Endocrinology — MCQs

A 30-year-old female presents with palpitations, increased appetite, and significant weight loss. She also reports a large neck swelling and has abnormal thyroid function tests showing elevated T3 and T4 with suppressed TSH. Her TSH receptor antibody test is negative. Ultrasound of the neck reveals multiple nodules, and a Radioactive Iodine Uptake (RAIU) scan shows increased uptake. After achieving a euthyroid state, what is the best definitive step in management?

Q1099Easy

All of the following are true regarding Grave's disease except?

Q1100Easy

A common cause of Cushing syndrome is:

Endocrinology Indian Medical PG Practice Questions and MCQs

Question 1091: Beta-blockers are used in hyperthyroidism:

A. As short-term symptomatic therapy until the effect of carbimazole develops (Correct Answer)
B. As long-term therapy after subtotal thyroidectomy
C. In patients not responding to carbimazole
D. To potentiate the effect of radioactive iodine

Explanation: **Explanation:** **1. Why Option A is Correct:** In hyperthyroidism, many clinical manifestations (tachycardia, palpitations, tremors, and anxiety) are due to increased beta-adrenergic sensitivity. Antithyroid drugs like **Carbimazole** or Methimazole inhibit thyroid hormone synthesis but take **3–6 weeks** to achieve a clinical effect because they do not affect pre-formed hormones already in circulation. Beta-blockers (specifically **Propranolol**) provide rapid symptomatic relief within hours, acting as a "bridge" or short-term therapy until the patient reaches a euthyroid state via definitive treatment [1]. **2. Why Other Options are Incorrect:** * **Option B:** After subtotal thyroidectomy, the source of excess hormone is removed. Long-term beta-blockers are unnecessary unless the patient develops permanent arrhythmias or has underlying cardiac disease. * **Option C:** If a patient does not respond to carbimazole, the next steps are usually radioactive iodine (RAI) or surgery, not just beta-blockers, which do not treat the underlying hyperthyroid state [1]. * **Option D:** Beta-blockers do not potentiate the mechanism of RAI. However, they are used to prevent the symptomatic "thyroid storm" that can occasionally be triggered by the release of stored hormones following RAI treatment. **3. High-Yield Clinical Pearls for NEET-PG:** * **Drug of Choice:** Propranolol is the preferred beta-blocker because it also inhibits the **peripheral conversion of T4 to T3** (at high doses). * **Contraindication:** Avoid beta-blockers in hyperthyroid patients with **bronchial asthma**; use cardioselective blockers (e.g., Atenolol) or Calcium Channel Bookers (Diltiazem/Verapamil) instead. * **Thyroid Storm:** Beta-blockers are a cornerstone of management in thyroid storm to control life-threatening sympathetic overactivity.

Question 1092: Calciphylaxis is more commonly seen in which of the following conditions?

A. Primary hyperparathyroidism
B. Secondary hyperparathyroidism (Correct Answer)
C. Tertiary hyperparathyroidism
D. Pseudohyperparathyroidism

Explanation: **Explanation:** **Calciphylaxis**, also known as **Calcific Uremic Arteriolopathy (CUA)**, is a rare but life-threatening syndrome characterized by systemic medial calcification of small arteries and arterioles, leading to skin ischemia and necrotic ulcers. **1. Why Secondary Hyperparathyroidism is Correct:** Calciphylaxis is most strongly associated with **End-Stage Renal Disease (ESRD)** [2]. In chronic kidney disease, patients develop **Secondary Hyperparathyroidism** due to phosphate retention and hypocalcemia [3], [4]. This leads to an elevated **Calcium-Phosphate product (>55 mg²/dL²)**. The high levels of PTH, hyperphosphatemia, and the use of calcium-based phosphate binders trigger the deposition of calcium in the tunica media of small vessels, causing the characteristic ischemic necrosis. **2. Why the Other Options are Incorrect:** * **Primary Hyperparathyroidism:** While calcium levels are high, phosphate levels are typically low or normal [1]. The Calcium-Phosphate product rarely reaches the threshold required for the systemic vascular calcification seen in calciphylaxis. * **Tertiary Hyperparathyroidism:** Though it involves high PTH and high calcium (post-renal transplant or long-standing ESRD), it is statistically less common than secondary hyperparathyroidism as a precursor to calciphylaxis [3]. * **Pseudohyperparathyroidism:** This condition involves end-organ resistance to PTH, resulting in *hypocalcemia* and hyperphosphatemia. Since calcium levels are low, the risk of metastatic calcification of vessels is significantly lower. **High-Yield NEET-PG Pearls:** * **Clinical Presentation:** Painful, violaceous, reticulated plaques (livedo reticularis) that progress to "punched-out" necrotic ulcers, typically on the thighs or abdomen. * **Diagnosis:** Skin biopsy is the gold standard (shows medial calcification and intimal fibrosis). * **Management:** Sodium thiosulfate (increases calcium solubility), aggressive wound care, and normalization of calcium/phosphate levels. * **Risk Factors:** Obesity, female gender, warfarin use, and hypoalbuminemia.

