Endocrinology — MCQs

Endocrinology Indian Medical PG Practice Questions and MCQs

Question 301: How is hyperthyroidism diagnosed?

A. Triiodothyronine (T3) and Thyroxine (T4)
B. Triiodothyronine (T3), Thyroxine (T4), and Thyroid Stimulating Hormone (TSH) (Correct Answer)
C. Triiodothyronine (T3), Thyroxine (T4), and Radioactive Iodine Uptake (RAI)
D. Triiodothyronine (T3), Thyroxine (T4), Radioactive Iodine Uptake (RAI), and TSH

Explanation: The diagnosis of hyperthyroidism relies on the biochemical assessment of the hypothalamic-pituitary-thyroid axis. The primary screening and diagnostic tool is the **Serum TSH level**, which is the most sensitive indicator. In primary hyperthyroidism, elevated levels of free **T4 and T3** exert negative feedback on the pituitary, leading to a suppressed TSH (usually <0.01 mU/L) [1]. **Why Option B is correct:** To confirm a diagnosis of hyperthyroidism, one must demonstrate both a suppressed TSH and elevated levels of thyroid hormones (T3 and T4) [3]. Measuring T3 is crucial because, in early Graves' disease or toxic nodules, "T3 toxicosis" may occur where T4 remains normal but T3 is elevated. **Why other options are incorrect:** * **Option A:** Lacks TSH. Without TSH, you cannot distinguish between primary hyperthyroidism and rare secondary causes (TSH-secreting tumors). * **Options C & D:** These include **Radioactive Iodine Uptake (RAI)**. While RAI is essential for determining the **etiology** (e.g., Graves' vs. Thyroiditis), it is not required for the initial biochemical **diagnosis** of the hyperthyroid state itself [2]. **NEET-PG High-Yield Pearls:** * **Best Initial Test:** Serum TSH. * **Subclinical Hyperthyroidism:** Low TSH with normal Free T4 and T3. * **T3 Toxicosis:** Low TSH, normal T4, but high T3 (seen in ~5% of patients). * **Amiodarone:** Can cause both hyperthyroidism (Type 1 or 2) and hypothyroidism (Wolff-Chaikoff effect). * **Pregnancy:** Always use Total T3/T4 (which increase due to TBG) or pregnancy-specific free hormone ranges.

Question 302: The insulin preparation of choice in diabetic ketoacidosis is

A. Regular insulin (Correct Answer)
B. Lente insulin
C. Isophane insulin
D. A 30:70 mixture of plain and isophane insulin

Explanation: **Explanation:** **1. Why Regular Insulin is the Correct Choice:** Regular (Short-acting) insulin is the gold standard for managing Diabetic Ketoacidosis (DKA) because of its **pharmacokinetic profile**. When administered intravenously (IV), it has an immediate onset of action and a short half-life (approx. 5–10 minutes). This allows for rapid titration and precise control over blood glucose and ketone suppression [1]. In DKA, the goal is to inhibit lipolysis and ketogenesis quickly; Regular insulin is the only preparation that can be safely administered via continuous IV infusion, which is the preferred route in acute emergencies [3]. **2. Why the Other Options are Incorrect:** * **Lente and Isophane (NPH) Insulin:** These are intermediate-acting insulins. They contain additives (like zinc or protamine) to delay absorption, making them unsuitable for IV use [2]. Their slow onset and prolonged duration of action make them impossible to titrate rapidly during a metabolic crisis. * **30:70 Mixture:** This is a premixed combination of Regular and NPH insulin. While it contains some short-acting insulin, the NPH component makes it inappropriate for IV administration and acute management. **3. Clinical Pearls for NEET-PG:** * **Route of Choice:** In DKA, the IV route is preferred over subcutaneous because of poor peripheral perfusion in dehydrated patients. * **Standard Dose:** The standard protocol involves an initial bolus (0.1 U/kg) followed by a continuous infusion (0.1 U/kg/hr) [1]. * **The "Rule of 50":** When blood glucose reaches **200–250 mg/dL**, 5% Dextrose should be added to the IV fluids to prevent hypoglycemia while continuing insulin to resolve the ketosis [4]. * **Potassium Warning:** Never start insulin if serum potassium is **<3.3 mEq/L**, as insulin will shift potassium intracellularly, potentially causing fatal arrhythmias [2].

