Endocrinology Practice Questions

Q: Addison's disease is associated with all of the following except:

Low renin levels. Addison’s disease (Primary Adrenocortical Insufficiency) is characterized by the destruction of the adrenal cortex, leading to a deficiency in both **cortisol** and **aldosterone** [1]. **Why "Low renin levels" is the correct answer:** In Addison’s disease, the lack of aldosterone (mineralocorticoid deficiency) leads to sodium wasting and potassium retention [2]. The resulting hypovolemia and hypotension trigger the juxtaglomerular apparatus to increase renin production [1]. Therefore, **High Renin levels** (Hyperreninemic hypoaldosteronism) are a hallmark of primary adrenal insufficiency. Low renin would instead suggest secondary adrenal insufficiency or mineralocorticoid excess. **Analysis of Incorrect Options:** * **Cardiac Atrophy:** Chronic hypotension and reduced workload on the heart due to low blood volume lead to "microcardia" or cardiac atrophy, a classic radiological finding in Addison’s. * **Decreased Diastolic Blood Pressure:** Aldosterone deficiency causes volume depletion, while cortisol deficiency leads to reduced vascular sensitivity to catecholamines [1]. This results in systemic hypotension (both systolic and diastolic) and orthostatic changes. * **Serum Cortisol < 8 µg/dL:** A morning serum cortisol level of less than 3–5 µg/dL is highly suggestive of adrenal insufficiency; levels below 8–10 µg/dL in a stressed patient are considered inappropriately low. **High-Yield Clinical Pearls for NEET-PG:** * **Hyperpigmentation:** Seen only in *Primary* adrenal insufficiency (Addison’s) due to increased ACTH and POMC cleavage products (MSH). * **Electrolytes:** Look for the triad of **Hyponatremia, Hyperkalemia, and Metabolic Acidosis** [2]. * **Gold Standard Test:** ACTH Stimulation Test (Cosyntropin test). Failure of cortisol to rise above 18 µg/dL confirms the diagnosis. * **Most Common Cause:** Autoimmune adrenalitis (Western world); Tuberculosis (Developing countries/India).

Q: A 52-year-old woman presents with polyuria, polydypsia, constipation, and fatigue. She has no significant past medical history and is not on any medications. She was recently diagnosed with hyperparathyroidism. What are the characteristic ECG findings in this condition?

Shortening of the QT interval. **Explanation:** The clinical presentation of polyuria, polydipsia, constipation, and fatigue in the setting of hyperparathyroidism points toward **Hypercalcemia** [1]. In hyperparathyroidism, excess parathyroid hormone (PTH) increases serum calcium levels [3]. **1. Why Option D is Correct:** Calcium ions play a critical role in the cardiac action potential. High extracellular calcium levels increase the gradient across the cell membrane, leading to a faster influx of calcium during Phase 2 (the plateau phase). This results in a **shortened plateau phase**, which translates to a **shortening of the ST segment** and, consequently, a **shortening of the QT interval** on the ECG. **2. Why the Other Options are Incorrect:** * **Option A & B:** While severe hypercalcemia can occasionally cause PR interval prolongation or heart block, it is not the *characteristic* or most common finding. PR interval changes are more typically associated with electrolyte imbalances like hyperkalemia or medications like digoxin. * **Option C:** A lengthened QU interval (or prominent U waves) is a classic sign of **Hypokalemia**, not hypercalcemia [2]. **3. NEET-PG High-Yield Pearls:** * **Hypercalcemia ECG:** Shortened QT interval, Osborne waves (rarely), and potential J-point elevation. * **Hypocalcemia ECG:** Prolonged QT interval (due to lengthening of the ST segment)—this is the direct opposite of hypercalcemia [2]. * **Mnemonic for Hypercalcemia Symptoms:** "Stones (renal), Bones (aches), Groans (abdominal pain/constipation), and Psychic Moans (fatigue/confusion)" [1]. * **Formula:** Corrected QT (QTc) = QT / √RR. A QTc < 390ms is generally considered short.

Q: What is the leading cause of ACTH-independent Cushing syndrome?

