Endocrinology — MCQs
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Which of the following is NOT a characteristic of hypocalcemia?
A patient presents with polyuria and elevated prolactin levels. There is a family history of the father dying due to renal stones. The patient has a Ca2+ of 12 g% and PTH levels of 260 IU/L. What is the most likely diagnosis?
A 30-year-old female patient complains of weakness and fatigability over the past 6 months. She has a 3-month history of severe hypertension unresponsive to antihypertensive medications. Fasting serum glucose is 140 mg/dl. A CT scan of the abdomen shows a 6-cm mass in the adrenal gland affecting the secretory cells of the adrenal medulla. Which of the following structures is most likely releasing products into the bloodstream to produce the hypertension and other signs?
Estimation of serum calcium (S. Ca2+) should be done only after estimation of which of the following?
What is true about pseudohypoparathyroidism?
What is the most characteristic symptom in a patient diagnosed with Pheochromocytoma?
Acromegaly is associated with all of the following EXCEPT:
Which of the following is NOT used in the management of painful diabetic neuropathy?
A patient admitted to the Intensive Care Unit following a head injury presented with signs of raised intracranial pressure. The patient was ventilated and managed with intravenous fluids and diuretics. Twenty-four hours later, the patient's urine output was 3.5 liters, serum sodium was 156 mEq/L, and serum osmolality was 316 mOsm/kg. Based on these parameters, what is the most likely diagnosis?
All are true about central hypothyroidism except?
Endocrinology Indian Medical PG Practice Questions and MCQs
Question 961: Which of the following is NOT a characteristic of hypocalcemia?
- A. Numbness and tingling of the circumoral region.
- B. Hyperactive tendon reflexes and positive Chvostek's sign.
- C. Shortening of the Q-T interval in ECG. (Correct Answer)
- D. Carpopedal spasm.
Explanation: The correct answer is **C (Shortening of the Q-T interval in ECG)** because hypocalcemia actually causes **prolongation of the QT interval**. [1] **1. Why Option C is the correct answer:** In hypocalcemia, the plateau phase (Phase 2) of the cardiac action potential is lengthened because the movement of calcium through L-type channels is delayed. This results in a prolonged ST segment and, consequently, a **prolonged QT interval** [1]. Conversely, *shortening* of the QT interval is a classic hallmark of **hypercalcemia**. **2. Why the other options are incorrect (Characteristics of Hypocalcemia):** * **Option A (Circumoral numbness):** Low extracellular calcium lowers the threshold for depolarization in peripheral nerves, leading to sensory symptoms like paresthesia (tingling) around the mouth and in the fingertips. * **Option B (Hyperactive reflexes & Chvostek's sign):** Hypocalcemia increases neuromuscular irritability. **Chvostek’s sign** is the twitching of facial muscles elicited by tapping the facial nerve. Tendon reflexes become brisk (hyperreflexia) due to this neuronal excitability. * **Option D (Carpopedal spasm):** This is a form of tetany characterized by adduction of the thumb, flexion of the MCP joints, and extension of interphalangeal joints. It can be elicited clinically as **Trousseau’s sign** by inflating a BP cuff above systolic pressure. **NEET-PG High-Yield Pearls:** * **Trousseau’s sign** is more sensitive and specific for latent tetany than Chvostek’s sign. * **Correction Formula:** Always check "Corrected Calcium" if albumin is low: *Corrected Ca = Measured Ca + 0.8 × (4.0 - Albumin).* [1] * **Basal Ganglia Calcification:** Chronic hypoparathyroidism (causing hypocalcemia) can lead to ectopic calcification in the brain. * **Hungry Bone Syndrome:** A common cause of postoperative hypocalcemia following parathyroidectomy for hyperparathyroidism.
Question 962: A patient presents with polyuria and elevated prolactin levels. There is a family history of the father dying due to renal stones. The patient has a Ca2+ of 12 g% and PTH levels of 260 IU/L. What is the most likely diagnosis?
