Endocrinology Practice Questions

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

80%. **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.

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

Pregabalin. **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].

Q: Cushing's disease is characterized by:

Increased ACTH and increased cortisol. **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.

Q: Which of the following is NOT seen in ACTH deficiency?

Hyperpigmentation. The correct answer is **Hyperpigmentation**. **1. Why Hyperpigmentation is NOT seen:** Hyperpigmentation is a hallmark of **Primary Adrenal Insufficiency** (Addison’s Disease) [1], not ACTH deficiency (Secondary Adrenal Insufficiency). In primary failure, the lack of cortisol feedback causes a massive compensatory increase in **ACTH** and its precursor, **Pro-opiomelanocortin (POMC)**. POMC is cleaved into ACTH and **Melanocyte-Stimulating Hormone (MSH)**. High levels of MSH/ACTH stimulate melanocytes, leading to skin darkening. In ACTH deficiency, ACTH levels are low or absent; therefore, MSH is not produced, and the skin typically appears pale. **2. Analysis of Incorrect Options:** * **Weight loss:** Cortisol is a catabolic hormone essential for maintaining appetite and metabolic tone. Its deficiency leads to anorexia and significant weight loss. * **Hyponatremia:** While aldosterone is usually normal in secondary insufficiency (as it is regulated by the RAAS, not ACTH) [2], hyponatremia occurs due to the **loss of cortisol's inhibitory effect on ADH**. High ADH levels lead to water retention and dilutional hyponatremia [2]. * **Hypoglycemia:** Cortisol is a counter-regulatory hormone that promotes gluconeogenesis. Its absence impairs glucose production, especially during fasting or stress. **Clinical Pearls for NEET-PG:** * **Mineralocorticoid Sparing:** Unlike Primary Adrenal Insufficiency, ACTH deficiency does **not** cause hyperkalemia because the Renin-Angiotensin-Aldosterone System (RAAS) remains intact [2]. * **The "Alabaster Skin":** Patients with Sheehan’s syndrome or pituitary tumors (ACTH deficiency) often present with a characteristic pale, "alabaster" skin tone. * **Crisis:** Adrenal crisis is generally less severe in secondary vs. primary insufficiency due to preserved aldosterone function.

Q: What are the symptoms of VIPOMA?

Secretory diarrhoea. **Explanation:** **VIPoma** (also known as Verner-Morrison syndrome or WDHA syndrome) is a rare neuroendocrine tumor, usually located in the pancreas, that secretes excessive amounts of **Vasoactive Intestinal Peptide (VIP)** [1]. 1. **Why Secretory Diarrhea is Correct:** VIP stimulates adenylate cyclase in intestinal epithelial cells, increasing cAMP levels. This leads to massive secretion of water and electrolytes (sodium, potassium, and chloride) into the intestinal lumen, inhibiting acid secretion in the stomach [2]. The hallmark is **profuse, watery diarrhea** (often >3 liters/day) that persists even during fasting (secretory type) [2]. 2. **Why Other Options are Incorrect:** * **A. Gallstones:** These are classically associated with **Somatostatinomas** due to the inhibition of cholecystokinin (CCK) release and gallbladder contractility. * **C. Fat Malabsorption (Steatorrhea):** This is more typical of **Zollinger-Ellison Syndrome** (where low pH inactivates pancreatic lipases) or Somatostatinomas, rather than the watery diarrhea of VIPoma. * **D. Flushing:** While VIP can cause vasodilation, episodic flushing is the classic hallmark of **Carcinoid Syndrome** (mediated by serotonin and bradykinins) [1]. **High-Yield Clinical Pearls for NEET-PG:** * **WDHA Syndrome Mnemonic:** **W**atery **D**iarrhea, **H**ypokalemia, **A**chlorhydria (or Hypochlorhydria). * **Metabolic Profile:** Look for **Hyperglycemia** and **Hypercalcemia** in clinical vignettes. * **Diagnosis:** Elevated fasting plasma VIP levels (>75 pg/mL). * **Treatment:** The initial medical management of choice to control diarrhea is **Octreotide** (Somatostatin analog). * **Association:** About 5% of VIPomas are associated with **MEN-1 syndrome** [1].

Q: A 57-year-old lady presents with type II diabetes mellitus with symptoms like polyuria, excessive thirst, fatigue, and blurred vision. Further investigation reveals insulin resistance. Which one of the following drugs is most appropriate for initiating treatment along with diet and exercise?

