Endocrinology — MCQs

Endocrinology Indian Medical PG Practice Questions and MCQs

Question 1101: Hypoparathyroidism is seen in all of the following conditions except:

A. DiGeorge syndrome
B. Chronic renal failure (Correct Answer)
C. Wilson's disease
D. Hemochromatosis

Explanation: **Explanation:** The core concept here is distinguishing between conditions that cause **primary hypoparathyroidism** (destruction/dysfunction of the gland) and those that cause **secondary hyperparathyroidism**. **Why Chronic Renal Failure (CRF) is the correct answer:** In CRF, there is a decrease in 1-alpha-hydroxylase activity (leading to Vitamin D deficiency) and phosphate retention [1]. Both factors result in **hypocalcemia**, which acts as a potent stimulus for the parathyroid glands [2]. This leads to **Secondary Hyperparathyroidism** (elevated PTH levels) to compensate for the low calcium [1]. Therefore, CRF is associated with high PTH, not hypoparathyroidism. **Why the other options are incorrect:** * **DiGeorge Syndrome:** A congenital dysgenesis of the 3rd and 4th pharyngeal pouches, leading to thymic hypoplasia and **parathyroid aplasia**, causing primary hypoparathyroidism. * **Wilson’s Disease:** Excessive copper deposition can occur in the parathyroid glands, leading to tissue damage and functional hypoparathyroidism. * **Hemochromatosis:** Iron overload leads to deposition in various endocrine organs; iron deposition in the parathyroid glands causes gland destruction and hypoparathyroidism. **NEET-PG High-Yield Pearls:** 1. **Magnesium Link:** Severe hypomagnesemia can cause functional hypoparathyroidism because magnesium is required for both PTH secretion and its peripheral action [2]. 2. **Hungry Bone Syndrome:** A state of profound hypocalcemia seen post-parathyroidectomy in patients with pre-existing hyperparathyroidism. 3. **DiGeorge Mnemonic (CATCH-22):** **C**ardiac defects, **A**bnormal facies, **T**hymic hypoplasia, **C**left palate, **H**ypocalcemia (due to hypoparathyroidism), **22**q11 deletion.

Question 1102: A 19-year-old female presents for follow-up of medical management for panhypopituitarism after brain tumor resection. Her recent reports show that her TSH is below the detection limit of the assay. What is the next step in her management?

A. Decrease levothyroxine dose to half of the current dose.
B. Order a free T4 level. (Correct Answer)
C. Order an MRI of her brain.
D. Order a thyroid uptake scan.

Explanation: In patients with **Central Hypothyroidism** (due to pituitary or hypothalamic disease), the standard feedback loop between the thyroid and the pituitary gland is broken. Therefore, TSH cannot be used to monitor or adjust levothyroxine therapy [1]. ### 1. Why the Correct Answer is Right In this patient with panhypopituitarism, the pituitary gland is unable to produce TSH. A TSH level below the detection limit is an **expected finding** and does not indicate hyperthyroidism or over-replacement [1]. To assess if the patient is receiving the correct dose of levothyroxine, clinicians must measure the **Free T4 (fT4)** level. The goal of treatment in central hypothyroidism is to maintain the fT4 in the **upper half of the normal reference range** [1]. ### 2. Why the Other Options are Wrong * **A. Decrease levothyroxine dose:** This would be appropriate in primary hypothyroidism (where TSH is high), but in central hypothyroidism, a low TSH is the baseline state. Decreasing the dose based on TSH alone would lead to under-replacement [1]. * **C. Order an MRI of her brain:** While she has a history of a brain tumor, an MRI is indicated for neurological changes or surveillance, not for interpreting thyroid function tests in a known panhypopituitary patient. * **D. Order a thyroid uptake scan:** This is used to evaluate the etiology of hyperthyroidism (e.g., Graves' vs. Thyroiditis). It has no role in managing central hypothyroidism. ### 3. NEET-PG Clinical Pearls * **Monitoring Rule:** In Primary Hypothyroidism, monitor **TSH**. In Central Hypothyroidism, monitor **Free T4** [1]. * **Steroid First:** In panhypopituitarism, always rule out or treat **adrenal insufficiency** before starting levothyroxine to avoid precipitating an acute adrenal crisis (as thyroid hormone increases the metabolic clearance of cortisol) [1]. * **Etiology:** Common causes of central hypothyroidism include pituitary adenomas, craniopharyngiomas, surgery/radiation, and Sheehan syndrome [2].

Question 1103: Which of the following statements regarding Graves' disease is false?