- A. MEN 1 (Correct Answer)
- B. PGA 1
- C. MEN 2
- D. Autoimmune polyendocrinopathy
Explanation: **Explanation:** The clinical presentation points towards **Multiple Endocrine Neoplasia Type 1 (MEN 1)**, also known as Wermer’s Syndrome. This autosomal dominant condition is characterized by the "3 Ps": **P**arathyroid, **P**ancreas, and **P**ituitary tumors. [1] 1. **Parathyroid (95% of cases):** The patient has hypercalcemia (12 mg/dL) and significantly elevated PTH (260 IU/L), indicating primary hyperparathyroidism. [3] The family history of renal stones in the father suggests a genetic predisposition to hypercalcemia [1] and occasionally, primary hyperparathyroidism presents with severe life-threatening hypercalcemia often due to dehydration. [3] 2. **Pituitary (30-40%):** Elevated prolactin levels indicate a prolactinoma, the most common pituitary tumor in MEN 1. 3. **Pancreas:** While not explicitly mentioned, polyuria in this context could be due to hypercalcemia (nephrogenic diabetes insipidus) [2] or potentially a co-existing gastrinoma/insulinoma. **Why other options are incorrect:** * **MEN 2:** Characterized by Medullary Thyroid Carcinoma and Pheochromocytoma. While MEN 2A includes hyperparathyroidism, it does **not** involve pituitary tumors (prolactinoma). * **PGA 1 (APS-1):** Characterized by the triad of Chronic Mucocutaneous Candidiasis, Autoimmune Hypoparathyroidism (low calcium), and Addison’s disease. This patient has *high* calcium. * **Autoimmune Polyendocrinopathy:** Usually involves glandular destruction (hypofunction) rather than the hormone-secreting tumors seen here. **Clinical Pearls for NEET-PG:** * **MEN 1 Gene:** Located on Chromosome **11q13** (encodes Menin protein). * **First manifestation:** Hyperparathyroidism is usually the earliest and most common sign of MEN 1. * **Screening:** In suspected MEN 1, the most sensitive initial screen is ionized calcium and PTH. [1] * **Pituitary:** Prolactinoma is the most common, followed by GH-secreting tumors.
Question 963: A 30-year-old female patient complains of weakness and fatigability over the past 6 months. She has a 3-month history of severe hypertension unresponsive to antihypertensive medications. Fasting serum glucose is 140 mg/dl. A CT scan of the abdomen shows a 6-cm mass in the adrenal gland affecting the secretory cells of the adrenal medulla. Which of the following structures is most likely releasing products into the bloodstream to produce the hypertension and other signs?
- A. Preganglionic sympathetic axons in thoracic splanchnic nerves
- B. Cells of neural crest origin that migrated to the adrenal medulla (Correct Answer)
- C. Preganglionic parasympathetic branches of the posterior vagal trunk
- D. Postganglionic parasympathetic branches of the left or right vagus nerves
Explanation: ### Explanation **Correct Option: B (Cells of neural crest origin that migrated to the adrenal medulla)** The clinical presentation of severe, resistant hypertension, hyperglycemia (fasting glucose 140 mg/dl), and a 6-cm adrenal medullary mass is classic for a **Pheochromocytoma**. The adrenal medulla is embryologically derived from **Neural Crest Cells**. These cells migrate into the center of the developing adrenal cortex and differentiate into **Chromaffin cells** (modified postganglionic sympathetic neurons). These cells act as the secretory units of the medulla, releasing catecholamines (epinephrine and norepinephrine) directly into the bloodstream. In pheochromocytoma, the neoplastic proliferation of these cells leads to excessive catecholamine secretion, causing the "classic triad" of headaches, palpitations, and diaphoresis, alongside resistant hypertension. **Why Incorrect Options are Wrong:** * **Option A:** Preganglionic sympathetic fibers (via thoracic splanchnic nerves) *innervate* the chromaffin cells to trigger secretion but do not release the products that cause systemic hypertension. * **Options C & D:** The adrenal medulla has no parasympathetic innervation. The vagus nerve does not play a role in the secretion of catecholamines or the pathophysiology of adrenal-mediated hypertension. --- ### NEET-PG High-Yield Pearls * **Rule of 10s for Pheochromocytoma:** 10% bilateral, 10% malignant, 10% pediatric, 10% extra-adrenal (Paragangliomas), and 10% familial. * **Embryology:** Adrenal **Cortex** is derived from **Mesoderm**, while the **Medulla** is derived from **Neural Crest** (Ectoderm). * **Diagnosis:** Best initial screening test is **Plasma free metanephrines**; most specific is **24-hour urinary metanephrines/catecholamines**. * **Management:** Always give **Alpha-blockers first** (e.g., Phenoxybenzamine) before Beta-blockers to avoid an "unopposed alpha" hypertensive crisis [1].
