Endocrinology — MCQs

Endocrinology Indian Medical PG Practice Questions and MCQs

Question 801: Radioiodine is used in the treatment of which condition?

A. Graves disease (Correct Answer)
B. Hypothyroidism
C. Medullary carcinoma
D. Anaplastic carcinoma

Explanation: **Explanation:** Radioactive Iodine (RAI), specifically the **I-131 isotope**, is a cornerstone in the management of hyperthyroidism [1]. Its therapeutic efficacy relies on the thyroid gland's unique ability to actively trap iodine via the Sodium-Iodide Symporter (NIS). Once trapped, I-131 emits **beta particles**, which cause local tissue destruction (pyknosis and necrosis) of the overactive follicular cells over 6–18 weeks, effectively treating **Graves’ disease** [1]. **Analysis of Options:** * **Graves’ Disease (Correct):** RAI is a definitive treatment for Graves’, especially in adults, those with relapses after antithyroid drugs, or patients with comorbidities [1]. * **Hypothyroidism:** This is a state of thyroid hormone deficiency. RAI would further destroy thyroid tissue, worsening the condition. In fact, permanent hypothyroidism is the most common *complication* of RAI therapy. * **Medullary Carcinoma:** This tumor arises from **Parafollicular C-cells**, which do not concentrate iodine. Therefore, RAI has no role in its treatment. * **Anaplastic Carcinoma:** This is a highly undifferentiated tumor that loses the expression of the NIS symporter. Consequently, it does not take up iodine and is resistant to RAI therapy. **NEET-PG High-Yield Pearls:** * **Contraindications:** RAI is strictly **contraindicated in pregnancy** (crosses placenta, destroys fetal thyroid) and **breastfeeding** [2]. It should be avoided in patients with severe Graves' ophthalmopathy (may worsen it). * **Cancer Management:** While not used for Medullary or Anaplastic types, RAI is used post-thyroidectomy for **Differentiated Thyroid Cancers** (Papillary and Follicular) to ablate residual tissue or metastases [3]. * **Pre-treatment:** In elderly patients or those with cardiac disease, render them euthyroid with antithyroid drugs (Methimazole) before RAI to prevent a thyroid storm.

Question 802: What is the best marker to diagnose thyroid-related disorders?

A. T3
B. T4
C. TSH (Correct Answer)
D. Thyroglobulin

Explanation: **Explanation:** The **Thyroid Stimulating Hormone (TSH)** assay is the single most sensitive and specific screening test for diagnosing thyroid dysfunction. This is due to the **inverse logarithmic relationship** between Serum TSH and Free T4; even a minute change in free thyroid hormone levels results in a dramatic, compensatory change in TSH levels from the anterior pituitary [1]. Therefore, TSH becomes abnormal well before T3 or T4 levels fall outside the reference range (as seen in subclinical states) [1]. **Analysis of Incorrect Options:** * **T3 (Triiodothyronine):** This is the least reliable marker for hypothyroidism because levels are often maintained within the normal range by increased TSH stimulation until the disease is advanced [1]. It is primarily useful for diagnosing T3-toxicosis. * **T4 (Thyroxine):** While Free T4 is used to confirm the degree of thyroid dysfunction, it is less sensitive than TSH [2]. Total T4 is further unreliable as it is affected by changes in Thyroid Binding Globulin (TBG) levels (e.g., pregnancy, OCP use) [2]. * **Thyroglobulin:** This is not a diagnostic marker for thyroid function. It is used as a **tumor marker** to monitor for recurrence or persistence in patients with differentiated thyroid cancer (Papillary or Follicular) post-thyroidectomy [3]. **Clinical Pearls for NEET-PG:** * **Best Screening Test:** TSH. * **Best test to monitor Levothyroxine replacement:** TSH (target 0.5–2.5 mIU/L). * **Exception:** In **Secondary (Central) Hypothyroidism**, TSH is unreliable; Free T4 must be used for diagnosis and monitoring [2]. * **Amiodarone:** Can cause both hypo- and hyperthyroidism; TSH is the initial screening tool here as well.

Question 803: Which of the following is not a genetic syndrome associated with diabetes?

