Endocrinology Practice Questions

Q: Which of the following findings would help to differentiate between SIADH and psychogenic polydipsia?

Urine osmolality 500 mOsm/L. In both **SIADH** and **Psychogenic Polydipsia**, patients present with **hypotonic hyponatremia** (low serum sodium and low serum osmolality). [2] The key to differentiating them lies in the body's physiological response to water excess, specifically the suppression of Antidiuretic Hormone (ADH). ### Why Option D is Correct * **Psychogenic Polydipsia:** Excessive water intake suppresses ADH. In the absence of ADH, the kidneys maximally dilute the urine to excrete the excess water. [1] Therefore, urine osmolality is typically **very low ( 100 mOsm/L, often >300-500 mOsm/L)**. * A urine osmolality of **500 mOsm/L** is concentrated, which is consistent with SIADH and rules out psychogenic polydipsia. ### Why Other Options are Incorrect * **A & B (BUN and Serum Osmolality):** Both conditions are characterized by **euvolemic hyponatremia**. [2] Dilutional effects lead to low serum osmolality and often low-to-normal BUN in both cases. They do not help in differentiation. * **C (Serum Potassium):** Potassium levels are typically normal in both SIADH and psychogenic polydipsia. Abnormal potassium would point toward other causes like diuretics or adrenal insufficiency. ### NEET-PG High-Yield Pearls * **Diagnostic Criteria for SIADH:** Hyponatremia, low serum osmolality ( 100), and high urine sodium (>40 mEq/L) in a euvolemic patient. * **Uric Acid:** Low serum uric acid (<4 mg/dL) is a classic finding in SIADH due to increased urate excretion. * **Treatment:** Fluid restriction is the first-line treatment for both; however, Vaptans (ADH antagonists) are specific for SIADH.

Q: Anti-thyroglobulin antibodies are seen in which of the following conditions?

Hashimoto thyroiditis. **Explanation:** **Hashimoto Thyroiditis (Correct Answer):** Hashimoto thyroiditis (chronic lymphocytic thyroiditis) is an autoimmune disorder characterized by the destruction of thyroid follicles by cellular and humoral immunity. **Anti-thyroglobulin (Anti-Tg)** antibodies are present in approximately 60-80% of patients, while **Anti-thyroid peroxidase (Anti-TPO)** antibodies are even more sensitive, appearing in over 95% of cases. These antibodies serve as markers of thyroid autoimmunity and are central to the diagnosis. **Analysis of Incorrect Options:** * **Graves Disease:** While Anti-Tg and Anti-TPO can be present in Graves disease, the hallmark and pathognomonic antibody is the **TSH Receptor Antibody (TRAb/TSI)**, which stimulates the gland to cause hyperthyroidism [1]. * **De Quervain Thyroiditis (Subacute Granulomatous):** This is a post-viral inflammatory condition, not an autoimmune one. It is characterized by a high ESR and painful thyroid; thyroid antibodies are typically absent or only transiently/weakly positive due to follicle leakage [2]. * **Subacute Lymphocytic Thyroiditis (Painless Thyroiditis):** Although this is an autoimmune variant (often postpartum), the question asks for the primary association. Hashimoto is the classic and most frequent association for high-titer Anti-Tg antibodies in medical examinations. **High-Yield Clinical Pearls for NEET-PG:** * **Most Sensitive Marker:** Anti-TPO is the most sensitive antibody for Hashimoto thyroiditis. * **Anti-Tg Significance:** Anti-Tg must be measured alongside Serum Thyroglobulin when monitoring **Thyroid Cancer** patients, as the presence of these antibodies can falsely interfere with thyroglobulin assays. * **Histology:** Look for **Hurthle cells** (Askanazy cells) and lymphoid follicles with germinal centers on FNAC/Biopsy in Hashimoto patients. * **Risk:** Hashimoto thyroiditis increases the risk of **B-cell Non-Hodgkin Lymphoma** of the thyroid.

Q: What is the most common malignancy of the endocrine system?