Question 964: Estimation of serum calcium (S. Ca2+) should be done only after estimation of which of the following?
- A. Urine calcium
- B. Total plasma protein
- C. Serum phosphate (S. Phosphate) (Correct Answer)
- D. Serum potassium (S. K+)
Explanation: ### Explanation The correct answer is **Serum phosphate (S. Phosphate)**. **Why Serum Phosphate is the Priority:** In clinical practice, the interpretation of serum calcium levels is inseparable from serum phosphate levels. Both ions are regulated by the same hormonal axis—primarily **Parathyroid Hormone (PTH)** and **Vitamin D** [2][3]. 1. **The Calcium-Phosphate Product:** The product of $[Ca^{2+}] \times [PO_4^{3-}]$ is a critical clinical marker. If this product exceeds **55–60 mg²/dL²**, there is a high risk of metastatic calcification (precipitation of calcium phosphate crystals in soft tissues like kidneys, heart, and blood vessels). 2. **Diagnostic Differentiation:** Measuring phosphate helps differentiate the etiology of calcium imbalances [4]. For example, in **Primary Hyperparathyroidism**, calcium is high while phosphate is low. In **Hypoparathyroidism** or **Chronic Kidney Disease (CKD)**, calcium is low while phosphate is high. Evaluating calcium without phosphate leads to an incomplete diagnostic picture. **Analysis of Incorrect Options:** * **A. Urine Calcium:** This is usually a secondary investigation (e.g., to rule out Familial Hypocalciuric Hypercalcemia) performed *after* an abnormal serum calcium is detected [4]. * **B. Total Plasma Protein:** While serum **Albumin** is necessary to calculate "Corrected Calcium," the question asks for the most critical concurrent electrolyte [1]. Phosphate is physiologically more significant for immediate clinical safety and diagnosis. * **D. Serum Potassium:** While important for general metabolic screening, potassium regulation is independent of the PTH-Vitamin D axis. **High-Yield Clinical Pearls for NEET-PG:** * **Corrected Calcium Formula:** $\text{Measured Ca} + [0.8 \times (4.0 - \text{Albumin})]$. Always check albumin if calcium is low [1]. * **Hypomagnesemia:** If a patient has refractory hypocalcemia that doesn't respond to calcium supplements, check **Magnesium** levels (Magnesium is required for PTH secretion and action) [5]. * **Hungry Bone Syndrome:** Characterized by profound hypocalcemia and hypophosphatemia following a parathyroidectomy.
Question 965: What is true about pseudohypoparathyroidism?