Question 1093: What is the primary hormone secreted by an extra-adrenal pheochromocytoma?

A. Norepinephrine (Correct Answer)
B. Epinephrine
C. Metanephrine
D. Dopamine

Explanation: **Explanation:** The correct answer is **Norepinephrine**. **1. Why Norepinephrine is correct:** Extra-adrenal pheochromocytomas (also known as **paragangliomas**) arise from the sympathetic chain or the Organ of Zuckerkandl [1]. Unlike the adrenal medulla, extra-adrenal chromaffin tissue lacks the enzyme **Phenylethanolamine N-methyltransferase (PNMT)**. This enzyme is responsible for converting norepinephrine into epinephrine and requires high concentrations of cortisol (from the adjacent adrenal cortex) to be induced. Since extra-adrenal sites lack this proximity to cortisol and the PNMT enzyme, they predominantly secrete **norepinephrine** [1]. **2. Why other options are incorrect:** * **Epinephrine:** This is primarily secreted by **intra-adrenal** pheochromocytomas because the adrenal medulla contains the PNMT enzyme [1]. A tumor secreting purely epinephrine is almost always located within the adrenal gland. * **Metanephrine:** This is a metabolite of epinephrine, not the primary hormone secreted. While metanephrines are diagnostic markers measured in urine/plasma, they are breakdown products. * **Dopamine:** While some paragangliomas (especially carotid body tumors) can secrete dopamine, it is not the "primary" hormone for extra-adrenal pheochromocytomas in general. **3. High-Yield Clinical Pearls for NEET-PG:** * **Rule of 10s:** Traditionally, 10% of pheochromocytomas are extra-adrenal, though recent data suggests this may be higher (up to 15-20%). * **Malignancy:** Extra-adrenal tumors have a higher risk of malignancy compared to adrenal tumors. * **Localization:** The most common extra-adrenal site is the **Organ of Zuckerkandl** (near the origin of the inferior mesenteric artery). * **Diagnosis:** Plasma free metanephrines or 24-hour urinary fractionated metanephrines are the initial screening tests of choice.

Question 1094: A 21-year-old male presented with short stature and lack of secondary sexual characteristics. He underwent surgery for a brain tumor 12 years ago and received cranial radiation. Which of the following is true regarding acquired hypopituitarism due to radiation?

A. At a dose of 50 Gy of radiation, only 5% of patients will manifest hypopituitarism.
B. The majority of patients who develop hypopituitarism after cranial radiation do so within a year of treatment.
C. Growth hormone is the most common hormonal deficiency. (Correct Answer)
D. Older adults are at the highest risk from radiation-induced hypopituitarism.

Explanation: Radiation-induced hypopituitarism is a common late complication of cranial irradiation for brain tumors. The pituitary gland and hypothalamus are sensitive to radiation, and the damage is typically **dose-dependent, progressive, and permanent.** [1] **1. Why Option C is Correct:** The anterior pituitary hormones follow a predictable sequence of loss after radiation. **Growth Hormone (GH) deficiency** is almost universally the first to manifest, followed by gonadotropins (LH/FSH), then TSH, and finally ACTH. In pediatric or young adult patients, this typically presents as short stature and delayed puberty, as seen in this case. [2] **2. Why the Other Options are Incorrect:** * **Option A:** At a dose of **50 Gy**, the risk is significantly higher than 5%. Approximately **50–90%** of patients receiving this dose will develop some form of hypothalamic-pituitary dysfunction within 5–10 years. * **Option B:** Radiation-induced damage is not immediate. While some changes occur early, the majority of clinical deficiencies manifest **years (typically 2 to 10 years)** after treatment. It requires long-term surveillance. * **Option D:** **Children and young adults** are at the highest risk. Their developing endocrine axes are more sensitive to radiation damage compared to older adults. **Clinical Pearls for NEET-PG:** * **Sequence of loss:** GH > LH/FSH > TSH > ACTH (Mnemonic: **"Go Look For The Adenoma"** – GH, LH, FSH, TSH, ACTH). * **Hyperprolactinemia:** Unlike other hormones which decrease, prolactin levels may **increase** after radiation due to damage to the hypothalamic dopaminergic pathways (loss of tonic inhibition). * **Primary site of damage:** In many cases of cranial radiation, the **hypothalamus** is more sensitive and is the primary site of injury rather than the pituitary gland itself.

