Endocrinology Practice Questions

Q: Which of the following statements is NOT true regarding Insulinoma?

Weight loss. **Explanation:** Insulinoma is the most common functional neuroendocrine tumor (NET) of the pancreas [2]. It is characterized by the autonomous secretion of insulin, leading to fasting hypoglycemia. **Why Weight Loss is NOT true:** The hallmark of insulinoma is **weight gain**, not weight loss. This occurs for two primary reasons: 1. **Anabolic Effect:** Insulin is a potent anabolic hormone that promotes lipogenesis and inhibits lipolysis [3]. 2. **Increased Caloric Intake:** Patients frequently overeat or consume high-calorie snacks to prevent or relieve the distressing symptoms of neuroglycopenia. **Analysis of Other Options:** * **Hypoglycemic attacks:** These are the cardinal clinical feature [1]. Patients present with **Whipple’s Triad**: (1) Symptoms of hypoglycemia, (2) Low plasma glucose (<55 mg/dL), and (3) Relief of symptoms after glucose administration. * **Usually solitary tumor:** Over 90% of insulinomas occur as single, isolated lesions. Multiple tumors are rare and often associated with **MEN-1 syndrome**. * **Mostly benign tumor:** Approximately 90% of insulinomas are benign. Only about 5-10% show features of malignancy (metastasis to liver or regional lymph nodes). **High-Yield Clinical Pearls for NEET-PG:** * **Diagnosis:** The "Gold Standard" is the **72-hour fasting test**. Diagnostic findings include elevated Insulin (≥3 μU/mL), elevated C-peptide (≥0.6 ng/mL), and absent sulfonylurea in the urine/plasma during hypoglycemia [1]. * **Localization:** Endoscopic Ultrasound (EUS) is highly sensitive for preoperative localization. * **Treatment:** Surgical resection (enucleation) is the treatment of choice. Medical management includes **Diazoxide** (inhibits insulin release) or Octreotide.

Q: Which one of the following statements about non-insulin-dependent diabetes mellitus (NIDDM) is NOT true?

Circulating islet cell antibodies are usually found.. **Explanation:** Non-insulin-dependent diabetes mellitus (NIDDM), now commonly referred to as **Type 2 Diabetes Mellitus (T2DM)**, is characterized by peripheral insulin resistance and relative insulin deficiency rather than an autoimmune destruction of beta cells [2]. **Why Option A is the correct answer (The False Statement):** Circulating islet cell antibodies (ICAs), such as anti-GAD65, IA-2, or Zinc transporter 8 antibodies, are hallmarks of **Type 1 Diabetes Mellitus (T1DM)** [3]. They indicate an autoimmune process. In T2DM, these antibodies are typically **absent**. Their presence in an adult clinically diagnosed with T2DM often suggests **LADA** (Latent Autoimmune Diabetes in Adults). **Analysis of Incorrect Options:** * **Option B (No HLA association):** Unlike T1DM, which is strongly linked to HLA-DR3 and HLA-DR4, T2DM has no strong association with the HLA system [3]. It is linked to polygenic risk factors and lifestyle. * **Option C (Ketosis is rare):** In T2DM, there is usually enough endogenous insulin to suppress lipolysis and prevent the formation of ketone bodies [1]. Therefore, patients typically present with Hyperosmolar Hyperglycemic State (HHS) rather than Diabetic Ketoacidosis (DKA). * **Option D (Relative resistance to insulin):** This is the primary pathophysiology of T2DM [4]. Tissues (muscle, liver, fat) fail to respond adequately to insulin, requiring the pancreas to produce more until beta-cell exhaustion occurs [2]. **High-Yield NEET-PG Pearls:** * **Strongest Risk Factor for T2DM:** Obesity (central/visceral) [4]. * **Genetic Predisposition:** T2DM has a **stronger** genetic component (concordance in identical twins >90%) than T1DM (approx. 50%) [3]. * **Amyloid Deposition:** Histology of the pancreas in long-standing T2DM often shows **Amylin (Islet Amyloid Polypeptide)** deposits in the Islets of Langerhans.

