Endocrinology Practice Questions

Q: Which of the following is NOT a characteristic of inappropriate ADH secretion?

Hypo-osmolar urine. **Explanation:** The hallmark of **Syndrome of Inappropriate Antidiuretic Hormone (SIADH)** is the excessive release of ADH despite low plasma osmolality. ADH acts on the V2 receptors in the renal collecting ducts, causing water reabsorption [1], [3]. **1. Why "Hypo-osmolar urine" is the correct answer:** In SIADH, the kidneys reabsorb excessive amounts of water, leading to concentrated urine. Therefore, the urine is **hyper-osmolar** (typically >100 mOsm/kg, and often greater than the plasma osmolality). **Hypo-osmolar urine** is characteristic of Diabetes Insipidus, not SIADH. **2. Analysis of incorrect options:** * **Water intoxication:** The continuous water reabsorption leads to dilutional hyponatremia, essentially a state of "water intoxication" where the body has too much water relative to sodium. * **Expanded fluid volume:** SIADH causes mild ECF volume expansion. However, it is clinically **euvolemic** [2] because the body compensates via pressure natriuresis (excreting sodium and water) to prevent overt edema or hypertension. * **Hypomagnesemia:** Chronic SIADH is frequently associated with secondary electrolyte disturbances, including hypomagnesemia and hypokalemia, due to increased urinary excretion of these ions alongside the natriuresis. **NEET-PG High-Yield Pearls:** * **Diagnosis:** Look for the triad of Hyponatremia + Low Plasma Osmolality ( 100 mOsm/kg) in a clinically euvolemic patient [2]. * **Urine Sodium:** Typically high (>40 mEq/L) due to the body's attempt to shed volume. * **Treatment:** Fluid restriction is the first-line treatment. For severe cases, use hypertonic saline (3%) but avoid rapid correction to prevent **Osmotic Demyelination Syndrome (Central Pontine Myelinolysis).** * **Drug of choice (Vaptans):** Tolvaptan (oral) or Conivaptan (IV) are vasopressin receptor antagonists used in refractory cases.

Q: Phaeochromocytoma arises from which of the following structures?

Adrenal gland. **Explanation:** **Phaeochromocytoma** is a catecholamine-secreting tumor that arises from the **chromaffin cells** of the adrenal medulla. These cells are derived from the neural crest and are responsible for synthesizing and secreting epinephrine and norepinephrine. * **Why Option A is correct:** Approximately **85-90%** of these tumors arise from the **adrenal gland**. The adrenal medulla is the primary site for chromaffin tissue in adults, making it the most common location for phaeochromocytoma. * **Why Options B, C, and D are incorrect:** While catecholamine-secreting tumors can occur outside the adrenal gland (in the mediastinum, neck, or abdomen), these are technically termed **Paragangliomas** (extra-adrenal phaeochromocytomas). While they share similar clinical features, the term "Phaeochromocytoma" specifically refers to the adrenal tumor in standard nomenclature. The chest wall is not a typical site for chromaffin tissue. **High-Yield Clinical Pearls for NEET-PG:** 1. **The Rule of 10s:** 10% are bilateral, 10% are malignant, 10% are extra-adrenal (paragangliomas), and 10% occur in children. 2. **Clinical Triad:** Episodic headache, sweating (diaphoresis), and tachycardia/palpitations, usually accompanied by hypertension. 3. **Diagnosis:** The best initial screening test is **24-hour urinary fractionated metanephrines** or plasma free metanephrines. 4. **Genetic Associations:** Often associated with **MEN 2A and 2B**, von Hippel-Lindau (VHL) syndrome, and Neurofibromatosis type 1 (NF1). 5. **Management:** Always start **Alpha-blockade** (e.g., Phenoxybenzamine) *before* Beta-blockade to prevent a hypertensive crisis caused by unopposed alpha-receptor stimulation.

Q: What is the most common cause of spontaneous hypoglycemia in a non-diabetic individual?