Thyroid cancer. **Explanation:** **Thyroid cancer** is the most common malignancy of the endocrine system, accounting for approximately 90% of all endocrine cancers. Among thyroid malignancies, **Papillary Thyroid Carcinoma (PTC)** is the most frequent subtype (80-85%). The incidence of thyroid cancer has been rising globally, primarily due to increased detection of small papillary microcarcinomas via high-resolution ultrasound. **Analysis of Incorrect Options:** * **Pancreatic cancer:** While the pancreas has endocrine functions (Islets of Langerhans), the vast majority (>95%) of pancreatic cancers are **exocrine** (adenocarcinomas). Endocrine tumors of the pancreas (PanNETs) are relatively rare. * **Pituitary adenoma:** These are common, but they are almost always **benign**. True pituitary carcinomas (malignancies with systemic metastasis) are exceedingly rare, representing less than 0.2% of pituitary tumors. * **Adrenal malignancy:** Adrenocortical carcinoma (ACC) is a rare and aggressive tumor with an incidence of only 1-2 per million population per year, making it far less common than thyroid cancer. **High-Yield Clinical Pearls for NEET-PG:** * **Most common thyroid cancer:** Papillary Carcinoma (associated with *BRAF* mutations and Psammoma bodies). * **Most common thyroid cancer post-radiation:** Papillary Carcinoma. * **Medullary Thyroid Carcinoma (MTC):** Arises from parafollicular C-cells; secretes Calcitonin; associated with **MEN 2A and 2B**. * **Anaplastic Carcinoma:** The most aggressive thyroid malignancy with the worst prognosis. * **Orphan Annie Eye nuclei:** Pathognomonic histological feature of Papillary Thyroid Carcinoma.

Q: Hypercalcemia would not be expected to occur as a result of which of the following conditions?

Hypothyroidism. **Explanation:** The correct answer is **Hypothyroidism**. In fact, **Hyperthyroidism** (not hypothyroidism) is a known cause of hypercalcemia due to increased bone turnover stimulated by high levels of thyroid hormones (T3/T4) [1]. Hypothyroidism is generally associated with normal calcium levels or, occasionally, a decrease in bone remodeling. **Analysis of Options:** * **A. Lung Carcinoma:** This is a classic cause of hypercalcemia of malignancy [1]. Squamous cell carcinoma of the lung frequently produces **PTH-related peptide (PTHrP)**, which mimics PTH action. Additionally, small cell lung cancer can cause bone metastasis leading to osteolytic hypercalcemia. * **B. Sarcoidosis:** This granulomatous disease involves macrophages that express **1-alpha-hydroxylase**. This enzyme converts 25-hydroxyvitamin D into its active form, **1,25-dihydroxyvitamin D (Calcitriol)**, leading to increased intestinal calcium absorption and hypercalcemia [1]. * **D. Thiazide Drugs:** Thiazides increase calcium reabsorption in the distal convoluted tubule of the kidney [1]. While they rarely cause severe hypercalcemia in healthy individuals, they can unmask underlying primary hyperparathyroidism or cause mild elevations in serum calcium. **High-Yield NEET-PG Pearls:** * **Mnemonic for Hypercalcemia:** "Stones (renal), Bones (pain), Groans (abdominal pain/constipation), and Psychic Moans (confusion)." [1] * **Thiazides vs. Loop Diuretics:** Thiazides *increase* serum calcium ("Thiazides **T**ake" calcium back into the blood), whereas Loop diuretics *decrease* it ("Loops **L**ose" calcium in urine). * **Vitamin D in Granulomas:** Besides Sarcoidosis, Tuberculosis and Leprosy can also cause hypercalcemia via the same 1-alpha-hydroxylase mechanism [1].

Q: A 34-year-old man presents with a chief complaint of blurring of vision in both eyes and headache for the past six months, accompanied by decreased libido. Examination reveals bitemporal hemianopia. An MRI was performed. What is the most likely diagnosis?

Pituitary macroadenoma. ***Pituitary macroadenoma*** - **Bitemporal hemianopia** indicates compression of the **optic chiasm** by a mass >10mm, which is characteristic of macroadenomas causing **mass effect**. - The combination of **headache**, **decreased libido** (hypogonadism), and **visual field defects** forms the classic triad of pituitary macroadenoma. *Pituitary microadenoma* - **Microadenomas** are <10mm in size and typically do **not cause compression** of surrounding structures like the optic chiasm. - They usually present with **hormonal excess** (prolactinomas, growth hormone excess) rather than **mass effect symptoms** like bitemporal hemianopia. *Meningioma* - **Meningiomas** arise from the **arachnoid mater** and would cause different visual field defects depending on location, not specifically bitemporal hemianopia. - They typically present with **seizures**, **focal neurological deficits**, or **personality changes** rather than endocrine dysfunction like decreased libido. *Hemangioma* - **Hemangiomas** are **vascular malformations** that rarely occur in the sellar region and would not typically cause optic chiasm compression. - They usually present with **hemorrhage** or **seizures** rather than the gradual onset of **visual field defects** and **endocrine symptoms**.

Q: Which of the following conditions can cause hypoglycemia, except?