Q: Hypertension with hyperkalemia is seen in which of the following conditions?

Gordon's syndrome. **Explanation:** The combination of **hypertension and hyperkalemia** is a classic "high-yield" clinical scenario. Most hypertensive endocrine disorders involve excess mineralocorticoids, which typically cause hypokalemia [1]. **1. Why Gordon’s Syndrome is correct:** Also known as **Pseudohypoaldosteronism Type II**, this is a rare genetic disorder caused by mutations in WNK kinases. This leads to overactivity of the **Na-Cl cotransporter (NCC)** in the distal convoluted tubule. The increased reabsorption of sodium and chloride causes volume expansion (hypertension). Because less sodium reaches the collecting duct, there is decreased secretion of potassium and hydrogen ions, resulting in **hyperkalemia** and metabolic acidosis, despite low or normal aldosterone levels. **2. Why the other options are incorrect:** * **Conn’s Syndrome (Primary Hyperaldosteronism):** Characterized by hypertension with **hypokalemia** (due to aldosterone-mediated potassium wasting) [2]. * **Addison’s Disease:** While it features hyperkalemia (due to aldosterone deficiency), it is characterized by **hypotension**, not hypertension. * **Renal Failure:** While advanced renal failure causes hyperkalemia and hypertension, Gordon’s syndrome is the specific endocrine/genetic "spot diagnosis" tested in this context, especially when renal function (GFR) is otherwise relatively preserved. **Clinical Pearls for NEET-PG:** * **Gordon’s Syndrome** is essentially the "mirror image" of Gitelman syndrome. * **Treatment:** It responds remarkably well to **Thiazide diuretics**, which block the overactive NCC transporter. * **Liddle’s Syndrome:** Another cause of hypertension, but it causes **hypokalemia** (due to overactive ENaC channels). * **Rule of Thumb:** Hypertension + Hyperkalemia = Think Gordon’s Syndrome or Renal Artery Stenosis with Renal Failure.

Q: Which of the following is NOT used in the diagnosis of insulinoma?

D-xylose test. The diagnosis of **Insulinoma** (an insulin-secreting pancreatic islet cell tumor) relies on demonstrating endogenous hyperinsulinemic hypoglycemia [1]. **Why D-xylose test is the correct answer:** The **D-xylose test** is a diagnostic tool used to evaluate the absorptive capacity of the proximal small intestine. It is primarily used to differentiate between malabsorption caused by intestinal mucosal disease (e.g., Celiac disease) and malabsorption due to pancreatic enzyme deficiency. It has no physiological or clinical relevance to glucose metabolism or insulin secretion. **Analysis of other options:** * **72-hour fasting blood glucose:** This is the **gold standard** provocative test for insulinoma. Patients are fasted until they develop symptoms of hypoglycemia (Whipple’s triad), at which point blood is drawn for glucose, insulin, and C-peptide [1]. * **C-peptide levels:** Insulinomas secrete insulin and C-peptide in equimolar amounts. High C-peptide levels during hypoglycemia help distinguish insulinoma from **factitious insulin injection** (where C-peptide would be suppressed) [1]. * **Insulin/glucose ratio:** In normal individuals, insulin levels fall as glucose falls. In insulinoma, the ratio is inappropriately high (typically **>0.3**). **Clinical Pearls for NEET-PG:** * **Whipple’s Triad:** 1. Symptoms of hypoglycemia, 2. Low plasma glucose (<55 mg/dL), 3. Relief of symptoms after glucose administration. * **Biochemical Diagnosis:** Glucose <55 mg/dL, Insulin ≥3 μU/mL, C-peptide ≥0.6 ng/mL, and Proinsulin ≥5.0 pmol/L. * **Localization:** Endoscopic Ultrasound (EUS) is the most sensitive imaging modality for localizing the tumor. * **Association:** 10% of insulinomas are associated with **MEN-1 syndrome**.

Q: Hypercholesterolemia is commonly associated with which of the following?

