Endocrinology — MCQs

A 27-year-old woman presents with weight loss, fatigue, and weakness. She also experiences nausea and vomiting but no dysphagia. Her physical examination is normal except for increased generalized skin pigmentation. Her serum sodium is low and potassium is high. Which of the following features is also most likely to be present?

Q949Medium

A 28-year-old man has semen analysis suggestive of azoospermia on two occasions, one month apart. FSH is normal and testosterone is normal. What is the most probable cause?

Q950Easy

Which of the following is NOT a consequence of primary hyperaldosteronism?

Endocrinology Indian Medical PG Practice Questions and MCQs

Question 941: In Type I Diabetes Mellitus, which of the following statements are true?

A. 90% family history
B. Antibodies against beta cells (Correct Answer)
C. Insulin is given to treat Diabetic Ketoacidosis
D. Diabetic Ketoacidosis occurrence

Explanation: **Explanation:** **Type 1 Diabetes Mellitus (T1DM)** is characterized by an absolute deficiency of insulin due to the autoimmune destruction of pancreatic beta cells. 1. **Why Option B is Correct:** The hallmark of T1DM (specifically Type 1A) is the presence of **autoantibodies** against beta-cell antigens [2]. These include **Anti-GAD65** (most common), **IA-2** (Insulinoma-associated protein 2), **ZnT8** (Zinc transporter 8), and **Islet Cell Antibodies (ICA)**. These markers confirm the autoimmune etiology and are often present years before clinical symptoms appear. 2. **Why Other Options are Incorrect:** * **Option A:** T1DM has a relatively **weak genetic link** compared to Type 2 DM. Only about 10–15% of patients have a positive family history [1]. In contrast, Type 2 DM has a >90% concordance in identical twins. In T1DM, identical twin concordance is significantly lower (around 33-35%) [1], [2]. * **Option C & D:** While these statements are clinically "true" (DKA is a common presentation and is treated with insulin), they are **complications or management strategies**, not the defining pathophysiological characteristic of the disease itself. In NEET-PG "Single Best Answer" formats, the underlying pathology (autoimmunity) takes precedence over clinical features. **High-Yield Clinical Pearls for NEET-PG:** * **HLA Association:** Strongly linked with **HLA-DR3 and HLA-DR4** [2]. HLA-DQB1*0602 provides protection. * **The "Honeymoon Phase":** A temporary period after diagnosis where exogenous insulin requirements decrease due to residual beta-cell function. * **Diagnosis:** Fasting Plasma Glucose ≥126 mg/dL or HbA1c ≥6.5%. * **Associated Conditions:** Always screen for other autoimmune diseases like Celiac disease and Hashimoto’s thyroiditis [1].

Question 942: All are features of Cushing's syndrome EXCEPT?

A. Violaceous striae
B. Hyperkalemia (Correct Answer)
C. Thin skin
D. Hypertension

Explanation: **Explanation:** Cushing’s syndrome results from chronic exposure to excess glucocorticoids (cortisol). The correct answer is **Hyperkalemia** because Cushing’s syndrome is actually associated with **Hypokalemia**, not hyperkalemia. **1. Why Hyperkalemia is the correct answer (The Exception):** Cortisol, when present in high concentrations, overwhelms the enzyme 11β-hydroxysteroid dehydrogenase type 2 (11β-HSD2), which normally inactivates cortisol in the kidneys. Consequently, excess cortisol binds to **mineralocorticoid receptors**, acting like aldosterone. This leads to sodium retention and increased urinary excretion of potassium and hydrogen ions, resulting in **hypokalemic metabolic alkalosis**. **2. Why the other options are features of Cushing’s:** * **Violaceous striae:** Excess cortisol inhibits fibroblasts and causes loss of collagen [1]. This leads to thinning of the dermis; the purple color (striae >1cm) arises from the visualization of underlying vascular subcutaneous tissue. * **Thin skin:** Protein catabolism leads to skin atrophy and easy bruising (ecchymosis), a hallmark clinical sign [1]. * **Hypertension:** Occurs due to the mineralocorticoid effect (sodium retention), increased sensitivity to catecholamines, and increased production of angiotensinogen. **Clinical Pearls for NEET-PG:** * **Screening Test:** 24-hour urinary free cortisol or Low-Dose Dexamethasone Suppression Test (LDDST) [3]. * **Gold Standard for localization:** Inferior Petrosal Sinus Sampling (IPSS). * **Ectopic ACTH:** Classically associated with Small Cell Carcinoma of the lung; it presents with the most severe hypokalemia and hyperpigmentation [2]. * **Mnemonic:** Cushing’s = **S**odium is high, **S**ugar is high (Hyperglycemia), but **P**otassium is low.