Adrenocortical adenoma. ### Explanation **Correct Answer: D. Adrenocortical adenoma** Cushing syndrome is classified into two categories based on the source of cortisol excess: **ACTH-dependent** (usually a pituitary adenoma or ectopic source) and **ACTH-independent** (primary adrenal pathology). [1] In **ACTH-independent Cushing syndrome**, the adrenal cortex autonomously overproduces cortisol, which subsequently suppresses pituitary ACTH via negative feedback. **Adrenocortical adenoma** is the most common cause of this subtype, accounting for approximately 60% of ACTH-independent cases. These are typically unilateral, benign tumors that function independently of hypothalamic-pituitary control. **Why the other options are incorrect:** * **A. Adrenocortical carcinoma:** While these also cause ACTH-independent Cushing syndrome, they are much rarer than adenomas. They often present with rapid onset of symptoms and signs of androgen excess (virilization). * **B & C. Macronodular and Micronodular adrenal hyperplasia:** These are rare genetic or sporadic conditions. Macronodular hyperplasia (AIMAH) involves bilateral large nodules, while micronodular disease (e.g., Carney Complex) involves small, pigmented nodules. Neither is as common as a solitary adenoma. **High-Yield Clinical Pearls for NEET-PG:** * **Most common cause of Cushing Syndrome overall:** Iatrogenic (Exogenous steroid use). [1] * **Most common endogenous cause:** Cushing Disease (Pituitary ACTH-secreting adenoma) ~70%. [1] * **Biochemical Hallmark:** In ACTH-independent Cushing, serum **ACTH levels will be low (<5 pg/mL)** due to negative feedback. * **Imaging:** Contrast-enhanced CT of the adrenals is the investigation of choice to differentiate between a unilateral adenoma and bilateral hyperplasia.

Q: Which of the following drugs is NOT used in the treatment of idiopathic hypercalcemia?

Thiazide. The core principle in managing hypercalcemia is to promote urinary calcium excretion and inhibit bone resorption. **Why Thiazides are the Correct Answer:** Thiazide diuretics (e.g., Hydrochlorothiazide) are **contraindicated** in hypercalcemia. They act on the distal convoluted tubule to inhibit the Na+/Cl- symporter, which indirectly **increases renal calcium reabsorption**. By reducing urinary calcium excretion and causing mild volume depletion, thiazides can exacerbate or even induce hypercalcemia. They are, however, the drug of choice for *hypercalciuria* (to prevent stones). **Analysis of Other Options:** * **Furosemide (Loop Diuretic):** This is a mainstay of treatment. It inhibits the Na+/K+/2Cl- cotransporter in the thick ascending limb of Henle, which abolishes the positive luminal potential, thereby **promoting calcium excretion** (calciuresis). It must be administered with aggressive normal saline hydration. * **Acetazolamide:** As a carbonic anhydrase inhibitor, it can increase the excretion of various electrolytes, including calcium, and is sometimes used as an adjunct in specific hypercalcemic states. [1] * **Allopurinol:** While not a primary treatment for calcium levels, it is used in conditions like **Sarcoidosis** (a common cause of idiopathic hypercalcemia/Williams syndrome) to manage associated hyperuricemia and prevent uric acid stones. **NEET-PG High-Yield Pearls:** * **Mnemonic:** "Loop Loses calcium (Furosemide), Thiazide Takes it back." * **First-line emergency treatment:** Aggressive IV hydration with 0.9% Normal Saline. [2] * **Drug of choice for malignancy-induced hypercalcemia:** IV Bisphosphonates (e.g., Zoledronic acid). [2] * **Williams Syndrome:** Characterized by "elfin" facies, supravalvular aortic stenosis, and idiopathic infantile hypercalcemia.

Q: A patient presents with hypercalcemia and a suppressed parathyroid hormone level. What is the most likely diagnosis?

