Endocrine Pathology — MCQs

A 40-year-old woman presents with a 2-month history of chest pain on exertion. Her medical history includes pneumonia one month prior, with Streptococcus pneumoniae identified in her sputum. On physical examination, her body mass index is 35. Initial random blood glucose was 132 mg/dL. Subsequent fasting blood glucose values were 120 mg/dL and 122 mg/dL. An oral glucose tolerance test revealed a blood glucose of 240 mg/dL two hours after a 75-g glucose load. She was prescribed an oral thiazolidinedione (TZD) drug. After two months of therapy, her fasting blood glucose decreased to 90 mg/dL. The beneficial effect of TZD in this patient is most likely related to which of the following processes?

Endocrine Pathology Indian Medical PG Practice Questions and MCQs

Question 171: Which of the following statements regarding Hashimoto's thyroiditis is FALSE?

A. It is an autoimmune thyroiditis.
B. It involves plasma cell and lymphocytic infiltration.
C. It typically leads to a hypothyroid state.
D. It results in a hypoparathyroid state. (Correct Answer)

Explanation: **Explanation** **1. Why Option D is the correct (False) statement:** Hashimoto’s thyroiditis is a localized autoimmune destruction of the **thyroid gland** [1]. It does not involve the parathyroid glands. Hypoparathyroidism typically occurs due to accidental surgical removal during thyroidectomy or autoimmune destruction in polyglandular syndromes, but it is not a feature of Hashimoto’s itself. Therefore, stating it results in a hypoparathyroid state is incorrect. **2. Why the other options are wrong (True statements):** * **Option A:** It is the most common cause of hypothyroidism in iodine-sufficient areas and is characterized by a breakdown in self-tolerance to thyroid autoantigens (anti-TPO and anti-thyroglobulin antibodies) [1, 2]. * **Option B:** Histologically, the hallmark is a dense inflammatory infiltrate consisting of **lymphocytes and plasma cells**, often forming well-developed germinal centers (lymphoid follicles) [1, 3]. * **Option C:** While there may be a transient "Hashitoxicosis" due to follicle rupture, the progressive destruction of thyroid parenchyma inevitably leads to primary **hypothyroidism** [1]. **3. High-Yield NEET-PG Pearls:** * **Hürthle Cells:** Look for "Askanazy cells"—follicular epithelial cells with abundant, granular, eosinophilic cytoplasm due to mitochondrial metaplasia [1, 3]. * **Genetics:** Strongly associated with **HLA-DR3** and **HLA-DR5**. * **Malignancy Risk:** Patients have an increased risk of developing **B-cell Non-Hodgkin Lymphoma** (specifically MALT lymphoma) and potentially papillary thyroid carcinoma [1]. * **Physical Exam:** Characterized by a painless, diffuse, "rubbery" goiter [3]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Endocrine System, pp. 1089-1090. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Liver And Biliary System Disease, pp. 426-427. [3] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Liver And Biliary System Disease, pp. 427-428.

Question 172: Which type of thyroid carcinoma is known to secrete ACTH?

