Endocrinology — MCQs

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?

Q694Easy

What percentage of beta cell mass is destroyed when type 1 diabetes becomes evident?

Q695Easy

What is the drug of choice for pain relief in diabetic neuropathy?

Q696Easy

In hyperosmolar hyperglycemic non-ketotic coma, what is the typical blood glucose level?

Q697Easy

Thyroxine levels are raised in:

Q698Medium

Secondary hyperparathyroidism is seen in all of the following conditions EXCEPT:

Q699Easy

Cushing's disease is characterized by:

Q700Medium

All of the following are associated with glucose intolerance except?

Endocrinology Indian Medical PG Practice Questions and MCQs

Question 691: 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 692: 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 693: 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 694: 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 695: 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 696: 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 697: 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 698: 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 699: 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.

Question 700: All of the following are associated with glucose intolerance except?

A. Hyperaldosteronism
B. Acromegaly
C. Panhypopituitarism (Correct Answer)
D. Cushing's syndrome

Explanation: The correct answer is **Panhypopituitarism**. To understand this, one must distinguish between hormones that are "diabetogenic" (increase blood glucose) and those that maintain glucose levels. **1. Why Panhypopituitarism is the correct answer:** Panhypopituitarism involves a deficiency of multiple anterior pituitary hormones, most notably **Growth Hormone (GH)** and **ACTH** (which leads to secondary cortisol deficiency). Both GH and Cortisol are counter-regulatory hormones that oppose the action of insulin. Their absence leads to **increased insulin sensitivity** and a tendency toward **hypoglycemia**, rather than glucose intolerance [1]. **2. Why the other options are incorrect:** * **Acromegaly (Excess GH):** Growth hormone induces insulin resistance in peripheral tissues and increases hepatic gluconeogenesis, frequently leading to impaired glucose tolerance or "Pituitary Diabetes" [1]. * **Cushing’s Syndrome (Excess Cortisol):** Glucocorticoids stimulate gluconeogenesis and inhibit peripheral glucose uptake. About 80% of patients with Cushing’s exhibit glucose intolerance [3]. * **Hyperaldosteronism:** High levels of aldosterone lead to hypokalemia. **Hypokalemia** inhibits the release of insulin from pancreatic beta cells, thereby causing glucose intolerance. **Clinical Pearls for NEET-PG:** * **The "Diabetogenic" Hormones:** Growth Hormone, Cortisol, Glucagon, and Epinephrine [2]. * **Hypokalemia & Glucose:** Always remember that low potassium impairs insulin secretion. This is why thiazide diuretics can sometimes worsen glycemic control. * **Somatostatinoma:** A rare pancreatic tumor that causes diabetes because somatostatin inhibits the release of both insulin and glucagon.

Practice by Chapter

Diabetes Mellitus

Practice Questions

Thyroid Disorders

Practice Questions

Adrenal Gland Disorders

Practice Questions

Pituitary Disorders

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Calcium and Bone Metabolism

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Reproductive Endocrinology

Practice Questions

Lipid Disorders

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Endocrine Hypertension

Practice Questions

Multiple Endocrine Neoplasia

Practice Questions

Obesity and Metabolic Syndrome

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Neuroendocrine Tumors

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Endocrine Emergencies

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