Endocrinology — MCQs

A 27-year-old woman complains of pain in her left shin. X-rays of the leg reveal a stress fracture of the tibia, decreased cortical bone density, and increased radiolucency. She is suspected of having osteomalacia (impaired mineralization of bone matrix). Which of the following is the most common biochemical manifestation of osteomalacia?

Endocrinology Indian Medical PG Practice Questions and MCQs

Question 571: What is the most appropriate management of diabetic ketoacidosis?

A. 500ml of 0.9% Saline over 15 minutes and a fixed rate insulin infusion
B. 500ml of 0.9% Saline over 15 minutes with potassium chloride and a fixed rate insulin infusion (Correct Answer)
C. 500ml of 0.9% Saline over 30 minutes with potassium chloride and a rapid acting subcutaneous insulin injection
D. 500ml of 0.9% Saline over 30 minutes and a rapid acting subcutaneous insulin injection

Explanation: The management of Diabetic Ketoacidosis (DKA) is a critical high-yield topic for NEET-PG, focusing on the triad of fluid resuscitation, insulin therapy, and electrolyte correction [1]. ### **Why Option B is Correct** The primary goals in DKA are restoring circulatory volume and clearing ketones. 1. **Fluid Resuscitation:** Initial management requires rapid volume expansion with **0.9% Normal Saline** (isotonic) to treat dehydration and improve tissue perfusion [2]. A bolus of 500ml over 15 minutes is standard for initial stabilization. 2. **Fixed-Rate Intravenous Insulin Infusion (FRIII):** IV insulin (usually 0.1 unit/kg/hr) is mandatory to suppress ketogenesis [3]. Subcutaneous insulin is avoided in the acute phase due to unpredictable absorption in dehydrated patients. 3. **Potassium Replacement:** Even if serum potassium levels appear normal, there is a total body potassium deficit due to osmotic diuresis [1]. Insulin therapy further shifts potassium intracellularly, risking fatal hypokalemia. Therefore, potassium must be replaced early in the infusion [2]. ### **Why Other Options are Wrong** * **Option A:** Fails to include potassium chloride. Initiating insulin without potassium coverage can lead to severe hypokalemia and cardiac arrhythmias [2]. * **Options C & D:** These are incorrect because they suggest **subcutaneous insulin**, which is inappropriate for DKA management (reserved for mild ketosis or post-recovery) [3]. Additionally, 30 minutes is often too slow for the initial fluid bolus in a patient with significant volume depletion. ### **Clinical Pearls for NEET-PG** * **Target:** The goal is to reduce blood ketones by **0.5 mmol/L/hr** or increase bicarbonate by **3.0 mmol/L/hr**. * **Fluid Choice:** 0.9% Saline is used initially; switch to **5% Dextrose** once blood glucose falls below **200–250 mg/dL** to prevent hypoglycemia while continuing insulin to clear ketones [2]. * **Most Common Cause of Death:** Cerebral edema (especially in children) due to over-aggressive fluid resuscitation [4]. * **Bicarbonate:** Not routinely recommended unless pH is **< 6.9**.

Question 572: An 18-year-old woman develops weakness, weight gain, amenorrhea, abdominal striae, and behavioral abnormalities. Physical examination reveals lateral visual field loss. Which of the following is the most likely diagnosis?

A. A functional pituitary tumor (Correct Answer)
B. Adrenal hyperplasia
C. Anorexia nervosa with bulimia
D. Glioblastoma multiforme

Explanation: ### Explanation The patient presents with a classic constellation of symptoms indicating **Cushing’s Syndrome** (weight gain, weakness, abdominal striae, amenorrhea) and psychiatric disturbances [2]. The presence of **lateral visual field loss (bitemporal hemianopia)** is the critical localizing sign. 1. **Why Option A is correct:** The clinical features suggest excess cortisol. When Cushing’s syndrome is accompanied by bitemporal hemianopia, it indicates a space-occupying lesion at the optic chiasm. A **functional pituitary tumor** (specifically an ACTH-secreting adenoma, known as Cushing’s Disease) can grow large enough (macroadenoma) to compress the decussating fibers of the optic nerve, leading to visual field defects [1]. While most ACTH-secreting tumors are microadenomas, a functional macroadenoma explains both the endocrine excess and the neurological findings. 2. **Why the other options are incorrect:** * **B. Adrenal hyperplasia:** While this causes Cushing’s syndrome, it is a peripheral pathology (adrenal glands) and would not cause compression of the optic chiasm or visual field loss. * **C. Anorexia nervosa with bulimia:** While this can cause amenorrhea and behavioral changes, it typically presents with weight loss (not gain) and lacks the striae and visual defects. * **D. Glioblastoma multiforme:** This is a highly malignant primary brain tumor. While it can cause behavioral changes and neurological deficits, it does not typically present with the specific endocrine profile of Cushing’s syndrome. ### NEET-PG High-Yield Pearls * **Bitemporal Hemianopia:** Always look for this in endocrine questions; it signifies a lesion at the **optic chiasm** [1]. * **Cushing’s Disease vs. Syndrome:** Cushing’s *Disease* specifically refers to a pituitary adenoma secreting ACTH [2]. * **Screening for Cushing’s:** The best initial tests are the 24-hour urinary free cortisol, late-night salivary cortisol, or the low-dose dexamethasone suppression test (LDDST) [3]. * **Visual Fields:** Pituitary macroadenomas (>10mm) are the most common cause of chiasmal compression in young adults [1].