Question 1095: Type I diabetes mellitus may be associated with which of the following conditions?

A. Obesity
B. Celiac Disease (Correct Answer)
C. Down's syndrome
D. Precocious puberty

Explanation: **Explanation:** **1. Why Celiac Disease is Correct:** Type 1 Diabetes Mellitus (T1DM) is an organ-specific autoimmune disorder characterized by the destruction of pancreatic beta cells [2]. It is frequently associated with other **autoimmune polyendocrine syndromes (APS)** because these conditions share a common genetic predisposition, specifically linked to **HLA-DR3 and HLA-DR4** genotypes [2]. Celiac disease is an autoimmune enteropathy triggered by gluten; approximately 5–10% of patients with T1DM are found to have biopsy-proven Celiac disease [1]. Screening for Celiac disease (via tissue transglutaminase antibodies) is a standard clinical recommendation for all newly diagnosed T1DM patients. **2. Analysis of Incorrect Options:** * **Obesity:** This is a hallmark risk factor for **Type 2 Diabetes Mellitus**, characterized by insulin resistance. T1DM patients are typically lean or present with weight loss at diagnosis due to an absolute insulin deficiency and catabolism [2]. * **Down’s Syndrome:** While Down’s syndrome is associated with an increased risk of T1DM and hypothyroidism, it is a chromosomal disorder (Trisomy 21), not an autoimmune condition directly "associated" in the context of shared pathophysiology like Celiac disease. * **Precocious Puberty:** There is no established pathophysiological link between T1DM and precocious puberty. In fact, poorly controlled T1DM is more commonly associated with **delayed puberty** and growth retardation (Mauriac Syndrome). **High-Yield Clinical Pearls for NEET-PG:** * **Common Autoimmune Associations with T1DM:** Hashimoto’s thyroiditis (most common), Graves' disease, Celiac disease, Addison’s disease, and Vitiligo [1]. * **HLA Associations:** HLA-DR3/DR4 and DQ8 are strongly linked to T1DM [2]. * **Screening Rule:** Always screen T1DM patients for **Thyroid Peroxidase (TPO) antibodies** and **Celiac disease** regardless of symptoms.

Question 1096: Which of the following is not a characteristic feature of Graves' disease?

A. Hyperreflexia
B. Chorea
C. Lid lag sign
D. Late diastolic murmur (Correct Answer)

Explanation: **Explanation:** **Graves’ disease** is an autoimmune condition characterized by hyperthyroidism due to TSH-receptor antibodies [1]. The correct answer is **Late diastolic murmur**, as this is typically associated with mitral stenosis, not hyperthyroidism. **1. Why "Late diastolic murmur" is the correct answer:** Hyperthyroidism induces a hyperdynamic circulatory state. Cardiovascular findings in Graves' disease include tachycardia, palpitations, and a wide pulse pressure [3]. While a **systolic murmur** (flow murmur) is common due to increased cardiac output, a diastolic murmur is not a feature of thyrotoxicosis. Occasionally, a "Means-Lerman scratch" (a systolic sound mimicking a friction rub) may be heard, but never a late diastolic murmur. **2. Analysis of incorrect options:** * **Hyperreflexia:** Excess thyroid hormone increases neuromuscular excitability and shortens the contraction/relaxation time of muscles, leading to "brisk" deep tendon reflexes. * **Chorea:** Though rare, thyrotoxicosis can manifest as movement disorders, including chorea or tremors, due to increased sensitivity of dopamine receptors in the basal ganglia. * **Lid lag sign (Griffith’s sign):** This is a classic sympathetic overactivity sign where the upper eyelid fails to follow the downward movement of the iris [3]. **Clinical Pearls for NEET-PG:** * **Specific to Graves’:** Exophthalmos (proptosis), Pretibial Myxedema (dermopathy), and Thyroid Acropachy (clubbing) are unique to Graves' and not seen in other forms of hyperthyroidism [1]. * **Cardiac complication:** Atrial Fibrillation is the most common arrhythmia in elderly patients with thyrotoxicosis [2]. * **Diagnosis:** Low TSH, High Free T4, and diffuse uptake on Radionuclide scan [3].

