Endocrinology Practice Questions

Q: What is the commonest thyroid tumor in MEN (Multiple Endocrine Neoplasia)?

Medullary carcinoma. **Explanation:** The correct answer is **Medullary Thyroid Carcinoma (MTC)**. **Why it is correct:** Medullary thyroid carcinoma originates from the **parafollicular C-cells**, which are derived from the neural crest. This tumor is a defining component of **Multiple Endocrine Neoplasia (MEN) type 2A and 2B**. In these syndromes, MTC occurs due to a germline mutation in the **RET proto-oncogene**. It is often the first clinical manifestation of the syndrome, is typically multifocal, and occurs at a much younger age compared to sporadic cases. **Why the other options are incorrect:** * **A. Follicular Carcinoma:** This is a differentiated thyroid cancer derived from follicular cells. It is associated with iodine deficiency and RAS mutations but has no association with MEN syndromes. * **B. Papillary Carcinoma:** While it is the most common thyroid cancer overall in the general population, it is not linked to MEN. It is associated with radiation exposure and BRAF mutations. * **C. Anaplastic Carcinoma:** This is a highly aggressive, undifferentiated tumor seen in elderly patients. It is not a feature of the MEN spectrum. **High-Yield Clinical Pearls for NEET-PG:** * **MEN 2A (Sipple Syndrome):** MTC + Pheochromocytoma + Parathyroid Hyperplasia. * **MEN 2B (Wermer-like):** MTC + Pheochromocytoma + Mucosal Neuromas/Marfanoid habitus. * **Tumor Marker:** Calcitonin is the specific marker used for diagnosis and monitoring recurrence. * **Prophylactic Surgery:** In children with known RET mutations, a prophylactic total thyroidectomy is recommended (age depends on the specific codon mutation). * **Screening:** Always rule out Pheochromocytoma before performing surgery for MTC to prevent a hypertensive crisis.

Q: Atrial fibrillation is common in which of the following conditions?

Hyperthyroidism. **Hyperthyroidism** is the correct answer because thyroid hormones (T3 and T4) have direct and indirect stimulatory effects on the cardiovascular system [1]. Excess thyroid hormone increases the expression of beta-adrenergic receptors in the myocardium, leading to a state of hyper-adrenergic sensitivity [4]. This results in increased heart rate (tachycardia), increased stroke volume, and shortened refractory periods of the atrial cardiomyocytes. These electrophysiological changes create a substrate for reentry, making **Atrial Fibrillation (AF)** the most common sustained arrhythmia in hyperthyroid patients (occurring in 10–15% of cases) [1], [3]. **Why other options are incorrect:** * **Adrenogenital Syndrome (CAH):** This involves enzyme deficiencies (like 21-hydroxylase) leading to cortisol deficiency and androgen excess. It typically presents with virilization or salt-wasting, not tachyarrhythmias. * **Addison’s Disease:** Primary adrenal insufficiency leads to hypotension and hyperkalemia. While severe hyperkalemia can cause peaked T-waves or bradycardia, AF is not a characteristic feature. * **Von-Willebrand’s Disease:** This is a qualitative or quantitative deficiency of Von-Willebrand factor leading to a bleeding diathesis. It has no direct pathophysiological link to cardiac rhythm disturbances. **Clinical Pearls for NEET-PG:** * **Apathetic Hyperthyroidism:** In elderly patients, AF may be the *only* presenting sign of hyperthyroidism [1]. * **Subclinical Hyperthyroidism:** Even a suppressed TSH with normal T3/T4 levels is a recognized risk factor for developing AF. * **Treatment:** In thyrotoxic AF, **Beta-blockers** (e.g., Propranolol) are the first-line treatment to control heart rate and inhibit the peripheral conversion of T4 to T3 [2]. Normal sinus rhythm often restores spontaneously once the patient becomes euthyroid.

Q: Which of the following is true about MEN-I?

Hyperprolactinemia. **Explanation:** Multiple Endocrine Neoplasia Type I (MEN-I), also known as **Wermer’s Syndrome**, is an autosomal dominant disorder caused by a mutation in the *MEN1* gene (encoding the protein Menin). It is classically characterized by the **"3 Ps"**: **P**arathyroid, **P**ancreas, and **P**ituitary. **Why Hyperprolactinemia is Correct:** Pituitary adenomas occur in approximately 30–40% of MEN-I patients. Among these, **Prolactinoma** is the most common functional pituitary tumor. Therefore, elevated prolactin levels (hyperprolactinemia) are a hallmark clinical finding in these patients. **Analysis of Incorrect Options:** * **A. Increased VMA in urine:** Vanillylmandelic acid (VMA) is a metabolite of catecholamines. Increased VMA is seen in **Pheochromocytoma**, which is a feature of **MEN-2A and 2B**, not MEN-1. * **B. Increased Calcitonin:** Elevated calcitonin is a marker for **Medullary Thyroid Carcinoma (MTC)**. MTC is a defining component of **MEN-2A and 2B**. * **C. Hypergastrinemia:** While Gastrinomas (Zollinger-Ellison Syndrome) are the most common functional pancreatic neuroendocrine tumors in MEN-I, **Hyperprolactinemia** is considered a more direct "classic" answer in many competitive exams when distinguishing between the MEN syndromes, as pituitary involvement is unique to MEN-1. (Note: In some clinical contexts, both C and D could occur, but Prolactinoma remains the most frequent pituitary lesion). **NEET-PG High-Yield Pearls:** * **Most common presentation of MEN-I:** Primary Hyperparathyroidism (seen in >95% of patients). * **Most common Pancreatic tumor in MEN-I:** Gastrinoma (though non-functional tumors are also frequent). * **MEN-2A (Sipple Syndrome):** Medullary Thyroid CA + Pheochromocytoma + Parathyroid Hyperplasia. * **MEN-2B:** Medullary Thyroid CA + Pheochromocytoma + Mucosal Neuromas + Marfanoid Habitus.