Question 303: In Sipple syndrome (MEN 2A), which of the following is typically absent?

A. Pheochromocytoma
B. Pituitary hyperplasia (Correct Answer)
C. Medullary carcinoma of the thyroid
D. Parathyroid hyperplasia

Explanation: Explanation: The correct answer is Pituitary hyperplasia because it is a classic feature of MEN 1 (Wermer Syndrome), not MEN 2A (Sipple Syndrome). Both syndromes are autosomal dominant neuroendocrine disorders, but they involve different genetic mutations and organ systems. 1. Why Pituitary Hyperplasia is the correct answer: MEN 2A is caused by a germline mutation in the RET proto-oncogene. Its clinical spectrum is strictly limited to the "MPH" triad: Medullary thyroid carcinoma, Pheochromocytoma, and Hyperparathyroidism. Pituitary adenomas or hyperplasia are characteristic of MEN 1 (the "3 Ps": Pituitary, Parathyroid, and Pancreas). 2. Analysis of Incorrect Options: * Pheochromocytoma (Option A): Present in approximately 50% of MEN 2A cases. They are often bilateral and almost always occur within the adrenal gland. * Medullary Carcinoma of Thyroid (MTC) (Option C): This is the most common feature (nearly 100% penetrance) and usually the first manifestation of MEN 2A. It arises from calcitonin-secreting C-cells. * Parathyroid Hyperplasia (Option D): Occurs in about 20-30% of MEN 2A patients, leading to primary hyperparathyroidism. High-Yield Clinical Pearls for NEET-PG: * MEN 2A (Sipple): MTC + Pheochromocytoma + Parathyroid hyperplasia. * MEN 2B (Williams): MTC + Pheochromocytoma + Mucosal neuromas + Marfanoid habitus (Note: Parathyroid involvement is rare in 2B). * Screening: For MEN 2A/2B, genetic testing for RET mutations is the gold standard. Prophylactic thyroidectomy is often indicated in childhood based on the specific codon mutation. * Rule of Thumb: Always rule out Pheochromocytoma (via plasma metanephrines) before performing surgery for MTC or Hyperparathyroidism to prevent a hypertensive crisis.

Question 304: The goals of therapy for type 1 or type 2 diabetes mellitus are all except?

A. Eliminate symptoms related to hyperglycemia
B. Reduce or eliminate the long-term microvascular and macrovascular complications of DM
C. Allow the patient to achieve as normal a lifestyle as possible
D. Restore the function of Beta cells (Correct Answer)

Explanation: ### Explanation The primary objective of diabetes management is to manage the metabolic consequences of the disease rather than reversing the underlying pathophysiology of insulin deficiency or resistance. **Why "Restore the function of Beta cells" is the correct answer:** Currently, there is no established clinical therapy that can "restore" or "regrow" functional Beta cells once they have been destroyed (Type 1 DM) or have undergone significant exhaustion/apoptosis (Type 2 DM). While research into stem cell therapy and islet cell transplantation is ongoing, it is not a standard goal of current medical therapy. Management focuses on **replacement** (exogenous insulin) or **compensation** (sensitizers/secretagogues), not restoration of the organ's original function. **Analysis of Incorrect Options:** * **Option A:** Eliminating symptoms like polyuria, polydipsia, and blurred vision is the immediate short-term goal to improve the patient's quality of life and prevent acute complications like DKA or HHS. * **Option B:** This is the most critical long-term goal [1]. Intensive glycemic control (as proven by the **DCCT** and **UKPDS** trials) significantly reduces the risk of retinopathy, nephropathy, neuropathy (microvascular), and cardiovascular events (macrovascular) [1]. * **Option C:** Modern diabetes care emphasizes patient-centered management, utilizing flexible insulin regimens and technology (CGMs/Pumps) to ensure the patient maintains a normal social, professional, and personal lifestyle [2]. **High-Yield Clinical Pearls for NEET-PG:** * **DCCT Trial:** Confirmed that intensive glycemic control reduces microvascular complications in **Type 1 DM**. * **UKPDS Trial:** Confirmed the same for **Type 2 DM** [1]. * **Legacy Effect (Metabolic Memory):** Early intensive glycemic control provides long-term protection against complications even if control worsens later. * **Glycemic Targets:** For most non-pregnant adults, the goal is an **HbA1c < 7.0%** [3].

