Trousseau’s Sign:** More sensitive and specific than Chvostek’s sign. It involves carpal spasm induced by inflating a BP cuff above systolic pressure for 3 minutes. 2. **Hypomagnesemia:** Can also cause a positive Chvostek’s sign because low magnesium often leads to refractory hypocalcemia [1]. 3. **Respiratory Alkalosis:** Hyperventilation can trigger these signs because increased pH causes more calcium to bind to albumin, reducing the ionized (active) fraction of calcium [1]. 4. **False Positives:** Chvostek’s sign can be present in approximately 10% of healthy individuals with normal calcium levels.

Q: Thyrotoxic periodic paralysis (TPP) is usually due to hypokalemia. What is the best treatment?

Propranolol. ### Explanation **Correct Answer: D. Propranolol** **Mechanism and Rationale:** Thyrotoxic periodic paralysis (TPP) is characterized by sudden muscle weakness due to an **intracellular shift of potassium**, rather than a true total-body potassium deficit. Excess thyroid hormone increases **Na+/K+-ATPase pump activity**, a process mediated by **beta-adrenergic stimulation**. **Propranolol** (a non-selective beta-blocker) is the treatment of choice because it directly antagonizes the hyper-adrenergic state, reversing the intracellular shift and normalizing serum potassium levels without the risk of rebound hyperkalemia [1]. **Why other options are incorrect:** * **A. Potassium:** While hypokalemia is present, giving intravenous potassium is risky. Since there is no actual loss of potassium from the body, as the attack resolves, the potassium shifts back into the extracellular space. Exogenous administration often leads to **rebound hyperkalemia** (seen in up to 40% of cases). If used, it must be given in very low doses and with extreme caution. * **B. Magnesium:** Magnesium deficiency can coexist with hypokalemia, but it is not the primary pathophysiology of TPP. * **C. Hydration:** While supportive, hydration does not address the underlying ion shift or the thyrotoxic state [1]. **NEET-PG High-Yield Pearls:** * **Demographics:** TPP is most common in **Asian males**, despite hyperthyroidism being more common in females. * **Triggers:** High carbohydrate meals (insulin release) and strenuous exercise followed by rest. * **Definitive Treatment:** Achieving a **euthyroid state** (e.g., antithyroid drugs, radioactive iodine, or surgery) is the only way to prevent recurrence [1]. * **Key Distinction:** Unlike Familial Periodic Paralysis, TPP patients will show signs of hyperthyroidism (tachycardia, tremors, low TSH).

Q: Impaired oral glucose tolerance test (OGTT) is indicated by which of the following criteria?

Fasting blood glucose < 126 mg/dL and two hours after glucose load 140-199 mg/dL. The diagnosis of glycemic status is based on specific thresholds defined by the American Diabetes Association (ADA). **Impaired Glucose Tolerance (IGT)** is a state of "Pre-diabetes" where blood glucose levels are higher than normal but do not yet meet the criteria for a diagnosis of Diabetes Mellitus [1]. **1. Why Option D is Correct:** The Oral Glucose Tolerance Test (OGTT) involves administering 75g of anhydrous glucose. IGT is specifically defined as a **2-hour post-load plasma glucose between 140 mg/dL and 199 mg/dL**. To fit the definition of IGT (rather than overt diabetes), the fasting plasma glucose must also be below the diabetic threshold ( 126 mg/dL):** This is the diagnostic threshold for **Diabetes Mellitus**, not impaired tolerance [1]. * **Option B (Random > 200 mg/dL):** A random plasma glucose ≥ 200 mg/dL in a symptomatic patient (polyuria, polydipsia) is diagnostic of **Diabetes Mellitus**. * **Option C (Fasting < 90 mg/dL):** This represents a normal fasting glucose level (Normal is < 100 mg/dL). **3. NEET-PG High-Yield Pearls:** * **Impaired Fasting Glucose (IFG):** Fasting plasma glucose between **100–125 mg/dL**. * **HbA1c Criteria:** Normal (< 5.7%), Pre-diabetes (5.7–6.4%), and Diabetes (≥ 6.5%). * **Gold Standard:** While HbA1c is convenient, the **OGTT** is considered more sensitive for diagnosing early glucose intolerance. * **Pregnancy (GDM):** Note that the Carpenter-Coustan or DIPSI criteria used in pregnancy have different thresholds than the general population.

Q: What are the diagnostic criteria for Diabetes Mellitus?