A. Goiter is diffuse and vascular.
B. Cardiac failure is common. (Correct Answer)
C. Remissions and exacerbations are not infrequent.
D. Hypertrophy/hyperplasia is due to TSH-receptor antibodies.

Explanation: **Explanation:** Graves' disease is an autoimmune disorder characterized by the production of **TSH-receptor antibodies (TRAb)** [1], specifically Thyroid Stimulating Immunoglobulins (TSI). These antibodies mimic TSH, leading to autonomous overproduction of thyroid hormones [3]. **Why Option B is the Correct (False) Statement:** While Graves' disease significantly impacts the cardiovascular system (causing tachycardia, palpitations, and atrial fibrillation) [2], **congestive cardiac failure is NOT common**. High-output heart failure typically occurs only in elderly patients with underlying structural heart disease or during a thyroid storm. In the general population of Graves' patients, the hypermetabolic state increases cardiac output, but the heart usually compensates effectively. **Analysis of Other Options:** * **Option A (True):** The goiter in Graves' is typically **diffuse, smooth, and firm** [1]. It is highly **vascular**, often presenting with an audible bruit or palpable thrill due to increased blood flow. * **Option C (True):** Graves' disease is characterized by a fluctuating clinical course. Spontaneous **remissions and exacerbations** are common, which is why some patients can be managed with a "titration" or "block-and-replace" regimen of antithyroid drugs. * **Option D (True):** The fundamental pathophysiology involves **Type II Hypersensitivity**, where TRAb binds to and activates the TSH receptor, leading to follicular cell hypertrophy and hyperplasia [1]. **NEET-PG High-Yield Pearls:** * **Most common cause** of hyperthyroidism worldwide [3]. * **Triad:** Hyperthyroidism + Diffuse Goiter + Ophthalmopathy (Exophthalmos) [3]. * **Specific Marker:** TSH-receptor antibody (TRAb/TSI) [1]. * **Radioactive Iodine Uptake (RAIU):** Shows diffuse, increased uptake (unlike Thyroiditis, which has low uptake) [2]. * **Pretibial Myxedema:** A specific dermopathy (non-pitting edema) seen in Graves' due to glycosaminoglycan deposition [1].

Question 1104: All of the following are true about Hyperthyroidism EXCEPT:

A. Anxiety
B. Palpitations
C. Tachycardia
D. Weight gain (Correct Answer)

Explanation: **Explanation:** Hyperthyroidism is characterized by an excess of circulating thyroid hormones ($T_3$ and $T_4$), which leads to a **hypermetabolic state** and increased sensitivity to catecholamines [1]. **Why "Weight Gain" is the correct answer:** The hallmark of hyperthyroidism is an increase in the **Basal Metabolic Rate (BMR)**. Despite a frequent increase in appetite (polyphagia), the body consumes calories faster than they are ingested, leading to **weight loss** [1]. Weight gain is typically associated with *hypothyroidism*, where the BMR is decreased. **Analysis of Incorrect Options:** * **Anxiety:** Excess thyroid hormone increases sympathetic nervous system activity and has a direct effect on the central nervous system, leading to irritability, nervousness, and anxiety [1]. * **Palpitations:** This is a subjective feeling of a rapid or irregular heartbeat caused by increased cardiac output and stroke volume [2]. * **Tachycardia:** Thyroid hormones increase the expression of beta-adrenergic receptors in the heart. This leads to an increased heart rate (sinus tachycardia), even at rest, which is a classic clinical sign [2]. **High-Yield Clinical Pearls for NEET-PG:** * **Exception to the rule:** While weight loss is standard, "Apathetic Hyperthyroidism" in the elderly may present only with depression and weight loss, and rarely, young patients with extreme polyphagia may actually gain weight. * **Cardiac Complication:** The most common arrhythmia associated with hyperthyroidism (especially in the elderly) is **Atrial Fibrillation** [2]. * **Physical Sign:** Look for **Pretibial Myxedema** and **Exophthalmos**, which are specific to Graves' Disease, the most common cause of hyperthyroidism [1]. * **Reflexes:** Hyperthyroidism causes "brisk" or hyperreflexia, whereas hypothyroidism causes a "delayed relaxation phase" of deep tendon reflexes (Woltman sign).

Question 1105: Which of the following is a feature of primary hyperparathyroidism?