Question 1097: Increased serum calcium and decreased serum phosphate may be seen in all of the following conditions, except:

A. Primary hyperparathyroidism
B. Hypercalcemia of malignancy
C. Vitamin D intoxication (Correct Answer)
D. Familial benign hypercalcemia

Explanation: **Explanation:** The biochemical hallmark of **Primary Hyperparathyroidism (PHPT)** and related conditions is the combination of hypercalcemia and hypophosphatemia [1][3]. This occurs because Parathyroid Hormone (PTH) increases bone resorption and renal calcium reabsorption while simultaneously inhibiting phosphate reabsorption in the proximal tubule (phosphaturic effect) [1]. **Why Vitamin D Intoxication is the correct answer:** In Vitamin D intoxication, there is an excess of 1,25-(OH)₂D (Calcitriol). Vitamin D acts on the GI tract and kidneys to **increase the absorption of both Calcium and Phosphate** [1]. Therefore, the biochemical profile shows **increased serum calcium and increased serum phosphate** [2]. This distinguishes it from PTH-mediated hypercalcemia. **Analysis of Incorrect Options:** * **Primary Hyperparathyroidism:** High PTH levels lead to high Ca²⁺ and low PO₄³⁻ due to renal phosphate wasting [3]. * **Hypercalcemia of Malignancy:** Often caused by **PTH-related peptide (PTHrP)** [2]. PTHrP mimics PTH by binding to the same receptors, leading to increased calcium and decreased phosphate. * **Familial Benign Hypercalcemia (FHH):** Caused by an inactivating mutation in the Calcium-Sensing Receptor (CaSR) [1]. The body "perceives" low calcium, leading to inappropriately high PTH levels, which results in hypercalcemia and low-to-normal phosphate [2]. **High-Yield Clinical Pearls for NEET-PG:** 1. **Phosphate Rule:** High Ca + Low PO₄ = PTH-mediated (or PTHrP). High Ca + High PO₄ = Vitamin D-mediated or Bone destruction (e.g., Milk-alkali, Sarcoidosis) [2]. 2. **FHH vs. PHPT:** To differentiate, check urinary calcium [2]. FHH has **low** urinary calcium (Urinary Calcium/Creatinine Clearance Ratio <0.01), whereas PHPT has **high** urinary calcium. 3. **PTHrP:** Most common cause of hypercalcemia in hospitalized patients (Squamous cell CA of lung, Renal cell CA) [2].

Question 1098: A 30-year-old female presents with palpitations, increased appetite, and significant weight loss. She also reports a large neck swelling and has abnormal thyroid function tests showing elevated T3 and T4 with suppressed TSH. Her TSH receptor antibody test is negative. Ultrasound of the neck reveals multiple nodules, and a Radioactive Iodine Uptake (RAIU) scan shows increased uptake. After achieving a euthyroid state, what is the best definitive step in management?

A. Continue antithyroid medication
B. Sub-total thyroidectomy
C. Radioactive iodine therapy
D. Near-total thyroidectomy (Correct Answer)

Explanation: **Explanation:** The patient presents with classic symptoms of hyperthyroidism (palpitations, weight loss, increased appetite) and biochemical evidence of thyrotoxicosis (↑T3/T4, ↓TSH). The presence of a large neck swelling with multiple nodules on ultrasound, combined with a negative TSH receptor antibody (TRAb) and increased uptake on RAIU scan, confirms the diagnosis of **Toxic Multinodular Goiter (TMNG)** [2]. **Why Near-total Thyroidectomy is the Correct Choice:** In TMNG, definitive management is required because, unlike Graves' disease, spontaneous remission does not occur. Surgery is preferred over Radioactive Iodine (RAI) when there is a **large goiter** causing compressive symptoms or for cosmetic reasons [1]. **Near-total or Total Thyroidectomy** is the surgical procedure of choice as it provides immediate cure and carries a lower risk of recurrence compared to sub-total resection. **Analysis of Incorrect Options:** * **Option A:** Antithyroid drugs (ATDs) are used to achieve a euthyroid state before surgery but are not definitive for TMNG, as relapse occurs immediately upon discontinuation [3]. * **Option B:** Sub-total thyroidectomy is now largely obsolete due to high recurrence rates of hyperthyroidism in the remaining thyroid tissue. * **Option C:** While RAI is a definitive option, it is less ideal for very large goiters as it may take months to work, can cause a transient increase in size due to radiation thyroiditis, and does not resolve the physical bulk of the gland [1]. **High-Yield Clinical Pearls for NEET-PG:** * **Plummer’s Disease:** Another name for Toxic Multinodular Goiter. * **RAIU Pattern:** Graves’ shows *diffuse* uptake; TMNG shows *patchy/heterogeneous* uptake with multiple "hot" nodules [2]. * **Pre-op Prep:** Patients must be rendered euthyroid using ATDs (usually Methimazole) and sometimes Beta-blockers to prevent a **Thyroid Storm** during surgery [3]. * **Complications:** Always monitor for recurrent laryngeal nerve injury and hypocalcemia (due to parathyroid damage) post-thyroidectomy.