A. Follicular carcinoma
B. Medullary carcinoma (Correct Answer)
C. Papillary carcinoma
D. Anaplastic carcinoma

Explanation: **Explanation:** **Medullary Thyroid Carcinoma (MTC)** is the correct answer because it originates from the **parafollicular C-cells**, which are neuroendocrine cells derived from the neural crest [1]. Unlike other thyroid cancers, MTC cells have the biochemical machinery to synthesize and secrete various peptide hormones. While **Calcitonin** is the most characteristic marker, MTC can also cause **paraneoplastic syndromes** by secreting hormones such as **ACTH** (leading to ectopic Cushing syndrome), Serotonin (leading to Carcinoid syndrome), and VIP (leading to watery diarrhea) [1],[2]. **Analysis of Incorrect Options:** * **Follicular Carcinoma (A) and Papillary Carcinoma (C):** These are "differentiated thyroid cancers" arising from follicular epithelial cells. Their primary function is related to thyroglobulin production and iodine metabolism; they do not possess neuroendocrine properties and thus do not secrete ACTH [4]. * **Anaplastic Carcinoma (D):** This is an undifferentiated, highly aggressive tumor. While it loses most specialized functions of thyroid tissue, it does not typically manifest with neuroendocrine hormone secretion like ACTH. **High-Yield Clinical Pearls for NEET-PG:** * **Amyloid Stroma:** Histologically, MTC is characterized by nests of cells in a prominent amyloid stroma (formed by pro-calcitonin) [2]. * **Genetics:** Approximately 25% of cases are familial, associated with **RET proto-oncogene** mutations (MEN 2A and 2B) [3]. * **Staining:** MTC stains positive for **Congo Red** (apple-green birefringence under polarized light) and neuroendocrine markers like **Chromogranin A** and **Synaptophysin**. * **Screening:** Serum Calcitonin levels are used for both diagnosis and monitoring recurrence. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Endocrine System, pp. 1102-1103. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Liver And Biliary System Disease, pp. 430-431. [3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Endocrine System, p. 1137. [4] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Liver And Biliary System Disease, pp. 428-429.

Question 173: Which hormone is produced by pheochromocytoma in MEN 2A (Sipple syndrome)?

A. Epinephrine (Correct Answer)
B. Norepinephrine
C. Dopamine
D. 5-Hydroxyindoleacetic acid

Explanation: **Explanation:** The correct answer is **Epinephrine (Option A)**. **Why Epinephrine is correct:** Pheochromocytomas are catecholamine-secreting tumors of the adrenal medulla. While sporadic (non-familial) pheochromocytomas predominantly secrete **norepinephrine**, those associated with **Multiple Endocrine Neoplasia type 2 (MEN 2A and 2B)** are unique. In MEN 2 syndromes, the tumors often exhibit high activity of the enzyme **Phenylethanolamine N-methyltransferase (PNMT)**, which converts norepinephrine into epinephrine. Consequently, these patients typically present with symptoms driven by epinephrine excess, such as episodic palpitations, sweating, and paroxysmal hypertension [1]. **Why the other options are incorrect:** * **B. Norepinephrine:** This is the primary hormone secreted by **sporadic** pheochromocytomas and extra-adrenal paragangliomas. In the context of MEN 2A, epinephrine is the more characteristic finding. * **C. Dopamine:** While some pheochromocytomas can secrete dopamine, it is rare and more commonly associated with malignant or extra-adrenal tumors (paragangliomas). * **D. 5-Hydroxyindoleacetic acid (5-HIAA):** This is the breakdown product of serotonin and is the diagnostic marker for **Carcinoid Syndrome**, not pheochromocytoma. **High-Yield Clinical Pearls for NEET-PG:** * **MEN 2A (Sipple Syndrome) Components:** Medullary Thyroid Carcinoma (100%), Pheochromocytoma (50%), and Parathyroid Hyperplasia (20%) [1]. * **Genetics:** Both MEN 2A and 2B are associated with germline mutations in the **RET proto-oncogene** [1]. * **Rule of 10s:** Pheochromocytoma is traditionally known as the "10% tumor" (10% bilateral, 10% malignant, 10% extra-adrenal, 10% pediatric). However, in MEN 2A, the incidence of **bilaterality** is much higher (approx. 50-80%). * **Diagnosis:** The most sensitive initial screening test is plasma free metanephrines; the most specific is 24-hour urinary metanephrines and catecholamines. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Endocrine System, pp. 1137-1139.

Question 174: Floating teeth is a clinical sign associated with which endocrine disorder?

