Endocrinology Practice Questions

Q: A 20-year-old male presents with chronic constipation, headache, and palpitations. On examination, he has Marfanoid habitus, neuromas of the tongue, medullated corneal nerve fibers, and a 2 x 2 cm nodule in the right lobe of the thyroid. This patient is a case of -

Multiple Endocrine Neoplasia (MEN) IIB. ### Explanation The patient presents with a classic constellation of symptoms diagnostic of **Multiple Endocrine Neoplasia Type 2B (MEN 2B)**. **Why Option D is Correct:** MEN 2B is characterized by the triad of **Medullary Thyroid Carcinoma (MTC)**, **Pheochromocytoma**, and **Mucosal Neuromas**. * **Marfanoid Habitus:** Unlike MEN 2A, patients with MEN 2B often exhibit a thin body habitus with long limbs and joint laxity. * **Mucosal Neuromas:** The "neuromas of the tongue" and "medullated corneal nerve fibers" are pathognomonic features of MEN 2B. * **Pheochromocytoma:** The symptoms of headache and palpitations suggest an underlying catecholamine-secreting tumor. * **MTC:** The thyroid nodule represents MTC, which is more aggressive and occurs earlier in MEN 2B than in other forms. **Why Other Options are Incorrect:** * **Option A & B:** While MTC is present, these options do not account for the extra-thyroidal manifestations like mucosal neuromas and Marfanoid habitus. * **Option C (MEN 2A):** While MEN 2A also features MTC and Pheochromocytoma, it is associated with **Primary Hyperparathyroidism** rather than mucosal neuromas or Marfanoid habitus. **High-Yield Clinical Pearls for NEET-PG:** 1. **Genetics:** Both MEN 2A and 2B are caused by germline mutations in the **RET proto-oncogene** (Chromosome 10). 2. **MTC Screening:** In MEN 2B, MTC is highly aggressive; prophylactic thyroidectomy is often recommended within the **first year of life**. 3. **Gastrointestinal Involvement:** Chronic constipation in these patients can be due to **intestinal ganglioneuromatosis**, a common feature of MEN 2B. 4. **Rule of Thumb:** If you see "Mucosal Neuromas" or "Marfanoid Habitus" in a thyroid case, think **MEN 2B**.

Q: Which one of the following biochemical measures would be most likely to be elevated in this patient?

Alkaline phosphatase. ***Alkaline phosphatase*** - In **Paget's disease**, there is **excessive osteoblastic activity** leading to dramatically elevated **alkaline phosphatase (ALP)** levels, often 10-25 times normal values. - ALP is a **bone formation marker** released by hyperactive osteoblasts during the abnormal bone remodeling process characteristic of Paget's disease. *Calcium* - Serum **calcium levels remain normal** in Paget's disease despite increased bone turnover due to effective **parathyroid hormone regulation**. - Hypercalcemia may only occur during **periods of immobilization** or in cases with extensive disease affecting large portions of the skeleton. *Ferritin* - **Ferritin is an iron storage protein** and is not directly involved in bone metabolism or Paget's disease pathophysiology. - Elevated ferritin would suggest **iron overload**, **inflammation**, or **liver disease**, none of which are primary features of Paget's disease. *Phosphorus* - Serum **phosphorus levels typically remain normal** in Paget's disease as the increased bone resorption and formation are balanced. - Phosphorus abnormalities are more commonly seen in **primary hyperparathyroidism** or **chronic kidney disease**, not in Paget's disease.

Q: Gynecomastia is not associated with which of the following?

