Endocrinology Practice Questions

Q: A 25-year-old male reports episodic spells characterized by palpitations, sweating, nervousness, and feelings of anxiety. On examination, the man's blood pressure is 165/95 mm Hg. Plasma norepinephrine is 450 pg/mL (normal, 150-400 pg/mL), plasma epinephrine is 115 pg/mL (normal, 25-100 pg/mL), and 24-hour urinary VMA is 11 mg (normal, < 8 mg). Which of the following is the most likely cause of the patient's hypertension?

Pheochromocytoma. The clinical presentation of episodic palpitations, sweating, anxiety, and hypertension forms the classic triad of **Pheochromocytoma**. This catecholamine-secreting tumor (usually arising from the adrenal medulla) leads to an excess of epinephrine and norepinephrine. The laboratory findings in this case—elevated plasma catecholamines and increased 24-hour urinary Vanillylmandelic acid (VMA)—confirm the diagnosis [2]. VMA is the end-stage metabolite of catecholamines, and its elevation is a high-yield diagnostic marker. **Why the other options are incorrect:** * **11-beta-hydroxylase deficiency:** This form of Congenital Adrenal Hyperplasia (CAH) causes hypertension due to the buildup of 11-deoxycorticosterone (a mineralocorticoid). However, it is typically associated with virilization (excess androgens) and would not cause elevated catecholamines or VMA. * **Conn’s Syndrome (Primary Hyperaldosteronism):** This presents with hypertension and hypokalemia due to excess aldosterone [1]. It does not cause episodic "spells" or elevated urinary VMA. * **Renin-secreting tumor:** This rare tumor leads to secondary hyperaldosteronism. While it causes severe hypertension, it is driven by the Renin-Angiotensin-Aldosterone System (RAAS), not the sympathetic nervous system. **High-Yield Clinical Pearls for NEET-PG:** * **Rule of 10s:** 10% are bilateral, 10% are extra-adrenal (Paragangliomas), 10% are malignant, and 10% occur in children. * **Diagnosis:** The most sensitive initial screening test is **Plasma free metanephrines**. 24-hour urinary metanephrines and VMA are highly specific. * **Management:** Always start **Alpha-blockers (e.g., Phenoxybenzamine)** before Beta-blockers to avoid an "unopposed alpha" hypertensive crisis [2]. * **Associations:** Often linked with **MEN 2A/2B**, von Hippel-Lindau (VHL) syndrome, and Neurofibromatosis type 1 [2].

Q: A 49-year-old man presents with recurrent episodes of drowsiness, sweating, and palpitations. During one episode, his blood glucose level was 52 mg/dL, and he recovered with intravenous 10% dextrose. His C-peptide levels are below the normal range. What is the most likely diagnosis?

Factitious insulin use. The patient presents with **Whipple’s Triad**: symptoms of hypoglycemia (drowsiness, sweating, palpitations), a documented low blood glucose level (52 mg/dL), and relief of symptoms upon glucose administration [2]. The key to differentiating the cause lies in the **C-peptide level**. **1. Why Factitious Insulin Use is Correct:** Insulin is synthesized as proinsulin, which is cleaved into equal amounts of active insulin and C-peptide. **Exogenous (injected) insulin** contains only the insulin hormone and lacks C-peptide. Therefore, in cases of factitious insulin use, the patient will have high circulating insulin levels but **suppressed/low C-peptide levels** due to the negative feedback of exogenous insulin on endogenous beta-cell secretion [1]. **2. Why Incorrect Options are Wrong:** * **Insulinoma (Option D):** This is an endogenous insulin-secreting tumor. Since the body is producing the insulin, both **insulin and C-peptide levels would be elevated** [1]. * **Gastrinoma (Option B):** This tumor secretes gastrin, leading to Zollinger-Ellison Syndrome (severe peptic ulcers and diarrhea), not hypoglycemia. * **Glucagonoma (Option C):** This tumor secretes glucagon, which causes **hyperglycemia** (diabetes mellitus), necrolytic migratory erythema, and weight loss. **3. NEET-PG High-Yield Pearls:** * **Whipple’s Triad:** 1. Symptoms of hypoglycemia; 2. Low plasma glucose; 3. Relief of symptoms after raising glucose. * **C-peptide:** The best marker for endogenous insulin production [1]. * **Factitious Hypoglycemia:** If C-peptide is low but insulin is high, suspect **Exogenous Insulin**. If both C-peptide and insulin are high, but a screen for oral hypoglycemics is positive, suspect **Sulfonylurea abuse** [1]. * **Insulinoma Diagnosis:** 72-hour supervised fast is the gold standard; look for high Insulin (>3 μU/mL) and high C-peptide (>0.6 ng/mL) during hypoglycemia [1].

