Endocrinology Practice Questions

Q: Congenital 17-hydroxylase deficiency leads to hypertension due to the accumulation of which substance?

Deoxycorticosterone. In **17α-hydroxylase deficiency**, there is a complete block in the conversion of Pregnenolone to 17-OH Pregnenolone and Progesterone to 17-OH Progesterone. This shunts the steroid biosynthetic pathway exclusively toward the mineralocorticoid pathway (the "outer" layer of the adrenal cortex). [1] **Why Deoxycorticosterone (DOC) is the correct answer:** Because the 17-alpha-hydroxylase enzyme is missing, precursors are diverted to produce excessive amounts of **11-Deoxycorticosterone (DOC)** and Corticosterone. DOC is a potent mineralocorticoid. Its accumulation leads to sodium and water retention, volume expansion, and subsequent **hypertension** and hypokalemia. [1] This volume expansion also causes a feedback suppression of Renin and Aldosterone (resulting in "Low-Renin Hypertension"). **Analysis of Incorrect Options:** * **B. Corticosterone:** While corticosterone levels are also elevated, it has much weaker mineralocorticoid activity compared to DOC. DOC is the primary driver of the hypertensive phenotype. * **C & D. 17-hydroxy pregnanediol / 17-hydroxyprogesterone:** These are products/intermediates *downstream* of the 17-hydroxylase enzyme. In this deficiency, these levels are characteristically **low or absent**. (Note: 17-OHP is elevated in 21-hydroxylase deficiency, not 17-hydroxylase deficiency). **NEET-PG High-Yield Pearls:** * **Clinical Triad:** Hypertension + Hypokalemia + Primary Amenorrhea/Delayed Puberty (due to lack of sex steroids). * **Genotype/Phenotype:** Females (46,XX) present with primary amenorrhea; Males (46,XY) present with female external genitalia or ambiguous genitalia (Pseudohermaphroditism) because testosterone cannot be synthesized. * **Key Lab Finding:** Low Renin, Low Aldosterone, Low Cortisol, and Low Sex Steroids.

Q: Which of the following is NOT a characteristic of hypocalcemia?

Shortening of the Q-T interval in ECG.. 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.

Q: 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?

MEN 1. **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.

Q: Acromegaly is associated with all of the following EXCEPT:

Muscle hypertrophy. **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].

Q: Which of the following is NOT used in the management of painful diabetic neuropathy?

Dextroamphetamine. **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.

Q: 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?

High urine output due to diuretics. 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 1

Congenital 17-hydroxylase deficiency leads to hypertension due to the accumulation of which substance?

Accepted Answer

Deoxycorticosterone

Answer

Corticosterone

Answer

17-hydroxy pregnanediol

Answer

17-hydroxyprogesterone

Question 2

Which of the following is NOT a characteristic of hypocalcemia?

Accepted Answer

Shortening of the Q-T interval in ECG.

Answer

Numbness and tingling of the circumoral region.

Answer

Hyperactive tendon reflexes and positive Chvostek's sign.

Answer

Carpopedal spasm.

Question 3

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?

Accepted Answer

MEN 1

Answer

PGA 1

Answer

MEN 2

Answer

Autoimmune polyendocrinopathy

Question 4

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?

Accepted Answer

Cells of neural crest origin that migrated to the adrenal medulla

Answer

Preganglionic sympathetic axons in thoracic splanchnic nerves

Answer

Preganglionic parasympathetic branches of the posterior vagal trunk

Answer

Postganglionic parasympathetic branches of the left or right vagus nerves

Question 5

Estimation of serum calcium (S. Ca2+) should be done only after estimation of which of the following?

Accepted Answer

Serum phosphate (S. Phosphate)

Answer

Urine calcium

Answer

Total plasma protein

Answer

Serum potassium (S. K+)

Question 6

What is true about pseudohypoparathyroidism?

Accepted Answer

Increased parathyroid hormone

Answer

Dystrophic calcification

Answer

Decreased serum calcium

Answer

Decreased serum phosphate

Question 7

What is the most characteristic symptom in a patient diagnosed with Pheochromocytoma?

Accepted Answer

Paroxysmal hypertension

Answer

Sweating attacks

Answer

Weight loss

Answer

Orthostatic hypotension

Question 8

Acromegaly is associated with all of the following EXCEPT:

Accepted Answer

Muscle hypertrophy

Answer

Nasal sinus enlargement

Answer

Increased heel pad thickness

Answer

Diabetes mellitus

Question 9

Which of the following is NOT used in the management of painful diabetic neuropathy?

Accepted Answer

Dextroamphetamine

Answer

Phenytoin

Answer

Local use of capsicum

Answer

Amitriptyline

Question 10

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?

Accepted Answer

High urine output due to diuretics

Answer

Diabetes insipidus

Answer

Excessive infusion of normal saline

Answer

Cerebral salt-wasting syndrome

Endocrinology — MCQs

Endocrinology — MCQs

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