Question 943: What is the most common cause of Addison's disease?

A. Autoimmune adrenalitis (Correct Answer)
B. Meningococcal septicemia
C. Malignancy
D. Tuberculosis

Explanation: **Explanation:** **Addison’s Disease (Primary Adrenal Insufficiency)** occurs when the adrenal cortex is destroyed, leading to a deficiency of mineralocorticoids, glucocorticoids, and androgens [1]. 1. **Why Autoimmune Adrenalitis is Correct:** In developed countries and globally today, **autoimmune adrenalitis** is the most common cause (responsible for ~80% of cases). It involves the destruction of the adrenal cortex by 21-hydroxylase antibodies [1]. It can occur in isolation or as part of Autoimmune Polyglandular Syndromes (APS I and II). 2. **Why Other Options are Incorrect:** * **Tuberculosis (D):** Historically, TB was the leading cause worldwide [2]. While it remains a significant cause in developing nations (like India), current global epidemiological trends and standardized textbooks (Harrison’s) prioritize autoimmune etiology as the most common overall. Tuberculosis causes adrenal calcification, visible on plain X-ray [1]. * **Meningococcal Septicemia (B):** This causes acute adrenal insufficiency due to bilateral adrenal hemorrhage, known as **Waterhouse-Friderichsen Syndrome**, rather than the chronic destruction seen in Addison’s. * **Malignancy (C):** Metastasis to the adrenal glands (commonly from lung or breast cancer) can cause insufficiency [1], but it is a much rarer cause compared to autoimmune or infectious processes. **High-Yield Clinical Pearls for NEET-PG:** * **Most common cause in India:** Historically TB, but recent trends show a rise in autoimmune cases. If "Autoimmune" is an option, it is the preferred answer for "most common." * **Earliest sign:** Hyperpigmentation (due to increased ACTH/MSH) and postural hypotension. * **Biochemical hallmark:** Hyponatremia, Hyperkalemia, and Metabolic Acidosis. * **Diagnosis:** Best initial test is the **ACTH Stimulation Test** (Cosyntropin test) [1].

Question 944: Which of the following is NOT a feature of hyperthyroidism?

A. Voracious appetite
B. Cold intolerance (Correct Answer)
C. Emotional disturbance
D. Sleeplessness

Explanation: The correct answer is **Cold intolerance**, which is a hallmark feature of **hypothyroidism**, not hyperthyroidism. [1] **1. Why Cold Intolerance is the Correct Answer:** Thyroid hormones ($T_3$ and $T_4$) are the primary regulators of the basal metabolic rate (BMR). In hyperthyroidism, an excess of these hormones increases mitochondrial activity and oxygen consumption, leading to **obligatory thermogenesis** (excess heat production). Consequently, patients develop **heat intolerance** and warm, moist skin. [1][3] Cold intolerance occurs when thyroid levels are low, leading to a decreased BMR and reduced heat production. **2. Analysis of Incorrect Options:** * **Voracious Appetite (A):** Hyperthyroidism induces a hypermetabolic state. Despite a significant increase in food intake (polyphagia), patients typically experience weight loss because the metabolic demand exceeds caloric intake. [1][3] * **Emotional Disturbance (C):** Excess thyroid hormone increases beta-adrenergic sensitivity in the central nervous system. This manifests as irritability, anxiety, emotional lability, and "thyroid jitters." [1] * **Sleeplessness (D):** Insomnia is a common complaint due to heightened sympathetic nervous system activity and mental hyperactivity. [1] **Clinical Pearls for NEET-PG:** * **Apathetic Hyperthyroidism:** Seen in the elderly; presents with depression and lethargy rather than typical hyperactivity. [2] * **Cardiovascular Sign:** Look for **wide pulse pressure** and **atrial fibrillation** (most common arrhythmia in hyperthyroidism). [1][2] * **Physical Exam:** Look for **Pretibial Myxedema** and **Exophthalmos**, which are specific to Graves' Disease (autoimmune) rather than general thyrotoxicosis. [1] * **Reflexes:** Hyperthyroidism is associated with "brisk" deep tendon reflexes (hyperreflexia), whereas hypothyroidism shows a delayed relaxation phase (hung-up reflex).

Question 945: Which of the following is NOT a drug therapy for Paget's disease (Osteitis Deformans)?

