Endocrinology Practice Questions

Q: Canagliflozin acts by:

Increasing urinary glucose excretion. **Explanation:** **Mechanism of Action:** Canagliflozin is a member of the **SGLT-2 (Sodium-Glucose Co-transporter 2) inhibitors** class. Under normal physiological conditions, approximately 90% of glucose filtered by the renal glomeruli is reabsorbed in the S1 segment of the proximal convoluted tubule via SGLT-2. By inhibiting this transporter, Canagliflozin reduces the renal threshold for glucose and prevents its reabsorption, leading to **increased urinary glucose excretion (glucosuria)**. This results in a reduction of plasma glucose levels in an insulin-independent manner. **Analysis of Incorrect Options:** * **Option A:** Decreasing hepatic glucose production is the primary mechanism of **Metformin** (Biguanides). * **Option C:** Increasing insulin secretion is the mechanism of **Sulfonylureas** and **Meglitinides** (secretagogues). * **Option D:** Prolonging endogenous GLP-1 action is the mechanism of **DPP-4 inhibitors** (Gliptins), which prevent the degradation of GLP-1. **High-Yield Clinical Pearls for NEET-PG:** * **Weight & BP:** SGLT-2 inhibitors promote weight loss (due to calorie loss via urine) and have a mild diuretic effect that lowers blood pressure. * **Cardio-Renal Protection:** These drugs are highly favored in exams for their proven benefits in reducing hospitalization for **Heart Failure** and slowing the progression of **Chronic Kidney Disease (CKD)**. * **Side Effects:** The most common side effect is **Genitourinary infections** (e.g., Vulvovaginal candidiasis) due to high glucose in the urine. A rare but serious complication is **Euglycemic Diabetic Ketoacidosis (eDKA)**. * **Suffix:** All drugs in this class end in **"-gliflozin"** (Dapagliflozin, Empagliflozin).

Q: All are the features of carcinoid syndrome except?

Acute appendicitis. **Explanation:** Carcinoid syndrome occurs when vasoactive substances (primarily **serotonin**, but also histamine, beautykinin, and prostaglandins) enter the systemic circulation. This typically happens with carcinoid tumors of the midgut that have metastasized to the liver, bypassing the "first-pass" metabolism that normally inactivates these substances [1]. **Why "Acute Appendicitis" is the correct answer:** While the **appendix** is the most common site for a carcinoid tumor, the tumor itself is usually an incidental finding during surgery. Carcinoid syndrome is a systemic manifestation of advanced disease (metastasis) [1]. Acute appendicitis is a localized inflammatory process caused by luminal obstruction; it is a potential *presentation* of a tumor, but it is **not a feature** of the systemic "Carcinoid Syndrome" complex [1]. **Analysis of other options:** * **Flushing (Option D):** The most common clinical feature (85%). It is a paroxysmal cyanotic/erythematous redness of the face and neck triggered by alcohol, exercise, or stress. * **Diarrhea (Option B):** Occurs in ~80% of cases due to increased intestinal motility caused by serotonin. It is typically secretory and does not resolve with fasting. * **Wheezing (Option A):** Seen in ~15% of patients. It is caused by serotonin-induced bronchospasm, mimicking asthma. **NEET-PG High-Yield Pearls:** * **Diagnosis:** The best initial screening test is **24-hour urinary 5-HIAA** (a metabolite of serotonin). * **Localization:** **Somatostatin receptor scintigraphy** (OctreoScan) is the imaging of choice. * **Cardiac Involvement:** Right-sided heart failure (Tricuspid regurgitation/Pulmonary stenosis) is common because the lungs contain monoamine oxidase (MAO) which inactivates serotonin before it reaches the left heart. * **Treatment:** **Octreotide** (Somatostatin analog) is used to manage symptoms and prevent a "carcinoid crisis" during surgery.

Q: A 17-year-old male presents with a 3-month history of headache, weight gain, decreased concentration, polyuria, and polydipsia. His headaches are mostly in the morning and involve the frontal region. On examination, he was found to have a bitemporal visual field defect and no facial hair. An MRI scan revealed a suprasellar partially calcified cystic lesion with displacement of the optic chiasm. What is the most likely pathology?

