Endocrinology — MCQs
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A patient presented with episodes of flushing and hypotension. His urinary 5HIAA levels were found to be increased. What is the diagnosis?
In Thyrotoxicosis, which type of Periodic Paralysis is commonly associated?
Early morning hyperglycemia with increased blood glucose at 3:00 AM suggests:
A 75-year-old female patient, who had a fracture of the neck of the femur 1 month ago, presents with a 2-day history of altered sensorium and decreased urine output. Her urea is 140 mg/dL, creatinine is 2 mg/dL, and calcium is 15.5 mg/dL. Which of the following will be useful in the immediate treatment, except?
What percentage of beta cell mass is destroyed when type 1 diabetes becomes evident?
What is the drug of choice for pain relief in diabetic neuropathy?
In hyperosmolar hyperglycemic non-ketotic coma, what is the typical blood glucose level?
Thyroxine levels are raised in:
Secondary hyperparathyroidism is seen in all of the following conditions EXCEPT:
Cushing's disease is characterized by:
Endocrinology Indian Medical PG Practice Questions and MCQs
Question 691: A patient presented with episodes of flushing and hypotension. His urinary 5HIAA levels were found to be increased. What is the diagnosis?
- A. Pheochromocytoma
- B. Carcinoid syndrome (Correct Answer)
- C. Addison's disease
- D. SIADH
Explanation: ### Explanation **Correct Answer: B. Carcinoid syndrome** **1. Why it is correct:** Carcinoid syndrome is caused by the systemic release of vasoactive substances, primarily **serotonin (5-HT)**, from neuroendocrine tumors (most commonly originating in the ileum and metastasizing to the liver). [1] * **Urinary 5-HIAA (5-Hydroxyindoleacetic acid):** This is the end-metabolite of serotonin. Elevated 24-hour urinary 5-HIAA is the gold-standard biochemical marker for diagnosing carcinoid syndrome. * **Clinical Presentation:** The classic triad includes **flushing**, secretory diarrhea, and wheezing. While serotonin usually causes hypertension, other co-released mediators like bradykinins and histamine can lead to **hypotension** during a "carcinoid crisis." **2. Why the other options are incorrect:** * **A. Pheochromocytoma:** Presents with the "classic triad" of headache, sweating, and palpitations. It is characterized by **hypertension** (not hypotension) and elevated urinary **VMA/metanephrines**, not 5-HIAA. [3] * **C. Addison’s Disease:** While it causes hypotension (due to cortisol/aldosterone deficiency) and skin hyperpigmentation, it does not cause episodic flushing or elevated 5-HIAA. * **D. SIADH:** Characterized by hyponatremia and concentrated urine. It does not present with flushing or 5-HIAA abnormalities. [2] **3. High-Yield Clinical Pearls for NEET-PG:** * **Localization:** Carcinoid tumors of the midgut only cause the syndrome once they **metastasize to the liver**, bypassing the portal metabolism (first-pass effect). [1] * **Cardiac Involvement:** Look for **Right-sided heart failure** (Tricuspid regurgitation and Pulmonary stenosis) due to endocardial fibrosis. Left-sided valves are usually spared as the lungs metabolize serotonin. * **Pellagra Connection:** Excessive serotonin production consumes dietary **Tryptophan**, leading to Niacin (Vitamin B3) deficiency, which can cause Pellagra (Dermatitis, Diarrhea, Dementia). * **Management:** **Octreotide** (somatostatin analog) is the drug of choice to control symptoms.
Question 692: In Thyrotoxicosis, which type of Periodic Paralysis is commonly associated?
