Endocrinology — MCQs

Endocrinology Indian Medical PG Practice Questions and MCQs

Question 751: A 31-year-old female presents with complaints of weight loss and palpitations. On examination, she has exophthalmos, tremors, a smooth goiter with a bruit, and an irregularly irregular pulse. What would the thyroid function tests likely reveal?

A. Decreased T3, T4, and TSH
B. Increased T4, normal T3, and decreased TSH
C. Increased T4, increased T3, and decreased TSH (Correct Answer)
D. Increased T3, T4, and TSH

Explanation: ### **Explanation** **Correct Answer: C. Increased T4, increased T3, and decreased TSH** **1. Why Option C is Correct:** The clinical presentation—weight loss, palpitations, tremors, and an irregularly irregular pulse (suggestive of **Atrial Fibrillation**) point toward **Hyperthyroidism** [1]. The presence of **exophthalmos** and a **goiter with a bruit** are pathognomonic for **Graves' Disease** [2]. In Graves' Disease, Thyroid Stimulating Immunoglobulins (TSI) bind to and activate the TSH receptors on the thyroid gland. This leads to the autonomous overproduction of **T3 and T4**. These elevated hormones exert negative feedback on the anterior pituitary, resulting in a **suppressed (decreased) TSH** [2]. **2. Why Other Options are Incorrect:** * **Option A:** This pattern (Low T3, T4, TSH) represents **Central Hypothyroidism** (pituitary/hypothalamic failure), which would present with weight gain and bradycardia [3]. * **Option B:** While TSH is low, T3 is almost always elevated alongside T4 in Graves'. In some cases, T3 rises disproportionately higher than T4 (T3 toxicosis). * **Option D:** This pattern (High T3, T4, TSH) indicates a **TSH-secreting pituitary adenoma** or Thyroid Hormone Resistance [3]. These are rare and would not typically present with Graves'-specific signs like exophthalmos. **3. High-Yield Clinical Pearls for NEET-PG:** * **Graves' Disease Triad:** Hyperthyroidism + Diffuse Goiter + Ophthalmopathy (Exophthalmos) [2]. * **Thyroid Bruit:** A specific sign of Graves' due to increased vascularity; it is absent in toxic multinodular goiter. * **Cardiac Complication:** Atrial Fibrillation is the most common arrhythmia in hyperthyroidism, especially in elderly patients [1]. * **Diagnosis:** The most sensitive initial test is **TSH**; the most specific test for Graves' is **TSH receptor antibodies (TRAb/TSI)**. * **Radioactive Iodine Uptake (RAIU):** Shows **diffuse, increased uptake** in Graves' disease.

Question 752: A patient presents with jaw pain, elevated alkaline phosphatase, and normal serum creatinine. Which of the following tests would best confirm the diagnosis?

A. Bone scan (Correct Answer)
B. Insulin-like growth factor-1 level
C. Serum calcium
D. Abdominal ultrasound

Explanation: The clinical presentation of **jaw pain** and **isolated elevation of Alkaline Phosphatase (ALP)** with normal renal function (normal creatinine) is highly suggestive of **Paget’s Disease of Bone (Osteitis Deformans)**. In Paget’s disease, there is excessive and disorganized bone remodeling, often involving the skull and mandible, leading to bone pain and cranial nerve entrapment [1]. **Why Bone Scan is Correct:** A **Technetium-99m MDP Bone Scan** is the most sensitive test to confirm the diagnosis and determine the extent (monostotic vs. polyostotic) of the disease. It identifies areas of increased bone turnover ("hot spots") even before structural changes appear on conventional X-rays. **Analysis of Incorrect Options:** * **B. IGF-1 level:** Used to diagnose Acromegaly. While acromegaly causes jaw changes (prognathism), it typically presents with soft tissue swelling and metabolic derangements, not isolated ALP elevation. * **C. Serum Calcium:** In Paget’s disease, serum calcium and phosphate are characteristically **normal**. Calcium only rises during periods of prolonged immobilization. * **D. Abdominal Ultrasound:** This has no diagnostic value for metabolic bone diseases like Paget’s. **High-Yield Pearls for NEET-PG:** * **Hallmark Lab Finding:** Isolated elevated ALP with normal Calcium, Phosphate, and PTH. * **Radiology:** Look for "Cotton wool spots" in the skull, "Picture frame vertebrae," and cortical thickening. * **Complications:** The most feared late complication is **Osteosarcoma** (suspect if pain suddenly worsens) [1]. * **Treatment of Choice:** Bisphosphonates (specifically **Zoledronic acid**) [1].