Multiple endocrine neoplasia (MEN) syndrome, type II. Explanation: The correct answer is **D. Multiple endocrine neoplasia (MEN) syndrome, type II.** **Why MEN II is the correct answer:** MEN II (Sipple Syndrome) is characterized by Medullary Thyroid Carcinoma (MTC), Pheochromocytoma, and Hyperparathyroidism (MEN IIA) or Mucosal Neuromas/Marfanoid habitus (MEN IIB). None of these components cause hypoglycemia. In contrast, **MEN I (Wermer Syndrome)** is associated with pancreatic islet cell tumors, specifically **Insulinomas**, which are a classic cause of fasting hypoglycemia. Therefore, MEN II is the "exception" in this list. **Analysis of other options:** * **Beta-blockers (A):** These can cause hypoglycemia by inhibiting catecholamine-induced glycogenolysis and gluconeogenesis [2]. Crucially, they also mask the autonomic warning symptoms (tachycardia, tremors), making hypoglycemia particularly dangerous. * **Hepatoma (B):** Large tumors like Hepatocellular Carcinoma (HCC) can cause **Non-Islet Cell Tumor Hypoglycemia (NICTH)**. This occurs due to the excessive production of "Big-IGF-II" (Insulin-like Growth Factor II), which activates insulin receptors. * **Pituitary Insufficiency (C):** A deficiency in Growth Hormone (GH) and ACTH (leading to secondary adrenal insufficiency/low cortisol) results in the loss of key counter-regulatory hormones, leading to severe hypoglycemia [1]. **NEET-PG High-Yield Pearls:** * **MEN I:** 3 Ps (Pituitary, Parathyroid, Pancreas—Insulinoma/Gastrinoma). * **MEN IIA:** 1 P (Parathyroid) + 2 Cs (Calcitonin/MTC, Catecholamines/Pheo). * **Drug-induced hypoglycemia:** Common culprits include Quinine, Pentamidine, and Salicylates (in children). * **Whipple’s Triad:** Symptoms of hypoglycemia, low plasma glucose, and relief of symptoms after glucose administration (essential for diagnosing Insulinoma) [1].

Q: The syndrome of inappropriate antidiuretic hormone (SIADH) is characterized by which of the following findings?

Hyponatremia and urine sodium excretion > 20 mEq/L. **Explanation:** The Syndrome of Inappropriate Antidiuretic Hormone (SIADH) is characterized by the excessive release of ADH from the posterior pituitary or ectopic sources, leading to water retention and dilutional hyponatremia [1]. **1. Why Option A is correct:** In SIADH, excessive ADH causes increased water reabsorption in the collecting ducts through the insertion of aquaporin (AQP-2) channels [1]. This leads to **euvolemic hyponatremia** (dilutional) [2]. Despite the low serum sodium, the body’s volume-sensing mechanisms (atrial natriuretic peptide) promote **natriuresis** to maintain euvolemia. Consequently, the urine is inappropriately concentrated (Urine Osmolality > 100 mOsm/kg) and contains significant sodium (**Urine Na+ > 20–40 mEq/L**). **2. Why the other options are incorrect:** * **Options B & D:** SIADH is defined by **hyponatremia**, not hypernatremia. Hypernatremia with high urine sodium is more characteristic of salt-loading or severe dehydration. * **Option C:** While SIADH causes hyponatremia, it typically presents with **normal potassium levels**. Hyponatremia combined with hyperkalemia is a hallmark of **Adrenal Insufficiency (Addison’s Disease)** due to aldosterone deficiency, which is a key differential diagnosis to rule out before diagnosing SIADH [2]. **High-Yield Clinical Pearls for NEET-PG:** * **Diagnostic Criteria:** Hyponatremia, low serum osmolality ( 100 mOsm/kg), and clinical euvolemia. * **Common Causes:** Small cell carcinoma of the lung (ectopic ADH), CNS disorders (stroke, trauma), and drugs (SSRIs, Carbamazepine, Cyclophosphamide). * **Management:** Fluid restriction is the first-line treatment. For symptomatic cases, use hypertonic saline (3%). * **Caution:** Rapid correction of hyponatremia can lead to **Osmotic Demyelination Syndrome (Central Pontine Myelinolysis)**. Limit correction to <8–10 mEq/L in 24 hours.

Q: A young lady was found unconscious while exercising. Her blood glucose was 250 mg/dL with metabolic acidosis on ABG, and no prior history of diabetes. DKA was diagnosed and managed. Her ECG is shown. Where is the pathology likely located in the heart of the patient in this clinical scenario?

