Endocrinology — MCQs

Endocrinology Indian Medical PG Practice Questions and MCQs

Question 221: What is the most common cause of a hypersecreting pituitary tumor?

A. Pituitary adenoma (Correct Answer)
B. Pituitary carcinoma
C. Autoimmune disease of the pituitary
D. Transection of the pituitary stalk

Explanation: **Explanation:** **1. Why Pituitary Adenoma is Correct:** Pituitary adenomas are benign neoplasms of the anterior pituitary gland and represent the most common cause of pituitary hormone hypersecretion [1]. These tumors are classified based on size (microadenomas <10mm; macroadenomas >10mm) and hormone production [1]. The most common hyperfunctioning adenoma is a **Prolactinoma** [3], followed by Growth Hormone-secreting adenomas (causing Acromegaly) [2] and ACTH-secreting adenomas (causing Cushing’s Disease) [4]. **2. Why the Other Options are Incorrect:** * **B. Pituitary Carcinoma:** These are extremely rare. The diagnosis of a pituitary carcinoma requires the presence of systemic or cerebrospinal metastases, not just local invasion. * **C. Autoimmune disease:** Conditions like Lymphocytic Hypophysitis typically lead to **hypopituitarism** (hormone deficiency) due to the destruction of pituitary tissue, rather than hypersecretion. * **D. Transection of the pituitary stalk:** This results in the "Stalk Effect." While it causes a mild rise in Prolactin (due to loss of inhibitory dopamine from the hypothalamus), it causes a **deficiency** of all other anterior pituitary hormones and leads to Diabetes Insipidus (loss of ADH) [3]. It is not a cause of a hypersecreting tumor. **High-Yield Clinical Pearls for NEET-PG:** * **Most common secretory adenoma:** Prolactinoma [3]. * **Most common symptom of any macroadenoma:** Bitemporal hemianopia (due to compression of the optic chiasm) [1]. * **MEN 1 Syndrome:** Remember the "3 Ps"—Pituitary, Parathyroid, and Pancreatic tumors. * **Treatment of choice:** Transsphenoidal surgery is the gold standard for most [2], **except Prolactinomas**, where medical management with Dopamine agonists (Cabergoline/Bromocriptine) is the first-line treatment.

Question 222: What is the treatment for hyperprolactinemia?

A. Estrogen
B. Bromocriptine (Correct Answer)
C. GnRH analogue
D. Cimetidine

Explanation: The primary treatment for hyperprolactinemia is medical management using **Dopamine Agonists**. Prolactin secretion is under tonic inhibition by dopamine (the prolactin-inhibiting factor) produced in the hypothalamus [2]. **Bromocriptine** is a dopamine receptor agonist that mimics this inhibitory effect, effectively reducing prolactin levels and shrinking prolactin-secreting pituitary adenomas (prolactinomas) [1]. **Analysis of Options:** * **Bromocriptine (Correct):** It is a classic D2 receptor agonist. While **Cabergoline** is now the preferred first-line agent due to higher efficacy and fewer side effects, Bromocriptine remains a standard correct answer in exams and is preferred during pregnancy [1]. * **Estrogen (Incorrect):** Estrogens actually stimulate the lactotrophs in the pituitary and can increase prolactin levels. * **GnRH Analogue (Incorrect):** These are used to suppress the pituitary-gonadal axis in conditions like endometriosis or prostate cancer, but they do not treat hyperprolactinemia. In fact, hyperprolactinemia itself causes low GnRH [3]. * **Cimetidine (Incorrect):** This H2-receptor antagonist is a known **cause** of drug-induced hyperprolactinemia, not a treatment. **NEET-PG High-Yield Pearls:** 1. **Drug of Choice:** Cabergoline is superior to Bromocriptine (longer half-life, twice-weekly dosing). 2. **Hook Effect:** In very high prolactin levels, lab assays may show falsely low results; serial dilution is required for diagnosis. 3. **Indications for Surgery:** Transsphenoidal surgery is reserved for patients who are refractory to or intolerant of dopamine agonists, or those with rapidly progressive visual field defects [1]. 4. **Common Causes:** Always rule out pregnancy, hypothyroidism (high TRH stimulates prolactin), and drugs (antipsychotics, metoclopramide, verapamil) before diagnosing a prolactinoma [2].

Question 223: A 36-year-old female, asymptomatic but with raised 24-hour urinary cortisol levels and raised ACTH, shows suppression in a high-dose dexamethasone suppression test. MRI of the head reveals no enlargement of the pituitary gland. What should be the next step in this case?