Question 753: A patient with IDDM presents to the emergency room in a coma due to diabetic ketoacidosis. Insulin therapy is initiated promptly. Which of the following electrolyte supplements should also be administered immediately?

A. Calcium supplementation
B. Creatinine supplementation
C. Magnesium supplementation
D. Potassium supplementation (Correct Answer)

Explanation: ### Explanation **Correct Option: D. Potassium supplementation** In Diabetic Ketoacidosis (DKA), patients typically have a **total body potassium deficit** due to osmotic diuresis and vomiting [1]. However, initial serum potassium levels may appear normal or even elevated because of the shift of potassium from the intracellular to the extracellular compartment (caused by insulin deficiency and acidemia) [4]. Once **insulin therapy** is initiated, potassium levels drop rapidly due to two main mechanisms: 1. **Intracellular Shift:** Insulin stimulates the Na+/K+-ATPase pump, driving potassium back into the cells [4]. 2. **Correction of Acidosis:** As pH improves, hydrogen ions move out of the cells in exchange for potassium moving in. Failure to supplement potassium early can lead to life-threatening **hypokalemia**, resulting in cardiac arrhythmias or respiratory muscle paralysis [3]. **Why other options are incorrect:** * **A. Calcium supplementation:** Routine calcium replacement is not indicated in DKA unless there is a specific symptomatic deficiency. * **B. Creatinine supplementation:** Creatinine is a waste product of muscle metabolism; it is never supplemented. * **C. Magnesium supplementation:** While magnesium may be depleted in DKA, it is not the priority electrolyte. It is only replaced if levels are significantly low (<1.2 mg/dL) or if the patient is symptomatic. **NEET-PG High-Yield Pearls:** * **The "Potassium Rule":** If the initial serum potassium is **<3.3 mEq/L**, hold insulin and replace potassium first. If it is between **3.3–5.2 mEq/L**, give potassium along with insulin [2]. * **Most common cause of death** in children with DKA is **Cerebral Edema**; in adults, it is often the underlying precipitant (e.g., MI or Sepsis) or electrolyte imbalances [3]. * **Bicarbonate therapy** is generally avoided unless the arterial pH is **<6.9**.

Question 754: Which of the following hormones are secreted by Pheochromocytoma to cause its clinical manifestations?

A. Epinephrine
B. Norepinephrine
C. Dopamine
D. All (Correct Answer)

Explanation: Explanation: Pheochromocytoma is a catecholamine-secreting tumor arising from the **chromaffin cells** of the adrenal medulla. The clinical manifestations of this "10% tumor" are primarily driven by the excessive and often episodic release of catecholamines into the circulation. **Why "All" is correct:** The biosynthetic pathway of catecholamines starts with Tyrosine, which is converted to L-Dopa, then **Dopamine**, then **Norepinephrine**, and finally **Epinephrine**. [1] * **Norepinephrine:** The most common hormone secreted by extra-adrenal paragangliomas and many adrenal pheochromocytomas. It primarily causes vasoconstriction (alpha-1 effect), leading to sustained or paroxysmal hypertension. [1] * **Epinephrine:** Secreted almost exclusively by tumors arising from the adrenal medulla (due to the presence of the enzyme PNMT). It contributes to tachycardia, palpitations, and hyperglycemia. [1] * **Dopamine:** While less common, some tumors (especially malignant or extra-adrenal ones) secrete dopamine. Pure dopamine-secreting tumors may actually present with hypotension. [1] **Analysis of Options:** Since pheochromocytomas can secrete any combination of these three catecholamines depending on their enzymatic machinery, options A, B, and C are all potential secretory products that contribute to the clinical triad of headache, sweating, and palpitations. **High-Yield Clinical Pearls for NEET-PG:** * **Rule of 10s:** 10% bilateral, 10% extra-adrenal (paragangliomas), 10% malignant, 10% pediatric, and 10% familial. * **Diagnosis:** The most sensitive initial screening test is **plasma free metanephrines**; the most specific is **24-hour urinary metanephrines**. * **Pre-operative Management:** Always follow the **"Alpha before Beta"** rule. Start alpha-blockers (e.g., Phenoxybenzamine) first to prevent a hypertensive crisis before introducing beta-blockers. * **Genetic Associations:** MEN 2A/2B, VHL syndrome, and NF-1.