Q: What is the leading cause of adrenal insufficiency?

Hypothalamic-pituitary disease. **Explanation:** The correct answer is **Hypothalamic-pituitary disease** because the question asks for the leading cause of adrenal insufficiency in general, without specifying "Primary" (Addison’s disease). 1. **Why D is correct:** Adrenal insufficiency is classified into Primary (adrenal gland failure) and Secondary/Tertiary (pituitary or hypothalamic failure) [4]. Globally, **Secondary adrenal insufficiency** (due to pituitary disease or exogenous steroid suppression) is significantly more common than primary adrenal failure [1]. Exogenous steroid use is the most frequent cause of suppressed ACTH, but among pathological lesions, hypothalamic-pituitary tumors and their treatment are the leading causes. 2. **Why the other options are incorrect:** * **A. Autoimmune adrenalitis:** This is the most common cause of **Primary** adrenal insufficiency (Addison’s disease) in **developed countries** (approx. 80% of cases) [3]. * **B. Tuberculosis:** This remains the most common cause of **Primary** adrenal insufficiency in **developing countries**, including India [2], [3]. However, it is not the leading cause of adrenal insufficiency overall. * **C. X-linked Adrenoleukodystrophy:** This is the most common **enzymatic/genetic** cause of adrenal insufficiency in young males but is rare in the general population. **NEET-PG High-Yield Pearls:** * **Most common cause of Primary AI (Global/Developed):** Autoimmune adrenalitis. * **Most common cause of Primary AI (India):** Tuberculosis. * **Most common cause of AI overall:** Exogenous steroid withdrawal (leading to secondary AI). * **Clinical Distinction:** Hyperpigmentation and hyperkalemia occur **only** in Primary AI (due to high ACTH and mineralocorticoid deficiency, respectively) [1]. These are absent in Secondary/Tertiary AI.

Q: Hyperpigmentation is seen with which of the following hormones?

ACTH. ### Explanation The correct answer is **C. ACTH**. [1] **Mechanism of Hyperpigmentation:** The primary reason ACTH causes hyperpigmentation is due to its structural similarity to **Melanocyte-Stimulating Hormone (MSH)**. Both ACTH and MSH are derived from a common precursor molecule called **Pro-opiomelanocortin (POMC)**. When ACTH levels are pathologically elevated (as seen in Addison’s disease or Nelson syndrome), the excess ACTH acts as a weak agonist on the **Melanocortin-1 receptors (MC1R)** located on melanocytes in the skin. [2] This stimulates the production of melanin, leading to the characteristic "bronzing" of the skin, particularly in sun-exposed areas, skin creases, and mucous membranes. **Analysis of Incorrect Options:** * **A & B (FSH and LH):** These are gonadotropins. While they share a common alpha-subunit with TSH and hCG, they do not share the POMC lineage and have no effect on melanocytes. [1] * **D (TSH):** Although TSH shares a common alpha-subunit with other glycoprotein hormones, it does not interact with melanocortin receptors. [1] Hyperpigmentation is not a feature of thyroid disorders unless they are part of a polyglandular autoimmune syndrome involving the adrenals. **High-Yield Clinical Pearls for NEET-PG:** * **Addison’s Disease (Primary Adrenal Insufficiency):** Characterized by **high ACTH** and **hyperpigmentation**. [2] * **Secondary Adrenal Insufficiency (Pituitary cause):** Characterized by **low ACTH** and **no hyperpigmentation** (skin appears pale). [2] * **Nelson Syndrome:** Rapid enlargement of an ACTH-secreting pituitary adenoma following bilateral adrenalectomy, leading to extreme hyperpigmentation. * **Cushing’s Disease:** May show mild hyperpigmentation, but it is much more prominent in **Ectopic ACTH syndrome** (e.g., Small Cell Lung Cancer). [3]

Q: A 40-year-old female presented with severe pain in the left forearm and left ankle following trauma. She reported difficulty walking and swelling in her right upper leg. She also experienced ankle pain and painful ankle joint movements for approximately two years. Relevant abnormal biochemical parameters included: raised serum calcium (11.9 mg/dl), raised alkaline phosphatase (717 U/L), low inorganic phosphorus (1.3 mg/dl), and raised serum parathyroid hormone (1265 pg/l). Protein electrophoresis for M band was negative. An X-ray of the right leg is provided. What is the most likely diagnosis given the clinical presentation and biochemical findings?