- A. Hyperkalemic Periodic Paralysis
- B. Hypokalemic Periodic Paralysis (Correct Answer)
- C. Normokalemic Periodic Paralysis
- D. No Periodic Paralysis
Explanation: Explanation: Thyrotoxic Periodic Paralysis (TPP) is a rare but life-threatening complication of thyrotoxicosis, characterized by sudden episodes of muscle weakness and hypokalemia. 1. Why Hypokalemic Periodic Paralysis is correct: The underlying mechanism is an intracellular shift of potassium, rather than a total body deficit. Excess thyroid hormones increase the activity of the Na+/K+-ATPase pump, which drives potassium from the extracellular fluid into the muscle cells. This hyperpolarizes the muscle membrane, making it unexcitable and leading to flaccid paralysis. This is often triggered by high carbohydrate meals (which release insulin, further stimulating the Na+/K+ pump) [3] or strenuous exercise. 2. Why other options are incorrect: * Hyperkalemic Periodic Paralysis: This is a genetic channelopathy (SCN4A mutation) where attacks are triggered by *increased* serum potassium or fasting. It is not associated with thyroid dysfunction. * Normokalemic Periodic Paralysis: A rare variant of sodium channelopathies where potassium levels remain normal during attacks. It has no clinical link to thyrotoxicosis. * No Periodic Paralysis: Incorrect, as TPP is a well-recognized clinical entity, particularly prevalent in males of Asian descent. Clinical Pearls for NEET-PG: * Demographics: Most common in Asian males (Male:Female ratio is 20:1), despite hyperthyroidism being more common in females. * Diagnosis: Low serum potassium during an attack with low TSH and high T3/T4 [1]. Low urinary potassium excretion distinguishes it from renal losses. * Management: * Acute: Cautious potassium replacement (risk of rebound hyperkalemia). * Prophylaxis: Propranolol (non-selective beta-blocker) is the drug of choice as it antagonizes the effect of thyroid hormones on the Na/K+ pump [2]. * Definitive: Achieving a euthyroid state [2].
Question 693: Early morning hyperglycemia with increased blood glucose at 3:00 AM suggests:
- A. Insufficient insulin (Correct Answer)
- B. Dawn phenomenon
- C. Somogyi effect
- D. None of the above
Explanation: This question tests the ability to differentiate between the three primary causes of early morning hyperglycemia in diabetic patients. The key to the diagnosis lies in the **3:00 AM blood glucose reading**. ### **1. Why "Insufficient Insulin" is Correct** Early morning hyperglycemia with an **elevated** 3:00 AM glucose level indicates that the basal insulin dose administered the previous evening was inadequate to cover the body's needs throughout the night. Since glucose is high at 3:00 AM and continues to rise until morning, it reflects a simple deficiency of insulin (waning effect) [1]. ### **2. Why the Other Options are Incorrect** * **Dawn Phenomenon:** This is a physiological rise in blood glucose between 4:00 AM and 8:00 AM caused by the nocturnal surge of counter-regulatory hormones (Growth Hormone, Cortisol, and Glucagon). Crucially, in Dawn Phenomenon, the **3:00 AM glucose is normal or slightly elevated**, not low. * **Somogyi Effect:** This is **rebound hyperglycemia**. It occurs when excessive evening insulin causes hypoglycemia in the middle of the night (around 3:00 AM) [2]. The body responds by releasing stress hormones (epinephrine, glucagon) that cause a spike in morning glucose. In Somogyi effect, the **3:00 AM glucose must be low (<70 mg/dL)**. ### **3. Clinical Pearls for NEET-PG** * **The "3 AM Rule":** To distinguish these conditions, always check the 3:00 AM blood sugar [2]. * **Low at 3 AM:** Somogyi Effect (Management: Decrease evening insulin or add a bedtime snack). * **High/Normal at 3 AM:** Dawn Phenomenon or Insufficient Insulin (Management: Increase evening insulin). * **Dawn Phenomenon** is most common in Type 1 Diabetics during puberty due to high Growth Hormone levels. * **Management Summary:** If glucose is high at 3 AM, you need **more** insulin; if it is low at 3 AM, you need **less** insulin.
Question 694: A 75-year-old female patient, who had a fracture of the neck of the femur 1 month ago, presents with a 2-day history of altered sensorium and decreased urine output. Her urea is 140 mg/dL, creatinine is 2 mg/dL, and calcium is 15.5 mg/dL. Which of the following will be useful in the immediate treatment, except?