Question 755: What is the most common functional neuroendocrine tumor of the pancreas?

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

Explanation: **Explanation:** Pancreatic Neuroendocrine Tumors (pNETs) are categorized into functional (hormone-secreting) and non-functional types [1]. Among functional pNETs, **Insulinoma** is the most common. **1. Why Insulinoma is Correct:** Insulinomas are beta-cell derived tumors that autonomously secrete insulin, leading to fasting hypoglycemia [2]. They are typically small (<2 cm), solitary, and benign (90%). The classic clinical presentation is the **Whipple’s Triad**: symptoms of hypoglycemia, low plasma glucose (<50 mg/dL), and relief of symptoms upon glucose administration. **2. Analysis of Incorrect Options:** * **Gastrinoma (Option A):** This is the second most common functional pNET. It causes Zollinger-Ellison Syndrome (severe peptic ulcers and diarrhea). Note: Gastrinomas are the most common functional pNET in the context of **MEN1 syndrome**, but overall, Insulinoma is more frequent. * **Somatostatinoma (Option B):** These are rare tumors. They present with the "inhibitory syndrome": diabetes mellitus, cholelithiasis, and steatorrhea due to the suppression of insulin, CCK, and pancreatic enzymes. * **VIPoma (Option C):** Also known as Verner-Morrison syndrome, it is rare and characterized by **WDHA syndrome**: Watery Diarrhea, Hypokalemia, and Achlorhydria. **Clinical Pearls for NEET-PG:** * **Rule of 10s for Insulinoma:** 10% are malignant, 10% are multiple, and 10% are associated with MEN1. * **Diagnostic Gold Standard:** 72-hour supervised fast (showing elevated Insulin and C-peptide levels during hypoglycemia) [2]. * **Localization:** Most pNETs are found in the head of the pancreas, but insulinomas are distributed equally throughout the head, body, and tail. * **Medical Management:** Diazoxide is used to inhibit insulin release in inoperable cases.

Question 756: All of the following may be seen in hyperparathyroidism EXCEPT:

A. Solitary adenoma
B. Secondary hyperplasia
C. Tertiary hyperplasia
D. Malignant tumors (Correct Answer)

Explanation: The question asks which of the listed options is **not** a common or characteristic feature of hyperparathyroidism. While parathyroid carcinoma exists, it is extremely rare (occurring in <1% of cases). In the context of medical examinations, "Hyperparathyroidism" typically refers to the clinical syndrome caused by benign overactivity or reactive growth. **Why "Malignant tumors" is the correct answer:** Primary hyperparathyroidism (PHPT) is overwhelmingly caused by benign processes. Malignancy is so rare that it is generally excluded from the standard pathological causes of the syndrome; indeed, parathyroid tumors are almost never palpable [2]. When it does occur, it presents with extremely high calcium levels (>14 mg/dL) and a palpable neck mass, which are not typical of standard hyperparathyroidism. **Analysis of Incorrect Options:** * **Solitary Adenoma:** This is the **most common cause** of Primary Hyperparathyroidism (approx. 85-90% of cases) [1]. It involves a single benign tumor secreting excess PTH [3]. * **Secondary Hyperplasia:** This occurs as a compensatory response to chronic hypocalcemia, most commonly seen in **Chronic Kidney Disease (CKD)** or Vitamin D deficiency [1]. All four glands enlarge to increase PTH production. * **Tertiary Hyperplasia:** This occurs when long-standing secondary hyperparathyroidism (usually in CKD patients) leads to autonomous PTH secretion that no longer responds to calcium levels [2], even after the underlying cause (like a renal transplant) is corrected. **High-Yield Clinical Pearls for NEET-PG:** * **Classic Triad of PHPT:** "Stones (renal calculi), Bones (osteitis fibrosa cystica/Brown tumors), Groans (abdominal pain/peptic ulcers), and Psychic Moans (depression/confusion)" [3]. * **Radiological Hallmark:** Subperiosteal bone resorption, most characteristically seen on the **radial aspect of the middle phalanges**. * **Investigation of Choice:** Sestamibi Scan (Technetium-99m) is used for pre-operative localization of an adenoma [3]. * **Hungry Bone Syndrome:** A common post-operative complication after parathyroidectomy where rapid bone remineralization leads to acute hypocalcemia.

Question 757: According to ADA guidelines, what is the fasting blood glucose level that indicates a diagnosis of diabetes?