HbA1c > 6.5%. The diagnosis of Diabetes Mellitus (DM) is based on specific glycemic thresholds established by the American Diabetes Association (ADA). [1] **Explanation of the Correct Answer:** **Option D (HbA1c ≥ 6.5%)** is a primary diagnostic criterion. HbA1c reflects the average blood glucose over the preceding 2–3 months. A value of **≥ 6.5%** (using a standardized assay) is diagnostic of DM. In the absence of unequivocal hyperglycemia, the diagnosis requires two abnormal test results from the same sample or in two separate test samples. **Analysis of Incorrect Options:** * **Option A:** These values (Fasting 100 mg/dL, PP 140 mg/dL) represent the upper limit of **normal** glycemic status. * **Option B:** These values (Fasting 125 mg/dL, 2-hr PP 199 mg/dL) fall into the **Prediabetes** category. For a DM diagnosis, Fasting Plasma Glucose (FPG) must be **≥ 126 mg/dL** and 2-hour Oral Glucose Tolerance Test (OGTT) must be **≥ 200 mg/dL**. [1] * **Option C:** Insulin levels are not used to diagnose DM. While they may help distinguish between Type 1 (low insulin/C-peptide) and Type 2 (high insulin/insulin resistance), they do not define the disease. [1] **High-Yield Clinical Pearls for NEET-PG:** * **Diagnostic Criteria Summary:** 1. **FPG:** ≥ 126 mg/dL (8-hour fast). [1] 2. **2-hr OGTT:** ≥ 200 mg/dL (using 75g anhydrous glucose). 3. **HbA1c:** ≥ 6.5%. 4. **Random Plasma Glucose:** ≥ 200 mg/dL **PLUS** classic symptoms of hyperglycemia (polyuria, polydipsia, weight loss). [1] * **Prediabetes Ranges:** HbA1c: 5.7–6.4%; FPG: 100–125 mg/dL (Impaired Fasting Glucose); 2-hr OGTT: 140–199 mg/dL (Impaired Glucose Tolerance). [1] * **Note:** HbA1c may be unreliable in conditions with high red cell turnover (e.g., hemolytic anemia, pregnancy, recent hemorrhage).

Question 1

Medullary thyroid carcinoma is associated with which of the following syndromes?

Accepted Answer

Multiple Endocrine Neoplasia type II (MEN II)

Answer

Multiple Endocrine Neoplasia type I (MEN I)

Answer

Multiple Endocrine Neoplasia type IV (MEN IV)

Answer

All of the above

Question 2

Which of the following is the most likely cause of hirsutism, when associated with anovulation, obesity, and amenorrhea?

Accepted Answer

Polycystic ovarian disease (PCOD)

Answer

Drug-induced hirsutism

Answer

Adrenal tumor

Answer

Idiopathic hirsutism

Question 3

In Conn's syndrome, which of the following statements are true?

Accepted Answer

Systolic hypertension without edema

Answer

Diastolic hypertension without edema

Answer

Pseudotetany

Answer

Hyperkalemia

Question 4

Whipple's triad is seen in which of the following conditions?

Accepted Answer

Insulinoma

Answer

Gastrinoma

Answer

Vipomas

Answer

Somatostatinoma

Question 5

Chovstek's sign is seen in which of the following conditions?

Accepted Answer

Hypocalcemia

Answer

Hypercalcemia

Answer

Hypokalemia

Answer

Hyperkalemia

Question 6

Thyrotoxic periodic paralysis (TPP) is usually due to hypokalemia. What is the best treatment?

Accepted Answer

Propranolol

Answer

Potassium

Answer

Magnesium

Answer

Hydration

Question 7

Impaired oral glucose tolerance test (OGTT) is indicated by which of the following criteria?

Accepted Answer

Fasting blood glucose < 126 mg/dL and two hours after glucose load 140-199 mg/dL

Answer

Fasting plasma glucose 
> 126 mg/dL

Answer

Random blood glucose > 200 mg/dL

Answer

Fasting blood glucose < 90 mg/dL

Question 8

What are the diagnostic criteria for Diabetes Mellitus?

Accepted Answer

HbA1c > 6.5%

Answer

Fasting blood glucose is 100 mg/dL and post prandial 140 mg/dL

Answer

Fasting blood sugar is 125 mg/dL and 2-hour postprandial blood sugar is 199 mg/dL

Answer

Elevated insulin level

Question 9

What is the most diagnostic test for Addison's disease?

Accepted Answer

ACTH stimulation test

Answer

Serum Na+, K+, and renin levels

Answer

Serum Na+, K+, and saline suppression test

Answer

Serum creatinine/urea ratio

Question 10

A 29-year-old woman complains of nervousness and muscle weakness of 6 months' duration. She is intolerant of heat and sweats excessively. She has lost 9 kg over the past 6 months despite an increased caloric intake. She frequently experiences a racing heart and palpitations. She has also missed several menstrual periods in the past few months. Physical examination reveals warm, moist skin and exophthalmos. What endocrine abnormality is most likely present in this patient?

Accepted Answer

Increased anti-TSH receptor antibodies

Answer

Increased anti-thyroid DNA antibodies

Answer

Decreased uptake of radioactive iodine in the thyroid

Answer

Increased serum TSH

Endocrinology — MCQs

Endocrinology — MCQs

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