- A. Dystrophic calcification
- B. Decreased serum calcium
- C. Decreased serum phosphate
- D. Increased parathyroid hormone (Correct Answer)
Explanation: **Explanation:** **Pseudohypoparathyroidism (PHP)** is a rare genetic disorder characterized by **target organ resistance** to Parathyroid Hormone (PTH). The defect typically lies in the Gsα subunit of the G protein-coupled receptor signaling pathway [2]. 1. **Why Option D is Correct:** Because the kidneys and bones are resistant to PTH, the body perceives a state of PTH deficiency despite the hormone being present. In response to low serum calcium and high phosphate, the parathyroid glands undergo hyperplasia and secrete **increased amounts of PTH** to overcome the resistance [1]. This "biochemical footprint" (High PTH + Low Calcium + High Phosphate) is the hallmark of PHP. 2. **Why Other Options are Incorrect:** * **Option B:** While decreased serum calcium (hypocalcemia) is a classic finding in PHP, it is **not the defining feature** that distinguishes it from true hypoparathyroidism. In the context of NEET-PG questions, when "Increased PTH" is an option, it is the more specific physiological marker for "pseudo" states. * **Option C:** Due to PTH resistance in the proximal tubule, there is a failure to inhibit phosphate reabsorption [1]. This leads to **increased serum phosphate** (hyperphosphatemia), not decreased. * **Option D:** While ectopic ossification can occur in Albright Hereditary Osteodystrophy (AHO), "dystrophic calcification" is a general pathological term and is less specific to the biochemical diagnosis of PHP than elevated PTH. **High-Yield Clinical Pearls for NEET-PG:** * **Albright Hereditary Osteodystrophy (AHO):** The physical phenotype of PHP Type 1a, characterized by short stature, round face, obesity, and **short 4th/5th metacarpals** (Archibald’s sign). * **Pseudopseudohypoparathyroidism (PPHP):** Patients have the AHO phenotype but **normal** biochemical levels (Normal PTH, Ca, and PO4) because the genetic defect is inherited paternally (genomic imprinting) [1]. * **Diagnostic Test:** Failure of urinary cAMP and phosphate levels to rise following an infusion of exogenous PTH (Ellsworth-Howard Test) [2].
Question 966: What is the most characteristic symptom in a patient diagnosed with Pheochromocytoma?
- A. Sweating attacks
- B. Weight loss
- C. Orthostatic hypotension
- D. Paroxysmal hypertension (Correct Answer)
Explanation: ### **Explanation** **Correct Answer: D. Paroxysmal hypertension** **Medical Concept:** Pheochromocytoma is a catecholamine-secreting tumor arising from the chromaffin cells of the adrenal medulla [2]. The hallmark of this condition is **hypertension**, which occurs due to the episodic or continuous release of norepinephrine and epinephrine [2]. While 50% of patients have sustained hypertension, the **most characteristic** presentation is **paroxysmal hypertension** (sudden, severe spikes in blood pressure), often triggered by physical activity, abdominal pressure, or certain medications. **Analysis of Options:** * **A. Sweating attacks:** This is part of the classic "triad" (Headache, Sweating, Palpitations). While highly suggestive when occurring with hypertension, it is a secondary symptom rather than the primary characteristic sign. * **B. Weight loss:** Catecholamines increase the basal metabolic rate, leading to weight loss. However, this is a non-specific finding seen in many endocrine and neoplastic disorders. * **C. Orthostatic hypotension:** This occurs due to low plasma volume and impaired sympathetic reflexes in these patients. While a high-yield clinical sign, it is less common and less characteristic than hypertension itself. **High-Yield Clinical Pearls for NEET-PG:** * **The Rule of 10s:** 10% are bilateral, 10% are extra-adrenal (Paragangliomas), 10% are malignant, and 10% are familial. * **Classic Triad:** Episodic headache, sweating, and palpitations (High specificity if all three are present with hypertension). * **Diagnosis:** Best initial screening test is **Plasma free metanephrines**; most specific confirmatory test is **24-hour urinary metanephrines and catecholamines** [1]. Serum chromogranin A is often elevated and may be a useful tumour marker [1]. * **Management:** Always give **Alpha-blockers (e.g., Phenoxybenzamine)** before Beta-blockers to avoid a hypertensive crisis (unopposed alpha-stimulation). Medical therapy is required to prepare the patient for surgery [1].
