Endocrinology — MCQs

A 42-year-old woman presents with complaints of dry skin, fatigue, and weight gain over the past 3 months. She has no significant past medical history and is not on any medications. Physical examination reveals a blood pressure of 110/70 mm Hg, pulse of 52/min, and normal heart and lung sounds. Her skin feels rough and dry. Her biochemistry is normal, but the thyroid-stimulating hormone (TSH) level is 39 mU/L (normal range: 0.5-5 mU/L). What is the most likely cause for her elevated TSH?

Q996Easy

Which of the following conditions are associated with osteoporosis?

Q997Medium

Which of the following conditions does NOT cause granulomatous hypercalcemia?

Q998Easy

Following hypophysectomy, why is vasopressin administered intramuscularly?

Q999Easy

Diagnostic criteria for diabetes include all EXCEPT?

Q1000Easy

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

Endocrinology Indian Medical PG Practice Questions and MCQs

Question 991: Which of the following is a risk factor for developing Type 1 Diabetes mellitus?

A. Male Gender
B. Old age
C. Gestational diabetes
D. HLA DR3 (Correct Answer)

Explanation: **Explanation:** Type 1 Diabetes Mellitus (T1DM) is an autoimmune disorder characterized by the destruction of pancreatic beta cells, leading to absolute insulin deficiency [1]. The primary risk factors are genetic susceptibility and environmental triggers [2]. **Why HLA DR3 is correct:** The strongest genetic association for T1DM lies within the **Major Histocompatibility Complex (MHC) Class II** genes on chromosome 6 [3]. Specifically, **HLA-DR3** and **HLA-DR4** are the most significant risk alleles. Approximately 90% of children with T1DM carry one or both of these alleles. Inheriting both (DR3/DR4 heterozygosity) confers the highest risk. These HLA molecules are involved in presenting antigens to T-cells; specific polymorphisms lead to the failure of self-tolerance and the subsequent autoimmune attack on islet cells. **Why other options are incorrect:** * **Male Gender:** T1DM does not show a strong gender predilection; it affects males and females almost equally (unlike many other autoimmune diseases which are female-dominant). * **Old Age:** T1DM typically presents in childhood or adolescence (peak incidence at puberty) [3]. While "Latent Autoimmune Diabetes in Adults" (LADA) exists, old age is a primary risk factor for **Type 2 DM**, not Type 1. * **Gestational Diabetes:** This is a risk factor for the future development of **Type 2 DM** in the mother, not Type 1. **High-Yield Clinical Pearls for NEET-PG:** * **HLA Associations:** DR3 and DR4 (Increased risk); **HLA-DQB1*0602** (Protective against T1DM). * **Autoantibodies:** Anti-GAD65 (most persistent), IA-2, and Zinc Transporter 8 (ZnT8) antibodies. * **Concordance:** The monozygotic twin concordance rate for T1DM is ~30-50% (much lower than T2DM, which is >90%) [1], [3]. * **Associated Conditions:** Always screen for other autoimmune diseases like Celiac disease and Hashimoto’s thyroiditis (Polyglandular Autoimmune Syndromes) [1].

Question 992: What is the pathognomic feature of hyperparathyroidism?

A. Pathognomic feature of hyperparathyroidism
B. Loss of lamina dura
C. Brown's tumor
D. Subperiosteal resorption of phalanges (Correct Answer)

Explanation: Primary Hyperparathyroidism (PHPT) is characterized by excessive secretion of Parathyroid Hormone (PTH), which stimulates osteoclast activity, leading to generalized bone resorption (Osteitis Fibrosa Cystica) [1]. **Why Subperiosteal Resorption is the Correct Answer:** Subperiosteal bone resorption is considered the **most specific and pathognomonic** radiographic sign of hyperparathyroidism. It occurs due to PTH-induced activation of osteoclasts in the subperiosteal region. It is most classically seen on the **radial aspect of the middle phalanges** of the 2nd and 3rd fingers. When seen on an X-ray, it is virtually diagnostic of hyperparathyroidism. **Analysis of Incorrect Options:** * **Loss of Lamina Dura (Option B):** This refers to the disappearance of the cortical bone lining the tooth socket. While it is a classic early sign of hyperparathyroidism, it is **not pathognomonic** because it can also be seen in other conditions like Paget’s disease, osteomalacia, and severe osteoporosis. * **Brown’s Tumor (Option C):** These are lytic bone lesions (osteoclastomas) filled with fibrous tissue and vascularized hemorrhage. While highly characteristic of advanced PHPT, they are a late manifestation and can mimic other giant cell tumors, making them less specific than subperiosteal resorption. * **Option A:** This is a repetition of the question stem and not a clinical feature. **NEET-PG High-Yield Pearls:** * **Salt and Pepper Skull:** A classic radiographic finding in PHPT due to multiple tiny lucencies in the calvarium. * **Rugger-Jersey Spine:** Characteristic of **Secondary Hyperparathyroidism** (seen in Chronic Kidney Disease) [2]. * **Most common cause of PHPT:** Solitary Parathyroid Adenoma (~85%) [3]. * **Biochemical Triad:** Hypercalcemia, Hypophosphatemia, and elevated PTH [2].