A. Down syndrome
B. Klinefelter syndrome
C. Turner syndrome
D. Angelman syndrome (Correct Answer)

Explanation: **Explanation:** The correct answer is **Angelman syndrome**. While many chromosomal and genetic disorders are associated with an increased risk of glucose intolerance and diabetes mellitus, Angelman syndrome is not typically one of them [1], [2]. **1. Why Angelman Syndrome is the correct answer:** Angelman syndrome is a neurodevelopmental disorder caused by a loss of function of the **UBE3A gene** on chromosome 15 (maternal inheritance). Its hallmark features include severe intellectual disability, speech impairment, ataxia, and a "happy" demeanor with frequent laughter. It is **not** associated with insulin resistance or pancreatic beta-cell dysfunction. **2. Why the other options are incorrect:** * **Down Syndrome (Trisomy 21):** Patients have a significantly higher risk of **Type 1 Diabetes** due to an increased predisposition to autoimmunity [1]. * **Klinefelter Syndrome (47, XXY):** This is strongly associated with metabolic syndrome, abdominal obesity, and **Type 2 Diabetes** due to hypogonadism and insulin resistance [3]. * **Turner Syndrome (45, X):** These patients have a high prevalence of glucose intolerance and diabetes (both Type 1 and Type 2) likely due to a combination of haploinsufficiency of X-chromosome genes and increased autoimmunity [3]. **High-Yield Clinical Pearls for NEET-PG:** * **Other Genetic Syndromes with Diabetes:** Prader-Willi syndrome (associated with obesity/Type 2 DM), Wolfram syndrome (DIDMOAD), Friedreich’s ataxia, and Myotonic dystrophy [2]. * **Wolfram Syndrome (DIDMOAD):** Diabetes Insipidus, Diabetes Mellitus, Optic Atrophy, and Deafness. * **Prader-Willi vs. Angelman:** Both involve Chromosome 15; however, Prader-Willi (paternal deletion) leads to hyperphagia and obesity-related diabetes, whereas Angelman (maternal deletion) does not.

Question 804: Primary hyperaldosteronism does not have which of the following findings?

A. Ankle edema (Correct Answer)
B. Polyuria
C. Hypertension
D. Hypokalemia

Explanation: ### Explanation **Primary Hyperaldosteronism (Conn’s Syndrome)** is characterized by the autonomous overproduction of aldosterone, leading to increased sodium reabsorption and potassium excretion in the distal nephron [2]. **1. Why Ankle Edema is absent (The Correct Answer):** Despite significant sodium and water retention, patients with primary hyperaldosteronism **do not** typically present with edema. This is due to the **"Aldosterone Escape" phenomenon** [1]. As the extracellular fluid volume expands, the body compensates by increasing the secretion of **Atrial Natriuretic Peptide (ANP)** and increasing the pressure natriuresis [4]. This leads to the excretion of excess sodium and water, preventing the formation of overt edema. **2. Analysis of Incorrect Options:** * **Hypertension:** This is the hallmark of the disease. Increased sodium reabsorption leads to volume expansion and increased peripheral resistance, causing secondary hypertension. * **Hypokalemia:** Aldosterone promotes potassium secretion in the cortical collecting duct [3]. Chronic depletion leads to muscle weakness, fatigue, and cardiac arrhythmias [2]. * **Polyuria:** Chronic hypokalemia causes **nephrogenic diabetes insipidus** (resistance to ADH). This results in an inability to concentrate urine, leading to polyuria and polydipsia. **3. High-Yield Clinical Pearls for NEET-PG:** * **Triad of Conn’s:** Hypertension, Hypokalemia, and Metabolic Alkalosis. * **Screening Test:** Plasma Aldosterone Concentration (PAC) to Plasma Renin Activity (PRA) ratio. A ratio **>20-30** is highly suggestive. * **Confirmatory Test:** Saline infusion test or Oral salt loading test (failure to suppress aldosterone). * **Management:** Surgical excision for unilateral adenoma; **Spironolactone** or Eplerenone (Aldosterone antagonists) for bilateral adrenal hyperplasia.

Question 805: A 25-year-old man presents with diabetes for the past year, which is well-controlled on oral hypoglycemic agents. He also has a family history of diabetes in young individuals. What is the most likely diagnosis?