A. Alendronate
B. Etidronate
C. Calcitonin
D. Plicamycin (Correct Answer)

Explanation: The primary goal of treating Paget’s disease (Osteitis Deformans) is to inhibit the overactive osteoclasts that drive excessive bone remodeling [1]. **Why Plicamycin is the correct answer:** While **Plicamycin (Mithramycin)** was historically used to treat refractory Paget’s disease due to its cytotoxic effect on osteoclasts, it is **no longer considered a standard drug therapy**. Due to its severe toxicity profile—including hepatotoxicity, nephrotoxicity, and thrombocytopenia—it has been replaced by safer, more potent alternatives. In the context of modern NEET-PG questions, it is classified as "not a drug of choice" or "obsolete" compared to Bisphosphonates. **Analysis of other options:** * **Alendronate (Option A):** A potent oral nitrogen-containing bisphosphonate. It is a first-line agent that induces osteoclast apoptosis and reduces bone turnover [1]. * **Etidronate (Option B):** A first-generation (non-nitrogen) bisphosphonate. While less potent than Alendronate or Zoledronate, it was the first bisphosphonate approved for Paget’s disease [1]. * **Calcitonin (Option C):** A hormone that directly inhibits osteoclast activity. It is used in patients who cannot tolerate bisphosphonates or those with severe bone pain, though its effect is less durable [1]. **High-Yield Clinical Pearls for NEET-PG:** * **Drug of Choice:** **Zoledronic acid** (IV) is currently the most effective and preferred treatment for Paget’s disease [1]. * **Indication for Treatment:** Asymptomatic patients usually don't require treatment unless the disease involves weight-bearing bones, joints, or the skull (to prevent deafness). * **Monitoring:** Serum **Alkaline Phosphatase (ALP)** is the most common marker used to monitor disease activity and response to therapy. * **Radiology Sign:** Look for "Blade of Grass" or "Flame-shaped" lytic lesions and "Cotton wool" appearance of the skull.

Question 946: A patient presents with low serum calcium, high phosphorus, and elevated PTH. Which of the following investigations is least contributory to establishing a diagnosis?

A. Vitamin D levels (Correct Answer)
B. Serum creatinine levels
C. Cyclic AMP response to PTH
D. Urine myoglobin

Explanation: This question tests your ability to differentiate between causes of **secondary hyperparathyroidism** and **pseudohypoparathyroidism (PHP)** based on biochemical markers. ### **Explanation of the Correct Answer** The patient presents with **hypocalcemia, hyperphosphatemia, and elevated PTH**. This triad is the hallmark of **PTH resistance (Pseudohypoparathyroidism)** or **Chronic Kidney Disease (CKD)** [1]. * **Vitamin D levels (Option A):** In Vitamin D deficiency, you would expect low calcium and high PTH, but **low or normal phosphorus** (because PTH causes phosphaturia) [1], [2]. Since this patient has *high* phosphorus, Vitamin D deficiency is already ruled out biochemically, making its measurement the least contributory to the differential diagnosis. ### **Analysis of Incorrect Options** * **Serum creatinine (Option B):** Essential to rule out CKD [1]. In renal failure, phosphorus is high because it cannot be excreted [2], leading to secondary hyperparathyroidism [3]. * **Cyclic AMP response to PTH (Option C):** This is the **Ellsworth-Howard test**. In PHP Type 1, the kidney is resistant to PTH, so administering exogenous PTH fails to increase urinary cAMP. This confirms a diagnosis of PHP. * **Urine myoglobin (Option D):** Used to rule out rhabdomyolysis. Massive muscle breakdown releases intracellular phosphorus into the blood, which acutely lowers calcium and raises PTH, mimicking this biochemical profile. ### **NEET-PG High-Yield Pearls** * **Pseudohypoparathyroidism (Albright’s Hereditary Osteodystrophy):** Look for short stature, round face, and short 4th/5th metacarpals (Archibald’s sign) [1]. * **Biochemical Differentiation:** * **Hypovitaminosis D:** ↓ Ca, **↓ PO4**, ↑ PTH [1]. * **CKD/PHP:** ↓ Ca, **↑ PO4**, ↑ PTH [1]. * **Hypoparathyroidism:** ↓ Ca, ↑ PO4, **↓ PTH** [1]. * **The Ellsworth-Howard Test** is the gold standard for distinguishing between PHP types (Type 1 has no cAMP response; Type 2 has a normal cAMP response but no phosphaturic response).

Question 947: A client with head trauma develops a urine output of 300 ml/hr, dry skin, and dry mucous membranes. Which of the following nursing interventions is the most appropriate to perform initially?