Craniopharyngioma. **Explanation:** The clinical presentation is classic for a **Craniopharyngioma**, a benign but locally aggressive tumor derived from remnants of **Rathke’s pouch** [1]. **Why Craniopharyngioma is correct:** 1. **Age & Symptoms:** It has a bimodal distribution (5–14 years and >50 years) [1]. In this 17-year-old, the tumor causes mass effect (morning headaches, bitemporal hemianopia due to optic chiasm compression) and endocrine dysfunction (delayed puberty/lack of facial hair due to GH/LH/FSH deficiency). 2. **Diabetes Insipidus (DI):** Polyuria and polydipsia indicate central DI, a hallmark of craniopharyngiomas due to hypothalamic-pituitary axis disruption [1]. 3. **Imaging:** The description of a **suprasellar, cystic, and calcified lesion** is pathognomonic [1]. Calcification is seen in ~90% of pediatric cases. **Why other options are incorrect:** * **Giant aneurysm:** While it can cause mass effect, it would not typically present with a cystic, calcified appearance on MRI or cause DI in a teenager. * **Pituitary macroadenoma:** These are rare in adolescents. While they cause bitemporal hemianopia [2], they are usually solid and **rarely calcified**. * **Glioblastoma multiforme:** This is a high-grade intraparenchymal malignancy, not a suprasellar cystic/calcified lesion, and is rare in this age group. **High-Yield Pearls for NEET-PG:** * **Histology:** Look for "Adamantinomatous" type (machinery oil fluid, wet keratin, stellate reticulum) in children. * **Imaging Triad:** Suprasellar location, Cystic components, and Calcification. * **Most common cause** of hypopituitarism in children. * **Visual field defect:** Bitemporal hemianopia (starts in the **inferior** quadrants because the tumor compresses the chiasm from above).

Q: Which laboratory value is most indicative of central diabetes insipidus?

Low urinary osmolality and high serum osmolality. Diabetes Insipidus (DI) is characterized by a deficiency of Antidiuretic Hormone (ADH) in Central DI or resistance to its action in Nephrogenic DI [1]. ADH is responsible for water reabsorption in the collecting ducts of the kidney. **1. Why Option A is Correct:** In Central DI, the lack of ADH prevents the kidneys from concentrating urine [1]. This leads to the excretion of large volumes of dilute urine, resulting in **low urinary osmolality** (typically 295 mOsm/kg) [3]. This "dilute urine in the face of concentrated plasma" is the hallmark of DI. **2. Why Incorrect Options are Wrong:** * **Option B:** High urinary and low serum osmolality is characteristic of **SIADH** (Syndrome of Inappropriate ADH), where excess ADH causes water retention and concentrated urine [2]. * **Option C:** Low urinary and low serum osmolality is seen in **Primary Polydipsia** [2]. Here, the patient drinks excessive water, lowering serum osmolality, which physiologically suppresses ADH, leading to dilute urine [3]. * **Option D:** This pattern is not typical for DI; very low serum osmolality would suggest severe water intoxication or SIADH. **Clinical Pearls for NEET-PG:** * **Water Deprivation Test:** The gold standard to differentiate DI from Primary Polydipsia [3]. * **Desmopressin (DDAVP) Challenge:** Used to differentiate Central from Nephrogenic DI. In **Central DI**, urinary osmolality increases by >50%; in **Nephrogenic DI**, there is little to no response (<10%) [3]. * **Imaging:** In Central DI, MRI may show the "loss of the posterior pituitary bright spot." * **Drug of Choice:** Desmopressin is the treatment of choice for Central DI [3].

Q: All of the following will be seen in a patient with hyperthyroidism except?

Constipation. In hyperthyroidism, the excess of circulating thyroid hormones ($T_3$ and $T_4$) leads to a hypermetabolic state and increased sympathetic nervous system activity. [1] **Explanation of the Correct Answer:** * **D. Constipation:** This is the correct answer because it is **not** seen in hyperthyroidism. Excess thyroid hormone increases gastrointestinal motility and transit time, typically resulting in **increased frequency of bowel movements** or diarrhea. Constipation is a classic feature of *hypothyroidism*. [2] **Analysis of Incorrect Options:** * **A. Myxedema:** While "Generalized Myxedema" is seen in hypothyroidism, **Pretibial Myxedema** (Graves' dermopathy) is a specific feature of Graves' disease, the most common cause of hyperthyroidism. [3] It occurs due to the deposition of glycosaminoglycans in the dermis. * **B. Dalrymple sign:** This refers to the widening of the palpebral fissures (staring look) due to upper eyelid retraction. It is a classic ocular sign of thyrotoxicosis caused by sympathetic overactivity of the Müller’s muscle. [2] * **C. Moist warm hands:** Hyperthyroidism increases the basal metabolic rate and cutaneous vasodilation to dissipate heat. This results in skin that is characteristically warm, moist (due to diaphoresis), and smooth. [1] **High-Yield Clinical Pearls for NEET-PG:** * **Cardiac:** Sinus tachycardia and Atrial Fibrillation (especially in elderly) are common. [2] * **Neuromuscular:** Fine tremors of outstretched hands and proximal muscle weakness (thyrotoxic myopathy). [1] * **Eye Signs:** Stellwag’s sign (infrequent blinking), Joffroy’s sign (absence of forehead wrinkling on upward gaze), and Von Graefe’s sign (lid lag). [2] * **Apathetic Hyperthyroidism:** Seen in the elderly; presents with depression and lethargy rather than typical hyperactivity.