A. Type 1 Diabetes mellitus
B. Type 2 Diabetes mellitus
C. Maturity Onset Diabetes in the Young (MODY) (Correct Answer)
D. Type A insulin resistance

Explanation: **Explanation:** The clinical presentation of a young patient (under 25 years) with a strong family history of diabetes and good glycemic control on oral hypoglycemic agents (OHAs) is classic for **Maturity Onset Diabetes in the Young (MODY)** [1]. **Why MODY is the correct answer:** MODY is a group of monogenic disorders characterized by an autosomal dominant inheritance pattern (affecting multiple generations) and primary defects in insulin secretion [1]. Unlike Type 1 DM, patients are typically non-obese, lack autoantibodies, and have preserved beta-cell function, allowing many subtypes (especially MODY 1 and 3) to be managed effectively with low-dose sulfonylureas rather than insulin. **Why other options are incorrect:** * **Type 1 Diabetes Mellitus:** Usually presents with an absolute insulin deficiency, ketosis-proneness, and requires lifelong insulin [2]. It is not typically controlled with oral agents. * **Type 2 Diabetes Mellitus:** While increasing in youth, it is usually associated with obesity, acanthosis nigricans, and insulin resistance [3]. The strong multi-generational history in a young, non-obese male points more specifically toward a monogenic cause. * **Type A Insulin Resistance:** This is a rare syndrome characterized by severe insulin resistance, acanthosis nigricans, and hyperandrogenism (in females), often due to insulin receptor mutations. **High-Yield Clinical Pearls for NEET-PG:** * **MODY 3 (HNF-1α mutation):** The most common subtype worldwide. * **MODY 2 (Glucokinase mutation):** Presents with mild, stable fasting hyperglycemia; often requires no treatment. * **Inheritance:** Autosomal Dominant (50% chance of transmission) [1]. * **Diagnostic Clue:** Absence of islet autoantibodies and detectable C-peptide levels 3–5 years after diagnosis [3].

Question 806: Which of the following is NOT seen in non-ketotic hyperosmolar coma?

A. Insidious onset
B. Kussmaul's breathing (Correct Answer)
C. Seen in elderly
D. Seen in type 2 DM

Explanation: ### Explanation **Hyperosmolar Hyperglycemic State (HHS)**, formerly known as non-ketotic hyperosmolar coma, is a metabolic complication of Diabetes Mellitus characterized by extreme hyperglycemia and hyperosmolality without significant ketoacidosis. **Why Kussmaul’s breathing is NOT seen:** Kussmaul’s breathing (deep, rapid, labored respiration) is a compensatory mechanism for **metabolic acidosis**. It occurs in Diabetic Ketoacidosis (DKA) to "blow off" CO2 and increase blood pH. In HHS, there is enough endogenous insulin to suppress lipolysis and prevent the formation of ketone bodies. Since there is no significant ketosis or acidosis, Kussmaul’s breathing is absent. **Analysis of other options:** * **Insidious onset:** Unlike DKA, which develops over hours, HHS develops over days to weeks. The slow progression allows for extreme dehydration and glucose levels often exceeding 600 mg/dL. * **Seen in elderly:** HHS typically affects older patients with Type 2 DM, often triggered by infections (like pneumonia or UTI), stroke, or myocardial infarction. * **Seen in Type 2 DM:** While DKA is the hallmark of Type 1 DM, HHS is the classic emergency associated with Type 2 DM, where residual insulin prevents ketogenesis but cannot control hyperglycemia. **High-Yield Clinical Pearls for NEET-PG:** * **Diagnostic Criteria for HHS:** Plasma glucose >600 mg/dL, Serum osmolality >320 mOsm/kg, and pH >7.3 (absence of acidosis). * **Neurological Symptoms:** HHS presents with more profound neurological deficits (coma, focal signs, seizures) than DKA due to extreme hyperosmolality. * **Management:** The priority in HHS is **aggressive fluid resuscitation** (Normal Saline) to correct the massive free water deficit, followed by insulin.