A. Evaluate urine specific gravity (Correct Answer)
B. Anticipate treatment for renal failure
C. Provide emollients to the skin to prevent breakdown
D. Slow down the IV fluids and notify the physician

Explanation: ### Explanation **Correct Answer: A. Evaluate urine specific gravity** The clinical presentation of head trauma followed by massive polyuria (300 ml/hr) and signs of dehydration (dry skin/mucous membranes) is highly suggestive of **Diabetes Insipidus (DI)**. In patients with head injury, damage to the hypothalamus or posterior pituitary can lead to a deficiency in Antidiuretic Hormone (ADH), known as Central DI. The initial nursing priority is to confirm the diagnosis by assessing the concentration of the urine. In DI, the kidneys cannot concentrate urine, resulting in a **low urine specific gravity (typically <1.005)** and low urine osmolality, despite systemic dehydration. **Analysis of Incorrect Options:** * **B. Anticipate treatment for renal failure:** Renal failure usually presents with oliguria (decreased urine output) and fluid overload, which contradicts this patient’s polyuria and dehydration. * **C. Provide emollients:** While skin care is important, it is a supportive measure and not the priority intervention for a life-threatening fluid imbalance. * **D. Slow down the IV fluids:** This is contraindicated. The patient is losing massive amounts of fluid; slowing the IV rate would worsen dehydration and potentially lead to hypovolemic shock. **NEET-PG High-Yield Pearls:** * **Triad of DI:** Polyuria, Polydipsia, and Low Urine Specific Gravity. * **Diagnostic Gold Standard:** Water Deprivation Test (though often bypassed in acute trauma settings for immediate ADH/Desmopressin challenge). * **Central vs. Nephrogenic:** Central DI (ADH deficiency) responds to Desmopressin (dDAVP), whereas Nephrogenic DI (ADH resistance) does not. * **Electrolyte Hallmark:** Hypernatremia (due to loss of free water).

Question 948: A 27-year-old woman presents with weight loss, fatigue, and weakness. She also experiences nausea and vomiting but no dysphagia. Her physical examination is normal except for increased generalized skin pigmentation. Her serum sodium is low and potassium is high. Which of the following features is also most likely to be present?

A. the skin is shiny and pale
B. a diabetic glucose tolerance is characteristic
C. water diuresis is impaired (Correct Answer)
D. the urinary steroids are high

Explanation: The clinical presentation of weight loss, fatigue, hyperpigmentation, hyponatremia, and hyperkalemia is classic for **Primary Adrenocortical Insufficiency (Addison’s Disease)** [1]. **Why Option C is correct:** In Addison’s disease, the deficiency of **cortisol** leads to impaired water excretion [4]. Cortisol is essential for the suppression of Antidiuretic Hormone (ADH). In its absence, ADH levels remain inappropriately high, leading to increased water reabsorption in the collecting ducts. Additionally, the lack of cortisol reduces the glomerular filtration rate (GFR). Consequently, patients cannot excrete a water load rapidly, leading to **impaired water diuresis** and dilutional hyponatremia. **Why other options are incorrect:** * **Option A:** The skin is **hyperpigmented**, not pale. This is due to increased ACTH levels (resulting from lack of negative feedback), which cross-reacts with melanocortin-1 receptors due to the shared precursor Pro-opiomelanocortin (POMC) [1]. * **Option B:** Patients with Addison’s disease tend to have **hypoglycemia** and increased insulin sensitivity due to cortisol deficiency. A diabetic (hyperglycemic) glucose tolerance curve is not seen. * **Option C:** Urinary steroids (17-hydroxycorticosteroids and 17-ketosteroids) are **low**, reflecting the failure of the adrenal cortex to produce cortisol and androgens [3]. **High-Yield Clinical Pearls for NEET-PG:** * **Most common cause:** Autoimmune adrenalitis (Worldwide/Developed countries); Tuberculosis (historically common in India) [1], [3]. * **Electrolyte Triad:** Hyponatremia, Hyperkalemia, and Metabolic Acidosis [4]. * **Diagnosis:** The gold standard is the **ACTH Stimulation Test** (Cosyntropin test) [2]. A subnormal rise in serum cortisol confirms the diagnosis. * **Hyperpigmentation:** Specifically involves palmar creases, buccal mucosa, and recent scars. This feature is **absent** in secondary adrenal insufficiency (pituitary cause) [4].

Question 949: A 28-year-old man has semen analysis suggestive of azoospermia on two occasions, one month apart. FSH is normal and testosterone is normal. What is the most probable cause?

