Endocrinology Practice Questions

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: Grave's disease is characterized by:

All of the above. Graves' disease is an autoimmune disorder and the most common cause of hyperthyroidism [1], [2]. It is characterized by the production of **Thyroid-Stimulating Immunoglobulins (TSI)**, which are autoantibodies that bind to and activate the TSH receptors on the thyroid gland [1], [2]. 1. **Goiter:** The continuous stimulation of TSH receptors by autoantibodies leads to glandular hyperplasia and hypertrophy, resulting in a **diffuse, non-tender goiter** [1]. 2. **Thyrotoxicosis:** The overstimulation causes excessive synthesis and release of thyroid hormones (T4 and T3), leading to the clinical state of thyrotoxicosis (tachycardia, weight loss, heat intolerance, etc.) [2]. 3. **Exophthalmos (Ophthalmopathy):** This is a specific extrathyroidal manifestation caused by autoantibodies reacting with orbital fibroblasts [1]. This leads to inflammation, accumulation of glycosaminoglycans, and edema of the extraocular muscles, causing the eyes to bulge forward [2]. **Why "All of the above" is correct:** Graves' disease is classically defined by the triad of **hyperthyroidism with diffuse goiter**, **ophthalmopathy** (exophthalmos), and occasionally **dermopathy** (pretibial myxedema) [1]. Since all three options (A, B, and C) are hallmark features of the disease, D is the correct choice. **High-Yield Clinical Pearls for NEET-PG:** * **Most specific sign:** Pretibial myxedema (though less common than exophthalmos). * **Antibody:** Anti-TSH receptor antibody (TRAb/TSI) is the diagnostic hallmark [1]. * **Radioiodine Uptake (RAIU):** Shows **diffuse, increased uptake** (unlike thyroiditis where uptake is low) [3]. * **Scintigraphy:** Characterized by a "hot" enlarged gland [3]. * **Treatment of choice (Permanent):** Radioactive Iodine (I-131) ablation or surgery; Thionamides (Methimazole/PTU) for medical management.

Q: Secondary hyperparathyroidism is seen in all of the following conditions EXCEPT:

Osteoporosis. **Explanation:** The core pathophysiology of **Secondary Hyperparathyroidism (sHPT)** is a compensatory increase in Parathyroid Hormone (PTH) secretion [2] in response to **hypocalcemia** [3] or **hyperphosphatemia** [2]. **Why Osteoporosis is the Correct Answer:** Osteoporosis is characterized by a decrease in total bone mass (both mineral and matrix) but with **normal serum levels** of calcium, phosphate, and PTH. Since there is no systemic mineral imbalance to trigger the parathyroid glands, sHPT does not occur. It is a disease of bone "quantity," not a systemic endocrine disturbance. **Analysis of Incorrect Options:** * **Rickets & Osteomalacia:** Both involve defective mineralization usually due to Vitamin D deficiency [1]. Low Vitamin D leads to decreased intestinal calcium absorption (hypocalcemia), which directly stimulates the parathyroid glands to secrete more PTH to restore calcium levels [1]. * **Renal Failure:** This is the most common cause of sHPT. Chronic Kidney Disease (CKD) leads to phosphate retention (hyperphosphatemia) and decreased production of 1,25-dihydroxyvitamin D (Calcitriol) [1]. Both factors trigger a massive compensatory rise in PTH [2]. **NEET-PG High-Yield Pearls:** * **Tertiary Hyperparathyroidism:** Occurs when long-standing sHPT (usually in CKD) leads to autonomous parathyroid hyperplasia, resulting in hypercalcemia. * **Biochemical Profile of sHPT:** Low/Normal Serum Calcium, High PTH, and High Alkaline Phosphatase (ALP) [2]. * **Pseudohypoparathyroidism:** A condition of PTH resistance that also presents with sHPT (High PTH) but features hypocalcemia and hyperphosphatemia [2].

Q: What is characteristic of primary hyperaldosteronism?

Metabolic alkalosis. **Explanation:** Primary hyperaldosteronism (Conn’s syndrome) is characterized by the autonomous overproduction of aldosterone from the adrenal cortex, independent of the renin-angiotensin system. **Why Metabolic Alkalosis is Correct:** Aldosterone acts on the principal cells of the collecting duct to reabsorb sodium and excrete potassium [2]. Simultaneously, it stimulates the **α-intercalated cells** to secrete hydrogen ions ($H^+$) into the tubular lumen via $H^+$-ATPase pumps. The loss of $H^+$ ions leads to an increase in serum bicarbonate levels, resulting in **metabolic alkalosis** [3]. **Analysis of Incorrect Options:** * **A. Hyperkalemia:** Aldosterone causes excessive renal potassium excretion [2]. Therefore, **hypokalemia** (not hyperkalemia) is a classic hallmark, often presenting with muscle weakness or cardiac arrhythmias [4]. * **B. Hyponatremia:** Aldosterone promotes sodium reabsorption. While patients are usually hypervolemic, they rarely show significant hypernatremia due to "aldosterone escape" [1] (atrial natriuretic peptide release); however, they definitely do **not** have hyponatremia. * **D. Fall in aldosterone with sodium loading:** In primary hyperaldosteronism, aldosterone secretion is **autonomous**. In a normal individual, a sodium load would suppress renin and aldosterone; in Conn’s syndrome, aldosterone levels remain high despite sodium loading (this is used as a confirmatory test). **NEET-PG High-Yield Pearls:** * **Screening Test:** Elevated Aldosterone-to-Renin Ratio (ARR). * **Confirmatory Test:** Saline infusion test or Oral salt loading (failure to suppress aldosterone). * **Classic Triad:** Hypertension, Hypokalemia, and Metabolic Alkalosis. * **Aldosterone Escape:** Patients do not develop overt edema despite sodium retention because increased ANP leads to pressure natriuresis [1].

Question 1

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 2

Activation of the renin stimulates which of the following?

Accepted Answer

Sodium retention

Answer

Water excretion

Answer

Potassium retention

Answer

Magnesium excretion

Question 3

What is the most common symptom of thyrotoxicosis?

Accepted Answer

Hyperactivity and irritability

Answer

Palpitations

Answer

Fatigue and weakness

Answer

Diarrhea

Question 4

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 5

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 6

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 7

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 8

Grave's disease is characterized by:

Accepted Answer

All of the above

Answer

Goiter

Answer

Thyrotoxicosis

Answer

Exophthalmos

Question 9

Secondary hyperparathyroidism is seen in all of the following conditions EXCEPT:

Accepted Answer

Osteoporosis

Answer

Rickets

Answer

Osteomalacia

Answer

Renal failure

Question 10

What is characteristic of primary hyperaldosteronism?

Accepted Answer

Metabolic alkalosis

Answer

Hyperkalemia

Answer

Hyponatremia

Answer

Fall in aldosterone with sodium loading

Endocrinology — MCQs

Endocrinology — MCQs

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