Endocrine Surgery Practice Questions

Q: Which of the following is FALSE regarding medullary carcinoma of the thyroid?

It is familial in 90% of cases.. **Explanation:** Medullary Thyroid Carcinoma (MTC) is a unique neuroendocrine tumor. The correct answer is **D** because the statement is factually reversed: **75–80% of MTC cases are sporadic**, while only **20–25% are familial** (associated with MEN 2A, MEN 2B, or Familial MTC). * **Option A (Incorrect):** Calcitonin is the primary tumor marker for MTC. It is used for diagnosis, screening of family members, and monitoring recurrence. Carcinoembryonic antigen (CEA) is also used as a secondary marker. * **Option B (Incorrect):** MTC arises from the **Parafollicular C-cells**, which are derived from the **ultimobranchial body** (neural crest origin). Unlike papillary or follicular cancers, MTC does not arise from follicular cells and thus does not concentrate iodine. * **Option C (Incorrect):** The **RET proto-oncogene** mutation is the hallmark of MTC. It is present in nearly 100% of familial cases (germline mutation) and approximately 50% of sporadic cases (somatic mutation). **High-Yield Clinical Pearls for NEET-PG:** * **Amyloid Stroma:** Histology typically shows nests of cells with "apple-green birefringence" on Congo Red staining due to procalcitonin deposition. * **Management:** The treatment of choice is **Total Thyroidectomy with Central Compartment Neck Dissection**. * **Screening:** In patients with known RET mutations, prophylactic thyroidectomy is recommended (at age 5 for MEN 2A and infancy for MEN 2B). * **Rule out Pheochromocytoma:** Always screen for pheochromocytoma before surgery in familial cases to prevent a hypertensive crisis during anesthesia.

Q: A male patient in a euthyroid state presents with which of the following conditions?

Multiple nodular goiter. ### Explanation **1. Why Multiple Nodular Goiter (MNG) is the Correct Answer:** In the context of standard surgical presentations, **Multinodular Goiter (MNG)** is the classic example of a thyroid swelling where the patient typically remains in a **euthyroid state**. The pathophysiology involves cycles of hyperplasia and involution due to fluctuating TSH levels or iodine deficiency, leading to thyroid enlargement without necessarily causing functional overactivity. While some MNGs can become toxic (Plummer’s disease), the vast majority encountered in clinical practice and exams are "non-toxic" or euthyroid. **2. Analysis of Incorrect Options:** * **Thyroglossal Cyst (Option A):** While patients are usually euthyroid, this is a **developmental anomaly** (persistent thyroglossal duct) rather than a primary thyroid gland pathology. It is often midline and moves with protrusion of the tongue. * **Solitary Thyroid Nodule (Option C):** A solitary nodule can be euthyroid, but it carries a higher risk of **malignancy** (approx. 5-15%) or may be a "hot" toxic nodule. MNG is a more definitive clinical representation of a benign euthyroid enlargement. * **Toxic Nodular Goiter (Option D):** By definition, "toxic" implies **hyperthyroidism**. These patients present with suppressed TSH and elevated T3/T4 levels, manifesting clinical symptoms like tachycardia and tremors. **3. Clinical Pearls for NEET-PG:** * **Most common cause of goiter worldwide:** Iodine deficiency. * **Pemberton’s Sign:** Used to detect retrosternal extension in MNG; look for facial flushing and inspiratory stridor upon raising both arms. * **Investigation of Choice:** FNAC is the gold standard for evaluating nodules within an MNG to rule out malignancy (Dominant nodule). * **Treatment:** For euthyroid MNG, surgery (Total Thyroidectomy) is indicated only if there are pressure symptoms, retrosternal extension, or cosmetic concerns.

Q: What serum marker is used after surgery for differentiated thyroid cancer?

Thyroglobulin. **Explanation:** **Thyroglobulin (Tg)** is the correct answer because it serves as a highly specific tumor marker for **Differentiated Thyroid Cancer (DTC)**, which includes Papillary and Follicular carcinomas. 1. **Why Thyroglobulin?** Tg is a glycoprotein produced exclusively by follicular cells of the thyroid. After a total thyroidectomy and radioactive iodine (RAI) ablation, there should be no remaining thyroid tissue. Therefore, any detectable serum Tg during follow-up indicates persistent or recurrent disease. It is often measured alongside **Anti-thyroglobulin antibodies (anti-TgAb)**, as their presence can falsely lower Tg readings. 2. **Why the others are incorrect:** * **T4 (Thyroxine):** This is a hormone used for replacement therapy post-surgery, not a marker for recurrence. * **Calcitonin:** This is the specific tumor marker for **Medullary Thyroid Cancer (MTC)**, which arises from parafollicular C-cells, not DTC. * **PTH (Parathyroid Hormone):** This is monitored post-thyroidectomy to check for accidental damage or removal of the parathyroid glands (hypoparathyroidism), but it is not a cancer marker. **High-Yield Clinical Pearls for NEET-PG:** * **Stimulated Tg:** Tg levels are most sensitive when TSH is high (either by stopping T4 or giving recombinant TSH). * **Mnemonic:** **M**edullary = **M**arker is Calcitonin; **D**ifferentiated = **D**etected by Thyroglobulin. * **Hurthle Cell Carcinoma:** Also uses Thyroglobulin as a marker. * **Anaplastic Carcinoma:** Does not have a reliable serum marker as the cells are too undifferentiated to produce Tg.