Question 807: Addison's disease is associated with all of the following except:

A. Cardiac atrophy
B. Decreased diastolic blood pressure
C. Serum cortisol < 8
D. Low renin levels (Correct Answer)

Explanation: Addison’s disease (Primary Adrenocortical Insufficiency) is characterized by the destruction of the adrenal cortex, leading to a deficiency in both **cortisol** and **aldosterone** [1]. **Why "Low renin levels" is the correct answer:** In Addison’s disease, the lack of aldosterone (mineralocorticoid deficiency) leads to sodium wasting and potassium retention [2]. The resulting hypovolemia and hypotension trigger the juxtaglomerular apparatus to increase renin production [1]. Therefore, **High Renin levels** (Hyperreninemic hypoaldosteronism) are a hallmark of primary adrenal insufficiency. Low renin would instead suggest secondary adrenal insufficiency or mineralocorticoid excess. **Analysis of Incorrect Options:** * **Cardiac Atrophy:** Chronic hypotension and reduced workload on the heart due to low blood volume lead to "microcardia" or cardiac atrophy, a classic radiological finding in Addison’s. * **Decreased Diastolic Blood Pressure:** Aldosterone deficiency causes volume depletion, while cortisol deficiency leads to reduced vascular sensitivity to catecholamines [1]. This results in systemic hypotension (both systolic and diastolic) and orthostatic changes. * **Serum Cortisol < 8 µg/dL:** A morning serum cortisol level of less than 3–5 µg/dL is highly suggestive of adrenal insufficiency; levels below 8–10 µg/dL in a stressed patient are considered inappropriately low. **High-Yield Clinical Pearls for NEET-PG:** * **Hyperpigmentation:** Seen only in *Primary* adrenal insufficiency (Addison’s) due to increased ACTH and POMC cleavage products (MSH). * **Electrolytes:** Look for the triad of **Hyponatremia, Hyperkalemia, and Metabolic Acidosis** [2]. * **Gold Standard Test:** ACTH Stimulation Test (Cosyntropin test). Failure of cortisol to rise above 18 µg/dL confirms the diagnosis. * **Most Common Cause:** Autoimmune adrenalitis (Western world); Tuberculosis (Developing countries/India).

Question 808: Symptoms associated with diabetes mellitus are all EXCEPT:

A. Nausea / Vomiting
B. Diarrhea (Correct Answer)
C. Abdominal pain
D. Shortness of breath

Explanation: The question focuses on the clinical presentation of **Diabetes Mellitus (DM)**, specifically acute complications like **Diabetic Ketoacidosis (DKA)**. **Why Diarrhea is the Correct Answer:** Diarrhea is not a classic or direct symptom of acute hyperglycemia or DKA. While long-term diabetic autonomic neuropathy can cause "diabetic diarrhea" due to gut dysmotility, it is a chronic complication rather than a presenting symptom of the disease itself. In the context of acute metabolic distress, gastrointestinal symptoms usually lean toward decreased motility (ileus) rather than diarrhea. **Analysis of Incorrect Options:** * **Nausea/Vomiting & Abdominal Pain (Options A & C):** These are hallmark features of **DKA** [1]. The accumulation of ketone bodies and metabolic acidosis leads to gastric irritation and delayed gastric emptying (gastroparesis). Abdominal pain in DKA can be so severe that it mimics an "acute abdomen" (pseudoperitonitis) [1]. * **Shortness of Breath (Option D):** This occurs due to **Kussmaul breathing**—deep, rapid, labored respirations [1]. It is a compensatory mechanism where the body attempts to blow off CO₂ to mitigate metabolic acidosis [2], [3]. **NEET-PG High-Yield Pearls:** * **DKA Triad:** Hyperglycemia, Ketosis, and Metabolic Acidosis (Anion Gap) [3]. * **Kussmaul Respiration:** A key clinical sign of metabolic acidosis (Mnemonic: **MUDPILES**) [1]. * **Abdominal Pain:** Always check blood sugar and urine ketones in a young patient presenting with unexplained abdominal pain to rule out DKA [1]. * **Electrolytes:** In DKA, total body potassium is depleted, even if serum levels appear normal or high initially [2].