Question 993: A 35-year-old male, a known case of MEN 1, presents to the OPD with urinary stones and increased serum calcium. What is the next investigation to be done?

A. Urinary metanephrine
B. Secretin study (Correct Answer)
C. Serum calcitonin levels
D. 72-hour prolonged fasting

Explanation: **Explanation:** The patient is a known case of **MEN 1 (Wermer Syndrome)**, which is characterized by the "3 Ps": **P**arathyroid (95% frequency), **P**ancreatic islet cell tumors, and **P**ituitary tumors. The presentation of urinary stones and hypercalcemia confirms **Primary Hyperparathyroidism** [1], the most common initial manifestation of MEN 1. Once a component of MEN 1 is identified, the clinician must screen for the other components. Among pancreatic neuroendocrine tumors (NETs) in MEN 1, **Gastrinoma (Zollinger-Ellison Syndrome)** is the most common symptomatic tumor. The **Secretin Stimulation Test** is the most sensitive and specific provocative test for diagnosing Gastrinoma. A positive result is a rise in serum gastrin >200 pg/mL above baseline. **Analysis of Incorrect Options:** * **A. Urinary metanephrine:** This is the screening test for Pheochromocytoma, which is a component of **MEN 2A and 2B**, not MEN 1. * **C. Serum calcitonin:** This is a marker for Medullary Thyroid Carcinoma (MTC), which is the hallmark of **MEN 2A and 2B**. * **D. 72-hour prolonged fasting:** This is the gold standard for diagnosing **Insulinoma**. While insulinomas occur in MEN 1, Gastrinomas are more frequent, and the Secretin study is the prioritized investigation for the most common MEN 1-associated pancreatic NET. **Clinical Pearls for NEET-PG:** * **MEN 1 Gene:** Mutation on Chromosome 11q13 (Menin protein). * **Order of appearance:** Hyperparathyroidism is usually the first clinical sign [1]. * **Gastrinoma Location:** In MEN 1, gastrinomas are often multiple and frequently located in the duodenum (Gastrinoma triangle) rather than the pancreas. * **MEN 2A:** Medullary Thyroid CA + Pheochromocytoma + Hyperparathyroidism. * **MEN 2B:** Medullary Thyroid CA + Pheochromocytoma + Mucosal Neuromas/Marfanoid habitus.

Question 994: Which of the following is NOT associated with hypothyroidism?

A. Low T3
B. High TSH
C. High Triglycerides
D. Low cholesterol (Correct Answer)

Explanation: In hypothyroidism, the metabolic rate slows down, leading to characteristic biochemical changes. [1] **Explanation of the Correct Answer:** **D. Low cholesterol** is the correct answer because hypothyroidism is actually associated with **Hypercholesterolemia** (High cholesterol). Thyroid hormones normally upregulate the expression of LDL receptors on hepatocytes. [1] In a hypothyroid state, there is a decrease in the number and activity of these receptors, leading to reduced clearance of LDL from the plasma. Consequently, total cholesterol and LDL levels rise, making hypothyroidism a secondary cause of dyslipidemia. [1] **Explanation of Incorrect Options:** * **A. Low T3:** In overt hypothyroidism, both T4 and T3 levels are typically low as the thyroid gland fails to produce sufficient hormones. (Note: T4 is the more reliable diagnostic marker as T3 may remain normal in early stages). [2] * **B. High TSH:** This is the most sensitive screening test for primary hypothyroidism. Due to the lack of negative feedback from low T4/T3, the anterior pituitary increases TSH production. [2] * **C. High Triglycerides:** Hypothyroidism leads to decreased activity of **Lipoprotein Lipase (LPL)**, the enzyme responsible for clearing triglyceride-rich lipoproteins (VLDL and chylomicrons), resulting in hypertriglyceridemia. **High-Yield Clinical Pearls for NEET-PG:** * **Most common cause:** Hashimoto’s Thyroiditis (look for anti-TPO antibodies). * **Lipid Profile:** Expect High LDL, High Total Cholesterol, and High Triglycerides. * **Hyponatremia:** Hypothyroidism can cause dilutional hyponatremia due to impaired free water excretion (increased ADH). * **Creatine Kinase (CK):** Often elevated in hypothyroidism due to increased muscle membrane permeability (hypothyroid myopathy). * **Anemia:** Most commonly Normocytic Normochromic, but can be Macrocytic (associated Pernicious Anemia).