A. MRI to assess the adrenals
B. CT of the chest
C. Inferior petrosal sinus venous sampling (Correct Answer)
D. Corticotropin-releasing hormone (CRH) levels

Explanation: ### Explanation This clinical scenario describes **ACTH-dependent Cushing’s Syndrome** (elevated cortisol and elevated ACTH). Measurement of plasma ACTH is the key to establishing the differential diagnosis [1]. The suppression of cortisol during a **High-Dose Dexamethasone Suppression Test (HDDST)** is a classic hallmark of **Cushing’s Disease** (pituitary etiology), as ectopic ACTH-producing tumors are typically autonomous and do not suppress. **Why Option C is correct:** The patient has biochemical evidence of a pituitary source (suppression on HDDST), but the **MRI is normal**. In approximately 40% of patients with Cushing’s Disease, the pituitary adenoma is too small to be detected by conventional MRI; notably, MRI may reveal 'abnormalities' in as many as 10% of healthy people, making biochemical confirmation essential [1]. **Inferior Petrosal Sinus Sampling (IPSS)** is the "Gold Standard" investigation to differentiate between a pituitary source and an ectopic source when imaging is occult or equivocal. A central-to-peripheral ACTH gradient (≥2:1 at baseline or ≥3:1 after CRH stimulation) confirms a pituitary origin. **Why other options are incorrect:** * **Option A:** Adrenal MRI is used for ACTH-independent Cushing’s (low ACTH). Here, ACTH is high, indicating the pathology is proximal to the adrenals. * **Option B:** CT Chest is used to look for ectopic ACTH sources (e.g., Small Cell Lung Cancer or Bronchial Carcinoid). However, the HDDST suppression already points toward a pituitary source; IPSS must confirm this before searching elsewhere. * **Option D:** CRH levels are not routinely measured in clinical practice to localize the source of Cushing’s syndrome. **Clinical Pearls for NEET-PG:** 1. **Screening tests:** 24-hour urinary free cortisol, Low-dose dexamethasone suppression test (LDDST), or Late-night salivary cortisol [1]. 2. **Localization:** If ACTH is >20 pg/mL, it is ACTH-dependent [1]. 3. **HDDST Rule:** >50% suppression of cortisol suggests Cushing’s Disease; no suppression suggests Ectopic ACTH. 4. **IPSS:** Perform only if biochemistry suggests Cushing's Disease but MRI is negative or shows a lesion <6mm.

Question 224: A 35-year-old female with children aged 5 and 6 years presents with amenorrhea and galactorrhea. Blood examination reveals increased prolactin. What is the most likely finding on CT of the head?

A. Pituitary adenoma (Correct Answer)
B. Craniopharyngioma
C. Sheehan's syndrome
D. Pinealoma

Explanation: ### Explanation **Correct Option: A. Pituitary Adenoma** The clinical triad of **amenorrhea, galactorrhea, and hyperprolactinemia** in a non-pregnant female is the classic presentation of a **Prolactinoma** (a prolactin-secreting pituitary adenoma) [1]. Prolactinomas are the most common functional pituitary tumors [1]. High prolactin levels inhibit the pulsatile release of GnRH from the hypothalamus, leading to decreased LH and FSH, which results in secondary amenorrhea and infertility. Prolactin also directly stimulates milk production (galactorrhea) [1]. **Analysis of Incorrect Options:** * **B. Craniopharyngioma:** These are suprasellar tumors derived from Rathke’s pouch remnants. While they can cause "stalk effect" (mildly elevated prolactin due to loss of dopamine inhibition), they typically present in children with growth retardation or adults with visual field defects and features of hypopituitarism, rather than isolated galactorrhea [1]. * **C. Sheehan’s Syndrome:** This refers to ischemic necrosis of the pituitary gland following postpartum hemorrhage. It presents with the **inability to lactate** (due to prolactin deficiency) and failure to resume menses, which is the opposite of this patient’s presentation. * **D. Pinealoma:** These tumors are located in the pineal gland (posterior to the midbrain). They typically present with Parinaud syndrome (upward gaze palsy) and precocious puberty (in children), not primary hyperprolactinemia. **High-Yield Clinical Pearls for NEET-PG:** * **Drug-induced hyperprolactinemia:** Always rule out dopamine antagonists (e.g., Metoclopramide, Haloperidol, Risperidone) and Methyldopa [1]. * **Gold Standard Investigation:** MRI Brain with contrast (Gadolinium) is superior to CT for visualizing microadenomas (<10mm) [3]. * **Treatment of Choice:** Medical management with **Dopamine agonists** (Cabergoline is preferred over Bromocriptine due to higher efficacy and fewer side effects) [2]. Surgery is reserved for refractory cases. * **Hook Effect:** In cases of extremely high prolactin, lab assays may show falsely low levels; serial dilution is required for accurate diagnosis.