A. Undescended testis
B. Klinefelter's syndrome
C. Kallmann syndrome
D. Vas obstruction (Correct Answer)

Explanation: **Explanation:** The clinical scenario describes **Obstructive Azoospermia**. In this condition, the hypothalamic-pituitary-testicular axis is intact, meaning the production of sperm (spermatogenesis) and hormones is normal, but there is a physical blockage preventing sperm from entering the ejaculate [1]. 1. **Why Vas Obstruction is correct:** * **Normal FSH:** FSH is a marker of germ cell integrity. In primary testicular failure, FSH rises due to loss of negative feedback [2]. A normal FSH level indicates that spermatogenesis is likely occurring normally. * **Normal Testosterone:** This indicates that Leydig cell function and the LH axis are intact [2]. * **Azoospermia + Normal FSH/LH/Testosterone = Obstruction.** Common causes include post-inflammatory scarring (e.g., tuberculosis, chlamydia), surgical ligation (vasectomy), or congenital bilateral absence of the vas deferens (CBAVD), often associated with CFTR gene mutations [1]. 2. **Why other options are incorrect:** * **Undescended Testis:** Usually leads to testicular atrophy and germ cell failure due to higher abdominal temperatures [1]. This typically results in **elevated FSH**. * **Klinefelter’s Syndrome (47, XXY):** This is a form of hypergonadotropic hypogonadism. It presents with small, firm testes, **high FSH**, and low testosterone. * **Kallmann Syndrome:** This is hypogonadotropic hypogonadism. It presents with **low FSH, low LH**, and low testosterone, along with anosmia. **High-Yield Clinical Pearls for NEET-PG:** * **Most common cause of Obstructive Azoospermia:** Epididymal obstruction (often post-infection). * **CBAVD:** Always look for a history of recurrent respiratory infections (Cystic Fibrosis link) [1]. * **Semen Fructose:** If the obstruction is at the level of the ejaculatory ducts or there is seminal vesicle agenesis, semen fructose will be **negative** and the pH will be acidic. * **Testicular Biopsy:** In obstructive azoospermia, the biopsy will show normal spermatogenesis.

Question 950: Which of the following is NOT a consequence of primary hyperaldosteronism?

A. Hyperkalemia (Correct Answer)
B. Hypernatremia
C. Hydrogen depletion and metabolic alkalosis
D. Hypertension

Explanation: Explanation: Primary hyperaldosteronism (Conn’s Syndrome) is characterized by the autonomous overproduction of aldosterone from the adrenal cortex. To understand the consequences, one must recall the action of aldosterone on the **principal cells** and **alpha-intercalated cells** of the distal convoluted tubule and collecting duct [1]. **Why Option A is the Correct Answer:** Aldosterone increases the activity of the **ENaC (Epithelial Sodium Channels)** and the **ROMK (Renal Outer Medullary Potassium)** channels [4]. This leads to sodium reabsorption in exchange for potassium excretion. Therefore, primary hyperaldosteronism causes **hypokalemia**, not hyperkalemia [5]. Hyperkalemia is actually a stimulus for aldosterone release [1], but its presence suggests adrenal insufficiency (Addison’s) or hypoaldosteronism. **Analysis of Incorrect Options:** * **B. Hypernatremia:** Aldosterone promotes sodium reabsorption. While the "aldosterone escape" [2] mechanism prevents massive edema, patients typically maintain a high-normal or mildly elevated serum sodium level [5]. * **C. Hydrogen depletion and metabolic alkalosis:** Aldosterone stimulates the H+-ATPase pump in alpha-intercalated cells, leading to increased secretion of hydrogen ions into the urine [1]. The loss of H+ results in systemic metabolic alkalosis [3]. * **D. Hypertension:** Increased sodium reabsorption leads to volume expansion and increased peripheral resistance, making hypertension a hallmark clinical feature. **NEET-PG High-Yield Pearls:** * **Screening Test:** Plasma Aldosterone Concentration (PAC) to Plasma Renin Activity (PRA) ratio. A ratio **>20-30** is highly suggestive. * **Confirmatory Test:** Oral or IV Saline Suppression Test (failure to suppress aldosterone). * **Aldosterone Escape:** This phenomenon explains why patients with Conn’s syndrome have hypertension but **rarely have overt edema**, as increased pressure natriuresis compensates for sodium retention [2]. * **Triad:** Hypertension + Hypokalemia + Metabolic Alkalosis [5].

Practice by Chapter

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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