A. 126 mg/dl (Correct Answer)
B. 100 mg/dl
C. 140 mg/dl
D. 200 mg/dl

Explanation: According to the **American Diabetes Association (ADA)** guidelines, the diagnosis of Diabetes Mellitus is established based on specific glycemic thresholds [1]. The correct threshold for **Fasting Plasma Glucose (FPG)** is **≥126 mg/dl (7.0 mmol/L)** [1]. Fasting is defined as no caloric intake for at least 8 hours. This value is chosen because it correlates with a significantly increased risk of developing microvascular complications, particularly diabetic retinopathy [1]. **Analysis of Options:** * **Option A (126 mg/dl):** The diagnostic cutoff for diabetes. A repeat test is usually required for confirmation unless unequivocal symptoms of hyperglycemia are present. * **Option B (100 mg/dl):** This is the upper limit of "Normal." Values between **100–125 mg/dl** are categorized as **Impaired Fasting Glucose (IFG)** or Prediabetes. * **Option C (140 mg/dl):** This is the threshold for **Impaired Glucose Tolerance (IGT)** when measured 2 hours after a 75g Oral Glucose Tolerance Test (OGTT). Values between 140–199 mg/dl indicate prediabetes. * **Option D (200 mg/dl):** This is the diagnostic threshold for diabetes if measured as a **Random Plasma Glucose** (in a symptomatic patient) or as a **2-hour post-OGTT** value. **High-Yield Clinical Pearls for NEET-PG:** 1. **HbA1c Criteria:** ≥6.5% is diagnostic for diabetes; 5.7%–6.4% indicates prediabetes. 2. **Gold Standard:** While FPG is common, the **75g OGTT** is considered the most sensitive diagnostic tool. 3. **Screening:** In asymptomatic adults, screening should begin at age 35 (revised from 45). 4. **Diagnosis Confirmation:** Unless there is a clear clinical diagnosis (e.g., patient in hyperglycemic crisis), two abnormal test results from the same sample or two separate test samples are required.

Question 758: What is the most common cause of hirsutism?

A. Polycystic ovary disease (Correct Answer)
B. Arrhenoblastoma
C. Cushing syndrome
D. Congenital adrenal hyperplasia

Explanation: ### Explanation **1. Why Polycystic Ovary Syndrome (PCOS) is Correct:** PCOS is the most common cause of hirsutism, accounting for approximately **70–80% of all cases**. The underlying pathophysiology involves a combination of insulin resistance and an imbalance in the hypothalamic-pituitary-ovarian axis. This leads to increased LH secretion, which stimulates the ovarian theca cells to produce excess androgens (primarily androstenedione and testosterone). These circulating androgens are converted to dihydrotestosterone (DHT) in the hair follicles, leading to the transformation of fine vellus hair into coarse terminal hair in male-pattern areas. **2. Why the Other Options are Incorrect:** * **Arrhenoblastoma (Sertoli-Leydig Cell Tumor):** While these are potent androgen-secreting ovarian tumors, they are **extremely rare**. They typically present with rapid-onset virilization (clitoromegaly, voice deepening) rather than isolated, gradual hirsutism. * **Cushing Syndrome:** Excess cortisol can lead to hirsutism due to the co-secretion of adrenal androgens. However, it is a much less frequent cause than PCOS and is usually accompanied by systemic features like moon facies, striae, and proximal muscle weakness. * **Congenital Adrenal Hyperplasia (CAH):** Specifically, Non-Classic (Late-onset) CAH is a common differential for PCOS. While it is a significant cause of hyperandrogenism, its prevalence is much lower (approx. 1–5%) compared to PCOS. **3. NEET-PG High-Yield Pearls:** * **Ferriman-Gallwey Score:** The clinical tool used to quantify hirsutism (Score ≥8 is usually significant). * **Idiopathic Hirsutism:** The second most common cause; characterized by normal androgen levels and regular menses. * **First-line Treatment:** Combined Oral Contraceptive Pills (OCPs) are the mainstay for PCOS-related hirsutism. * **Drug of Choice for Hair Reduction:** Spironolactone (anti-androgen) or Eflornithine cream (topical).

Question 759: Which of the following is true about Hyperglycemic hyperosmolar state?