AV Node. ***AV Node*** - **DKA** commonly causes **hyperkalemia**, which preferentially affects the **AV node** causing **PR prolongation** (first-degree AV block) or **Wenckebach block**. - The **AV node** is most sensitive to potassium changes, and hyperkalemia impairs **conduction velocity** through this structure before affecting other cardiac tissues. *His bundle* - **His bundle** pathology would manifest as **QRS widening** rather than PR prolongation seen in hyperkalemia. - Hyperkalemia affects the **AV node first** before progressing to His-Purkinje system at much higher potassium levels. *Left bundle branch* - **Left bundle branch block** would show characteristic **wide QRS** with **RSR' pattern** in V1 and **broad R waves** in lateral leads. - **Hyperkalemia** does not selectively target bundle branches until very advanced stages with severe electrolyte disturbance. *SA node* - **SA node** dysfunction would present as **sinus bradycardia** or **sinus arrest**, not the conduction delays typical of hyperkalemia. - The **SA node** is less sensitive to potassium changes compared to the **AV node** in the context of DKA-induced hyperkalemia.

Question 1

Which of the following findings would help to differentiate between SIADH and psychogenic polydipsia?

Accepted Answer

Urine osmolality 500 mOsm/L

Answer

Blood urea nitrogen (BUN) 16 mg/dL

Answer

Serum osmolality 265 mOsm/L

Answer

Serum potassium 4 meq/L

Question 2

Anti-thyroglobulin antibodies are seen in which of the following conditions?

Accepted Answer

Hashimoto thyroiditis

Answer

Graves disease

Answer

De Quervain thyroiditis

Answer

Subacute lymphocytic thyroiditis

Question 3

What is the most common malignancy of the endocrine system?

Accepted Answer

Thyroid cancer

Answer

Pancreatic cancer

Answer

Pituitary adenoma

Answer

Adrenal malignancy

Question 4

A 40-year-old woman presents with an 8-month history of severe headaches, weakness, and dizziness. Her blood pressure is 180/110 mm Hg. Physical examination shows diminished tendon reflexes. An abdominal CT scan reveals a 4-cm mass in the right adrenal gland. Laboratory studies include serum potassium of 2.3 mEq/L, serum sodium of 155 mEq/L, plasma cortisol of 25 mg/dL (8 AM) and 20 mg/dL (4 PM), and low plasma renin. These clinical and laboratory findings are consistent with an adrenal tumor that secretes which of the following hormones?

Accepted Answer

Aldosterone

Answer

Cortisol

Answer

Epinephrine

Answer

Renin

Question 5

Hypercalcemia would not be expected to occur as a result of which of the following conditions?

Accepted Answer

Hypothyroidism

Answer

Lung carcinoma

Answer

Sarcoidosis

Answer

Administration of thiazide drugs

Question 6

A 34-year-old man presents with a chief complaint of blurring of vision in both eyes and headache for the past six months, accompanied by decreased libido. Examination reveals bitemporal hemianopia. An MRI was performed. What is the most likely diagnosis?

Accepted Answer

Pituitary macroadenoma

Answer

Pituitary microadenoma

Answer

Meningioma

Answer

Hemangioma

Question 7

Which of the following conditions can cause hypoglycemia, except?

Accepted Answer

Multiple endocrine neoplasia (MEN) syndrome, type II

Answer

Beta blockers

Answer

Hepatoma

Answer

Pituitary insufficiency

Question 8

The syndrome of inappropriate antidiuretic hormone (SIADH) is characterized by which of the following findings?

Accepted Answer

Hyponatremia and urine sodium excretion > 20 mEq/L

Answer

Hypernatremia and urine sodium excretion > 20 mEq/L

Answer

Hyponatremia and hyperkalemia

Answer

Hypernatremia and hypokalemia

Question 9

A young lady was found unconscious while exercising. Her blood glucose was 250 mg/dL with metabolic acidosis on ABG, and no prior history of diabetes. DKA was diagnosed and managed. Her ECG is shown. Where is the pathology likely located in the heart of the patient in this clinical scenario?

Accepted Answer

AV Node

Answer

His bundle

Answer

Left bundle branch

Answer

SA node

Question 10

A 37-year-old woman presents with a one-week history of difficulty swallowing and a feeling of fullness in the anterior neck. She had a mild upper respiratory tract infection one month prior. On examination, her temperature is 37.4°C, pulse is 74/min, respirations are 16/min, and blood pressure is 122/80 mm Hg. Palpation of her diffusely enlarged thyroid is painful. Laboratory studies reveal an increased serum T4 level and a decreased TSH level. Two months later, her symptoms have resolved, and her T4 level is normal. Which of the following conditions is most likely to have produced these findings?

Accepted Answer

Subacute granulomatous thyroiditis

Answer

Hashimoto thyroiditis

Answer

Medullary thyroid carcinoma

Answer

Toxic follicular adenoma

Endocrinology — MCQs

Endocrinology — MCQs

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