Hodgkin's lymphoma. **Explanation:** The clinical presentation of **hypercalcemia with suppressed Parathyroid Hormone (PTH)** indicates **PTH-independent hypercalcemia** [1]. This occurs when calcium levels rise due to factors other than the parathyroid gland, leading to negative feedback that shuts down endogenous PTH production. **Why Hodgkin’s Lymphoma is correct:** In Hodgkin’s lymphoma (and other granulomatous diseases like sarcoidosis), the primary mechanism of hypercalcemia is the **extra-renal conversion of 25-hydroxyvitamin D to 1,25-dihydroxyvitamin D (Calcitriol)** [1]. This is mediated by the enzyme **1-alpha-hydroxylase** expressed by activated macrophages/lymphoma cells [2]. Increased calcitriol leads to enhanced intestinal calcium absorption, which suppresses PTH. **Analysis of Incorrect Options:** * **B. Hyperthyroidism:** While it can cause mild hypercalcemia due to increased bone turnover (thyrotoxicosis), it is a less common cause compared to malignancy-associated mechanisms in exam scenarios [1]. * **C. Parathyroid Carcinoma:** This would present with **markedly elevated PTH levels** (often >5–10 times the upper limit), as the tumor autonomously secretes PTH [3]. * **D. Small-cell Lung Cancer:** This is classically associated with **SIADH** or **Ectopic ACTH**. Hypercalcemia of malignancy via PTHrP (PTH-related protein) is typically associated with **Squamous Cell Lung Cancer**, not small-cell. **NEET-PG High-Yield Pearls:** * **Most common cause of hypercalcemia (Outpatient):** Primary Hyperparathyroidism (↑ PTH). * **Most common cause of hypercalcemia (Inpatient):** Malignancy (↓ PTH) [1]. * **Mechanism in Squamous Cell CA:** Secretion of **PTHrP** (mimics PTH but is not detected by standard PTH assays). * **Mechanism in Multiple Myeloma:** Local osteolytic bone destruction via cytokines (IL-6, RANKL) [1]. * **Mechanism in Lymphoma/Sarcoid:** Increased **1,25-dihydroxyvitamin D** [1].

Q: Which is the screening test for evaluation of mineralocorticoid excess?

Aldosterone renin ratio. The evaluation of mineralocorticoid excess (Primary Aldosteronism/Conn’s Syndrome) follows a specific diagnostic hierarchy: **Screening → Confirmation → Localization.** **1. Why Aldosterone Renin Ratio (ARR) is correct:** The ARR is the preferred **initial screening test**. In primary aldosteronism, the adrenal gland autonomously produces high levels of aldosterone, which suppresses renin via negative feedback. Therefore, a high plasma aldosterone concentration (PAC) combined with a low plasma renin activity (PRA) results in an elevated ratio (typically >20-30). It is highly sensitive and can be performed while the patient is ambulatory. **2. Why other options are incorrect:** * **A & B (Saline infusion/Salt loading tests):** These are **confirmatory tests**, not screening tests. They work on the principle that in a normal individual, a high salt load should suppress aldosterone. Failure to suppress aldosterone levels after salt loading confirms the diagnosis of autonomous production. * **C (Cosyntropin test):** This is the gold standard for diagnosing **Adrenal Insufficiency** (Addison’s disease), not mineralocorticoid excess [1]. It measures the cortisol response to synthetic ACTH [1]. **Clinical Pearls for NEET-PG:** * **Classic Triad:** Hypertension, hypokalemia, and metabolic alkalosis (though many patients are normokalemic). * **Drug Interference:** Spironolactone (aldosterone antagonist) must be stopped for at least 4–6 weeks before testing ARR as it can cause false positives [2]. * **Localization:** Once confirmed, the next step is a **CT scan** of the adrenals [2]. If imaging is inconclusive, **Adrenal Venous Sampling (AVS)** is the gold standard to differentiate between a unilateral adenoma (surgery) and bilateral hyperplasia (medical management) [2].

Q: A 26-year-old man was admitted with electrolyte disturbances. Which of the following is typically NOT seen in primary hyperaldosteronism?