Hyperparathyroidism. ***Hyperparathyroidism*** • Classic biochemical triad of **hypercalcemia (11.9 mg/dl)**, **hypophosphatemia (1.3 mg/dl)**, and **elevated PTH (1265 pg/l)** confirms primary hyperparathyroidism. • **Elevated alkaline phosphatase (717 U/L)** indicates increased bone turnover, while fractures and bone pain suggest **osteitis fibrosa cystica** with possible **brown tumors**. *Multiple Myeloma* • Would typically show **positive M band** on protein electrophoresis and **lytic bone lesions** without sclerotic borders. • Usually presents with **normocalcemia** or **suppressed PTH** due to **PTH-related protein (PTHrP)** secretion, not elevated PTH. *Paget's Disease of Bone* • Characterized by **mixed lytic and sclerotic lesions** with **cortical thickening** and **bone deformity**. • Typically shows **normal calcium**, **normal or slightly elevated phosphorus**, and **normal PTH** with isolated **alkaline phosphatase elevation**. *Osteomalacia* • Usually presents with **low or normal calcium**, **low phosphorus**, and **elevated or normal PTH** as secondary response. • **Alkaline phosphatase** is typically **mildly elevated**, not markedly raised as seen in this case with bone resorption.

Question 1

What is the commonest thyroid tumor in MEN (Multiple Endocrine Neoplasia)?

Accepted Answer

Medullary carcinoma

Answer

Follicular carcinoma

Answer

Papillary carcinoma

Answer

Anaplastic carcinoma

Question 2

Atrial fibrillation is common in which of the following conditions?

Accepted Answer

Hyperthyroidism

Answer

Adrenogenital syndrome

Answer

Addison's disease

Answer

Von-Willebrand's disease

Question 3

Which of the following is true about MEN-I?

Accepted Answer

Hyperprolactinemia

Answer

Increased VMA in urine

Answer

Increased Calcitonin

Answer

Hypergastrinemia

Question 4

A 28-year-old lady has gained 10 kg over 3 years and has oligomenorrhea followed by amenorrhea for 8 months. Her blood pressure is 160/100 mm Hg. Which of the following is the most appropriate investigation?

Accepted Answer

T3, T4, and TSH

Answer

Serum electrolytes

Answer

Plasma cortisol

Answer

Plasma testosterone and ultrasound evaluation of pelvis

Question 5

A young hypertensive patient has serum K+ 2.8 meq/L and elevated plasma aldosterone level with suppressed plasma renin activity. What is the likely cause?

Accepted Answer

Conn's syndrome

Answer

Renal artery stenosis

Answer

Ectopic ACTH syndrome

Answer

Diuretic therapy

Question 6

What is the leading cause of adrenal insufficiency?

Accepted Answer

Hypothalamic-pituitary disease

Answer

Autoimmune adrenalitis

Answer

Tuberculosis of the adrenals

Answer

X-linked Adrenoleukodystrophy

Question 7

A 52-year-old woman, diagnosed with osteoporosis via dual-energy x-ray absorptiometry of the hip, presents for management of bone loss prevention. She experienced menopause at age 50 and did not initiate hormone replacement therapy due to a family history of breast cancer. She is concerned about future hip fracture. Which of the following pharmaceutical agents is most appropriate for this patient?

Accepted Answer

Raloxifene

Answer

Calcitonin nasal spray

Answer

Oral conjugated estrogen

Answer

Tamoxifen

Question 8

Which of the following statements is true regarding thyroglobulin?

Accepted Answer

Elevation after complete therapy suggests recurrence in well-differentiated thyroid malignancies.

Answer

It is a specific marker for anaplastic carcinoma.

Answer

Preoperative elevation always suggests thyroidal disease.

Answer

Intraoperative estimation from thyroid veins is very useful for prognosis.

Question 9

Hyperpigmentation is seen with which of the following hormones?

Accepted Answer

ACTH

Answer

FSH

Answer

LH

Answer

TSH

Question 10

A 40-year-old female presented with severe pain in the left forearm and left ankle following trauma. She reported difficulty walking and swelling in her right upper leg. She also experienced ankle pain and painful ankle joint movements for approximately two years. Relevant abnormal biochemical parameters included: raised serum calcium (11.9 mg/dl), raised alkaline phosphatase (717 U/L), low inorganic phosphorus (1.3 mg/dl), and raised serum parathyroid hormone (1265 pg/l). Protein electrophoresis for M band was negative. An X-ray of the right leg is provided. What is the most likely diagnosis given the clinical presentation and biochemical findings?

Accepted Answer

Hyperparathyroidism

Answer

Multiple Myeloma

Answer

Paget's Disease of Bone

Answer

Osteomalacia

Endocrinology — MCQs

Endocrinology — MCQs

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