Question 995: A 42-year-old woman presents with complaints of dry skin, fatigue, and weight gain over the past 3 months. She has no significant past medical history and is not on any medications. Physical examination reveals a blood pressure of 110/70 mm Hg, pulse of 52/min, and normal heart and lung sounds. Her skin feels rough and dry. Her biochemistry is normal, but the thyroid-stimulating hormone (TSH) level is 39 mU/L (normal range: 0.5-5 mU/L). What is the most likely cause for her elevated TSH?

A. Trauma
B. Radioactive iodine ingestion
C. Autoimmune hypothyroidism (Correct Answer)
D. Parathyroid surgery

Explanation: ### Explanation **Correct Answer: C. Autoimmune hypothyroidism** The patient presents with classic clinical features of **hypothyroidism**: bradycardia (pulse 52/min), dry skin, fatigue, and weight gain [1]. The biochemical hallmark is a significantly elevated **TSH (39 mU/L)**, indicating primary thyroid failure [2]. In an adult female with no prior history of surgery or radiation, the most common cause of primary hypothyroidism worldwide (in iodine-sufficient areas) is **Hashimoto’s Thyroiditis** (Chronic Autoimmune Thyroiditis). This condition involves the autoimmune destruction of the thyroid gland, mediated by antithyroid peroxidase (anti-TPO) and antithyroglobulin (anti-Tg) antibodies. **Analysis of Incorrect Options:** * **A. Trauma:** Physical trauma to the neck is an extremely rare cause of hypothyroidism and would typically present with acute pain or hematoma rather than an insidious 3-month progression. * **B. Radioactive iodine ingestion:** While I-131 therapy is a common cause of hypothyroidism, the clinical vignette specifies the patient has **no significant past medical history** and is not on medications, ruling out prior treatment for hyperthyroidism. * **D. Parathyroid surgery:** While thyroid damage can occur during neck surgery, parathyroidectomy usually risks hypocalcemia (due to accidental removal of remaining parathyroid tissue) rather than overt hypothyroidism, unless a total thyroidectomy was also performed. **Clinical Pearls for NEET-PG:** * **Most common cause of hypothyroidism:** Hashimoto’s Thyroiditis (Iodine-sufficient areas); Iodine deficiency (Worldwide). * **Early sign:** The earliest biochemical abnormality in primary hypothyroidism is an **elevated TSH** (even before T4 falls below normal—known as Subclinical Hypothyroidism) [2]. * **Associated markers:** Anti-TPO antibodies are present in >90% of Hashimoto’s patients. * **Wolff-Chaikoff Effect:** Excessive iodine intake can paradoxically inhibit thyroid hormone synthesis, leading to hypothyroidism in susceptible individuals.

Question 996: Which of the following conditions are associated with osteoporosis?