Alcohol consumption. The most common cause of spontaneous hypoglycemia in a non-diabetic individual is **alcohol consumption** [3]. **Mechanism of Alcohol-Induced Hypoglycemia:** Alcohol metabolism by the enzyme *alcohol dehydrogenase* increases the **NADH/NAD+ ratio** in the liver. High levels of NADH inhibit gluconeogenesis by diverting key substrates (pyruvate to lactate and oxaloacetate to malate). In individuals with depleted glycogen stores (e.g., due to fasting or malnutrition), the body becomes entirely dependent on gluconeogenesis to maintain blood glucose. When this pathway is blocked by alcohol [3], profound hypoglycemia occurs. **Analysis of Incorrect Options:** * **A & B (Insulin and Oral Hypoglycemic Agents):** While these are the most common causes of hypoglycemia in **diabetic** patients (iatrogenic), they are considered "factitious" or accidental rather than "spontaneous" [1] in non-diabetics. * **C (Von Gierke’s Disease):** This is a Type I Glycogen Storage Disease (Glucose-6-Phosphatase deficiency). While it causes severe fasting hypoglycemia, it is a rare genetic disorder typically diagnosed in infancy, not the most common cause in the general population. **NEET-PG High-Yield Pearls:** * **Whipple’s Triad:** Essential for diagnosing true hypoglycemia: (1) Symptoms of hypoglycemia, (2) Low plasma glucose level, and (3) Relief of symptoms when glucose is raised. [2] * **Fasting vs. Postprandial:** Alcohol causes *fasting* hypoglycemia. In contrast, Insulinoma (a rare neuroendocrine tumor) also causes fasting hypoglycemia but is characterized by high insulin and C-peptide levels [2]. * **Key Lab Finding:** In alcohol-induced hypoglycemia, look for an elevated **Lactate:Pyruvate ratio** due to the high NADH state.

Q: Which of the following is NOT a manifestation of carcinoid syndrome?

Steatorrhea. Explanation: Carcinoid syndrome results from the systemic release of vasoactive substances (primarily **serotonin**, histamine, and bradykinin) by neuroendocrine tumors, typically after they have metastasized to the liver [1]. **Why Steatorrhea is the Correct Answer:** Steatorrhea is **not** a direct manifestation of the syndrome itself. In fact, the diarrhea in carcinoid syndrome is **secretory** in nature (due to increased intestinal motility and fluid secretion caused by serotonin). However, steatorrhea can occur as a **side effect of treatment** with Somatostatin analogs (like Octreotide), which inhibit pancreatic enzyme secretion. It is not a primary clinical feature of the disease process. **Analysis of Other Options:** * **Retroperitoneal Fibrosis & Peyronie’s Disease:** High levels of serotonin stimulate fibroblast proliferation. This leads to **fibrotic complications**, including right-sided endocardial fibrosis, retroperitoneal fibrosis, and Peyronie’s disease (fibrosis of the corpus cavernosum). * **Occlusion of Mesenteric Arteries:** The intense local fibrotic reaction (desmoplastic reaction) in the mesentery can lead to kinking of the bowel and vascular compromise, potentially causing mesenteric ischemia or occlusion. **NEET-PG High-Yield Pearls:** * **Classic Triad:** Flushing (most common), Secretory Diarrhea, and Right-sided heart failure (Tricuspid regurgitation/Pulmonary stenosis) [1]. * **Diagnosis:** Best initial screening test is **24-hour urinary 5-HIAA** (metabolite of serotonin). * **Localization:** Somatostatin receptor scintigraphy (OctreoScan) or 68Ga-DOTATATE PET/CT. * **Pellagra Connection:** Serotonin is synthesized from Tryptophan. Excessive production can deplete Tryptophan stores, leading to **Niacin (Vitamin B3) deficiency** and Pellagra (Dermatitis, Dementia, Diarrhea).

Q: Non-pitting edema is seen in which of the following conditions?

Myxedema. **Explanation:** **Correct Answer: B. Myxedema** The hallmark of hypothyroidism (specifically severe cases or "myxedema") is **non-pitting edema**. This occurs due to the excessive deposition of **glycosaminoglycans** (primarily hyaluronic acid and chondroitin sulfate) in the dermis. These molecules are osmotic and trap water, but because they are bound in a mucopolysaccharide matrix, the fluid cannot be displaced by manual pressure, resulting in a firm, non-pitting surface [1]. This is most commonly seen in the pretibial area and periorbital tissues. **Incorrect Options:** * **A, C, and D (CCF, Liver Failure, Renal Failure):** These conditions cause **pitting edema**. The underlying mechanism is a disturbance in Starling forces—either an increase in capillary hydrostatic pressure (Heart Failure) or a decrease in plasma oncotic pressure due to hypoalbuminemia (Liver Cirrhosis and Nephrotic Syndrome). In these cases, the edema consists of free-moving interstitial fluid that is easily displaced upon pressure, leaving a "pit." **NEET-PG High-Yield Pearls:** * **Pretibial Myxedema:** Despite the name, this is actually a feature of **Graves' disease** (Hyperthyroidism), caused by thyroid-stimulating antibodies reacting with TSH receptors on fibroblasts [1]. It is also non-pitting. * **Lymphedema:** Another classic cause of non-pitting edema (e.g., in Filariasis or post-mastectomy) due to impaired lymphatic drainage and subsequent fibrosis. * **Stem Clue:** If a question mentions "puffy face," "macroglossia," and "non-pitting edema," always think of **Hypothyroidism**.

Q: Which of the following signs is characteristic of Graves' disease?