- A. Normal Saline (NS) infusion
- B. Furosemide (Correct Answer)
- C. Hemodialysis
- D. Bisphosphonates
Explanation: ### Explanation This patient presents with **Hypercalcemic Crisis** (Calcium >14 mg/dL) complicated by acute kidney injury (AKI) and altered sensorium. Severe hypercalcaemia is often exacerbated by dehydration and should be managed medically with intravenous fluids and bisphosphonates [1]. The goal of immediate management is to restore intravascular volume and enhance urinary calcium excretion. **Why Furosemide is the correct answer (The "Except"):** Historically, loop diuretics like Furosemide were used to promote calciuresis. However, current guidelines (including Harrison’s) state that Furosemide should **not** be used routinely. It is only indicated **after** full volume resuscitation if the patient develops fluid overload or heart failure. Using it early in a dehydrated patient with AKI can worsen volume depletion, exacerbate hypercalcemia, and further damage renal function. **Analysis of Other Options:** * **Normal Saline (NS) Infusion:** This is the **first-line** treatment. It restores volume and increases the glomerular filtration rate (GFR), promoting the excretion of calcium. * **Hemodialysis:** Indicated in severe hypercalcemia (usually >18 mg/dL) or when hypercalcemia is complicated by **oliguric renal failure** (as suggested by the patient's decreased urine output and high urea/creatinine), where fluid resuscitation is risky. * **Bisphosphonates (e.g., Zoledronic acid):** These are the mainstay for long-term stabilization as they inhibit osteoclast activity. While they take 48–72 hours to work, they are started early in the management of severe hypercalcemia [1]. **Clinical Pearls for NEET-PG:** * **Most common cause of Hypercalcemia:** Primary Hyperparathyroidism (outpatients); Malignancy (inpatients). * **ECG finding:** Shortened QT interval. * **Calcitonin:** Used for rapid (but transient) reduction of calcium within 4–6 hours (Tachyphylaxis occurs after 48 hours). * **Avoid Thiazides:** They increase renal calcium reabsorption and worsen hypercalcemia.
Question 695: What percentage of beta cell mass is destroyed when type 1 diabetes becomes evident?
- A. 20%
- B. 40%
- C. 60%
- D. 80% (Correct Answer)
Explanation: **Explanation:** Type 1 Diabetes Mellitus (T1DM) is characterized by the autoimmune destruction of pancreatic beta cells. The clinical onset of the disease (hyperglycemia and symptoms like polyuria/polydipsia) occurs only after a significant "honeymoon period" of subclinical destruction [1]. **Why 80% is correct:** The pancreas possesses a massive functional reserve. Clinical symptoms of diabetes typically manifest only when **80% to 90%** of the beta-cell mass has been irreversibly destroyed. At this threshold, the remaining insulin-producing cells can no longer maintain euglycemia, leading to absolute insulin deficiency. In many standardized exams and textbooks (like Harrison’s Principles of Internal Medicine), the threshold for symptomatic presentation is cited as approximately 80-90%. **Why other options are incorrect:** * **A (20%) & B (40%):** At these stages, the patient is usually asymptomatic. The body compensates for the minor loss through increased efficiency of remaining cells. * **C (60%):** While significant destruction has occurred, the functional reserve of the pancreas is still sufficient to prevent overt fasting hyperglycemia in most individuals. **High-Yield Clinical Pearls for NEET-PG:** * **Markers of Destruction:** The presence of islet cell antibodies (ICA), anti-GAD65, and anti-IA2 antibodies are markers of the autoimmune process before clinical onset [1]. * **The "Honeymoon Phase":** After the initial diagnosis and start of insulin, some patients experience a temporary recovery of the remaining beta cells, requiring very low doses of insulin. * **Genetic Association:** Strongest association is with **HLA-DR3 and HLA-DR4** [1]. * **C-Peptide:** In T1DM, C-peptide levels are low or undetectable, reflecting the loss of endogenous insulin production.