Q: What is true about Klinefelter syndrome?

Puberty is attained at a normal age. **Explanation:** **Klinefelter Syndrome (47, XXY)** is the most common cause of congenital hypogonadism in males [1]. **Why Option D is Correct:** In Klinefelter syndrome, the onset of puberty typically occurs at the **normal age**. However, as puberty progresses, the primary testicular failure becomes evident. The seminiferous tubules undergo hyalinization and fibrosis [3], leading to a failure in testosterone production and a compensatory rise in gonadotropins (FSH and LH). This results in the failure of secondary sexual characteristic completion rather than a delay in the initiation of puberty. **Analysis of Incorrect Options:** * **Option A:** Patients typically exhibit **eunuchoid body proportions**, where the **arm span is greater than the height** (by >2 cm) [3] and the lower segment is longer than the upper segment. This is due to delayed epiphyseal closure caused by testosterone deficiency. * **Option B:** The classic karyotype is **47, XXY** [1]. 45, X is the karyotype for Turner Syndrome. * **Option C:** Characteristically, patients have **small, firm testes** (usually <2 cm or <6 mL) and **azoospermia** (absence of sperm) due to tubular atrophy [3]. **High-Yield Clinical Pearls for NEET-PG:** * **Hormonal Profile:** High FSH, High LH, Low/Low-normal Testosterone, and High Estradiol [3]. * **Clinical Features:** Gynecomastia (increased risk of male breast cancer), female-type hair distribution, and mitral valve prolapse. * **Diagnosis:** Karyotyping is the gold standard [3]. Barr bodies are present on buccal smear (due to the extra X chromosome). * **Comorbidities:** Increased risk of Germ Cell Tumors (specifically mediastinal), Type 2 Diabetes, and autoimmune disorders (like SLE) [2]. * **Treatment:** patients with Klinefelter syndrome are often supplemented with androgens to improve virilization and libido [4].

Q: Which of the following has NOT been proven to delay or prevent diabetes in individuals with impaired glucose tolerance?

Atorvastatin. ### Explanation The prevention of Type 2 Diabetes Mellitus (T2DM) in high-risk individuals with Impaired Glucose Tolerance (IGT) focuses on improving insulin sensitivity and reducing beta-cell exhaustion. **Why Atorvastatin is the Correct Answer:** Statins, including **Atorvastatin**, are primarily used for lipid management [3], [4]. However, large-scale clinical trials (such as JUPITER) and meta-analyses have shown that statins are actually associated with a **slight increase in the risk of developing new-onset diabetes**. This is thought to occur via the inhibition of glucose-stimulated insulin secretion and a reduction in peripheral insulin sensitivity. While their cardiovascular benefits outweigh this risk, they do *not* prevent diabetes [4]. **Analysis of Other Options:** * **Lifestyle Modification:** The landmark **Diabetes Prevention Program (DPP)** study proved that intensive lifestyle intervention (weight loss of 7% and 150 minutes of exercise/week) reduced the risk of T2DM by **58%**, making it the most effective intervention [2]. * **Metformin:** The DPP study also showed that Metformin reduced the risk by **31%**, particularly in younger, more obese individuals (BMI >35) [1]. * **Orlistat:** The **XENDOS study** demonstrated that Orlistat, by promoting weight loss through gastric/pancreatic lipase inhibition, significantly reduced the progression to T2DM in obese patients with IGT. **High-Yield Clinical Pearls for NEET-PG:** * **DPP Study Gold Standard:** Lifestyle modification > Metformin for diabetes prevention. * **Other proven drugs:** Alpha-glucosidase inhibitors (Acarbose - STOP-NIDDM trial), Thiazolidinediones (Pioglitazone), and GLP-1 receptor agonists (Liraglutide). * **Statin Paradox:** Statins increase the risk of T2DM but are still indicated in diabetic patients due to their significant reduction in Major Adverse Cardiovascular Events (MACE).

Q: A young patient presents with a midline, tender swelling in the neck that occurred after an attack of sore throat. What is the most likely diagnosis?