A. Reversible growth of parathyroid gland
B. Irreversible growth of parathyroid gland (Correct Answer)
C. Hypercalcemia and hyperphosphatemia
D. Hypocalcemia and hyperphosphatemia

Explanation: **Explanation:** **Primary Hyperparathyroidism (PHPT)** is characterized by the autonomous, unregulated overproduction of Parathyroid Hormone (PTH), most commonly due to a solitary parathyroid adenoma (85%) or diffuse hyperplasia [2]. 1. **Why Option B is Correct:** In PHPT, the growth of the parathyroid gland is **irreversible**. Unlike secondary hyperparathyroidism (where gland hyperplasia is a reversible compensatory response to low calcium), the pathology in PHPT involves a genetic or clonal shift (e.g., *MEN1* or *CCND1* mutations) that leads to autonomous proliferation [2]. This growth does not regress even if physiological triggers are altered. 2. **Why Other Options are Incorrect:** * **Option A:** Reversible growth is a feature of **Secondary Hyperparathyroidism** (e.g., in early Vitamin D deficiency), where the glands return to normal size once the underlying stimulus (hypocalcemia) is corrected [2]. * **Option C & D:** The hallmark biochemical profile of PHPT is **Hypercalcemia and Hypophosphatemia** [2]. PTH increases bone resorption and renal calcium reabsorption (causing hypercalcemia) while simultaneously inhibiting phosphate reabsorption in the proximal tubule (phosphaturic effect), leading to low serum phosphate [1]. **High-Yield Clinical Pearls for NEET-PG:** * **Classic Mnemonic:** "Stones, bones, abdominal groans, and psychic overtones" (Renal calculi, Osteitis fibrosa cystica, peptic ulcers/pancreatitis, and depression) [3]. * **Radiological Sign:** Subperiosteal bone resorption, most specifically seen on the **radial aspect of the middle phalanges**. * **Diagnosis:** Elevated Serum Calcium + Inappropriately elevated/normal PTH. * **Hungry Bone Syndrome:** A common postoperative complication after parathyroidectomy characterized by severe hypocalcemia.

Question 1106: A raised serum creatinine phosphokinase level is unusual in which of the following conditions?

A. Acute alcoholic myopathy
B. Viral polymyositis
C. Myopathy of Cushing's syndrome (Correct Answer)
D. Duchenne's muscular dystrophy

Explanation: **Explanation:** The correct answer is **C. Myopathy of Cushing's syndrome.** **Core Concept:** Creatinine Phosphokinase (CPK) is an enzyme released into the bloodstream when there is significant **necrosis or structural damage** to the muscle fibers (sarcolemma). In **Cushing’s syndrome** (and exogenous steroid use), the myopathy is primarily **catabolic** rather than inflammatory or necrotic [2]. Glucocorticoids cause muscle wasting by inhibiting protein synthesis and increasing protein degradation, particularly in Type IIb (fast-twitch) fibers [2]. Because there is no significant membrane destruction or inflammation, **serum CPK levels remain characteristically normal**, despite significant clinical weakness [2]. **Analysis of Incorrect Options:** * **A. Acute alcoholic myopathy:** This condition involves direct toxic rhabdomyolysis. Massive muscle fiber necrosis leads to very high elevations of CPK and myoglobinuria. * **B. Viral polymyositis:** Inflammatory myopathies (viral, autoimmune, or toxic) involve inflammation and damage to the muscle cell membrane, leading to leakage of enzymes and elevated CPK [3]. Typical presentation includes symmetrical proximal muscle weakness and difficulty rising from a chair [3]. * **D. Duchenne's muscular dystrophy:** This is characterized by a genetic defect in dystrophin, leading to constant muscle fiber breakdown [1]. CPK levels are typically 10 to 100 times the upper limit of normal. **High-Yield Clinical Pearls for NEET-PG:** * **Steroid Myopathy:** Presents as insidious, symmetric **proximal** muscle weakness (difficulty climbing stairs/rising from a chair) [2]. * **Normal CPK Myopathies:** Always consider **Cushing’s syndrome, Hyperthyroidism, and Glucocorticoid use** when a patient has proximal weakness but normal CPK levels. * **Hypothyroidism:** Conversely, hypothyroidism often presents with **elevated CPK** (due to increased membrane permeability and slowed enzyme clearance), even without significant weakness.

Question 1107: Which of the following is a true statement about primary hyperparathyroidism?

A. Adenoma is the commonest cause. (Correct Answer)
B. Associated with low serum calcium.
C. Surgery is indicated if biochemical findings are abnormal in an asymptomatic patient.
D. MIBG isotope is useful in the localization of the tumor.