Question 967: Acromegaly is associated with all of the following EXCEPT:
- A. Nasal sinus enlargement
- B. Increased heel pad thickness
- C. Diabetes mellitus
- D. Muscle hypertrophy (Correct Answer)
Explanation: **Explanation:** In Acromegaly, the chronic hypersecretion of Growth Hormone (GH) leads to the overgrowth of bone and soft tissues [1]. However, the effect on skeletal muscle is paradoxical. **Why "Muscle Hypertrophy" is the correct answer:** While GH is an anabolic hormone, the prolonged excess in acromegaly leads to **proximal myopathy** rather than true hypertrophy. Although the muscles may appear large due to increased connective tissue and water retention (pseudohypertrophy), they are functionally weak. Patients typically present with **muscle weakness** and easy fatigability, not increased strength or functional hypertrophy. **Analysis of Incorrect Options:** * **Nasal sinus enlargement:** GH stimulates the growth of facial bones, leading to frontal bossing and enlargement of the paranasal sinuses (contributing to the characteristic "hollow" resonance of the voice). * **Increased heel pad thickness:** This is a classic radiological sign of acromegaly. A heel pad thickness **>21 mm in females and >25 mm in males** is highly suggestive of the condition. * **Diabetes mellitus:** GH is a counter-regulatory hormone that antagonizes insulin action and increases hepatic glucose production [2]. Approximately 25-50% of acromegalic patients develop secondary Diabetes Mellitus or Impaired Glucose Tolerance. **High-Yield Clinical Pearls for NEET-PG:** * **Best Screening Test:** Serum IGF-1 levels (more stable than GH) [2]. * **Confirmatory Test:** Oral Glucose Tolerance Test (OGTT)—failure to suppress GH to <0.4 ng/mL after 75g glucose [3]. * **Most Common Cause:** Pituitary Somatotroph Adenoma [2]. * **Associated Features:** Carpal Tunnel Syndrome, Sleep Apnea, and increased risk of **Colon Polyps/Cancer** [3].
Question 968: Which of the following is NOT used in the management of painful diabetic neuropathy?
- A. Phenytoin
- B. Local use of capsicum
- C. Dextroamphetamine (Correct Answer)
- D. Amitriptyline
Explanation: **Explanation:** The management of painful diabetic neuropathy focuses on modulating neurotransmitters involved in pain signaling (Serotonin, Norepinephrine, and GABA) or blocking sodium channels. **Why Dextroamphetamine is the correct answer:** Dextroamphetamine is a central nervous system (CNS) stimulant primarily used for ADHD and narcolepsy. It has **no established role** in the clinical management of neuropathic pain. While it increases synaptic dopamine and norepinephrine, it does not provide the peripheral or spinal cord analgesia required for diabetic neuropathy and carries a high risk of addiction and cardiovascular side effects. **Analysis of other options:** * **Amitriptyline:** A Tricyclic Antidepressant (TCA) and often the **first-line agent**. It inhibits the reuptake of serotonin and norepinephrine, enhancing descending inhibitory pain pathways. * **Phenytoin:** An antiepileptic that acts as a sodium channel blocker. While newer agents like Pregabalin or Gabapentin are now preferred, Phenytoin was historically used to stabilize neuronal membranes and reduce ectopic discharges in painful neuropathy. * **Local use of Capsicum (Capsaicin):** Derived from chili peppers, topical capsaicin cream desensitizes nociceptors by depleting **Substance P** from peripheral sensory neurons. **NEET-PG High-Yield Pearls:** * **First-line drugs:** Pregabalin (Calcium channel α2-δ ligand), Duloxetine (SNRI), or Amitriptyline (TCA). * **FDA-approved specifically for DPNP:** Pregabalin and Duloxetine. * **Topical therapy:** Capsaicin cream or Lidocaine patches are useful for localized symptoms. * **Mechanism of TCAs:** Inhibition of norepinephrine and serotonin reuptake + Sodium channel blockade.
Question 969: A patient admitted to the Intensive Care Unit following a head injury presented with signs of raised intracranial pressure. The patient was ventilated and managed with intravenous fluids and diuretics. Twenty-four hours later, the patient's urine output was 3.5 liters, serum sodium was 156 mEq/L, and serum osmolality was 316 mOsm/kg. Based on these parameters, what is the most likely diagnosis?