Question 305: Which of the following is NOT a cause of fasting hypoglycemia?

A. Excess glucagon (Correct Answer)
B. Glucose-6-phosphatase deficiency
C. Uremia
D. Glycogen synthase deficiency

Explanation: **Explanation:** The core physiological mechanism of fasting hypoglycemia involves an inability to maintain blood glucose levels during periods of starvation, usually due to defects in glycogenolysis, gluconeogenesis, or hormonal regulation [3]. **Why Option A is correct:** **Glucagon** is a counter-regulatory hormone produced by the alpha cells of the pancreas. Its primary function is to **increase** blood glucose levels by stimulating glycogenolysis and gluconeogenesis in the liver [1]. Therefore, an **excess of glucagon** (as seen in a Glucagonoma) would lead to **hyperglycemia**, not hypoglycemia. **Why the other options are incorrect:** * **B. Glucose-6-phosphatase deficiency (Von Gierke Disease):** This is Type I Glycogen Storage Disease (GSD). This enzyme is essential for the final step of both glycogenolysis and gluconeogenesis [2]. Its absence leads to severe fasting hypoglycemia because the liver cannot release free glucose into the blood. * **C. Uremia:** Chronic kidney disease/uremia causes hypoglycemia through multiple mechanisms, including reduced renal gluconeogenesis (the kidney contributes ~20% of glucose production), impaired insulin clearance, and malnutrition. * **D. Glycogen synthase deficiency:** Known as Type 0 GSD, this condition prevents the liver from storing glycogen [3]. Without glycogen stores to draw upon during a fast, patients develop ketotic hypoglycemia. **High-Yield NEET-PG Pearls:** * **Whipple’s Triad for Hypoglycemia:** 1. Symptoms of hypoglycemia, 2. Low plasma glucose (<55 mg/dL), 3. Relief of symptoms after glucose administration. * **Common causes of fasting hypoglycemia:** Insulinoma, exogenous insulin (factitious), adrenal insufficiency (Addison’s), and severe liver disease. * **Glucagonoma Clinical Triad:** Hyperglycemia (Diabetes), Necrolytic Migratory Erythema (NME), and weight loss.

Question 306: What is the most likely diagnosis in a patient with generalized weakness and the given cutaneous finding?

A. Lichen planus pigmentosus
B. Smoker's melanosis
C. Cushing's disease
D. Diffuse melanosis cutis (Correct Answer)

Explanation: ***Diffuse melanosis cutis*** - Generalized weakness combined with diffuse cutaneous hyperpigmentation suggests **Addison's disease** (primary adrenal insufficiency) causing excess **ACTH and MSH** stimulation. - The **melanosis cutis** results from increased melanin deposition due to elevated **melanocyte-stimulating hormone** levels when cortisol feedback is lost. *Lichen planus pigmentosus* - Presents with **localized hyperpigmented patches** rather than generalized melanosis, typically following inflammatory lichen planus lesions. - Does not cause **systemic weakness** or constitutional symptoms like adrenal insufficiency. *Smoker's melanosis* - Characterized by **localized oral mucosal pigmentation** from chronic smoking, not generalized cutaneous involvement. - Associated with **tobacco use** and does not cause generalized weakness or systemic symptoms. *Cushing's disease* - Typically causes **central obesity**, **purple striae**, and **moon facies** rather than generalized hyperpigmentation. - Results in **hyperglycemia** and **hypertension**, not the weakness and hyperpigmentation seen in adrenal insufficiency.