Question 573: Dawn phenomenon refers to what?

A. Early morning hyperglycemia (Correct Answer)
B. Early morning hypoglycemia
C. Hypoglycemia followed by hyperglycemia
D. High insulin levels

Explanation: **Explanation:** The **Dawn Phenomenon** refers to an abnormal early morning increase in blood glucose levels (hyperglycemia), typically occurring between 4:00 AM and 8:00 AM, in patients with diabetes. **1. Why the Correct Answer is Right:** The underlying mechanism is the physiological surge of counter-regulatory hormones—primarily **Growth Hormone (GH)**, but also cortisol, glucagon, and epinephrine—secreted in the early morning hours. These hormones increase hepatic glucose production (gluconeogenesis and glycogenolysis) and decrease peripheral insulin sensitivity [1]. In patients with diabetes, the body cannot compensate with increased insulin secretion, resulting in **early morning hyperglycemia**. **2. Analysis of Incorrect Options:** * **Option B (Early morning hypoglycemia):** This is the opposite of the Dawn phenomenon. It may occur due to excessive evening insulin or skipped meals but is not a named physiological phenomenon. * **Option C (Hypoglycemia followed by hyperglycemia):** This describes the **Somogyi Effect** (Rebound Hyperglycemia). In this case, nocturnal hypoglycemia (often due to too much evening insulin) triggers a massive counter-regulatory hormone surge, leading to high fasting glucose [2]. * **Option D (High insulin levels):** In the Dawn phenomenon, insulin levels are relatively or absolutely deficient compared to the rising glucose levels. **3. NEET-PG High-Yield Pearls:** * **Differentiating Dawn vs. Somogyi:** To distinguish them, check blood glucose at **3:00 AM**. * If 3 AM glucose is **High/Normal** $\rightarrow$ Dawn Phenomenon (Management: Increase evening insulin dose). * If 3 AM glucose is **Low** $\rightarrow$ Somogyi Effect (Management: Decrease evening insulin dose or add a bedtime snack) [2]. * **Growth Hormone** is considered the primary driver of the Dawn phenomenon.

Question 574: Serum TSH level is the most sensitive test for which of the following conditions?

A. Hyperthyroidism
B. Hypothyroidism (Correct Answer)
C. Both hyperthyroidism and hypothyroidism
D. None of the above

Explanation: **Explanation:** The serum TSH level is widely regarded as the single most sensitive screening test for the diagnosis of **primary hypothyroidism** [1]. **1. Why Hypothyroidism is the correct answer:** The relationship between serum Free T4 and TSH is **log-linear** [1]. This means that even a very small decrease in circulating thyroid hormone levels (T4/T3) results in a disproportionately large, exponential increase in TSH secretion from the anterior pituitary [1]. In early or subclinical hypothyroidism, the TSH will become elevated even while the T4 remains within the normal reference range [1]. Therefore, TSH is the earliest indicator of thyroid failure. **2. Why other options are incorrect:** * **Hyperthyroidism:** While TSH is suppressed in primary hyperthyroidism, it is generally considered slightly less "sensitive" as a standalone diagnostic marker compared to its role in hypothyroidism. In cases of T3-toxicosis, TSH is suppressed, but the diagnosis relies on T3 levels. Furthermore, in rare cases of secondary hyperthyroidism (TSH-secreting pituitary adenoma), TSH will be inappropriately normal or high, not suppressed. * **Both:** While TSH is the initial screening test for both, the physiological "amplification" of the TSH signal is most clinically profound and diagnostic for primary hypothyroidism. **Clinical Pearls for NEET-PG:** * **Best Screening Test:** Serum TSH is the best initial test for thyroid dysfunction in the general population [1]. * **Subclinical Hypothyroidism:** Defined as Elevated TSH with Normal Free T4 [1]. * **Exception:** TSH is **NOT** a reliable marker in **Central (Secondary) Hypothyroidism** (pituitary/hypothalamic disease) [1]. In such cases, both TSH and T4 will be low, and diagnosis depends on Free T4 levels. * **Amiodarone:** Can cause both hypo- and hyperthyroidism; TSH monitoring is mandatory.