Question 696: What is the drug of choice for pain relief in diabetic neuropathy?
- A. Gabapentin
- B. Lamotrigine
- C. Pregabalin (Correct Answer)
- D. Mexiletine
Explanation: **Explanation:** **Pregabalin** is currently considered the first-line drug of choice (DOC) for the management of painful diabetic peripheral neuropathy (DPN). It is an **alpha-2-delta ($\alpha_2\delta$) ligand** [1] that binds to voltage-gated calcium channels in the central nervous system, decreasing the release of excitatory neurotransmitters (like glutamate and substance P). It is preferred over other agents due to its superior pharmacokinetic profile, predictable linear absorption, and established efficacy in multiple randomized controlled trials. **Analysis of Options:** * **Pregabalin (Correct):** FDA-approved as a first-line treatment. It has a faster onset of action and higher bioavailability compared to Gabapentin. * **Gabapentin (Incorrect):** While also an $\alpha_2\delta$ ligand and highly effective, it requires frequent dosing and complex titration due to non-linear pharmacokinetics. It is often considered a first-line alternative but is second to Pregabalin in most recent guidelines (ADA/AAN). * **Lamotrigine (Incorrect):** This antiepileptic has shown inconsistent results in clinical trials for DPN and is not recommended as a primary treatment. * **Mexiletine (Incorrect):** An oral Class IB antiarrhythmic (sodium channel blocker). It is rarely used today due to its narrow therapeutic index and significant side effect profile. **High-Yield Clinical Pearls for NEET-PG:** 1. **First-line agents for DPN:** Pregabalin, Duloxetine (SNRI), and Gabapentin. 2. **Tricyclic Antidepressants (TCAs):** Amitriptyline is effective but should be avoided in elderly patients due to anticholinergic side effects and risk of orthostatic hypotension. 3. **Duloxetine:** Preferred if the patient has comorbid depression. 4. **Mechanism:** Both Pregabalin and Gabapentin do *not* bind to GABA receptors; they act solely on the $\alpha_2\delta$ subunit of calcium channels [1].
Question 697: In hyperosmolar hyperglycemic non-ketotic coma, what is the typical blood glucose level?
- A. 55 mmol/L (Correct Answer)
- B. 20 mmol/L
- C. 80 mmol/L
- D. 5 mmol/L
Explanation: Hyperosmolar Hyperglycemic State (HHS), formerly known as HONK, is a life-threatening complication of Type 2 Diabetes Mellitus. It is characterized by extreme hyperglycemia, hyperosmolality, and profound dehydration without significant ketosis. **Why Option A is Correct:** The diagnostic criteria for HHS typically require a blood glucose level **>33.3 mmol/L (600 mg/dL)**. In clinical practice and exam scenarios, glucose levels in HHS are often much higher than in Diabetic Ketoacidosis (DKA), frequently reaching **55 mmol/L (approx. 1000 mg/dL)** or more. This extreme elevation occurs because the presence of residual insulin prevents lipolysis (avoiding ketoacidosis), allowing the patient to remain relatively asymptomatic until severe osmotic diuresis leads to profound dehydration and massive glucose concentration. Hyperosmolality is common, and consciousness is typically impaired when plasma osmolarity exceeds 340 mmol/L [1]. **Why Other Options are Incorrect:** * **Option B (20 mmol/L):** This level (~360 mg/dL) is more characteristic of DKA. While high, it does not meet the threshold for the "hyperosmolar" state seen in HHS. * **Option C (80 mmol/L):** While theoretically possible in extreme cases, 80 mmol/L (~1440 mg/dL) is far above the "typical" presentation and is less common than the 50–60 mmol/L range. * **Option D (5 mmol/L):** This represents a normal fasting blood glucose level. **High-Yield Clinical Pearls for NEET-PG:** * **Diagnostic Triad of HHS:** Blood glucose >600 mg/dL, Serum osmolality >320 mOsm/kg, and absence of significant ketosis (pH >7.3, Bicarbonate >18 mEq/L). * **Calculated Osmolality:** $2 \times [Na^+] + \text{Glucose} + \text{Urea}$ is often used as a surrogate measurement [1]. * **Management Priority:** Aggressive fluid resuscitation with Normal Saline (0.9% NaCl) is the most critical initial step, followed by insulin infusion [1]. * **Key Difference from DKA:** HHS has a higher mortality rate and presents with more severe dehydration and altered mental status.