Question 307: Liddle syndrome is characterized by

A. Hypokalemic metabolic alkalosis with hypotension
B. Hypokalemic metabolic alkalosis with hypertension (Correct Answer)
C. Hyperkalemic metabolic acidosis with hypotension
D. Hyperkalemic metabolic acidosis with hypertension

Explanation: **Explanation:** **Liddle Syndrome** is an autosomal dominant genetic disorder caused by a **gain-of-function mutation** in the genes encoding the **ENaC (Epithelial Sodium Channel)** in the collecting tubules of the kidney. 1. **Why Option B is Correct:** The overactive ENaC leads to constitutive (unregulated) reabsorption of sodium, regardless of aldosterone levels. This causes: * **Hypertension:** Due to excessive sodium and water retention (volume expansion). * **Hypokalemic Metabolic Alkalosis:** Increased sodium reabsorption creates a negative luminal potential, which forces the secretion of Potassium ($K^+$) and Hydrogen ions ($H^+$) into the urine [1]. [2]. 2. **Why Other Options are Incorrect:** * **Option A:** Hypotension is seen in "salt-wasting" syndromes like Bartter or Gitelman syndrome, not Liddle. * **Options C & D:** Hyperkalemia and acidosis are characteristic of **Hypoaldosteronism** or **Type 4 Renal Tubular Acidosis (RTA)** [1]. Liddle syndrome mimics *excess* mineralocorticoid activity, leading to the opposite (hypokalemia/alkalosis) [2]. **High-Yield Clinical Pearls for NEET-PG:** * **Pseudo-hyperaldosteronism:** Liddle syndrome presents like primary hyperaldosteronism (Conn’s syndrome) but with **Low Renin** and **Low Aldosterone** levels (due to feedback suppression by volume expansion) [2]. * **Treatment:** It does **not** respond to Spironolactone (as the defect is distal to the aldosterone receptor). It is treated with ENaC blockers like **Amiloride** or **Triamterene**. * **Mnemonic:** "Liddle behaves like **Little** Aldosterone is present, but the channel is actually **Large** (overactive)."

Question 308: A patient presents with symptoms of hypoglycemia. Investigations reveal decreased blood glucose and increased insulin levels. A C-peptide assay shows normal levels of C-peptide. What is the most likely diagnosis?

A. Insulinoma
B. Accidental sulfonylurea ingestion
C. Accidental exogenous insulin administration (Correct Answer)
D. Accidental metformin ingestion

Explanation: ### Explanation The key to solving this clinical scenario lies in understanding the synthesis of endogenous insulin. Insulin is synthesized as **proinsulin**, which is cleaved into equal molar amounts of **active insulin** and **C-peptide** before being released into the bloodstream. **1. Why Option C is Correct:** In **exogenous insulin administration**, the patient injects pre-formed, purified insulin. This commercial insulin does not contain C-peptide. Therefore, the patient will present with the biochemical triad of: * **Low Blood Glucose** (Hypoglycemia) [3] * **High Insulin** (Exogenous) * **Low/Normal C-peptide** (Endogenous production is actually suppressed due to negative feedback from hypoglycemia) [1]. **2. Why the other options are incorrect:** * **Insulinoma (A):** This is an insulin-secreting tumor of the pancreas. Since it produces endogenous insulin, both **Insulin and C-peptide levels will be elevated** [1]. * **Sulfonylurea Ingestion (B):** Sulfonylureas are secretagogues that stimulate the pancreas to release its own insulin [2]. Consequently, both **Insulin and C-peptide levels will be elevated**, mimicking an insulinoma [1]. * **Metformin Ingestion (D):** Metformin works by increasing insulin sensitivity and decreasing hepatic glucose production; it does not increase insulin secretion and typically does not cause hypoglycemia in isolation. **3. NEET-PG High-Yield Pearls:** * **Factitious Hypoglycemia:** Suspect this in healthcare workers or relatives of diabetics. [1] * **Differential Diagnosis:** To differentiate Insulinoma from Sulfonylurea abuse (as both have high C-peptide), a **Screening for Oral Hypoglycemic Agents** in the urine or plasma is required [1]. * **Whipple’s Triad:** 1. Symptoms of hypoglycemia, 2. Low plasma glucose, 3. Relief of symptoms after glucose administration. This triad confirms a hypoglycemic disorder.