Pedal edema. The hallmark of primary hyperaldosteronism (Conn’s Syndrome) is the autonomous overproduction of aldosterone, leading to sodium retention and potassium excretion [1]. ### **Why Pedal Edema is NOT seen (The "Aldosterone Escape" Phenomenon)** In primary hyperaldosteronism, excess aldosterone causes initial sodium and water retention, which increases extracellular fluid (ECF) volume [1]. However, this volume expansion triggers compensatory mechanisms: 1. **Atrial Natriuretic Peptide (ANP) release:** Increased atrial stretch leads to ANP secretion. 2. **Pressure Natriuresis:** Elevated blood pressure promotes sodium excretion by the kidneys [1]. These mechanisms result in a "spontaneous diuresis" of sodium and water, preventing significant fluid overload. Consequently, patients remain **euvolemic** and do **not** develop clinical edema. ### **Analysis of Other Options** * **Diastolic Hypertension:** Increased sodium reabsorption and peripheral vascular resistance lead to hypertension, often characterized by a significant rise in diastolic pressure. * **Hypokalemia:** Aldosterone acts on the principal cells of the collecting duct to secrete potassium into the urine [2]. This can lead to muscle weakness or cardiac arrhythmias. * **Polyuria:** Chronic hypokalemia causes **nephrogenic diabetes insipidus** (impaired urinary concentrating ability), leading to polyuria and polydipsia. ### **High-Yield Clinical Pearls for NEET-PG** * **Screening Test:** Plasma Aldosterone Concentration (PAC) to Plasma Renin Activity (PRA) ratio. A ratio **>20–30** is highly suggestive. * **Metabolic State:** Patients typically show **Hypokalemic Metabolic Alkalosis** (due to H+ ion secretion in the distal tubule) [1]. * **Triad of Conn’s:** Hypertension, Hypokalemia, and Metabolic Alkalosis [1]. * **Most Common Cause:** Adrenal Adenoma (Conn's Syndrome), followed by Bilateral Adrenal Hyperplasia.

Q: Low serum calcium and high serum phosphate are typically seen in which condition?

Hypoparathyroidism. **Explanation:** The biochemical hallmark of **Hypoparathyroidism** is the combination of **hypocalcemia** and **hyperphosphatemia** [1]. This occurs due to a deficiency of Parathyroid Hormone (PTH). **1. Why Hypoparathyroidism is correct:** PTH is the primary regulator of calcium and phosphate homeostasis. Under normal conditions, PTH increases serum calcium (by mobilizing it from bone and increasing renal reabsorption) and decreases serum phosphate (by inhibiting reabsorption in the proximal convoluted tubule, causing phosphaturia) [2]. In hypoparathyroidism, the absence of PTH leads to: * **Decreased renal calcium reabsorption** and decreased bone resorption (leading to low serum calcium). * **Increased renal phosphate reabsorption** (leading to high serum phosphate) [1]. **2. Why other options are incorrect:** * **Hyperparathyroidism:** Characterized by high PTH levels, resulting in **hypercalcemia** and **hypophosphatemia** (due to excessive renal phosphate wasting) [3]. * **Hyperthyroidism & Hypothyroidism:** Thyroid hormone disorders primarily affect metabolic rate. While severe hyperthyroidism can occasionally cause mild hypercalcemia due to increased bone turnover, they do not typically present with the classic reciprocal calcium-phosphate pattern seen in PTH disorders [4]. **High-Yield Clinical Pearls for NEET-PG:** * **Pseudohypoparathyroidism:** Presents with the same biochemical profile (Low Ca²⁺, High PO₄³⁻) but with **high PTH** levels due to end-organ resistance [1]. * **Clinical Signs:** Look for **Chvostek’s sign** (facial twitching) and **Trousseau’s sign** (carpedal spasm) as indicators of hypocalcemia. * **ECG Finding:** The most characteristic finding in hypocalcemia is **QT interval prolongation** [1]. * **Basal Ganglia Calcification:** A classic radiological association with chronic hypoparathyroidism due to high phosphate levels.

Q: A 20-year-old woman with Hirschsprung disease presents with acute leg pain. An X-ray film of the leg reveals a fracture of the left tibia. Laboratory studies show elevated serum levels of calcium and parathyroid hormone. A CT scan of the patient's neck demonstrates a solitary parathyroid mass. Two years later, the patient presents with hypertension, and a CT scan of the abdomen displays a 4-cm mass in the right adrenal. Genetic studies conducted on this patient would likely reveal germline mutations in which of the following protooncogenes?