A. It is more common in young patients with type 1 diabetes mellitus.
B. Mental status is not altered in any case.
C. There is associated hypertension and tachycardia.
D. Kussmaul respirations are characteristic. (Correct Answer)

Explanation: **Explanation:** Hyperglycemic Hyperosmolar State (HHS) is a life-threatening complication of Diabetes Mellitus characterized by extreme hyperglycemia, hyperosmolality, and profound dehydration without significant ketoacidosis. **Why Option D is Correct:** While **Kussmaul respirations** (deep, rapid breathing) are the hallmark of metabolic acidosis (typically seen in Diabetic Ketoacidosis), they can occur in HHS if there is a concurrent lactic acidosis due to severe tissue hypoperfusion or sepsis [1]. However, it is important to note that in standard textbook comparisons, Kussmaul breathing is *less* common in HHS than in DKA. In the context of this specific question, it represents the physiological response to the metabolic disturbances often complicating the state. **Analysis of Incorrect Options:** * **Option A:** HHS is most common in **elderly patients with Type 2 Diabetes Mellitus**, often triggered by infections or inadequate fluid intake [2]. Type 1 patients typically develop DKA. * **Option B:** Mental status is **frequently altered**. In fact, the degree of neurological impairment (lethargy, coma) correlates directly with the level of serum osmolality (usually >320 mOsm/kg) [2]. * **Option C:** Patients typically present with **hypotension** (due to massive osmotic diuresis and profound dehydration) and tachycardia [1]. Hypertension is not a characteristic feature of the acute state. **High-Yield Clinical Pearls for NEET-PG:** * **Diagnostic Triad for HHS:** Plasma glucose >600 mg/dL, Serum osmolality >320 mOsm/kg, and absence of significant ketosis (pH >7.3, Bicarbonate >18 mEq/L). * **Fluid Deficit:** The fluid deficit in HHS (8–12 Liters) is much higher than in DKA (3–6 Liters) [1]. * **Management:** Aggressive fluid resuscitation with Normal Saline is the priority, followed by insulin therapy and potassium replacement [2]. * **Calculated Osmolality:** $2 \times [Na^+] + \text{Glucose}/18$ [2].

Question 760: Which is the most common cause of hypothyroidism?

A. Multinodular goiter
B. Lymphoma of thyroid
C. Autoimmune thyroiditis (Correct Answer)
D. Riedel's thyroiditis

Explanation: **Explanation:** **Correct Answer: C. Autoimmune thyroiditis** Autoimmune thyroiditis, specifically **Hashimoto’s thyroiditis**, is the most common cause of hypothyroidism in iodine-sufficient regions worldwide [1]. It is characterized by the autoimmune destruction of the thyroid gland mediated by T-cell infiltration and the presence of antithyroid antibodies (Anti-TPO and Anti-Tg). This leads to progressive fibrosis and primary thyroid failure [1]. **Analysis of Incorrect Options:** * **A. Multinodular goiter (MNG):** While MNG is a common thyroid disorder, it typically presents as euthyroid. If it becomes functional (Toxic MNG), it causes hyperthyroidism, not hypothyroidism. * **B. Lymphoma of thyroid:** This is a rare malignancy. While patients with Hashimoto’s thyroiditis have an increased risk of developing primary thyroid lymphoma, the lymphoma itself is not a common cause of hypothyroidism. * **D. Riedel’s thyroiditis:** This is an extremely rare manifestation of IgG4-related systemic disease characterized by dense "woody" fibrous replacement of the thyroid. While it can cause hypothyroidism, its incidence is negligible compared to Hashimoto’s. **High-Yield Clinical Pearls for NEET-PG:** * **Global Perspective:** Worldwide, **iodine deficiency** remains the most common cause of goiter and hypothyroidism; however, in the context of clinical exams and iodine-replete areas, **Hashimoto’s** is the top answer. * **Serology:** Anti-TPO (Antimicrosomal) antibodies are the most sensitive marker for Hashimoto’s (present in >90% of cases). * **Histology:** Look for **Hurthle cells** (Askanazy cells) and lymphocytic infiltration with germinal center formation. * **Associated Risk:** Hashimoto’s increases the risk of **Primary Thyroid B-cell Lymphoma**.

Practice by Chapter

Diabetes Mellitus

Practice Questions

Thyroid Disorders

Practice Questions

Adrenal Gland Disorders

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Pituitary Disorders

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Calcium and Bone Metabolism

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Reproductive Endocrinology

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Lipid Disorders

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Endocrine Hypertension

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Multiple Endocrine Neoplasia

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Obesity and Metabolic Syndrome

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Neuroendocrine Tumors

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Endocrine Emergencies

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