A person with (45, XO) karyotype. **Explanation:** The core pathophysiology of gynecomastia involves an **imbalance between free estrogen and free androgen** actions on breast tissue. **Why (45, XO) is the correct answer:** A person with a **(45, XO) karyotype has Turner Syndrome**. These individuals are phenotypically female but experience gonadal dysgenesis (streak ovaries), leading to primary hypogonadism. Because they lack functional testicular tissue and do not produce significant male levels of androgens or the subsequent peripheral conversion to estrogens, they do not develop gynecomastia. In fact, Turner syndrome is characterized by a lack of secondary sexual characteristics, including minimal breast development (thelarche). **Analysis of Incorrect Options:** * **Anabolic Steroids:** Exogenous testosterone or its analogs are often peripherally aromatized into estrogen. Additionally, they suppress the HPO axis, leading to decreased endogenous testosterone, thus tilting the ratio in favor of estrogen. * **Alcoholic Cirrhosis:** The liver is responsible for metabolizing estrogen and producing Sex Hormone Binding Globulin (SHBG). In cirrhosis, decreased estrogen clearance and increased SHBG (which binds testosterone more tightly than estrogen) lead to hyperestrogenism. * **Antiretroviral Therapy (ART):** Specifically, Protease Inhibitors (PIs) and Efavirenz are associated with lipodystrophy and true gynecomastia, likely due to metabolic disturbances or mitochondrial toxicity. **High-Yield Clinical Pearls for NEET-PG:** * **Klinefelter Syndrome (47, XXY):** This is the most common chromosomal cause of gynecomastia (increased risk of breast cancer). * **Drugs causing Gynecomastia (Mnemonic: DISCO):** **D**igoxin, **I**soniazid, **S**pironolactone (most common drug cause), **C**imetidine, **O**estrogens/Ketoconazole. * **Physiological Gynecomastia:** Occurs in three peaks—Neonatal, Pubertal, and Senile (old age).

Q: What is the best initial advice to be given to a patient newly diagnosed with type 2 Diabetes Mellitus?

Engage in regular exercise.. **Explanation:** The management of newly diagnosed Type 2 Diabetes Mellitus (T2DM) focuses on lifestyle modification as the cornerstone of therapy. **Why "Engage in regular exercise" is correct:** Physical activity is the most critical initial intervention because it directly addresses the primary pathophysiology of T2DM: **Insulin Resistance**. Exercise increases glucose uptake in skeletal muscles via insulin-independent mechanisms (translocation of **GLUT-4 receptors**) and improves systemic insulin sensitivity [2]. The ADA recommends at least 150 minutes of moderate-intensity aerobic activity per week, spread over at least 3 days, with no more than 2 consecutive days without activity. **Analysis of Incorrect Options:** * **Option A:** While reducing saturated fat is part of a heart-healthy diet, the specific recommendation is usually to keep it to **<7% of total calories** (not 10% of total fat intake). This is a secondary goal compared to improving glycemic control through activity. * **Option B:** Consistency in calorie intake is helpful for weight management, but the *quality* of nutrients and the *timing* of meals in relation to medication/activity are more clinically significant for glycemic stability. * **Option C:** Restricting carbohydrates is no longer the primary recommendation. Current guidelines emphasize the **Glycemic Index (GI)** and fiber content rather than total restriction [1]. Carbohydrates should still constitute 45-60% of the total daily caloric intake. **High-Yield Clinical Pearls for NEET-PG:** * **First-line Drug:** Metformin (Biguanide) is the drug of choice if lifestyle changes fail. * **Diagnosis:** HbA1c ≥ 6.5%, Fasting Plasma Glucose ≥ 126 mg/dL, or 2-hour OGTT ≥ 200 mg/dL. * **Screening:** In asymptomatic adults, screening should begin at age 35 (ADA 2022 update). * **Exercise Benefit:** Resistance training should be added to aerobic exercise for maximal benefit in T2DM [2].

Q: What percentage of pheochromocytomas are malignant?