RET. **Explanation:** The clinical presentation describes a classic case of **Multiple Endocrine Neoplasia Type 2A (MEN 2A)**. The patient exhibits primary hyperparathyroidism (elevated calcium/PTH, parathyroid mass) and a pheochromocytoma (hypertension, adrenal mass). The crucial diagnostic clue is the history of **Hirschsprung disease**, which is strongly associated with germline mutations in the **RET proto-oncogene**. 1. **Why RET is correct:** The *RET* gene (located on chromosome 10) encodes a receptor tyrosine kinase. Gain-of-function mutations lead to MEN 2A (Medullary Thyroid Carcinoma, Pheochromocytoma, and Parathyroid hyperplasia) and MEN 2B. Interestingly, loss-of-function mutations in the same *RET* gene are the most common genetic cause of Hirschsprung disease. 2. **Why other options are incorrect:** * **BRCA1:** Associated with hereditary breast and ovarian cancer syndromes. * **Rb:** A tumor suppressor gene associated with Retinoblastoma and Osteosarcoma. * **VHL:** Associated with Von Hippel-Lindau syndrome (Hemangioblastomas, Renal Cell Carcinoma, and Pheochromocytoma), but it does not involve parathyroid tumors or Hirschsprung disease. **High-Yield Clinical Pearls for NEET-PG:** * **MEN 2A (Sipple Syndrome):** MPH — **M**edullary Thyroid CA (100%), **P**heochromocytoma, **H**yperparathyroidism. * **MEN 2B (Williams-Pollock Syndrome):** MMP — **M**edullary Thyroid CA, **M**arfanoid habitus/Mucosal neuromas, **P**heochromocytoma. * **Prophylactic Thyroidectomy:** Recommended for *RET* mutation carriers because Medullary Thyroid Carcinoma is nearly 100% penetrant. * **Screening:** Always rule out Pheochromocytoma (via urinary/plasma metanephrines) before any surgery to prevent a hypertensive crisis.

Question 1

Addison's disease is associated with all of the following except:

Accepted Answer

Low renin levels

Answer

Cardiac atrophy

Answer

Decreased diastolic blood pressure

Answer

Serum cortisol < 8

Question 2

A 52-year-old woman presents with polyuria, polydypsia, constipation, and fatigue. She has no significant past medical history and is not on any medications. She was recently diagnosed with hyperparathyroidism. What are the characteristic ECG findings in this condition?

Accepted Answer

Shortening of the QT interval

Answer

Shortened PR interval

Answer

Lengthened PR interval

Answer

Lengthened QU interval

Question 3

A patient with hypoglycemia fails to regain consciousness even after blood glucose levels are restored to normal. What complication should be suspected?

Accepted Answer

Cerebral edema

Answer

Lacunar infarct

Answer

Postictal state

Answer

Cerebral hemorrhage

Question 4

What is the leading cause of ACTH-independent Cushing syndrome?

Accepted Answer

Adrenocortical adenoma

Answer

Adrenocortical carcinoma

Answer

Macronodular adrenal hyperplasia

Answer

Micronodular adrenal hyperplasia

Question 5

Which of the following drugs is NOT used in the treatment of idiopathic hypercalcemia?

Accepted Answer

Thiazide

Answer

Allopurinol

Answer

Furosemide

Answer

Acetazolamide

Question 6

A patient presents with hypercalcemia and a suppressed parathyroid hormone level. What is the most likely diagnosis?

Accepted Answer

Hodgkin's lymphoma

Answer

Hyperthyroidism

Answer

Parathyroid carcinoma

Answer

Small-cell lung cancer

Question 7

Which is the screening test for evaluation of mineralocorticoid excess?

Accepted Answer

Aldosterone renin ratio

Answer

Saline infusion test

Answer

Salt loading test

Answer

Cosyntropin test

Question 8

A 26-year-old man was admitted with electrolyte disturbances. Which of the following is typically NOT seen in primary hyperaldosteronism?

Accepted Answer

Pedal edema

Answer

Diastolic hypertension

Answer

Polyuria

Answer

Hypokalemia

Question 9

Low serum calcium and high serum phosphate are typically seen in which condition?

Accepted Answer

Hypoparathyroidism

Answer

Hyperparathyroidism

Answer

Hyperthyroidism

Answer

Hypothyroidism

Question 10

A 20-year-old woman with Hirschsprung disease presents with acute leg pain. An X-ray film of the leg reveals a fracture of the left tibia. Laboratory studies show elevated serum levels of calcium and parathyroid hormone. A CT scan of the patient's neck demonstrates a solitary parathyroid mass. Two years later, the patient presents with hypertension, and a CT scan of the abdomen displays a 4-cm mass in the right adrenal. Genetic studies conducted on this patient would likely reveal germline mutations in which of the following protooncogenes?

Accepted Answer

RET

Answer

BRCA1

Answer

Rb

Answer

VHL

Endocrinology — MCQs

Endocrinology — MCQs

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