Question 698: Thyroxine levels are raised in:
- A. Myxedema
- B. Endemic goitre
- C. Idiopathic nontoxic colloid goitre
- D. Grave's disease (Correct Answer)
Explanation: **Explanation:** **Correct Answer: D. Grave's Disease** Grave’s disease is an autoimmune disorder characterized by the production of **Thyroid Stimulating Immunoglobulins (TSI)** [1]. These antibodies act as agonists to the TSH receptors on the thyroid gland, leading to unregulated synthesis and secretion of thyroid hormones [2]. Consequently, serum levels of **Thyroxine (T4)** and Triiodothyronine (T3) are significantly elevated, while TSH is suppressed [3]. **Analysis of Incorrect Options:** * **A. Myxedema:** This term refers to severe, advanced hypothyroidism. In this state, the thyroid gland fails to produce adequate hormones, resulting in **decreased** thyroxine levels and elevated TSH [3]. * **B. Endemic Goitre:** Usually caused by dietary **iodine deficiency**, this condition leads to impaired hormone synthesis. While patients may remain euthyroid due to compensatory thyroid enlargement (goitre), thyroxine levels are typically low or low-normal, never raised. * **C. Idiopathic Nontoxic Colloid Goitre:** This is a form of diffuse enlargement of the thyroid gland without clinical or laboratory evidence of thyroid dysfunction. By definition, "nontoxic" implies that hormone levels (T3/T4) remain within the **normal range**. **High-Yield Clinical Pearls for NEET-PG:** * **Grave’s Triad:** Hyperthyroidism (Goitre), Exophthalmos (Ophthalmopathy), and Pretibial Myxedema (Dermopathy) [1]. * **Diagnosis:** Elevated Free T4, suppressed TSH, and diffuse uptake on Radioactive Iodine Uptake (RAIU) scan [2]. * **Antibody Marker:** Anti-TSH receptor antibodies (TRAb/TSI) are highly specific for Grave’s [1]. * **Treatment of Choice:** Antithyroid drugs (Methimazole/PTU) for medical management; Radioiodine ablation is often the definitive treatment in adults.
Question 699: Secondary hyperparathyroidism is seen in all of the following conditions EXCEPT:
- A. Chronic renal failure
- B. Parathyroid adenoma (Correct Answer)
- C. Vitamin D deficiency
- D. Medullary carcinoma thyroid
Explanation: ### Explanation **Secondary hyperparathyroidism** is a compensatory physiological response where the parathyroid glands overproduce Parathyroid Hormone (PTH) in response to **hypocalcemia** [3] or hyperphosphatemia. The goal is to restore normal serum calcium levels. **Why Parathyroid Adenoma is the correct answer:** A parathyroid adenoma is the most common cause of **Primary Hyperparathyroidism** [4]. In this condition, the pathology lies within the gland itself (autonomous secretion), leading to high PTH levels which subsequently cause **hypercalcemia** [1]. In secondary hyperparathyroidism, the gland is normal but reacting to external stimuli (low calcium); in primary, the gland is abnormal and causing high calcium. **Analysis of Incorrect Options:** * **Chronic Renal Failure (CRF):** This is the most common cause of secondary hyperparathyroidism. Reduced phosphate excretion (hyperphosphatemia) and failure of 1-alpha-hydroxylation of Vitamin D lead to low serum calcium, triggering PTH release [1], [2]. * **Vitamin D Deficiency:** Low Vitamin D leads to decreased intestinal calcium absorption. The resulting hypocalcemia stimulates the parathyroid glands to secrete more PTH [2]. * **Medullary Carcinoma Thyroid (MCT):** MCT secretes **Calcitonin**, which lowers serum calcium levels. This hypocalcemic state can lead to a compensatory (secondary) rise in PTH. (Note: In MEN 2A syndrome, MCT is associated with primary hyperparathyroidism, but the physiological effect of calcitonin itself induces a secondary response). **NEET-PG High-Yield Pearls:** 1. **Primary Hyperparathyroidism:** ↑ PTH, ↑ Calcium, ↓ Phosphate. 