10%. In clinical medicine and endocrinology, pheochromocytoma is famously known as the **"Rule of 10" tumor**. This mnemonic is a high-yield concept for NEET-PG, as it summarizes the epidemiological distribution of these catecholamine-secreting tumors. ### **Why 10% is Correct** Statistically, approximately **10% of pheochromocytomas are malignant**. Unlike many other tumors, malignancy in pheochromocytoma cannot be determined by histological appearance alone (cellular atypia or mitosis). Instead, malignancy is strictly defined by the **presence of distant metastasis** to non-chromaffin tissues, such as the lungs, liver, or bones. ### **Analysis of Incorrect Options** * **A (5%):** This underestimates the malignancy rate. While some pediatric series show variation, 10% remains the standard teaching for general boards. * **C & D (20% & 15%):** These percentages are too high for sporadic pheochromocytomas. However, it is important to note that malignancy rates can be significantly higher (up to 35-50%) in patients with specific genetic mutations, such as **SDHB mutations**. ### **Clinical Pearls for NEET-PG** To master this topic, remember the complete **"Rule of 10s"**: 1. **10% Malignant:** Defined by metastasis. 2. **10% Bilateral:** Often associated with familial syndromes. 3. **10% Extra-adrenal:** These are called **Paragangliomas** (most common site: Organ of Zuckerkandl). 4. **10% Pediatric:** Though rare, they are a classic cause of secondary hypertension in children. 5. **10% Familial:** (Note: Modern genetics suggests this may now be as high as 30-35%, but "10%" remains the classic exam answer). **High-Yield Fact:** The most sensitive screening test is **Plasma free metanephrines**, while the most specific is **24-hour urinary metanephrines**. For localization, **MIBG scan** is used if CT/MRI is inconclusive.

Q: Ectopic ACTH syndrome is most commonly associated with which of the following conditions?

Bronchogenic carcinoma. **Explanation:** **Ectopic ACTH Syndrome** occurs when a non-pituitary tumor secretes adrenocorticotropic hormone (ACTH), leading to hypercortisolism (Cushing’s syndrome) [1]. **1. Why Bronchogenic Carcinoma is Correct:** The most common cause of ectopic ACTH production is **Small Cell Carcinoma of the Lung (SCLC)**, a subtype of bronchogenic carcinoma [2], [3]. These tumors are derived from neuroendocrine cells (Kulchitsky cells) which have the metabolic machinery to synthesize and secrete polypeptide hormones like ACTH. Unlike pituitary-dependent Cushing’s disease, ectopic ACTH syndrome often presents with rapid onset, severe hypokalemia, and significant hyperpigmentation due to very high levels of ACTH and its precursor, POMC. **2. Analysis of Incorrect Options:** * **Renal cell carcinoma (A):** While RCC is a classic "great imitator" known for paraneoplastic syndromes (like Erythropoietin or PTHrP production), it is a rare cause of ectopic ACTH [2]. * **Lymphoma (B):** Lymphomas can occasionally cause hypercalcemia (via Vitamin D production), but they are not a primary source of ACTH. * **Pituitary adenoma (D):** A pituitary adenoma secreting ACTH is the cause of **Cushing’s Disease**. This is the most common cause of endogenous Cushing’s syndrome overall, but it is *not* considered "ectopic" because the pituitary is the physiological site of ACTH production [1]. **3. NEET-PG High-Yield Pearls:** * **Most common cause of Ectopic ACTH:** Small Cell Lung Cancer (SCLC) [3]. * **Second most common cause:** Bronchial Carcinoid tumors. * **Biochemical Hallmark:** High-dose dexamethasone suppression test (HDDST) fails to suppress cortisol levels in ectopic ACTH (unlike Cushing’s Disease, where suppression occurs). * **Clinical Clue:** If a patient has Cushingoid features plus profound **hypokalemic metabolic alkalosis**, suspect ectopic ACTH.

Q: In Multiple Endocrine Neoplasia type I (MEN I), which of the following tumors is seen most commonly?

Gastrinoma. Explanation: Multiple Endocrine Neoplasia type I (MEN I), also known as **Wermer’s Syndrome**, is characterized by the "3 Ps": **P**arathyroid hyperplasia (most common overall manifestation), **P**ituitary adenomas, and **P**ancreatic neuroendocrine tumors (NETs). **Why Gastrinoma is correct:** Among the pancreatic neuroendocrine tumors associated with MEN I, **Gastrinoma** is the most common functional tumor. It typically presents as **Zollinger-Ellison Syndrome (ZES)**, characterized by refractory peptic ulcers and diarrhea. While non-functional tumors are technically the most frequent pancreatic lesions found on imaging/autopsy, Gastrinoma remains the most common symptomatic/functional pancreatic tumor in MEN I patients. **Analysis of Incorrect Options:** * **A. Insulinoma:** This is the second most common functional pancreatic NET in MEN I. It presents with fasting hypoglycemia (Whipple’s triad). * **C. Glucagonoma:** These are rare in MEN I. They present with the "4 Ds": Diabetes, Dermatitis (Necrolytic migratory erythema), Deep vein thrombosis, and Depression. * **D. Somatostatinoma:** These are extremely rare and typically present with a triad of diabetes mellitus, cholelithiasis, and steatorrhea. **High-Yield Clinical Pearls for NEET-PG:** * **Inheritance:** Autosomal Dominant; mutation in the *MEN1* gene (Menin protein) on Chromosome 11q13. * **Most Common Initial Manifestation:** Hyperparathyroidism (seen in >95% of patients by age 30). * **Gastrinoma Location:** In MEN I, gastrinomas are frequently multiple and often located in the **duodenum** (Gastrinoma Triangle) rather than the pancreas. * **Pituitary:** Prolactinoma is the most common pituitary tumor in MEN I.