A. Hyperparathyroidism (Correct Answer)
B. Hypoparathyroidism
C. Rickets
D. Scurvy

Explanation: ### Explanation **Correct Option: A. Hyperparathyroidism** The "floating teeth" appearance is a classic radiographic sign of **Primary Hyperparathyroidism**. This occurs due to excessive secretion of Parathyroid Hormone (PTH), which stimulates osteoclastic activity [1]. In the jaw, this leads to the **loss of the lamina dura** (the dense cortical bone lining the tooth socket) and generalized demineralization of the alveolar bone [2]. When the supporting alveolar bone is resorbed, the teeth appear to be "floating" in soft tissue on a radiograph. Additionally, focal areas of intense bone resorption can lead to **Brown tumors** (Osteitis fibrosa cystica), which further displace or loosen teeth [1]. **Why other options are incorrect:** * **B. Hypoparathyroidism:** Characterized by low PTH levels, leading to increased bone density (osteosclerosis) rather than resorption. Dental findings include enamel hypoplasia and delayed tooth eruption, but not floating teeth. * **C. Rickets:** Caused by Vitamin D deficiency in children. While it leads to delayed eruption and enamel defects, the hallmark is a failure of osteoid mineralization, not the aggressive cortical bone resorption seen in hyperparathyroidism. * **D. Scurvy:** Vitamin D deficiency leads to defective collagen synthesis. While it causes gingival bleeding and tooth mobility (due to weakened periodontal ligaments), it does not produce the specific radiographic "floating teeth" sign associated with bone loss. **High-Yield Clinical Pearls for NEET-PG:** * **Radiographic Triad of Hyperparathyroidism:** Subperiosteal resorption (most common in radial aspect of middle phalanges), loss of lamina dura, and "Salt and Pepper" appearance of the skull [2]. * **Brown Tumors:** These are not true neoplasms but masses of fibrous tissue, woven bone, and giant cells (hemosiderin gives the brown color) [1]. * **Clinical Mnemonic:** "Stones, bones, abdominal groans, and psychic overtones" [3]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Endocrine System, pp. 1105-1106. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Bones, Joints, and Soft Tissue Tumors, p. 1194. [3] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Osteoarticular And Connective Tissue Disease, pp. 667-668.

Question 175: Mitosis is a characteristic feature of which of the following conditions?

A. Follicular carcinoma
B. Anaplastic carcinoma (Correct Answer)
C. Papillary carcinoma
D. All of the above

Explanation: Explanation: In thyroid pathology, the presence of **frequent and atypical mitoses** is a hallmark of high-grade malignancy, specifically **Anaplastic Carcinoma** [1]. **1. Why Anaplastic Carcinoma is correct:** Anaplastic carcinoma is one of the most aggressive solid tumors in humans [2]. Histologically, it is characterized by extreme cytological pleomorphism, giant cells, spindle cells, and extensive areas of necrosis [1]. Because it is a high-grade, undifferentiated tumor with a very high proliferation rate, **brisk mitotic activity** (often atypical) is a defining feature required for diagnosis [1]. **2. Why other options are incorrect:** * **Follicular Carcinoma (A):** The diagnosis of follicular carcinoma depends on identifying **capsular or vascular invasion**, not mitotic count [3]. These tumors are usually well-differentiated and show very few mitoses [3]. * **Papillary Carcinoma (C):** This is the most common thyroid cancer [2]. Its diagnosis is based entirely on **nuclear features** (Orphan Annie eye nuclei, nuclear grooves, and pseudo-inclusions) [4]. Mitoses are characteristically rare or absent in conventional papillary carcinoma. **Clinical Pearls for NEET-PG:** * **Anaplastic Carcinoma:** Associated with *TP53* mutations; presents as a rapidly enlarging neck mass in elderly patients; carries a dismal prognosis [1], [2]. * **Psammoma bodies:** Highly characteristic of Papillary carcinoma (also seen in Meningioma and Serous cystadenocarcinoma of the ovary). * **Ground-glass nuclei:** Another name for Orphan Annie eye nuclei (Papillary Ca) [2]. * **PAX8-PPARG fusion:** Commonly associated with Follicular carcinoma. * **Rule of thumb:** In thyroid pathology, "Nuclear features = Papillary," "Invasion = Follicular," and "Mitosis/Necrosis = Anaplastic." **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Endocrine System, pp. 1101-1102. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Liver And Biliary System Disease, pp. 429-430. [3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Endocrine System, pp. 1096-1097. [4] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Endocrine System, pp. 1099-1100.