2. **Secondary Hyperparathyroidism:** ↑ PTH, ↓/Normal Calcium, ↑ Phosphate (in CRF) or ↓ Phosphate (in Vit D deficiency) [2]. 3. **Tertiary Hyperparathyroidism:** Seen after long-standing secondary hyperparathyroidism (usually CRF) where the glands become autonomous. Results in ↑ PTH and ↑ Calcium. 4. **Hungry Bone Syndrome:** Post-parathyroidectomy complication leading to profound hypocalcemia.
Question 700: Cushing's disease is characterized by:
- A. Increased ADH
- B. Increased urinary catecholamines
- C. Increased ACTH and decreased cortisol
- D. Increased ACTH and increased cortisol (Correct Answer)
Explanation: **Explanation:** **Cushing’s Disease** specifically refers to hypercortisolism caused by a **pituitary adenoma** (usually a microadenoma) that hypersecretes Adrenocorticotropic Hormone (ACTH) [1]. 1. **Why Option D is Correct:** In Cushing’s Disease, the primary pathology is in the anterior pituitary [1]. The adenoma secretes excessive **ACTH**, which then stimulates the adrenal cortex (zona fasciculata) to produce and release high levels of **cortisol** [2]. Unlike the normal physiological state, the pituitary tumor is relatively resistant to negative feedback, leading to the simultaneous elevation of both ACTH and cortisol. 2. **Why Other Options are Incorrect:** * **Option A:** ADH (Vasopressin) is related to water balance (Diabetes Insipidus or SIADH) and is not the primary hormone involved in Cushing’s pathology. * **Option B:** Increased urinary catecholamines are diagnostic for **Pheochromocytoma**, not Cushing’s. * **Option C:** Increased ACTH with decreased cortisol is seen in **Primary Adrenal Insufficiency (Addison’s Disease)**, where the pituitary tries to compensate for adrenal failure. **High-Yield Clinical Pearls for NEET-PG:** * **Cushing’s Syndrome vs. Disease:** "Syndrome" is the broad term for hypercortisolism of any cause (most common cause is exogenous steroids). "Disease" is specifically the pituitary cause [1]. * **Screening Tests:** Overnight Dexamethasone Suppression Test (ONDST) or 24-hour urinary free cortisol [3]. * **Gold Standard Localization:** Inferior Petrosal Sinus Sampling (IPSS) is used to differentiate a pituitary source from ectopic ACTH production (e.g., Small Cell Lung Cancer). * **Dexamethasone Suppression:** Cushing’s Disease usually shows suppression with **High-Dose** Dexamethasone, whereas ectopic ACTH and adrenal tumors do not.
Practice by Chapter
Diabetes Mellitus
Practice Questions
Thyroid Disorders
Practice Questions
Adrenal Gland Disorders
Practice Questions
Pituitary Disorders
Practice Questions
Calcium and Bone Metabolism
Practice Questions
Reproductive Endocrinology
Practice Questions
Lipid Disorders
Practice Questions
Endocrine Hypertension
Practice Questions
Multiple Endocrine Neoplasia
Practice Questions
Obesity and Metabolic Syndrome
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Neuroendocrine Tumors
Practice Questions
Endocrine Emergencies
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