Kocher sign. The correct answer is **Kocher sign**. While all the options listed are ocular signs associated with hyperthyroidism, the question asks for a sign specifically characteristic of **Graves' disease** (Graves' ophthalmopathy), rather than just general thyrotoxicosis. 1. **Kocher Sign:** This refers to an appearance of a "frightened expression" or a fixed stare on upward gaze. It is caused by increased sympathetic activity and, more importantly, the inflammatory involvement of the levator palpebrae superioris muscle. In the context of NEET-PG, it is frequently associated with the infiltrative ophthalmopathy unique to Graves' disease. 2. **Why the others are incorrect:** * **Von Graefe sign:** This is "lid lag" (the upper eyelid fails to follow the globe smoothly on downward gaze). While common in Graves', it is a non-specific sign of thyrotoxicosis caused by sympathetic overactivity of the Müller’s muscle. * **Stellwag sign:** This refers to infrequent or incomplete blinking. Like lid lag, it is a general sign of sympathetic overstimulation seen in any form of hyperthyroidism. * **Chemosis:** This is edema of the conjunctiva. While it occurs in severe Graves' ophthalmopathy due to venous congestion, it is a clinical finding rather than a named "eponymous sign" like Kocher’s. **High-Yield Clinical Pearls for NEET-PG:** * **Dalrymple Sign:** Widening of the palpebral fissures (staring look) at rest [1]. * **Joffroy Sign:** Absence of forehead wrinkling on upward gaze. * **Mobius Sign:** Inability to maintain convergence of the eyes. * **Pathogenesis:** Graves' ophthalmopathy is caused by TSH-receptor antibodies (TRAb) reacting with receptors on orbital fibroblasts, leading to GAG accumulation and muscle edema [1, 2]. Smoking is the most significant modifiable risk factor for progression.

Question 1

A 35-year-old man develops symptoms of hyperthyroidism with tachycardia and heat intolerance over a one-month period. Thyroid biopsy demonstrates a heavy mononuclear cell infiltrate with multinucleated giant cells, follicular disruption, and loss of colloid. About one month later, the patient develops symptoms of hypothyroidism. To which of the following is this patient's condition thought to be most closely related?

Accepted Answer

Viral infection

Answer

Blocking TSH receptor autoantibodies

Answer

Carcinoma

Answer

Lymphoma

Question 2

Which of the following is NOT a characteristic of inappropriate ADH secretion?

Accepted Answer

Hypo-osmolar urine

Answer

Water intoxication

Answer

Expanded fluid volume

Answer

Hypomagnesemia

Question 3

Phaeochromocytoma arises from which of the following structures?

Accepted Answer

Adrenal gland

Answer

Mediastinum

Answer

Chest wall

Answer

Neck

Question 4

What is the most common cause of spontaneous hypoglycemia in a non-diabetic individual?

Accepted Answer

Alcohol consumption

Answer

Insulin

Answer

Oral hypoglycemic agents

Answer

Von Gierke's disease

Question 5

Which of the following is NOT a manifestation of carcinoid syndrome?

Accepted Answer

Steatorrhea

Answer

Retroperitoneal fibrosis

Answer

Peyronie's disease of the penis

Answer

Occlusion of the mesenteric arteries

Question 6

Which of the following is true about the therapy of obesity?

Accepted Answer

Adjuvant pharmacotherapy is indicated for BMI > 30 kg/m2.

Answer

Bariatric surgery is indicated for BMI > 30 kg/m2.

Answer

Lifestyle modification is not required.

Answer

Reducing appetite by centrally active drugs is not an option.

Question 7

Non-pitting edema is seen in which of the following conditions?

Accepted Answer

Myxedema

Answer

Congestive cardiac failure

Answer

Liver failure

Answer

Renal failure

Question 8

A 29-year-old male on oral hypoglycemic drugs has never had ketonuria. His BMI is 20.5. His grandfather had diabetes, and his father, who was his grandfather's only son, also had the disease. Which type of diabetes mellitus is this person most likely to have?

Accepted Answer

Maturity-onset diabetes of the young (MODY)

Answer

Pancreatic diabetes

Answer

Type I diabetes mellitus

Answer

Type II diabetes mellitus

Question 9

Which of the following signs is characteristic of Graves' disease?

Accepted Answer

Kocher sign

Answer

Chemosis

Answer

Von Graefe sign

Answer

Stellwag sign

Question 10

A 58-year-old man is referred for evaluation of a 2-cm adrenal mass discovered incidentally on a CT scan performed for abdominal pain. The patient has no history of malignancy and denies erectile dysfunction. Physical examination reveals a blood pressure of 122/78 mmHg with no gynecomastia or evidence of Cushing syndrome. His serum potassium is normal. What is the next step in determining whether this patient's adrenal mass should be resected?

Accepted Answer

Plasma metanephrines and dexamethasone-suppressed cortisol level

Answer

Plasma aldosterone/renin ratio

Answer

Estradiol level

Answer

Testosterone level

Endocrinology — MCQs

Endocrinology — MCQs

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