- A. High urine output due to diuretics (Correct Answer)
- B. Diabetes insipidus
- C. Excessive infusion of normal saline
- D. Cerebral salt-wasting syndrome
Explanation: The patient presents with polyuria (3.5 L/day), hypernatremia (156 mEq/L), and high serum osmolality (316 mOsm/kg) following management for raised intracranial pressure (ICP). **Why Option A is correct:** In the management of raised ICP, osmotic diuretics like **Mannitol** are the gold standard. Mannitol works by creating an osmotic gradient that draws fluid from the brain parenchyma into the intravascular space, which is then excreted by the kidneys. This leads to an **osmotic diuresis**, resulting in high urine output and a relative loss of free water, which explains the elevated serum sodium and osmolality [1]. **Why the other options are incorrect:** * **B. Diabetes Insipidus (DI):** While DI (Central or Nephrogenic) causes polyuria and hypernatremia, it typically presents with **low urine osmolality** (dilute urine). In the context of ICU management for head injury, diuretic use is a more immediate pharmacological cause for these lab values. * **C. Excessive Normal Saline:** While this could cause hypernatremia, it would not typically result in significant polyuria unless the kidneys are compensating perfectly; furthermore, it doesn't align with the specific management protocol for raised ICP. * **D. Cerebral Salt-Wasting (CSW):** CSW presents with polyuria but is characterized by **hyponatremia** and volume depletion due to excessive renal sodium excretion, which contradicts this patient’s hypernatremic state. **Clinical Pearls for NEET-PG:** * **Mannitol Side Effects:** Initial volume expansion (risk of pulmonary edema) followed by osmotic diuresis leading to dehydration and hypernatremia [1]. * **DI vs. CSW vs. SIADH:** * **DI:** High Na+, High Osmolality, Low Urine Osmolality. * **CSW:** Low Na+, High Urine Na+, Hypovolemia. * **SIADH:** Low Na+, High Urine Osmolality, Euvolemia. * Always check the **medication history** in ICU scenarios before diagnosing primary endocrine disorders.
Question 970: All are true about central hypothyroidism except?
- A. Craniopharyngioma
- B. Treatment is guided by TSH levels in plasma (Correct Answer)
- C. TSH level is not a good marker for diagnosis
- D. Before starting treatment, check for adrenal insufficiency
Explanation: **Explanation:** Central hypothyroidism (secondary/tertiary) occurs due to pathology in the pituitary gland or hypothalamus, leading to insufficient TSH production or activity [3]. **1. Why Option B is the Correct Answer (The False Statement):** In central hypothyroidism, the TSH level is unreliable because the pituitary is the source of the pathology. TSH may be low, inappropriately "normal," or even slightly elevated (due to biologically inactive TSH) [2]. Therefore, **treatment is guided by Free T4 (FT4) levels**, aiming for the upper half of the reference range [2]. Using TSH to monitor therapy would lead to under-treatment. **2. Analysis of Other Options:** * **Option A (Craniopharyngioma):** This is the most common tumor causing central hypothyroidism in children and young adults by compressing the hypothalamus or pituitary stalk. * **Option C (TSH not a good marker for diagnosis):** Correct. Diagnosis relies on finding a **low Free T4** in the presence of a TSH that is not appropriately elevated (low or normal). * **Option D (Check for adrenal insufficiency):** Crucial clinical step. Central hypothyroidism often coexists with ACTH deficiency. Starting Levothyroxine before Glucocorticoids can precipitate an **acute adrenal crisis** by increasing the metabolic clearance of the little cortisol remaining [2]. **High-Yield Clinical Pearls for NEET-PG:** * **Rule of Thumb:** In Primary Hypothyroidism, follow TSH. In Central Hypothyroidism, follow Free T4 [2]. * **The "Pituitary-Adrenal" Rule:** Always rule out or treat adrenal insufficiency *before* thyroid replacement in any patient with suspected pituitary disease [2]. * **Common Causes:** Pituitary adenomas (most common in adults), Sheehan syndrome, trauma, and surgery/radiation [1].
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Diabetes Mellitus
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Thyroid Disorders
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Adrenal Gland Disorders
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Pituitary Disorders
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Calcium and Bone Metabolism
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Reproductive Endocrinology
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Lipid Disorders
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Endocrine Hypertension
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Multiple Endocrine Neoplasia
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Obesity and Metabolic Syndrome
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Neuroendocrine Tumors
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Endocrine Emergencies
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