Explanation: Primary hyperparathyroidism (PHPT) is characterized by the autonomous overproduction of parathyroid hormone (PTH), leading to hypercalcemia [2]. **Explanation of Options:** * **A. Adenoma is the commonest cause (Correct):** Approximately **80-85%** of PHPT cases are caused by a single solitary parathyroid adenoma [1]. Other causes include four-gland hyperplasia (10-15%) and parathyroid carcinoma (<1%). * **B. Associated with low serum calcium (Incorrect):** PHPT is defined by **hypercalcemia** (elevated serum calcium) and inappropriately high or normal PTH levels [3]. Low serum calcium is seen in secondary hyperparathyroidism (usually due to chronic kidney disease) [2]. * **C. Surgery is indicated if biochemical findings are abnormal in an asymptomatic patient (Incorrect):** Surgery is not indicated for *all* asymptomatic patients. Specific criteria (Asymptomatic PHPT Guidelines) must be met, such as: Serum calcium >1 mg/dL above the upper limit of normal, T-score ≤ -2.5, age <50 years, or creatinine clearance <60 ml/min [1]. * **D. MIBG isotope is useful (Incorrect):** **99mTc-Sestamibi (MIBI)** scan is the gold standard for localizing parathyroid adenomas [1]. MIBG scans are used for neuroendocrine tumors like pheochromocytoma. **High-Yield Clinical Pearls for NEET-PG:** * **Classic Presentation:** "Stones (renal calculi), bones (osteitis fibrosa cystica), abdominal groans (peptic ulcers/pancreatitis), and psychic overtones (depression)" [1]. * **Biochemical Profile:** ↑ Calcium, ↓ Phosphate, ↑ PTH, and ↑ Urinary cAMP [2]. * **Hungry Bone Syndrome:** A common postoperative complication following parathyroidectomy, characterized by profound hypocalcemia as the "starved" bones rapidly uptake calcium. * **Association:** Always screen for **MEN 1 and MEN 2A** syndromes if multiple glands are involved [3].

Question 1108: A 39-year-old obese patient presents with features of a Urinary Tract Infection (UTI) and a Random Blood Sugar (RBS) of 200 mg/dL. Urine analysis shows pus cells. What is true about the management?

A. Glipizide is the drug of choice.
B. Insulin can be administered. (Correct Answer)
C. Ciprofloxacin is indicated.
D. Testing for microalbuminuria is indicated.

Explanation: **Explanation:** The patient presents with hyperglycemia (RBS 200 mg/dL) and clinical evidence of a Urinary Tract Infection (UTI), indicated by pus cells in the urine [3]. This scenario represents **Diabetes Mellitus with an acute infection**, a state of physiological stress. **1. Why Option B is Correct:** In the presence of an acute infection, glycemic control often becomes difficult due to the release of counter-regulatory hormones (like cortisol and catecholamines) that increase insulin resistance. **Insulin** is the preferred agent in this setting because it allows for rapid, precise titration of blood glucose levels and helps prevent metabolic complications like Diabetic Ketoacidosis (DKA) or Hyperosmolar Hyperglycemic State (HHS) during acute illness [2]. **2. Why Other Options are Incorrect:** * **Option A:** Sulfonylureas like Glipizide are generally avoided during acute infections due to the risk of unpredictable hypoglycemia [4] and their inability to provide the rapid dose adjustments required during systemic stress. * **Option C:** While the patient has a UTI, the choice of antibiotic depends on local sensitivity patterns and the severity of the infection. Ciprofloxacin is not automatically the "indicated" drug of choice without culture results [1], especially with rising resistance. The question focuses on the metabolic management of the diabetic state. * **Option D:** Microalbuminuria testing is used to screen for diabetic nephropathy. However, it should **not** be performed during an active UTI, as pyuria and inflammation cause false-positive results. **Clinical Pearls for NEET-PG:** * **Sick Day Rules:** During infection, insulin requirements usually increase. Never omit insulin during illness, even if oral intake is reduced. * **Diagnosis:** A single RBS of 200 mg/dL with symptoms is diagnostic of Diabetes Mellitus. * **Microalbuminuria:** Defined as 30–300 mg/day. It is the earliest clinical sign of diabetic nephropathy but must be confirmed when the patient is stable and infection-free.

Question 1109: All of the following are associated with thyroid storm, except?