Q: Which of the following features is NOT typically seen in Cushing's Syndrome?

Hypoglycemia. Cushing’s Syndrome is characterized by chronic exposure to excess glucocorticoids (cortisol). Cortisol is a "stress hormone" that acts as a potent **insulin antagonist**. **1. Why Hypoglycemia is the Correct Answer:** Glucocorticoids stimulate gluconeogenesis in the liver and decrease peripheral glucose uptake in muscles and adipose tissue. Therefore, excess cortisol leads to **Hyperglycemia** (impaired glucose tolerance or "Steroid Diabetes"), not hypoglycemia. Hypoglycemia is instead a hallmark of Adrenal Insufficiency (Addison’s Disease). **2. Analysis of Incorrect Options:** * **Hypertension (B):** This is a classic feature. Cortisol causes hypertension by increasing peripheral vascular resistance, enhancing sensitivity to catecholamines, and exerting mineralocorticoid effects (sodium and water retention) at high levels. * **Frank Psychosis (C):** Glucocorticoids significantly impact the central nervous system. Neuropsychiatric manifestations range from emotional lability and depression to overt "steroid psychosis" and cognitive deficits. * **Hypokalemia (D):** At high concentrations (especially in Ectopic ACTH syndrome), cortisol overwhelms the 11β-HSD2 enzyme in the kidneys and binds to mineralocorticoid receptors, leading to potassium excretion and metabolic alkalosis. **Clinical Pearls for NEET-PG:** * **Screening Test of Choice:** 24-hour urinary free cortisol or Low-dose Dexamethasone Suppression Test (LDDST) [2]. * **Most Common Cause:** Iatrogenic (exogenous steroids). * **Most Common Endogenous Cause:** Cushing’s Disease (Pituitary adenoma) [1]. * **High-Yield Sign:** Proximal muscle wasting (due to protein catabolism) with centripetal obesity and violaceous striae (>1cm wide) [1].

Q: Which of the following are the extraintestinal manifestations of Sipple syndrome?

All the above. **Sipple Syndrome**, also known as **Multiple Endocrine Neoplasia Type 2A (MEN 2A)**, is an autosomal dominant disorder caused by a germline mutation in the **RET proto-oncogene**. It is classically characterized by the triad of Medullary Thyroid Carcinoma (MTC), Pheochromocytoma, and Parathyroid Hyperplasia. The correct answer is **"All the above"** because MEN 2A is uniquely associated with several non-endocrine (extraintestinal) manifestations: 1. **Cutaneous Lichen Amyloidosis (Option A & B):** This is a highly specific dermatological marker for MEN 2A. It presents as intensely pruritic, scaly, pigmented papules, typically located in the interscapular region of the back. The "amyloidosis" here refers to localized cutaneous deposits, not systemic amyloidosis. 2. **Hirschsprung Disease (Option C):** There is a known genetic association between RET mutations and Hirschsprung disease (congenital megacolon). Patients with MEN 2A may present with chronic constipation or bowel obstruction due to colonic aganglionosis. **Clinical Pearls for NEET-PG:** * **MEN 2A (Sipple):** MTC (100%), Pheo (50%), Parathyroid (20-30%) + Lichen Amyloidosis + Hirschsprung. * **MEN 2B (Wermer):** MTC, Pheo + **Mucosal Neuromas** (lips/tongue), **Marfanoid habitus**, and Medullated corneal nerve fibers. (Note: MEN 2B does *not* usually feature parathyroid hyperplasia). * **Screening:** The most important initial step in a suspected case is checking for **RET proto-oncogene mutations**. If positive, prophylactic thyroidectomy is often indicated. * **Rule of Thumb:** Always exclude/treat Pheochromocytoma *before* any surgery (including thyroidectomy) to prevent a hypertensive crisis.

Q: Werner syndrome is associated with which of the following endocrine neoplasia syndromes?