All of the above. Hypercholesterolemia is a common feature of several metabolic and systemic disorders. The correct answer is **All of the above** because each condition disrupts lipid metabolism through distinct pathophysiological mechanisms. ### **Pathophysiology of Hypercholesterolemia:** 1. **Hypothyroidism:** This is one of the most common causes of secondary hyperlipidemia. Thyroid hormones normally increase the expression of **LDL receptors** on hepatocytes. In hypothyroidism, a deficiency of these receptors leads to decreased clearance of LDL from the plasma, resulting in elevated serum cholesterol levels. 2. **Diabetes Mellitus:** Insulin deficiency or resistance leads to increased lipolysis in adipose tissue, flooding the liver with free fatty acids. This results in increased production of VLDL [2]. Furthermore, insulin is required for the activity of **Lipoprotein Lipase (LPL)**; its deficiency impairs the clearance of triglyceride-rich lipoproteins, often leading to a "diabetic dyslipidemia" characterized by high triglycerides and low HDL, but frequently accompanied by elevated LDL/Total Cholesterol [1]. 3. **Nephrotic Syndrome:** The liver compensates for the massive urinary loss of albumin by increasing the synthesis of all proteins, including **apolipoproteins (Apo-B)**. This leads to an overproduction of VLDL and LDL. Additionally, there is decreased catabolism of these lipoproteins due to reduced plasma levels of LPL. ### **NEET-PG High-Yield Pearls:** * **Most common lipid abnormality in Hypothyroidism:** Hypercholesterolemia (Type IIa or IIb phenotype). * **Most common lipid abnormality in Diabetes:** Hypertriglyceridemia [4]. * **Clinical Sign:** Look for **Xanthelasma** or **Xanthomas** in patients with severe secondary hyperlipidemia [3], [4]. * **Rule of Thumb:** Always screen for TSH and urinary protein before starting a patient on long-term statin therapy to rule out these reversible secondary causes.

Q: Which of the following agents is the drug of choice for Central Diabetes Insipidus?

Desmopressin. **Explanation:** **Central Diabetes Insipidus (CDI)** is characterized by a deficiency in the synthesis or release of Antidiuretic Hormone (ADH/Vasopressin) from the posterior pituitary. This leads to the inability to concentrate urine, resulting in polyuria and polydipsia [1]. **Why Desmopressin (dDAVP) is the Drug of Choice:** Desmopressin is a synthetic analogue of vasopressin. It is highly selective for **V2 receptors** located in the renal collecting ducts, which mediate the antidiuretic effect [2]. Unlike natural vasopressin, it has minimal activity at V1 receptors (which cause vasoconstriction), making it safer and more potent for long-term use [2]. It can be administered intranasally, orally, or parenterally [1]. **Analysis of Incorrect Options:** * **B. Demeclocycline:** This is a tetracycline derivative that induces a state of nephrogenic DI by inhibiting ADH action in the kidney. It is used to treat **SIADH**, not CDI. * **C. Thiazide Diuretics:** While used in *Nephrogenic* DI to create mild hypovolemia (leading to increased proximal water reabsorption), they are not the first-line treatment for CDI. * **D. Lithium:** This is a common **cause** of drug-induced Nephrogenic DI; it is never used as a treatment. **NEET-PG High-Yield Pearls:** * **Water Deprivation Test:** In CDI, urine osmolality increases by >50% after exogenous ADH administration. In Nephrogenic DI, there is little to no response [1]. * **Drug of Choice for Nephrogenic DI:** Amiloride (especially if lithium-induced) or Thiazides. * **Chlorpropamide & Carbamazepine:** These can be used in partial CDI as they sensitize the kidney to remaining ADH or stimulate ADH release. * **Pregnancy:** Desmopressin is the preferred agent for DI in pregnancy as it is resistant to degradation by placental vasopressinase.

Q: All of the following conditions cause SIADH, except?