Question 309: Hypocalcemia is seen with which of the following conditions?

A. Thyrotoxicosis
B. Hyperparathyroidism
C. Acute pancreatitis (Correct Answer)
D. Addison disease

Explanation: Hypocalcemia is a classic metabolic complication of acute pancreatitis [2]. The primary mechanism is saponification: during pancreatic inflammation, released lipases break down peripancreatic fat into free fatty acids. These fatty acids bind to circulating ionized calcium, forming insoluble calcium soaps (salts) in the retroperitoneum. Additionally, a transient "parathyroid hormone (PTH) resistance" and hypomagnesemia may contribute to the decline in serum calcium levels [2]. In the Ranson Criteria, a fall in serum calcium (<8 mg/dL) within 48 hours is a marker of severe disease and poor prognosis. **Incorrect Options:** * **A. Thyrotoxicosis:** Excess thyroid hormone increases bone turnover by stimulating osteoclastic activity, which typically leads to **mild hypercalcemia** and hypercalciuria [1]. * **B. Hyperparathyroidism:** Primary hyperparathyroidism is characterized by the "classic triad" of **hypercalcemia**, hypophosphatemia, and elevated PTH [1]. * **D. Addison Disease:** Adrenal insufficiency is associated with **hypercalcemia** [1]. This occurs due to decreased renal calcium excretion and increased bone resorption, though the exact mechanism remains multifactorial. **High-Yield Clinical Pearls for NEET-PG:** * **Chvostek sign** (facial twitching on tapping the facial nerve) and **Trousseau sign** (carpal spasm on BP cuff inflation) are clinical markers of hypocalcemia. * **ECG finding:** The hallmark of hypocalcemia is **QT interval prolongation** (specifically the ST segment) [2]. * **Correction:** Always check serum albumin; for every 1 g/dL drop in albumin below 4 g/dL, add 0.8 mg/dL to the measured calcium to get the "corrected calcium" [2].

Question 310: De Quervain's disease is:

A. Acute suppurative thyroiditis.
B. Autoimmune thyroiditis.
C. Subacute thyroiditis. (Correct Answer)
D. None.

Explanation: **Explanation:** **De Quervain’s thyroiditis**, also known as **Subacute Granulomatous Thyroiditis**, is the correct answer (Option C). It is a self-limiting inflammatory condition of the thyroid gland, typically triggered by a **viral infection** (e.g., Coxsackievirus, Mumps, or Adenovirus). It classically presents in middle-aged women following an upper respiratory tract infection. **Why Option C is correct:** The underlying pathology involves the destruction of thyroid follicles and the formation of **multinucleated giant cells (granulomas)**. This leads to a characteristic clinical triad: 1. **Exquisite thyroid pain and tenderness** (often radiating to the jaw or ears). 2. **Transient hyperthyroidism** (due to the release of preformed hormones), followed by hypothyroidism, and eventual recovery [1]. 3. **Systemic symptoms** like fever and malaise. **Why other options are incorrect:** * **Option A (Acute Suppurative Thyroiditis):** This is a rare **bacterial infection** (usually *Staph* or *Strep*) characterized by abscess formation and high fever. It is distinct from the viral/granulomatous nature of De Quervain’s. * **Option B (Autoimmune Thyroiditis):** This refers to conditions like **Hashimoto’s thyroiditis**, which is typically painless and characterized by goiter and positive anti-TPO antibodies [1]. **High-Yield Clinical Pearls for NEET-PG:** * **ESR:** Characteristically **very high** (>50–100 mm/hr) [1]. * **Radioactive Iodine Uptake (RAIU):** Characteristically **low/depressed** (due to follicular damage), despite the patient being in a thyrotoxic state [1]. * **Treatment:** NSAIDs for mild cases; **Corticosteroids** for severe pain [1]. Antithyroid drugs (PTU/Methimazole) are **not** indicated as there is no new hormone synthesis [1].

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

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Endocrine Hypertension

Practice Questions

Multiple Endocrine Neoplasia

Practice Questions

Obesity and Metabolic Syndrome

Practice Questions

Neuroendocrine Tumors

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Endocrine Emergencies

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