Question 575: Which of the following features is NOT seen in Cushing's Syndrome?

A. Hypoglycemia (Correct Answer)
B. Hypertension
C. Frank psychosis
D. Hypokalemia

Explanation: **Explanation:** Cushing’s Syndrome is characterized by a chronic excess of glucocorticoids (cortisol). To identify the correct answer, one must understand the physiological actions of cortisol on metabolism, electrolytes, and the central nervous system. **1. Why Hypoglycemia is the correct answer:** Cortisol is a "stress hormone" and a potent **insulin antagonist** [1]. It promotes gluconeogenesis in the liver and decreases peripheral glucose uptake in muscles and adipose tissue [1]. Therefore, Cushing’s Syndrome leads to **hyperglycemia** (secondary diabetes or impaired glucose tolerance), not hypoglycemia. **2. Analysis of incorrect options:** * **Hypertension:** Cortisol causes hypertension through multiple mechanisms: mineralocorticoid activity (sodium/water retention), increased sensitivity to catecholamines, and activation of the Renin-Angiotensin system [2]. * **Frank Psychosis:** Glucocorticoids cross the blood-brain barrier. Excess levels can cause significant neuropsychiatric symptoms, ranging from emotional lability and depression to overt "steroid psychosis" [2]. * **Hypokalemia:** At high concentrations (especially in ectopic ACTH syndrome), cortisol overwhelms the 11β-HSD2 enzyme in the kidneys and acts on mineralocorticoid receptors, leading to potassium excretion and metabolic alkalosis. **Clinical Pearls for NEET-PG:** * **Screening Test of Choice:** 24-hour urinary free cortisol or Low-Dose Dexamethasone Suppression Test (LDDST). * **Most Common Cause:** Iatrogenic (exogenous steroid use). * **Cushing’s Disease:** Specifically refers to a pituitary adenoma secreting ACTH [2]. * **High-Yield Sign:** Proximal muscle wasting (due to protein catabolism) with centripetal obesity and "buffalo hump" [2].

Question 576: Which of the following statements is true for MEN type 1?

A. There is hyperplasia of the parathyroid gland.
B. Chromophobe adenoma of the pituitary gland may result in acromegaly.
C. Pancreatic tumors may produce gastrin, insulin, glucagon, and somatostatin.
D. All the above. (Correct Answer)

Explanation: **Explanation:** Multiple Endocrine Neoplasia Type 1 (MEN1), also known as **Wermer’s Syndrome**, is an autosomal dominant disorder caused by a mutation in the *MEN1* gene (encoding the protein Menin) [2]. It is classically characterized by the "3 Ps": **P**arathyroid, **P**ancreas, and **P**ituitary [1]. * **Option A is correct:** Primary Hyperparathyroidism is the most common and earliest manifestation (occurring in >95% of patients). Unlike sporadic cases which are often single adenomas, MEN1 typically involves **multiglandular hyperplasia**. * **Option B is correct:** Pituitary adenomas occur in about 30-40% of cases. While prolactinomas are most common, growth hormone-secreting adenomas can occur, leading to **acromegaly** [3]. Historically, these were often classified as "chromophobe adenomas" based on their staining characteristics under light microscopy. * **Option C is correct:** Pancreatic Neuroendocrine Tumors (NETs) are highly diverse. **Gastrinomas** (Zollinger-Ellison Syndrome) are the most frequent symptomatic pancreatic manifestation, followed by **insulinomas**. However, these tumors can also secrete glucagon, somatostatin, or VIP. **Conclusion:** Since all three statements accurately describe the clinical components of MEN1, **Option D** is the correct answer. [2] **High-Yield Clinical Pearls for NEET-PG:** * **Gene/Chromosome:** *MEN1* gene on **Chromosome 11q13**. * **Order of Appearance:** Parathyroid (1st) > Pancreas > Pituitary. * **Associated Lesions:** Adrenal cortical tumors, facial angiofibromas, collagenomas, and lipomas. * **Screening:** Annual biochemical screening (Calcium, PTH, Gastrin, Prolactin) is recommended for first-degree relatives [2].