Question 176: Hürthle cells are seen in which of the following conditions?

A. Granulomatous thyroid disease
B. Hashimoto's thyroiditis (Correct Answer)
C. Papillary carcinoma of the thyroid
D. Thyroglossal duct cyst

Explanation: **Explanation:** **Hürthle cells** (also known as Askanazy cells or oxyphil cells) are modified follicular epithelial cells characterized by abundant, granular, eosinophilic cytoplasm. This appearance is due to the accumulation of a massive number of **altered mitochondria**. [1] 1. **Why Hashimoto’s Thyroiditis is correct:** In Hashimoto’s thyroiditis, the chronic autoimmune-mediated destruction of the thyroid gland leads to a compensatory transformation of follicular cells. The presence of Hürthle cells, alongside a dense lymphocytic infiltrate and germinal center formation, is a hallmark histological feature of this condition. [2] 2. **Why other options are incorrect:** * **Granulomatous thyroid disease (De Quervain’s):** Characterized by multinucleated giant cells and granulomas surrounding pools of colloid, not Hürthle cell metaplasia. * **Papillary carcinoma of the thyroid:** Defined by nuclear features such as "Orphan Annie eye" nuclei, Psammoma bodies, and nuclear grooves. While a "Hürthle cell variant" of follicular neoplasms exists, it is not a feature of classic papillary carcinoma. * **Thyroglossal duct cyst:** Typically lined by squamous or respiratory epithelium; it is a developmental remnant rather than an inflammatory or metaplastic process. **High-Yield Clinical Pearls for NEET-PG:** * **Hürthle Cell Metaplasia:** While most common in Hashimoto’s, it can also be seen in **Follicular Adenoma/Carcinoma** (Hürthle cell variant) and occasionally in Graves' disease after treatment. * **Mnemonic:** "Hürthle cells are **H**uge, **H**ighly eosinophilic, and have **H**eaps of mitochondria." * **Scintigraphy:** Hürthle cell tumors are typically "cold" on iodine scans but may show uptake on Sestamibi scans due to high mitochondrial content. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Liver And Biliary System Disease, pp. 427-428. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Endocrine System, pp. 1090-1091.

Question 177: Malignant potential is least with which of the following gastrointestinal neuroendocrine tumors?

A. Insulinoma (Correct Answer)
B. Glucagonoma
C. VIPoma
D. Somatostatinoma

Explanation: **Explanation:** The malignant potential of Gastrointestinal Neuroendocrine Tumors (NETs) varies significantly based on their hormone production and anatomical location. **Why Insulinoma is the correct answer:** Insulinomas are the most common functional pancreatic neuroendocrine tumors (PanNETs). The vast majority—approximately **90%**—are **benign**, solitary, and small (<2 cm) [1]. They typically present with the classic **Whipple’s triad** (symptoms of hypoglycemia, low blood glucose levels, and relief of symptoms upon glucose administration) [1]. Because such a high percentage are benign, they carry the least malignant potential among the options provided. **Why the other options are incorrect:** * **Glucagonoma:** These are frequently large at the time of diagnosis, and approximately **60-90%** are metastatic (malignant) upon presentation. * **VIPoma:** These tumors cause Verner-Morrison syndrome (WDHA: Watery Diarrhea, Hypokalemia, Achlorhydria). About **60-80%** of VIPomas are malignant at the time of discovery. * **Somatostatinoma:** These are rare tumors associated with diabetes, gallstones, and steatorrhea [3]. They have a very high rate of malignancy, with over **70-90%** showing metastasis at diagnosis. **High-Yield Clinical Pearls for NEET-PG:** * **Rule of 10s for Insulinoma:** 10% are malignant, 10% are multiple, and 10% are associated with **MEN1 syndrome** [1]. * **Most common site for NETs:** The small intestine (specifically the ileum) is the most common site for GI carcinoids [2], but among PanNETs, Insulinoma is the most common. * **Zollinger-Ellison Syndrome (Gastrinoma):** About 60-90% of gastrinomas are malignant, ranking them high in malignant potential alongside glucagonomas [1], [3]. * **Staining:** NETs characteristically stain positive for **Chromogranin A** and **Synaptophysin**. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Endocrine System, p. 1125. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Gastrointestinal Tract, pp. 780-781. [3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Gastrointestinal Tract, pp. 776-777.