Question 809: Pretibial myxedema is seen in:

A. Papillary carcinoma of the thyroid
B. Follicular carcinoma of the thyroid
C. Thyrotoxicosis (Correct Answer)
D. Myxedema

Explanation: **Explanation:** **Pretibial Myxedema** (also known as Thyroid Dermopathy) is a classic extrathyroidal manifestation of **Graves' Disease** [1], which is the most common cause of **Thyrotoxicosis** [3]. 1. **Why Thyrotoxicosis is Correct:** The condition is caused by the activation of thyrotropin receptor antibodies (TSHR-Ab) on fibroblasts in the dermis [1]. This leads to the excessive production of glycosaminoglycans (primarily hyaluronic acid), resulting in non-pitting edema, thickening, and a "peau d'orange" appearance of the skin, most commonly over the pretibial area [2]. While it is associated with hyperthyroidism, it is specifically a feature of the autoimmune process (Graves') rather than the high thyroid hormone levels themselves [1]. 2. **Why Other Options are Incorrect:** * **Options A & B (Thyroid Carcinomas):** Papillary and Follicular carcinomas are localized malignancies of the thyroid follicular cells. They do not involve the systemic autoimmune antibodies (TSHR-Ab) required to trigger dermal fibroblast activity. * **Option D (Myxedema):** Despite the confusing name, "Pretibial Myxedema" is **not** a feature of generalized myxedema (hypothyroidism). Hypothyroidism causes generalized non-pitting edema due to different metabolic reasons, but the specific localized dermopathy of the shins is unique to Graves' thyrotoxicosis [1]. **High-Yield Clinical Pearls for NEET-PG:** * **The Graves' Triad:** Hyperthyroidism (Goiter), Ophthalmopathy (Exophthalmos), and Dermopathy (Pretibial Myxedema) [3]. * **Occurrence:** Pretibial myxedema occurs in only 1–5% of Graves' patients and is almost always preceded by Graves' ophthalmopathy [1]. * **Diagnosis:** It is a clinical diagnosis; biopsy shows increased hyaluronic acid in the dermis. * **Treatment:** Topical glucocorticoids under occlusive dressings are the first-line therapy.

Question 810: A 52-year-old woman presents with polyuria, polydypsia, constipation, and fatigue. She has no significant past medical history and is not on any medications. She was recently diagnosed with hyperparathyroidism. What are the characteristic ECG findings in this condition?

A. Shortened PR interval
B. Lengthened PR interval
C. Lengthened QU interval
D. Shortening of the QT interval (Correct Answer)

Explanation: **Explanation:** The clinical presentation of polyuria, polydipsia, constipation, and fatigue in the setting of hyperparathyroidism points toward **Hypercalcemia** [1]. In hyperparathyroidism, excess parathyroid hormone (PTH) increases serum calcium levels [3]. **1. Why Option D is Correct:** Calcium ions play a critical role in the cardiac action potential. High extracellular calcium levels increase the gradient across the cell membrane, leading to a faster influx of calcium during Phase 2 (the plateau phase). This results in a **shortened plateau phase**, which translates to a **shortening of the ST segment** and, consequently, a **shortening of the QT interval** on the ECG. **2. Why the Other Options are Incorrect:** * **Option A & B:** While severe hypercalcemia can occasionally cause PR interval prolongation or heart block, it is not the *characteristic* or most common finding. PR interval changes are more typically associated with electrolyte imbalances like hyperkalemia or medications like digoxin. * **Option C:** A lengthened QU interval (or prominent U waves) is a classic sign of **Hypokalemia**, not hypercalcemia [2]. **3. NEET-PG High-Yield Pearls:** * **Hypercalcemia ECG:** Shortened QT interval, Osborne waves (rarely), and potential J-point elevation. * **Hypocalcemia ECG:** Prolonged QT interval (due to lengthening of the ST segment)—this is the direct opposite of hypercalcemia [2]. * **Mnemonic for Hypercalcemia Symptoms:** "Stones (renal), Bones (aches), Groans (abdominal pain/constipation), and Psychic Moans (fatigue/confusion)" [1]. * **Formula:** Corrected QT (QTc) = QT / √RR. A QTc < 390ms is generally considered short.

Practice by Chapter

Diabetes Mellitus

Practice Questions

Thyroid Disorders

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Adrenal Gland Disorders

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Pituitary Disorders

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Calcium and Bone Metabolism

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Reproductive Endocrinology

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Lipid Disorders

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Endocrine Hypertension

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Multiple Endocrine Neoplasia

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Obesity and Metabolic Syndrome

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Neuroendocrine Tumors

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Endocrine Emergencies

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