Question 577: A patient with cushingoid features presents with hemoptysis. The patient shows no response to a dexamethasone suppression test. What is the most likely diagnosis?

A. Adrenal hyperplasia
B. Adrenal adenoma
C. Lung cancer with ectopic ACTH production (Correct Answer)
D. Pituitary microadenoma

Explanation: The patient presents with **Cushing syndrome** (cushingoid features) and **hemoptysis**, which is a classic "red flag" for underlying pulmonary pathology [4]. **1. Why Option C is Correct:** The key to this diagnosis is the combination of ectopic ACTH production and the failure of the **High-Dose Dexamethasone Suppression Test (HDDST)**. In **Ectopic ACTH Syndrome** (most commonly caused by **Small Cell Lung Cancer**), the tumor cells produce ACTH autonomously [1]. Unlike pituitary adenomas, these ectopic sources do not possess glucocorticoid receptors that respond to feedback inhibition; therefore, cortisol levels remain high despite dexamethasone administration. The hemoptysis points directly to a lung malignancy as the source [4]. **2. Why Other Options are Incorrect:** * **Pituitary Microadenoma (Cushing’s Disease):** While this is the most common cause of endogenous Cushing syndrome, these tumors usually retain some sensitivity to negative feedback. They typically show **>50% suppression** of cortisol during an HDDST. * **Adrenal Adenoma/Hyperplasia:** These are primary adrenal causes where ACTH levels would be **suppressed** (low) due to autonomous cortisol production by the adrenal gland itself [3]. The question implies an ACTH-dependent process given the context of ectopic production. **3. NEET-PG High-Yield Pearls:** * **Small Cell Lung Carcinoma** is the most common cause of rapid-onset Ectopic ACTH [1]. * **Bronchial Carcinoid** is another ectopic source but usually presents with a more chronic course. * **Hyperpigmentation and Hypokalemia** are more common in ectopic ACTH than in Cushing’s disease due to very high ACTH levels (cross-reactivity with MSH receptors) and mineralocorticoid effects of high cortisol. * **Localization:** If HDDST fails to suppress cortisol, the next step is a **CT Chest/Abdomen** to locate the ectopic tumor [2].

Question 578: A 57-year-old female presents with a one-month history of burning epigastric pain after eating, associated with a 4 kg weight loss in the past month. She also complains of severe diarrhea, with 8-10 loose stools daily. What is the most common site of this condition?

A. Head of the pancreas
B. Tail of the pancreas
C. Body of the pancreas
D. Between the head of the pancreas and the bile duct (Correct Answer)

Explanation: ### Explanation **Diagnosis: Gastrinoma (Zollinger-Ellison Syndrome)** The clinical presentation of refractory peptic ulcers (epigastric pain), significant weight loss, and chronic secretory diarrhea (due to high gastric acid inactivating pancreatic enzymes) is classic for **Zollinger-Ellison Syndrome (ZES)**, caused by a gastrin-secreting tumor (Gastrinoma) [1]. **Why Option D is Correct:** The majority of gastrinomas (over 70-90%) are located within the **Gastrinoma Triangle** (also known as Passaro’s Triangle). The boundaries of this triangle are: 1. Superiorly: The confluence of the cystic and common hepatic ducts. 2. Inferiorly: The junction of the second and third portions of the duodenum. 3. Medially: The junction of the **neck/head of the pancreas** and the body of the pancreas. Most gastrinomas are found specifically in the **duodenum** or the **head of the pancreas**, making the anatomical space between the pancreatic head and the bile duct the most common site. **Why Other Options are Incorrect:** * **Options A, B, and C:** While gastrinomas can occur in the pancreas [1], they are rarely found in the **body or tail**. While the **head of the pancreas** is a common site, the "Gastrinoma Triangle" (Option D) is the more precise anatomical answer for NEET-PG, as it encompasses both the pancreatic head and the duodenum (the most frequent primary site). **High-Yield Clinical Pearls for NEET-PG:** * **Most common site:** Duodenum (specifically the second part) is now considered more common than the pancreas for primary gastrinomas. * **MEN-1 Association:** Approximately 25% of gastrinomas are associated with Multiple Endocrine Neoplasia Type 1 (3Ps: Parathyroid, Pancreas, Pituitary). * **Screening Test:** Best initial test is **Fasting Serum Gastrin** (>1000 pg/mL is diagnostic). * **Confirmatory Test:** **Secretin Stimulation Test** (Gastrin levels rise >200 pg/mL after secretin injection). * **Localization:** Somatostatin Receptor Scintigraphy (Octreotide scan) or Endoscopic Ultrasound (EUS) are preferred for imaging.