A. Cushing's syndrome
B. Anorexia nervosa
C. Acromegaly
D. All the above (Correct Answer)

Explanation: **Explanation:** Osteoporosis is a systemic skeletal disorder characterized by low bone mass and micro-architectural deterioration. It can be primary or secondary to various endocrine and systemic conditions. **Why "All the above" is correct:** * **Cushing’s Syndrome:** Glucocorticoid excess is a leading cause of secondary osteoporosis. It acts through multiple mechanisms: decreasing osteoblast activity (bone formation), increasing osteoclast activity (bone resorption), and inhibiting intestinal calcium absorption. * **Anorexia Nervosa:** This condition leads to osteoporosis via a "triple hit": severe malnutrition (low Vitamin D and Calcium), excessive physical activity, and most importantly, **functional hypothalamic amenorrhea**. The resulting estrogen deficiency leads to rapid bone loss, similar to menopause. * **Acromegaly:** While Growth Hormone (GH) stimulates bone turnover, chronic excess leads to an imbalance where bone resorption often exceeds formation. Additionally, associated complications like hypogonadism (due to pituitary stalk compression) and hypercalciuria contribute significantly to decreased bone mineral density. **Clinical Pearls for NEET-PG:** 1. **Most common endocrine cause:** Hyperthyroidism and Hyperparathyroidism are also major triggers for secondary osteoporosis. 2. **Drug-induced:** Aside from steroids, long-term use of Heparin, Phenytoin (Anticonvulsants), and Proton Pump Inhibitors (PPIs) are high-yield causes of bone loss. 3. **Gold Standard Diagnosis:** Dual-energy X-ray absorptiometry (DEXA) scan. A **T-score of ≤ -2.5** defines osteoporosis. 4. **First-line Treatment:** Bisphosphonates (e.g., Alendronate) are generally the first-line pharmacological choice, provided there are no contraindications like achalasia or CKD.

Question 997: Which of the following conditions does NOT cause granulomatous hypercalcemia?

A. Tuberculosis
B. Sarcoidosis
C. Berylliosis
D. Systemic lupus erythematosus (Correct Answer)

Explanation: The underlying mechanism of **granulomatous hypercalcemia** is the autonomous, extra-renal production of **1,25-dihydroxyvitamin D (Calcitriol)**. In granulomatous diseases, activated macrophages within the granuloma express the enzyme **1-alpha-hydroxylase**. Unlike the renal enzyme, this macrophage-derived enzyme is not inhibited by high levels of calcitriol or low PTH, leading to unregulated intestinal calcium absorption and hypercalcemia. * **Systemic Lupus Erythematosus (SLE) (Correct Answer):** SLE is a systemic autoimmune connective tissue disorder characterized by immune complex deposition and autoantibody production [2]. It is **not** a granulomatous disease. While SLE can rarely be associated with hypercalcemia (usually due to co-existing hyperparathyroidism or malignancy), it does not cause hypercalcemia via the 1-alpha-hydroxylase mechanism [2], [3]. * **Sarcoidosis:** The classic prototype of granulomatous hypercalcemia. Up to 10% of patients develop hypercalcemia due to high calcitriol levels produced by sarcoid granulomas [1]. * **Tuberculosis:** A common infectious cause of granulomatous hypercalcemia. Chronic inflammation and macrophage activation in TB lead to increased 1-alpha-hydroxylase activity. * **Berylliosis:** A chronic occupational lung disease caused by beryllium exposure, which histologically presents with non-caseating granulomas identical to sarcoidosis, leading to similar vitamin D-mediated hypercalcemia. **High-Yield Clinical Pearls for NEET-PG:** * **PTH Levels:** In granulomatous hypercalcemia, PTH is typically **suppressed** (low), while 1,25(OH)₂D is **elevated**. * **Treatment:** Glucocorticoids are the first-line treatment as they inhibit the 1-alpha-hydroxylase enzyme in macrophages. * **Other Causes:** Other granulomatous causes include Leprosy, Histoplasmosis, Coccidioidomycosis, and Cat-scratch disease. Certain lymphomas (Hodgkin’s) can also utilize this mechanism.

Question 998: Following hypophysectomy, why is vasopressin administered intramuscularly?

A. To manage growth failure
B. To prevent syndrome of inappropriate antidiuretic hormone (SIADH)
C. To decrease cerebral edema and lower intracranial pressure
D. To replace antidiuretic hormone (ADH) that is normally secreted by the pituitary (Correct Answer)