Metformin. **Explanation:** **Why Metformin is the Correct Choice:** Metformin, a Biguanide, is the **first-line drug of choice** for Type 2 Diabetes Mellitus (T2DM) according to ADA and EASD guidelines [1]. Its primary mechanism of action is the activation of **AMP-activated protein kinase (AMPK)**, which leads to decreased hepatic gluconeogenesis and improved peripheral insulin sensitivity [2]. It is preferred for initiation because it is weight-neutral (or promotes slight weight loss), does not cause hypoglycemia, has a proven cardiovascular safety profile, and is cost-effective [1]. **Why Other Options are Incorrect:** * **Pioglitazone (Thiazolidinedione):** While it effectively reduces insulin resistance via PPAR-̳ activation [2], it is generally a second-line agent due to side effects like weight gain, edema, and risks of heart failure and osteoporosis [2]. * **Glimepiride (Sulfonylurea):** These are "insulin secretagogues." They carry a high risk of hypoglycemia and weight gain, making them less ideal than Metformin for initial monotherapy [1]. * **Repaglinide (Meglitinide):** Also a secretagogue with a short duration of action used primarily for postprandial hyperglycemia [3]. It requires multiple daily dosing and is not the standard first-line agent. **High-Yield Clinical Pearls for NEET-PG:** * **Mnemonic for Metformin SE:** **M**etallic taste, **M**egaloblastic anemia (Vitamin B12 deficiency), and **M**ost serious side effect: Lactic Acidosis [2]. * **Contraindication:** Metformin should be avoided if eGFR < 30 mL/min due to the risk of lactic acidosis [2]. * **Efficacy:** Metformin typically reduces HbA1c by 1.0% to 1.5% [2]. * **Pleiotropic effect:** It is also used in Polycystic Ovary Syndrome (PCOS) to improve insulin sensitivity and ovulation.

Q: A 25-year-old male presents with weakness, occasional vomiting, hypotension, and skin and mucous membrane pigmentation. The diagnosis can be best established by?

ACTH stimulation test. The clinical presentation of weakness, vomiting, hypotension, and **hyperpigmentation** (skin and mucous membranes) is a classic triad for **Primary Adrenocortical Insufficiency (Addison’s Disease)**. The pigmentation occurs because low cortisol levels lead to a compensatory increase in ACTH and its precursor, POMC, which contains Melanocyte-Stimulating Hormone (MSH) sequences [2]. **Why the ACTH Stimulation Test is the Correct Answer:** The **Short Synacthen (ACTH) Stimulation Test** is the gold standard for diagnosing adrenal insufficiency [1]. It assesses the adrenal gland's reserve. In a healthy individual, administering synthetic ACTH (Cosyntropin) should significantly increase serum cortisol. In Addison’s disease, the damaged adrenal cortex fails to respond, resulting in a flat or blunted cortisol response [1]. **Analysis of Incorrect Options:** * **Metyrapone Test:** This blocks 11-beta-hydroxylase and is primarily used to assess the integrity of the entire HPA axis (Secondary insufficiency) or to differentiate causes of Cushing’s syndrome. It is not the first-line diagnostic test for Addison’s. * **Basal Plasma Cortisol:** Cortisol is secreted in a diurnal rhythm and can be low in healthy individuals during the evening. A single random basal level is often non-diagnostic unless it is extremely low (<3 mcg/dL) in the early morning [1]. * **24-hour Urinary 17-ketosteroid:** This measures androgen metabolites and is an outdated, non-specific test with low sensitivity for diagnosing adrenal failure. **Clinical Pearls for NEET-PG:** * **Most common cause:** Autoimmune adrenalitis (Western world); Tuberculosis (Developing countries/India) [2]. * **Electrolyte profile:** Hyponatremia, Hyperkalemia, and Metabolic Acidosis. * **Acute Crisis Management:** Do not wait for tests; treat immediately with IV fluids (Normal Saline) and IV Hydrocortisone [1].

Question 1

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

Accepted Answer

80%

Answer

20%

Answer

40%

Answer

60%

Question 2

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

Accepted Answer

Pregabalin

Answer

Gabapentin

Answer

Lamotrigine

Answer

Mexiletine

Question 3

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

Accepted Answer

55 mmol/L

Answer

20 mmol/L

Answer

80 mmol/L

Answer

5 mmol/L

Question 4

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

Accepted Answer

Parathyroid adenoma

Answer

Chronic renal failure

Answer

Vitamin D deficiency

Answer

Medullary carcinoma thyroid

Question 5

Cushing's disease is characterized by:

Accepted Answer

Increased ACTH and increased cortisol

Answer

Increased ADH

Answer

Increased urinary catecholamines

Answer

Increased ACTH and decreased cortisol

Question 6

Which of the following is NOT seen in ACTH deficiency?

Accepted Answer

Hyperpigmentation

Answer

Weight loss

Answer

Hyponatremia

Answer

Hypoglycemia

Question 7

What are the symptoms of VIPOMA?

Accepted Answer

Secretory diarrhoea

Answer

Gall stones

Answer

Fat malabsorption

Answer

Flushing

Question 8

A 57-year-old lady presents with type II diabetes mellitus with symptoms like polyuria, excessive thirst, fatigue, and blurred vision. Further investigation reveals insulin resistance. Which one of the following drugs is most appropriate for initiating treatment along with diet and exercise?

Accepted Answer

Metformin

Answer

Pioglitazone

Answer

Glimepiride

Answer

Repaglinide

Question 9

A 25-year-old male presents with weakness, occasional vomiting, hypotension, and skin and mucous membrane pigmentation. The diagnosis can be best established by?

Accepted Answer

ACTH stimulation test

Answer

Metyrapone test

Answer

Basal plasma cortisol level

Answer

24-hour urinary 17-ketosteroid

Question 10

What is the goal blood pressure to be maintained in a patient with diabetes mellitus and hypertension?

Accepted Answer

<130/80 mm Hg

Answer

<160/90 mm Hg

Answer

<140/80 mm Hg

Answer

<120/80 mm Hg

Endocrinology — MCQs

Endocrinology — MCQs

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