Question 178: Which among the following is the most common type of thyroid cancer?

A. Papillary (Correct Answer)
B. Medullary
C. Follicular
D. Anaplastic

Explanation: ### Explanation **Correct Option: A. Papillary Thyroid Carcinoma (PTC)** Papillary carcinoma is the **most common** type of thyroid malignancy, accounting for approximately **80–85%** of all thyroid cancers [1]. It is strongly associated with exposure to ionizing radiation [1] and mutations in the **BRAF gene** (specifically V600E) or **RET/PTC rearrangements** [3]. It has an excellent prognosis and typically spreads via the **lymphatics** to cervical lymph nodes [2]. **Incorrect Options:** * **B. Medullary Thyroid Carcinoma (MTC):** This arises from the parafollicular C-cells and accounts for only about 5% of cases [2]. It is associated with **MEN 2A and 2B** syndromes and secretes **Calcitonin**. * **C. Follicular Thyroid Carcinoma (FTC):** This is the second most common type (approx. 10–15%). It is more prevalent in iodine-deficient areas and characteristically spreads **hematogenously** (to lungs and bone) [2], [4]. * **D. Anaplastic Thyroid Carcinoma:** This is a rare (<5%) but highly aggressive and undifferentiated tumor. It typically occurs in elderly patients and has a very poor prognosis [2]. **High-Yield Clinical Pearls for NEET-PG:** * **Microscopic Hallmarks of PTC:** Look for **Orphan Annie eye nuclei** (cleared-out chromatin), **Psammoma bodies** (laminated calcifications), and **Nuclear grooves/pseudoinclusions** [2], [5]. * **Diagnosis:** Fine Needle Aspiration Cytology (FNAC) is the gold standard for PTC, but it **cannot** distinguish between Follicular Adenoma and Follicular Carcinoma (which requires histological proof of capsular or vascular invasion) [4]. * **Most common site of metastasis:** Papillary = Cervical Lymph Nodes; Follicular = Bone (Osteolytic lesions) [2]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Endocrine System, pp. 1098-1099. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Liver And Biliary System Disease, pp. 429-430. [3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Endocrine System, pp. 1099-1100. [4] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Endocrine System, pp. 1100-1101. [5] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Endocrine System, p. 1099.

Question 179: What is true regarding follicular carcinoma of the thyroid?

A. Hematogenous spread is common. (Correct Answer)
B. It is commonly multifocal.
C. It is readily diagnosed by fine-needle aspiration cytology (FNAC).
D. It is the most common carcinoma of the thyroid.

Explanation: **Explanation:** **1. Why Option A is correct:** Follicular Thyroid Carcinoma (FTC) is characterized by its propensity for **hematogenous (blood-borne) spread** [1]. Unlike most epithelial malignancies that spread via lymphatics, FTC typically metastasizes through the bloodstream to distant sites, most commonly the **lungs and bones** (often presenting as osteolytic lesions). **2. Why the other options are incorrect:** * **Option B:** FTC is typically a **solitary** nodule [1]. Multifocality is a classic feature of Papillary Thyroid Carcinoma (PTC), not FTC. * **Option C:** FTC **cannot** be diagnosed by FNAC. The distinction between a benign follicular adenoma and a malignant follicular carcinoma depends entirely on identifying **capsular or vascular invasion**. FNAC only samples cells (cytology) and cannot evaluate the intactness of the capsule; therefore, histopathology is mandatory for diagnosis. * **Option D:** **Papillary Thyroid Carcinoma (PTC)** is the most common thyroid malignancy (approx. 85%) [2]. FTC is the second most common (approx. 5-15%). **High-Yield Clinical Pearls for NEET-PG:** * **Risk Factor:** FTC is more common in areas of **iodine deficiency** [2]. * **Genetics:** Associated with **RAS mutations** and the **PAX8-PPARG** fusion gene. * **Hürthle Cell Carcinoma:** A variant of FTC characterized by cells with abundant granular eosinophilic cytoplasm (due to mitochondria). * **Treatment:** Total thyroidectomy followed by Radioiodine ($I^{131}$) ablation, as FTC cells often retain the ability to take up iodine. * **Tumor Marker:** Serum **Thyroglobulin** is used to monitor for recurrence post-surgery. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Liver And Biliary System Disease, pp. 428-429. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Endocrine System, pp. 1098-1099.