Explanation: ### Explanation **Concept Overview:** The posterior pituitary gland (neurohypophysis) stores and releases **Antidiuretic Hormone (ADH)**, also known as vasopressin, which is synthesized in the hypothalamus. A **hypophysectomy** (surgical removal of the pituitary gland) results in the immediate loss of this storage and release mechanism [1]. **Why Option D is Correct:** Without the pituitary gland, the body cannot release ADH to regulate water reabsorption in the collecting ducts of the kidney [4]. This leads to **Central Diabetes Insipidus (DI)**, characterized by polyuria and polydipsia [1]. Exogenous vasopressin is administered intramuscularly (or via other routes like intranasal desmopressin) as **hormone replacement therapy** to maintain fluid balance and prevent dehydration [4]. **Analysis of Incorrect Options:** * **Option A:** Growth failure is managed by replacing **Growth Hormone (GH)**, which is an anterior pituitary hormone [1]. While GH is lost after hypophysectomy, vasopressin specifically targets water balance, not linear growth. * **Option B:** SIADH is a state of *excess* ADH. Hypophysectomy causes a *deficiency* of ADH. Administering vasopressin would worsen SIADH, not prevent it. * **Option C:** While steroids (like Dexamethasone) or osmotic diuretics (like Mannitol) are used to manage cerebral edema post-neurosurgery, vasopressin is not used for this purpose; in fact, its water-retaining effect could theoretically worsen edema if not monitored. **NEET-PG High-Yield Pearls:** * **Triphasic Response:** Post-pituitary surgery, patients may exhibit a triphasic pattern: 1. Initial DI (axonal shock), 2. Transient SIADH (leakage of stored ADH), 3. Permanent DI (destruction of hypothalamic neurons). * **Drug of Choice:** For chronic management of Central DI, **Desmopressin (dDAVP)** is preferred over vasopressin due to its longer half-life and minimal V1 (vasoconstrictor) activity [3]. * **Anatomy:** Remember that ADH is produced in the **supraoptic and paraventricular nuclei** of the hypothalamus, not the pituitary itself [1]. DI only becomes permanent if the hypothalamic nuclei or the upper pituitary stalk are damaged [2].

Question 999: Diagnostic criteria for diabetes include all EXCEPT?

A. A fasting plasma glucose >= 126 mg/dL
B. A random plasma glucose >= 200 mg/dL (in a patient with classic hyperglycemic signs)
C. 2-hour plasma glucose >= 200 mg/dL during an oral glucose tolerance test (OGTT) with a loading dose of 75 gm
D. A glycated hemoglobin (HbA1C) level >= 5.5% (Correct Answer)

Explanation: The diagnostic criteria for Diabetes Mellitus are standardized by the American Diabetes Association (ADA) and are frequently tested in NEET-PG. [1] **Explanation of the Correct Answer:** **Option D** is the correct answer because an **HbA1C level ≥ 6.5%** is the established threshold for diagnosing diabetes, not 5.5%. A level of 5.7% to 6.4% is categorized as **Prediabetes**, while a level below 5.7% is considered normal. HbA1C reflects the average blood glucose over the preceding 2–3 months (the lifespan of an RBC). **Analysis of Incorrect Options:** * **Option A:** A **Fasting Plasma Glucose (FPG) ≥ 126 mg/dL** (7.0 mmol/L) is a standard diagnostic criterion [1]. "Fasting" is defined as no caloric intake for at least 8 hours. * **Option B:** A **Random Plasma Glucose ≥ 200 mg/dL** (11.1 mmol/L) is diagnostic *only* if the patient presents with classic symptoms of hyperglycemia (polyuria, polydipsia, unexplained weight loss) or a hyperglycemic crisis [1]. * **Option C:** A **2-hour Plasma Glucose ≥ 200 mg/dL** during a 75g Oral Glucose Tolerance Test (OGTT) is a definitive diagnostic criterion. **High-Yield Clinical Pearls for NEET-PG:** 1. **Repeat Testing:** Unless there is clear clinical diagnosis (symptomatic hyperglycemia), a second abnormal test result (either from the same sample or a different sample) is required for confirmation. 2. **Prediabetes Ranges:** FPG (100–125 mg/dL), 2-hr OGTT (140–199 mg/dL), and HbA1C (5.7–6.4%). 3. **HbA1C Limitations:** It may be inaccurate in conditions with high RBC turnover (e.g., pregnancy, hemolytic anemia, recent blood loss, or certain hemoglobinopathies). In these cases, plasma glucose criteria must be used.

Question 1000: Medullary thyroid carcinoma is associated with which of the following syndromes?

A. Multiple Endocrine Neoplasia type I (MEN I)
B. Multiple Endocrine Neoplasia type II (MEN II) (Correct Answer)
C. Multiple Endocrine Neoplasia type IV (MEN IV)
D. All of the above

Explanation: 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.

Practice by Chapter

Diabetes Mellitus

Practice Questions

Thyroid Disorders

Practice Questions

Adrenal Gland Disorders

Practice Questions

Pituitary Disorders

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Calcium and Bone Metabolism

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Reproductive Endocrinology

Practice Questions

Lipid Disorders

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Endocrine Hypertension

Practice Questions

Multiple Endocrine Neoplasia

Practice Questions

Obesity and Metabolic Syndrome

Practice Questions

Neuroendocrine Tumors

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Endocrine Emergencies

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