Question 1099: All of the following are true regarding Grave's disease except?

A. Orbital proptosis
B. Presents as primary thyrotoxicosis
C. Anti-TPO antibodies (Correct Answer)
D. Pretibial myxoedema

Explanation: **Explanation:** The correct answer is **C (Anti-TPO antibodies)**. While Anti-TPO antibodies can be present in Graves' disease (up to 70-80% of cases), they are **not specific** to it and are the hallmark of Hashimoto’s Thyroiditis. The pathognomonic antibody for Graves' disease is **TSH-Receptor Antibody (TRAb)** [1], specifically Thyroid Stimulating Immunoglobulins (TSI), which mimic TSH and cause hyperthyroidism [2]. **Analysis of Options:** * **A. Orbital proptosis:** This is a classic extrathyroidal manifestation of Graves' disease (Graves' Ophthalmopathy) [1]. It is caused by the inflammation and accumulation of glycosaminoglycans in the retro-orbital tissues, leading to forward displacement of the eye [2]. * **B. Presents as primary thyrotoxicosis:** Graves' disease is the most common cause of primary hyperthyroidism [2]. "Primary" indicates the pathology lies within the thyroid gland itself, characterized by elevated T4/T3 and suppressed TSH [1]. * **D. Pretibial myxoedema:** Also known as localized dermopathy, this is a specific feature of Graves' disease [1]. It presents as non-pitting edema and "orange-peel" (peau d'orange) skin, usually over the anterior tibia. **High-Yield Clinical Pearls for NEET-PG:** * **Triad of Graves:** Hyperthyroidism + Diffuse Goiter + Exophthalmos. * **Radioiodine Uptake (RAIU):** Shows **diffuse, increased uptake** (unlike Toxic Multinodular Goiter which shows "patchy" uptake). * **Most Specific Sign:** Graves' Ophthalmopathy (Proptosis). * **Treatment of Choice:** Antithyroid drugs (Methimazole/PTU) for initial management; Radioiodine (I-131) is the most common definitive therapy in adults [3].

Question 1100: A common cause of Cushing syndrome is:

A. Cancer producing ectopic ACTH
B. Pituitary adenoma (Correct Answer)
C. Adrenal tuberculosis
D. None of the above

Explanation: Cushing syndrome refers to the clinical state resulting from chronic exposure to excessive glucocorticoids. When the cause is a pituitary adenoma secreting excess ACTH, it is specifically termed **Cushing Disease**. [1] **1. Why Pituitary Adenoma is Correct:** Among the endogenous causes of Cushing syndrome, **Cushing Disease (Pituitary ACTH-secreting adenoma)** is the most common, accounting for approximately **70%** of cases. [1] It typically involves a microadenoma (<10 mm) that stimulates the adrenal cortex to produce excess cortisol bilaterally. [4] **2. Why Other Options are Incorrect:** * **A. Cancer producing ectopic ACTH:** While this is a known cause of ACTH-dependent Cushing syndrome (most commonly Small Cell Carcinoma of the Lung), it is less frequent than pituitary adenomas, accounting for only about 10-15% of cases. [1] * **C. Adrenal Tuberculosis:** This is a classic cause of **Addison’s Disease** (Primary Adrenal Insufficiency), not Cushing syndrome. Tuberculosis destroys the adrenal cortex, leading to a deficiency of cortisol and aldosterone, rather than an excess. **High-Yield Clinical Pearls for NEET-PG:** * **Most Common Cause Overall:** Exogenous (Iatrogenic) administration of glucocorticoids. [1], [3] * **Most Common Endogenous Cause:** Cushing Disease (Pituitary Adenoma). * **Screening Tests:** Overnight Dexamethasone Suppression Test (ONDST), 24-hour urinary free cortisol, or Late-night salivary cortisol. [2], [3] * **Differential Diagnosis:** High-dose dexamethasone suppression test (HDDST) and CRH stimulation test typically show suppression/response in Cushing Disease but *not* in ectopic ACTH production. [4] * **Imaging:** MRI Brain (Pituitary) is the investigation of choice for Cushing Disease. [4]

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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