Subacute thyroiditis. **Explanation:** **Subacute Thyroiditis (De Quervain’s Thyroiditis)** is the most likely diagnosis. The classic presentation involves a **painful, tender midline neck swelling** that typically follows a **viral upper respiratory tract infection** (sore throat). It is an inflammatory condition, likely post-viral, characterized by the destruction of thyroid follicles and the release of preformed thyroid hormones. **Why the other options are incorrect:** * **Acute Thyroiditis:** This is a rare bacterial infection (usually *S. aureus*). While it presents with severe pain and fever, it is typically associated with a pyriform sinus fistula and presents as an abscess rather than a post-viral swelling. * **Thyroglossal Cyst:** While this is a midline swelling, it is typically **painless** unless infected. It characteristically moves upward on protrusion of the tongue, which is not mentioned here. * **Toxic Goiter:** Conditions like Graves' disease present with features of hyperthyroidism and a diffuse, non-tender goiter. Pain and tenderness are not features of toxic goiter. **High-Yield Clinical Pearls for NEET-PG:** * **Pathognomonic Feature:** Elevated ESR (often >50-100 mm/hr) with low radioactive iodine uptake (RAIU) due to follicular damage. * **Histology:** Presence of **multinucleated giant cells** and granulomatous inflammation. * **Treatment:** Primarily symptomatic with NSAIDs; steroids are used for severe pain. It is usually self-limiting. * **Triad to remember:** Post-viral + Exquisite tenderness + High ESR = Subacute Thyroiditis.

Q: Which of the following statements is not true regarding Hashimoto's thyroiditis?

Presents after 6-8 weeks of upper respiratory tract infection. The correct answer is **C**, as this statement describes **Subacute Granulomatous (De Quervain’s) Thyroiditis**, not Hashimoto’s thyroiditis. De Quervain’s is a post-viral inflammatory condition that typically follows an upper respiratory tract infection (URTI) by 2–8 weeks and presents with a painful, tender thyroid [1]. In contrast, Hashimoto’s thyroiditis is a chronic autoimmune process characterized by painless goiter and gradual thyroid failure. **Analysis of Options:** * **Option A (More common in females):** This is true. Like most autoimmune diseases, Hashimoto’s shows a strong female predilection (ratio approx. 10:1 to 20:1). * **Option B (HLA-B8 association):** This is true. Hashimoto’s is associated with HLA-DR3, HLA-DR5, and **HLA-B8**. (Note: HLA-B8 is also linked to Graves' disease and Myasthenia Gravis). * **Option D (Can lead to thyroid lymphoma):** This is true. Patients with Hashimoto’s have a significantly increased risk (approx. 60–80 fold) of developing **Primary Thyroid Lymphoma** (usually B-cell MALT lymphoma). **High-Yield NEET-PG Pearls:** * **Most common cause** of hypothyroidism in iodine-sufficient areas. * **Pathology:** Characterized by intense lymphocytic infiltrate, **germinal centers**, and **Hürthle cells** (oxyphilic, granular eosinophilic cytoplasm). * **Antibodies:** Anti-TPO (95%) and Anti-Thyroglobulin (60%) [1]. * **Hashitoxicosis:** A transient thyrotoxic phase early in the disease due to follicular rupture and leak of preformed hormones [1].

Q: What laboratory test is most appropriate for this patient?

Calcitonin. ***Calcitonin*** - **Calcitonin** is the most specific tumor marker for **medullary thyroid carcinoma (MTC)**, produced by parafollicular **C-cells**. - Elevated serum calcitonin levels help diagnose MTC and monitor treatment response, especially in **MEN 2 syndrome** cases. *Alpha-fetoprotein* - **AFP** is primarily elevated in **hepatocellular carcinoma** and **germ cell tumors** (testicular/ovarian). - It has no association with **thyroid malignancies** and would not be useful for suspected MTC. *Beta2-microglobulin* - **Beta2-microglobulin** is elevated in **multiple myeloma**, **lymphomas**, and other hematologic malignancies. - It is not a marker for **thyroid cancer** and lacks specificity for MTC diagnosis. *Insulin-like growth factor-1* - **IGF-1** is used to diagnose **acromegaly** caused by **growth hormone excess** from pituitary adenomas. - It has no role in thyroid cancer evaluation and is unrelated to **C-cell tumors**.

Q: A 68-year-old patient, postoperative from thyroidectomy, presents with muscle cramps. Chvostek's and Trousseau's signs are noted on examination. What is the most likely finding on electrocardiogram?