A. Surgery for thyroiditis (Correct Answer)
B. Surgery for thyrotoxicosis
C. Stressful illness in thyrotoxicosis
D. I131 therapy for thyrotoxicosis

Explanation: Thyroid storm is a life-threatening exacerbation of hyperthyroidism characterized by a hypermetabolic state. The key to understanding this question lies in identifying the underlying condition required for a "storm" to occur. ### **Explanation of the Correct Answer** **Option A (Surgery for thyroiditis)** is the correct answer because thyroiditis (such as Hashimoto’s or Subacute thyroiditis) typically involves inflammation of the gland. While it can cause a transient "leak" of hormones (thyrotoxicosis), it does not involve the sustained hyperfunction of the thyroid gland seen in Graves' disease or Toxic Multinodular Goiter [1]. Surgery on a thyroiditis-affected gland is not a recognized trigger for thyroid storm. Antithyroid drugs are of no benefit in thyroiditis because thyroid hormone synthesis is impaired rather than enhanced [1]. ### **Analysis of Incorrect Options** * **Option B (Surgery for thyrotoxicosis):** Historically, "surgical storm" occurred when patients with uncontrolled Graves' disease underwent thyroidectomy [1]. Manipulating a hyperactive gland releases massive amounts of T3/T4 into the circulation. * **Option C (Stressful illness in thyrotoxicosis):** Sepsis, myocardial infarction, or trauma in a patient with pre-existing thyrotoxicosis are classic precipitants that shift the body from compensated hyperthyroidism to a decompensated thyroid storm. * **Option D (I131 therapy):** Radioactive iodine therapy can cause radiation-induced thyroiditis, leading to an acute release of stored thyroid hormones, potentially triggering a storm in poorly prepared patients. ### **High-Yield Clinical Pearls for NEET-PG** * **Diagnosis:** Primarily clinical. The **Burch-Wartofsky Point Scale (BWPS)** is used (Score ≥45 is highly suggestive). * **Key Features:** Hyperpyrexia (out of proportion to infection), tachycardia, agitation/delirium, and GI dysfunction. * **Management Sequence (P-I-B-S):** 1. **P**ropylthiouracil (PTU): Inhibits new synthesis and peripheral T4 to T3 conversion. 2. **I**odine (Lugol’s): Give **1 hour after** PTU to prevent the iodine from being used as substrate (Wolff-Chaikoff effect). 3. **B**eta-blockers (Propranolol): Controls adrenergic symptoms. 4. **S**teroids (Hydrocortisone): Inhibits T4 to T3 conversion and treats potential relative adrenal insufficiency.

Question 1110: Which drug is used in Acute Intermittent Porphyria?

A. Opioids (Correct Answer)
B. Phenobarbitone
C. Primidone
D. Blood transfusion

Explanation: ### Explanation **Correct Option: A (Opioids)** Acute Intermittent Porphyria (AIP) is an autosomal dominant metabolic disorder caused by a deficiency of the enzyme **Porphobilinogen (PBG) deaminase** [1], [3]. The hallmark of an acute attack is severe, poorly localized abdominal pain [1]. **Opioids** (such as Morphine or Fentanyl) are the mainstay for pain management in AIP because they are considered "porphyrinogenic-safe." Unlike many other drugs, they do not induce the cytochrome P450 system or stimulate the enzyme ALA synthase, thus they do not exacerbate the underlying biochemical crisis [2]. **Why Incorrect Options are Wrong:** * **B & C (Phenobarbitone and Primidone):** These are potent inducers of the hepatic **Cytochrome P450 system**. Induction of these enzymes increases the demand for heme, which upregulates **ALA synthase** (the rate-limiting enzyme) [2]. This leads to a massive accumulation of toxic precursors (ALA and PBG), potentially triggering a life-threatening neurovisceral crisis [2], [3]. * **D (Blood Transfusion):** This is not a treatment for AIP. While blood transfusions (or phlebotomy) are relevant in *Porphyria Cutanea Tarda* to manage iron overload [1], they have no role in the acute management of AIP. **Clinical Pearls for NEET-PG:** 1. **Management Triad for Acute Attack:** * **Stop offending drugs** (e.g., Barbiturates, Sulfonamides, Phenytoin) [1]. * **IV Glucose (Dextrose):** High carbohydrate intake inhibits ALA synthase. * **IV Hematin (Heme Arginate):** The specific treatment of choice; it provides negative feedback to shut down ALA synthase [2]. 2. **Classic Presentation:** "Painful abdomen, Polyneuropathy, and Psychosis" with urine that turns **dark/port-wine colored** on standing [1]. 3. **Diagnosis:** Elevated urinary **PBG** and **ALA** during an attack [3].

Practice by Chapter

Diabetes Mellitus

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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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