Question 1

A 20-year-old male presents with chronic constipation, headache, and palpitations. On examination, he has Marfanoid habitus, neuromas of the tongue, medullated corneal nerve fibers, and a 2 x 2 cm nodule in the right lobe of the thyroid. This patient is a case of -

Accepted Answer

Multiple Endocrine Neoplasia (MEN) IIB

Answer

Sporadic medullary carcinoma of the thyroid

Answer

Familial medullary carcinoma of the thyroid

Answer

Multiple Endocrine Neoplasia (MEN) IIA

Question 2

Which one of the following biochemical measures would be most likely to be elevated in this patient?

Accepted Answer

Alkaline phosphatase

Answer

Calcium

Answer

Ferritin

Answer

Phosphorus

Question 3

Which of the following is NOT a cardiovascular finding in an elderly patient with thyrotoxicosis?

Accepted Answer

Early diastolic murmur

Answer

Systolic ejection murmur

Answer

Scratch in the left 2nd intercostal space

Answer

Irregularly irregular pulse

Question 4

Gynecomastia is not associated with which of the following?

Accepted Answer

A person with (45, XO) karyotype

Answer

Use of Anabolic steroids

Answer

Alcoholic cirrhosis

Answer

Antiretroviral therapy

Question 5

What is the best initial advice to be given to a patient newly diagnosed with type 2 Diabetes Mellitus?

Accepted Answer

Engage in regular exercise.

Answer

Reduce saturated fat intake to less than 10% of total fat intake.

Answer

Maintain a consistent calorie intake.

Answer

Restrict carbohydrate intake.

Question 6

A 30-year-old nurse is evaluated for recurrent hypoglycemia. She feels shaky, anxious, and sweaty; her plasma glucose is 50 mg/dl during an attack at work. She then drinks coffee and feels better. These episodes have not happened outside the work environment. She takes no medications and is otherwise healthy. Which is the most appropriate diagnostic test in this patient?

Accepted Answer

Measurement of insulin, glucose, and C-peptide levels during a symptomatic episode

Answer

Measurement of IGF-1

Answer

Measurement of fasting insulin and glucose levels

Answer

Measurement of fasting insulin, glucose, and C-peptide levels

Question 7

A 42-year-old patient presents with obesity, glucose intolerance, hypertension, alkalosis, and proximal myopathy. Her ACTH levels did not drop after administering steroids. What is the diagnosis?

Accepted Answer

ACTH-producing tumor

Answer

Pituitary adenoma

Answer

Steroid supplementation

Answer

Adrenal tumor

Question 8

What percentage of pheochromocytomas are malignant?

Accepted Answer

10%

Answer

5%

Answer

20%

Answer

15%

Question 9

Ectopic ACTH syndrome is most commonly associated with which of the following conditions?

Accepted Answer

Bronchogenic carcinoma

Answer

Renal cell carcinoma

Answer

Lymphoma

Answer

Pituitary adenoma

Question 10

In Multiple Endocrine Neoplasia type I (MEN I), which of the following tumors is seen most commonly?

Accepted Answer

Gastrinoma

Answer

Insulinoma

Answer

Glucagonoma

Answer

Somatostatinoma

Endocrinology — MCQs

Endocrinology — MCQs

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