Interstitial nephritis. **Explanation:** The Syndrome of Inappropriate Antidiuretic Hormone (SIADH) is characterized by the excessive release of ADH, leading to water retention and dilutional hyponatremia [2]. **Why Interstitial Nephritis is the correct answer:** Interstitial nephritis is a cause of **Nephrogenic Diabetes Insipidus (NDI)**, not SIADH [1]. In interstitial nephritis, the renal tubules become damaged and resistant to the action of ADH. This results in the inability to concentrate urine, leading to polyuria and potential hypernatremia—the physiological opposite of SIADH. **Analysis of Incorrect Options:** * **Lung Abscess:** Pulmonary infections (abscess, pneumonia, tuberculosis) are classic triggers for SIADH [2]. The exact mechanism is unclear but is thought to involve localized hypoxia or inflammation stimulating the posterior pituitary. * **Thymoma:** Certain tumors, particularly those in the chest like thymomas and lymphomas, can cause ectopic ADH production or stimulate the neurohypophysis. * **Carcinoma of Pancreas:** This is a recognized cause of ectopic ADH secretion. While Small Cell Lung Cancer (SCLC) is the most common neoplastic cause (75%), other GI and GU malignancies like pancreatic cancer can also secrete ADH. **High-Yield Clinical Pearls for NEET-PG:** * **Most common cause of SIADH:** Small Cell Carcinoma of the Lung. * **Diagnostic Criteria:** Euvolemic hyponatremia [2], low serum osmolality ( 100 mOsm/kg). * **Drug-induced SIADH:** Remember the "Cs": Cyclophosphamide, Carbamazepine, and Chlorpropamide. * **Treatment:** Fluid restriction is the first-line treatment. For severe symptomatic cases, use hypertonic saline (3%) with caution to avoid **Osmotic Demyelination Syndrome**.

Question 1

Which of the following statements is NOT true regarding Insulinoma?

Accepted Answer

Weight loss

Answer

Hypoglycemic attacks

Answer

Usually solitary tumor

Answer

Mostly benign tumor

Question 2

Which one of the following statements about non-insulin-dependent diabetes mellitus (NIDDM) is NOT true?

Accepted Answer

Circulating islet cell antibodies are usually found.

Answer

There is no HLA association.

Answer

Ketosis is rare.

Answer

Relative resistance to insulin is present.

Question 3

Hypertension with hyperkalemia is seen in which of the following conditions?

Accepted Answer

Gordon's syndrome

Answer

Conn's syndrome

Answer

Addison's disease

Answer

Renal failure

Question 4

Which of the following is NOT used in the diagnosis of insulinoma?

Accepted Answer

D-xylose test

Answer

72-hour fasting blood glucose levels

Answer

C-peptide levels

Answer

Insulin/glucose ratio

Question 5

Hypercholesterolemia is commonly associated with which of the following?

Accepted Answer

All of the above

Answer

Diabetes mellitus

Answer

Hypothyroidism

Answer

Nephrotic syndrome

Question 6

Dehydration in ketoacidosis is best treated with?

Accepted Answer

Normal saline

Answer

Isolyte P

Answer

Isolyte M

Answer

Molar 1/6 lactate

Question 7

Which disorder is associated with thyrotoxicosis but not with hyperthyroidism?

Accepted Answer

De Quervain thyroiditis

Answer

Graves disease

Answer

Hyperfunctioning ("toxic") multinodular goiter

Answer

Iodine-induced hyperthyroidism

Question 8

Sarcodiosis can be associated with which of the following?

Accepted Answer

Cranial diabetes insipidus

Answer

Psychogenic polydypsia

Answer

Nephrogenic diabetes insipidus

Answer

Syndrome of inappropriate antidiuretic hormone secretion (SIADH)

Question 9

Which of the following agents is the drug of choice for Central Diabetes Insipidus?

Accepted Answer

Desmopressin

Answer

Demeclocycline

Answer

Thiazide Diuretics

Answer

Lithium

Question 10

All of the following conditions cause SIADH, except?

Accepted Answer

Interstitial nephritis

Answer

Lung abscess

Answer

Thymoma

Answer

Carcinoma of pancreas

Endocrinology — MCQs

Endocrinology — MCQs

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