Question 180: A 40-year-old woman presents with a 2-month history of chest pain on exertion. Her medical history includes pneumonia one month prior, with Streptococcus pneumoniae identified in her sputum. On physical examination, her body mass index is 35. Initial random blood glucose was 132 mg/dL. Subsequent fasting blood glucose values were 120 mg/dL and 122 mg/dL. An oral glucose tolerance test revealed a blood glucose of 240 mg/dL two hours after a 75-g glucose load. She was prescribed an oral thiazolidinedione (TZD) drug. After two months of therapy, her fasting blood glucose decreased to 90 mg/dL. The beneficial effect of TZD in this patient is most likely related to which of the following processes?

A. Activation of PPAR-gamma nuclear receptor in adipocytes (Correct Answer)
B. Decreased production of insulin autoantibodies
C. Greater density of insulin receptors in adipocytes
D. Increased half-life of circulating plasma insulin

Explanation: ### Explanation **Correct Answer: A. Activation of PPAR-gamma nuclear receptor in adipocytes** The patient’s clinical presentation (BMI of 35, fasting glucose >126 mg/dL or OGTT >200 mg/dL) confirms a diagnosis of **Type 2 Diabetes Mellitus (T2DM)** [2]. The primary pathophysiology in T2DM is insulin resistance, often exacerbated by obesity [1]. **Thiazolidinediones (TZDs)**, such as Pioglitazone and Rosiglitazone, are insulin sensitizers. They act as selective ligands for the **Peroxisome Proliferator-Activated Receptor-gamma (PPAR-γ)**, a nuclear receptor highly expressed in adipose tissue [2]. Activation of PPAR-γ leads to: 1. **Adiponectin secretion:** Increases insulin sensitivity [4]. 2. **Lipogenesis:** Promotes the storage of fatty acids in peripheral fat rather than in the liver or muscle (reducing "lipotoxicity"). 3. **GLUT-4 Expression:** Increases glucose uptake in peripheral tissues [1]. --- ### Why Other Options are Incorrect: * **B. Decreased production of insulin autoantibodies:** This describes the management of Type 1 DM (an autoimmune process) [2]. TZDs do not affect antibody production. * **C. Greater density of insulin receptors:** While TZDs improve insulin signaling, they do not significantly increase the absolute *number* or *density* of insulin receptors; they primarily enhance post-receptor signaling and glucose transporter (GLUT-4) translocation [1]. * **D. Increased half-life of circulating plasma insulin:** This is not a mechanism of TZDs. Drugs that affect insulin levels directly (like Sulfonylureas) increase secretion, while DPP-4 inhibitors increase the half-life of GLP-1, not insulin itself [3]. --- ### NEET-PG High-Yield Pearls: * **PPAR-γ vs. PPAR-α:** TZDs act on PPAR-**γ** (Glucose metabolism), whereas Fibrates act on PPAR-**α** (Lipid metabolism). * **Side Effects of TZDs:** Weight gain (due to adipogenesis), fluid retention/edema (contraindicated in NYHA Class III/IV heart failure), and increased risk of bone fractures. * **Diagnostic Criteria for DM:** Fasting Plasma Glucose ≥126 mg/dL, 2-hr OGTT ≥200 mg/dL, or HbA1c ≥6.5%. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Endocrine System, pp. 1114-1115. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Endocrine System, p. 1111. [3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Endocrine System, pp. 1111-1113. [4] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Liver and Gallbladder, pp. 851-852.

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