Q: True regarding Papillary carcinoma of thyroid is:

Excellent prognosis. **Explanation:** **Papillary Thyroid Carcinoma (PTC)** is the most common type of thyroid malignancy (80–85%). The correct answer is **Excellent prognosis** because PTC is a slow-growing, well-differentiated tumor with a 10-year survival rate exceeding 90–95%. **Analysis of Options:** * **A. Undifferentiated carcinoma:** Incorrect. PTC is a **well-differentiated** carcinoma. Anaplastic carcinoma is the undifferentiated type, which is highly aggressive. * **B. Blood-borne metastasis is commoner:** Incorrect. PTC characteristically spreads via the **lymphatics** to regional cervical lymph nodes. Hematogenous (blood-borne) spread is rare in PTC but is the hallmark of Follicular Thyroid Carcinoma. * **D. Capsulated:** Incorrect. PTC is typically **unencapsulated** and often shows multifocality. Follicular carcinoma and Follicular adenomas are the ones characterized by a distinct capsule. **High-Yield Clinical Pearls for NEET-PG:** * **Risk Factor:** Prior exposure to ionizing radiation is the most significant risk factor. * **Microscopic Hallmarks:** * **Orphan Annie Eye nuclei:** Large, pale, empty-appearing nuclei. * **Psammoma bodies:** Laminated calcifications (found in ~50% of cases). * **Nuclear grooves and Pseudo-inclusions.** * **Diagnosis:** Fine Needle Aspiration Cytology (FNAC) is the investigation of choice. Note: FNAC can diagnose PTC but *cannot* distinguish between follicular adenoma and carcinoma. * **Variant:** The **Tall Cell variant** is a more aggressive subtype of PTC.

Q: Hypocalcemia in the immediate postoperative period following excision of a parathyroid adenoma is due to which of the following?

Increased uptake by bones. **Explanation:** The correct answer is **Increased uptake by bones**, a clinical phenomenon known as **Hungry Bone Syndrome (HBS)**. In patients with primary hyperparathyroidism, chronically high levels of Parathyroid Hormone (PTH) lead to high bone turnover and significant demineralization. Once the parathyroid adenoma is excised, PTH levels drop precipitously. This sudden withdrawal of PTH stops osteoclastic bone resorption, while osteoblastic activity continues or increases. Consequently, the "hungry" bones rapidly sequester calcium, magnesium, and phosphate from the plasma to remineralize the bone matrix, leading to profound postoperative hypocalcemia. **Analysis of Incorrect Options:** * **A. Stress response:** While surgery triggers a metabolic stress response (releasing cortisol and catecholamines), this typically causes hyperglycemia or leukocytosis, not acute hypocalcemia. * **C. Persistent hypercalcemia:** This would occur if the surgery failed (e.g., an ectopic adenoma was missed), which is the opposite of the scenario described. * **D. Increased calcitonin secretion:** Calcitonin is secreted by the parafollicular C-cells of the thyroid. While it lowers calcium, its role in post-parathyroidectomy hypocalcemia is negligible compared to the massive shift of calcium into the bones. **Clinical Pearls for NEET-PG:** * **Risk Factors for HBS:** Large adenomas, very high preoperative PTH/alkaline phosphatase levels, and radiological evidence of bone disease (e.g., Osteitis fibrosa cystica). * **Biochemical Profile of HBS:** Hypocalcemia, **hypophosphatemia**, and often hypomagnesemia. * **Management:** Treatment involves aggressive supplementation with intravenous/oral calcium and Vitamin D (Calcitriol). * **Differential:** Always rule out accidental injury to the remaining normal parathyroid glands (permanent hypoparathyroidism), though HBS is the classic "immediate" cause in bone-involved cases.

Q: A patient after thyroid surgery presents with perioral paresthesia and a serum calcium level of 7 mg/dL. What is the most appropriate initial management?