Prolonged QT interval. ### Explanation **Correct Answer: A. Prolonged QT interval** **Concept:** The patient is presenting with signs of **hypocalcemia** (muscle cramps, Chvostek's sign, and Trousseau's sign) following a thyroidectomy. This is a classic complication caused by accidental removal or devascularization of the parathyroid glands, leading to **Hypoparathyroidism** [1]. Calcium ions play a critical role in the ventricular action potential. In hypocalcemia, there is a **prolongation of Phase 2 (the plateau phase)** of the action potential. Since the QT interval represents the total duration of ventricular depolarization and repolarization, a lengthened plateau phase manifests on the ECG as a **prolonged QT interval** [1]. **Analysis of Incorrect Options:** * **B. Short QT interval:** This is a characteristic finding in **Hypercalcemia**. High calcium levels shorten the plateau phase of the action potential. * **C & D. ST elevation/depression:** These are typically associated with myocardial ischemia, infarction, or electrolyte imbalances like hyperkalemia (ST depression), but are not the primary or classic findings of isolated hypocalcemia. **NEET-PG High-Yield Pearls:** * **Chvostek’s Sign:** Tapping the facial nerve (anterior to the ear) causes 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 in Hypocalcemia:** Specifically, it is the **ST segment** that prolongs, leading to a long QT [1]. The T-wave usually remains normal. * **Danger:** A prolonged QT interval can predispose patients to **Torsades de Pointes** (a form of polymorphic ventricular tachycardia) [2]. * **Management:** Acute symptomatic hypocalcemia is treated with **IV Calcium Gluconate**.

Question 1

A 25-year-old male reports episodic spells characterized by palpitations, sweating, nervousness, and feelings of anxiety. On examination, the man's blood pressure is 165/95 mm Hg. Plasma norepinephrine is 450 pg/mL (normal, 150-400 pg/mL), plasma epinephrine is 115 pg/mL (normal, 25-100 pg/mL), and 24-hour urinary VMA is 11 mg (normal, < 8 mg). Which of the following is the most likely cause of the patient's hypertension?

Accepted Answer

Pheochromocytoma

Answer

11-beta-hydroxylase deficiency

Answer

Conn's syndrome

Answer

Renin-secreting tumor

Question 2

A perimenopausal woman presents with increasing swallowing difficulty and fatigue. Physical examination reveals a palpable goiter. Laboratory examination of her serum reveals T4 of 4.9 mg/dL, free T4 of 2.5 ng/dL, and TSH of 5.5 mIU/mL. No thyroid-stimulating immunoglobulins are identified in the serum, but antimicrosomal antibodies are present. Which one of the listed histologic findings, if present in a thyroid biopsy from this individual, would be most consistent with a diagnosis of Hashimoto's thyroiditis?

Accepted Answer

Intense lymphoplasmacytic infiltrate with lymphoid follicles and scattered oxyphilic cells

Answer

Lymphocytic infiltrate without follicle formation

Answer

Hyperplasia of follicular cells with scalloping of colloid at the margin of follicles

Answer

Granulomatous inflammation with multinucleated giant cells surrounding fragments of colloid

Question 3

A 49-year-old man presents with recurrent episodes of drowsiness, sweating, and palpitations. During one episode, his blood glucose level was 52 mg/dL, and he recovered with intravenous 10% dextrose. His C-peptide levels are below the normal range. What is the most likely diagnosis?

Accepted Answer

Factitious insulin use

Answer

Gastrinoma

Answer

Glucagonoma

Answer

Insulinoma

Question 4

What is true about Klinefelter syndrome?

Accepted Answer

Puberty is attained at a normal age

Answer

Height is greater than arm span

Answer

Karyotype is 45, X

Answer

Testes and sperm count are normal

Question 5

Gestational hyperthyroidism occurs due to which of the following?

Accepted Answer

Beta HCG from placenta

Answer

Trans-placental transfer of TSH

Answer

TPO antibodies

Answer

Anti thyroglobulin antibody

Question 6

Which of the following has NOT been proven to delay or prevent diabetes in individuals with impaired glucose tolerance?

Accepted Answer

Atorvastatin

Answer

Lifestyle modification

Answer

Metformin

Answer

Orlistat

Question 7

A young patient presents with a midline, tender swelling in the neck that occurred after an attack of sore throat. What is the most likely diagnosis?

Accepted Answer

Subacute thyroiditis

Answer

Acute thyroiditis

Answer

Thyroglossal cyst

Answer

Toxic goiter

Question 8

Which of the following statements is not true regarding Hashimoto's thyroiditis?

Accepted Answer

Presents after 6-8 weeks of upper respiratory tract infection

Answer

More common in females

Answer

HLA-B8 association

Answer

Can lead to thyroid lymphoma

Question 9

What laboratory test is most appropriate for this patient?

Accepted Answer

Calcitonin

Answer

Alpha-fetoprotein

Answer

Beta2-microglobulin

Answer

Insulin-like growth factor-1

Question 10

A 68-year-old patient, postoperative from thyroidectomy, presents with muscle cramps. Chvostek's and Trousseau's signs are noted on examination. What is the most likely finding on electrocardiogram?

Accepted Answer

Prolonged QT interval

Answer

Short QT interval

Answer

ST elevation

Answer

ST depression

Endocrinology — MCQs

Endocrinology — MCQs

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