Question 579: Which one of the following features may NOT be seen in hypocalcemia/tetany?

A. Prolongation of QT interval
B. Cataract formation
C. Clotting defects (Correct Answer)
D. Intestinal and biliary colic

Explanation: The correct answer is **Clotting defects**. While calcium (Factor IV) is essential for the coagulation cascade, clinical hypocalcemia does not manifest as bleeding or clotting disorders. This is because the level of ionized calcium required for blood clotting is significantly lower than the level required to sustain life; a patient would succumb to fatal tetany or cardiac arrest long before calcium levels dropped low enough to impair coagulation. **Analysis of other options:** * **Prolongation of QT interval:** This is a classic ECG finding in hypocalcemia [1]. It occurs due to the lengthening of Phase 2 (the plateau phase) of the cardiac action potential. * **Cataract formation:** Chronic hypocalcemia (often seen in hypoparathyroidism) leads to the formation of subcapsular cataracts. Low calcium levels in the aqueous humor interfere with the metabolic pumps of the lens, leading to hydration and opacification. * **Intestinal and biliary colic:** Hypocalcemia increases neuromuscular irritability [1], which can lead to spasms of smooth muscles in the gastrointestinal and biliary tracts, manifesting as abdominal pain or colic. **High-Yield Clinical Pearls for NEET-PG:** * **Neuromuscular Signs:** Look for **Chvostek’s sign** (facial twitching on tapping the facial nerve) and **Trousseau’s sign** (carpal spasm after inflating a BP cuff). Trousseau’s is more specific. * **ECG:** Hypocalcemia = Long QT; Hypercalcemia = Short QT [1]. * **Basal Ganglia Calcification:** Chronic hypocalcemia can lead to ectopic calcification in the brain, often presenting as extrapyramidal symptoms. * **Emergency Management:** IV Calcium Gluconate (10%) is the preferred treatment for symptomatic tetany.

Question 580: A 27-year-old woman complains of pain in her left shin. X-rays of the leg reveal a stress fracture of the tibia, decreased cortical bone density, and increased radiolucency. She is suspected of having osteomalacia (impaired mineralization of bone matrix). Which of the following is the most common biochemical manifestation of osteomalacia?

A. Hyperphosphatemia
B. Hypoparathyroidism
C. Decreased vitamin D (Correct Answer)
D. Hypercalcemia

Explanation: **Explanation:** Osteomalacia is a metabolic bone disease characterized by **impaired mineralization of the osteoid (bone matrix)** [1], most commonly due to a deficiency in Vitamin D. **1. Why Vitamin D deficiency is the correct answer:** Vitamin D is essential for the intestinal absorption of calcium and phosphorus. In its absence, serum calcium levels drop, triggering the parathyroid glands to release Parathyroid Hormone (PTH). This **Secondary Hyperparathyroidism** attempts to maintain serum calcium by mobilizing it from bones and increasing renal phosphorus excretion [1]. Consequently, low Vitamin D is the primary biochemical driver and the most common finding in these patients. **2. Analysis of Incorrect Options:** * **A. Hyperphosphatemia:** Incorrect. Due to secondary hyperparathyroidism, PTH increases renal phosphate excretion, leading to **hypophosphatemia**, not hyperphosphatemia [1]. * **B. Hypoparathyroidism:** Incorrect. Osteomalacia typically presents with **Secondary Hyperparathyroidism** (elevated PTH) as a compensatory mechanism for low serum calcium [1]. * **D. Hypercalcemia:** Incorrect. Patients are usually **hypocalcemic** or have low-normal calcium levels [1]. Hypercalcemia would suggest primary hyperparathyroidism or malignancy. **3. NEET-PG High-Yield Pearls:** * **Biochemical Profile:** ↓/Normal Calcium, ↓ Phosphate, **↑ Alkaline Phosphatase (ALP)**, ↑ PTH, and ↓ 25(OH) Vitamin D. * **Radiological Signs:** Look for **Looser’s zones** (pseudofractures/Milkman’s lines), which are pathognomonic—transverse lucent bands perpendicular to the bone cortex [2]. * **Clinical Presentation:** Diffuse bone pain, muscle weakness (proximal myopathy), and "waddling gait" [1]. * **Histology:** Characterized by an **increased thickness of unmineralized osteoid seams** [2].

Practice by Chapter

Diabetes Mellitus

Practice Questions

Thyroid Disorders

Practice Questions

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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