Oral calcium supplement. ### Explanation **Correct Answer: D. Oral calcium supplement** **1. Why it is correct:** Post-thyroidectomy hypocalcemia occurs due to transient or permanent hypoparathyroidism (injury or devascularization of the parathyroid glands). This patient presents with **mild/asymptomatic hypocalcemia** (Calcium 7 mg/dL; normal: 8.5–10.5 mg/dL) and **mild symptoms** (perioral paresthesia). According to standard surgical protocols, patients who are hemodynamically stable and exhibiting only mild symptoms (paresthesia without tetany or ECG changes) should be managed initially with **oral calcium supplements** (usually 1–2g of elemental calcium three times daily). **2. Why other options are incorrect:** * **A & B (Vitamin D3):** While Vitamin D (Calcitriol) is often added to enhance calcium absorption, it is an adjunct. The immediate requirement is to replace the deficient calcium itself. Vitamin D alone will not correct the acute deficit quickly enough. * **C (Intravenous calcium gluconate):** IV calcium is reserved for **emergency/symptomatic management** of severe hypocalcemia (e.g., carpopedal spasm, tetany, seizures, or prolonged QTc interval on ECG). Giving IV calcium for mild symptoms increases the risk of cardiac arrhythmias and thrombophlebitis unnecessarily. **3. NEET-PG High-Yield Pearls:** * **Most common complication** of total thyroidectomy: Hypocalcemia (Transient in 20%, Permanent in <1%). * **Chvostek’s sign:** Tapping the facial nerve leads to twitching of facial muscles. * **Trousseau’s sign:** Carpal spasm induced by inflating a BP cuff above systolic pressure for 3 minutes (more sensitive than Chvostek’s). * **ECG finding:** Prolonged QT interval. * **Management Rule:** If Ca <7.5 mg/dL or symptomatic → Start Oral Calcium. If tetany/seizures occur → 10ml of 10% Calcium Gluconate IV over 10 minutes.

Question 1

In which type of thyroid carcinoma is treatment with radioactive iodine (1-131) most beneficial?

Accepted Answer

Follicular carcinoma

Answer

Papillary carcinoma

Answer

Anaplastic carcinoma

Answer

Medullary carcinoma

Question 2

What is true regarding incidental adrenal masses?

Accepted Answer

May represent adrenocortical carcinoma if greater than 6 cm in diameter.

Answer

May be seen in as many as 10% of abdominal CT studies.

Answer

Most commonly represent pheochromocytoma; adrenocortical adenoma, adrenocortical carcinoma, and metastases from other primary cancers occur less frequently.

Answer

Should be routinely evaluated by measurement of 24-hour urine levels of catecholamines and their metabolites, cortisol, and aldosterone plus fine-needle aspiration.

Question 3

Which of the following is FALSE regarding medullary carcinoma of the thyroid?

Accepted Answer

It is familial in 90% of cases.

Answer

The tumor marker is calcitonin.

Answer

It arises from parafollicular cells.

Answer

It is associated with RET mutations.

Question 4

A male patient in a euthyroid state presents with which of the following conditions?

Accepted Answer

Multiple nodular goiter

Answer

Thyroglossal cyst

Answer

Solitary thyroid nodule

Answer

Toxic nodular goiter

Question 5

Which of the following is NOT true about pheochromocytoma?

Accepted Answer

Urinary vanillylmandelic acid (VMA) is the most specific test.

Answer

Paraganglioma can occur at the skull base.

Answer

10% of pheochromocytomas are extra-adrenal.

Answer

The organ of Zuckerkandl is the most common extra-adrenal site.

Question 6

What serum marker is used after surgery for differentiated thyroid cancer?

Accepted Answer

Thyroglobulin

Answer

T4

Answer

Calcitonin

Answer

PTH

Question 7

True regarding Papillary carcinoma of thyroid is:

Accepted Answer

Excellent prognosis

Answer

Undifferentiated carcinoma

Answer

Blood-borne metastasis is commoner

Answer

Capsulated

Question 8

Which is the best investigation for metastatic gastrinoma?

Accepted Answer

Octreoscan

Answer

Selective arterial secretin injection

Answer

Basal acid output/Maximal acid output ratio

Answer

Ultrasound

Question 9

Hypocalcemia in the immediate postoperative period following excision of a parathyroid adenoma is due to which of the following?

Accepted Answer

Increased uptake by bones

Answer

Stress response

Answer

Persistent hypercalcemia

Answer

Increased calcitonin secretion

Question 10

A patient after thyroid surgery presents with perioral paresthesia and a serum calcium level of 7 mg/dL. What is the most appropriate initial management?

Accepted Answer

Oral calcium supplement

Answer

Oral vitamin D3

Answer

Oral vitamin D3 with calcium

Answer

Intravenous calcium gluconate

Endocrine Surgery — MCQs

Endocrine Surgery — MCQs

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