Multiple Endocrine Neoplasia Type 1 (MEN 1). **Explanation:** **Werner Syndrome** is the eponymous name for **Multiple Endocrine Neoplasia Type 1 (MEN 1)**. It is an autosomal dominant disorder caused by a mutation in the *MEN1* gene on chromosome 11q13, which encodes the protein **menin**, a tumor suppressor. The syndrome is classically characterized by the **"3 Ps"**: 1. **Parathyroid:** Primary Hyperparathyroidism (most common initial manifestation, >95% of cases). 2. **Pancreas:** Enteropancreatic neuroendocrine tumors (e.g., Gastrinoma/Zollinger-Ellison Syndrome, Insulinoma). 3. **Pituitary:** Anterior pituitary adenomas (most commonly Prolactinomas). **Analysis of Incorrect Options:** * **MEN IIA (Sipple Syndrome):** Characterized by Medullary Thyroid Carcinoma (MTC), Pheochromocytoma, and Parathyroid hyperplasia. It is associated with the *RET* proto-oncogene. * **MEN IIB (Wagenmann-Froboese Syndrome):** Characterized by MTC, Pheochromocytoma, mucosal neuromas, and Marfanoid habitus. It does *not* typically involve the parathyroid glands. * **Acute Intermittent Porphyria (AIP):** A metabolic disorder of heme biosynthesis; it has no association with the MEN syndromes. **High-Yield Clinical Pearls for NEET-PG:** * **Wermer vs. Werner:** Do not confuse **Wermer** Syndrome (MEN 1) with **Werner** Syndrome (Adult Progeria/Premature Aging). * **Screening:** The first biochemical sign of MEN 1 is usually an elevated serum Calcium and PTH. * **Cutaneous Markers:** MEN 1 is also associated with non-endocrine tumors like angiofibromas, collagenomas, and lipomas. * **Most common cause of death** in MEN 1 is now malignant pancreatic neuroendocrine tumors (pNETs).

Question 1

Canagliflozin acts by:

Accepted Answer

Increasing urinary glucose excretion

Answer

Decreasing hepatic glucose production

Answer

Increasing insulin secretion

Answer

Prolonging endogenous GLP-1 action

Question 2

All are the features of carcinoid syndrome except?

Accepted Answer

Acute appendicitis

Answer

Wheezing

Answer

Diarrhea

Answer

Flushing

Question 3

A 17-year-old male presents with a 3-month history of headache, weight gain, decreased concentration, polyuria, and polydipsia. His headaches are mostly in the morning and involve the frontal region. On examination, he was found to have a bitemporal visual field defect and no facial hair. An MRI scan revealed a suprasellar partially calcified cystic lesion with displacement of the optic chiasm. What is the most likely pathology?

Accepted Answer

Craniopharyngioma

Answer

Giant aneurysm of the carotid artery

Answer

Pituitary macroadenoma

Answer

Glioblastoma multiforme

Question 4

A 36-year-old male presents with recent darkening of his skin, which has a dark, bronze color. Workup reveals signs of diabetes mellitus. His serum iron is 1150 mg/dL, and his transferrin saturation is 98%. A liver biopsy reveals extensive deposits of hemosiderin in hepatocytes and Kupffer cells. What is the most likely mechanism responsible for this constellation of findings?

Accepted Answer

Excessive reabsorption of iron from the small intestines

Answer

Defective excretion of copper into the bile

Answer

Defective synthesis of a1 antitrypsin

Answer

Excessive absorption of galactose from the small intestines

Question 5

Which laboratory value is most indicative of central diabetes insipidus?

Accepted Answer

Low urinary osmolality and high serum osmolality

Answer

High urinary osmolality and low serum osmolality

Answer

Low urinary osmolality and low serum osmolality

Answer

High urinary osmolality and very low serum osmolality

Question 6

All of the following will be seen in a patient with hyperthyroidism except?

Accepted Answer

Constipation

Answer

Myxedema

Answer

Dalrymple sign

Answer

Moist warm hands

Question 7

Which of the following features is NOT typically seen in Cushing's Syndrome?

Accepted Answer

Hypoglycemia

Answer

Hypertension

Answer

Frank psychosis

Answer

Hypokalemia

Question 8

Which of the following are the extraintestinal manifestations of Sipple syndrome?

Accepted Answer

All the above

Answer

Cutaneous lichen

Answer

Amyloidosis

Answer

Hirschsprung disease

Question 9

Werner syndrome is associated with which of the following endocrine neoplasia syndromes?

Accepted Answer

Multiple Endocrine Neoplasia Type 1 (MEN 1)

Answer

Multiple Endocrine Neoplasia Type IIA (MEN IIA)

Answer

Multiple Endocrine Neoplasia Type IIB (MEN IIB)

Answer

Acute Intermittent Porphyria (AIP)

Question 10

A 25-year-old female, several months postpartum and breast-feeding, presents with acute cessation of lactation. She has not menstruated since delivery and reports fatigue and cold intolerance. Laboratory workup reveals deficiency of ACTH and other anterior pituitary hormones. What is the most likely cause of this patient's signs and symptoms?

Accepted Answer

Sheehan's syndrome

Answer

Craniopharyngioma

Answer

Cushing's disease

Answer

Empty sella syndrome

Endocrinology — MCQs

Endocrinology — MCQs

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