Question 225: Thyrotoxicosis not associated with hyperthyroidism is caused by all EXCEPT?

A. Factitious thyrotoxicosis
B. TSH-secreting pituitary adenoma (Correct Answer)
C. Granulomatous thyroiditis
D. Struma ovarii

Explanation: To answer this question, it is essential to distinguish between **Thyrotoxicosis** and **Hyperthyroidism**, as these terms are often used interchangeably but have distinct pathophysiological meanings. * **Thyrotoxicosis:** The clinical state resulting from inappropriate high levels of circulating thyroid hormones ($T_3$ and $T_4$), regardless of the source [1]. * **Hyperthyroidism:** A subset of thyrotoxicosis caused specifically by **excessive synthesis and secretion** of thyroid hormones by the thyroid gland itself [2]. ### Why Option B is the Correct Answer In a **TSH-secreting pituitary adenoma**, the pituitary gland overproduces TSH, which chronically stimulates the thyroid gland to synthesize and release excess hormones. Because the thyroid gland is hyperfunctioning, this condition is a true form of **hyperthyroidism**. ### Explanation of Incorrect Options (Thyrotoxicosis without Hyperthyroidism) These conditions involve high hormone levels without increased thyroid gland activity: * **Factitious thyrotoxicosis (A):** Caused by the exogenous ingestion of thyroid hormones [1]. The thyroid gland is actually suppressed (low radioactive iodine uptake). * **Granulomatous thyroiditis (C):** Also known as De Quervain’s thyroiditis. Thyrotoxicosis occurs due to the **leakage** of pre-formed hormones from inflamed/damaged follicles, not due to new synthesis [1]. * **Struma ovarii (D):** Ectopic thyroid tissue within an ovarian teratoma produces hormones. The patient is thyrotoxic, but the actual thyroid gland in the neck is inactive. ### NEET-PG High-Yield Pearls * **Radioactive Iodine Uptake (RAIU):** This is the gold standard test to differentiate these states. RAIU is **increased** in hyperthyroidism (e.g., Graves’, TSH-oma) and **decreased** in thyrotoxicosis without hyperthyroidism (e.g., Thyroiditis, Factitious) [1]. * **Thyroglobulin levels:** Low/Absent in factitious thyrotoxicosis (since the hormone is synthetic) but elevated in thyroiditis (due to follicular leakage) [1]. * **Silent Thyroiditis:** Another common cause of thyrotoxicosis without hyperthyroidism, often seen postpartum [1].

Question 226: A 21-year-old lady presented with a history of tiredness, weight gain, depression, and excessive somnolence. What will NOT be seen in this patient?

A. Hypertension
B. Delayed relaxation of tendon reflexes
C. Anemia
D. Tachycardia (Correct Answer)

Explanation: **Explanation:** The clinical presentation of tiredness, weight gain, depression, and excessive somnolence in a young female is a classic description of **Hypothyroidism** [1]. **Why Tachycardia is the correct answer:** In hypothyroidism, there is a generalized slowing of metabolic processes and a decrease in sympathetic activity. This leads to **Bradycardia** (a slow heart rate) rather than tachycardia. Tachycardia is a hallmark feature of *Hyperthyroidism*, where increased thyroid hormones upregulate beta-adrenergic receptors in the heart [1]. **Analysis of other options:** * **Hypertension:** While it may seem counterintuitive, hypothyroidism often causes **Diastolic Hypertension**. This occurs due to increased systemic vascular resistance and arterial stiffness, despite the low cardiac output. * **Delayed relaxation of tendon reflexes:** Also known as "Woltman’s sign," this is a classic physical finding in hypothyroidism. The slow relaxation phase (pseudomyotonia) is due to delayed calcium reuptake by the sarcoplasmic reticulum in muscles. * **Anemia:** Hypothyroidism is frequently associated with anemia. It can be normocytic (due to decreased erythropoietin), microcytic (due to associated menorrhagia or iron malabsorption), or macrocytic (due to associated Vitamin B12 deficiency in autoimmune cases like Hashimoto’s). **High-Yield Clinical Pearls for NEET-PG:** * **Most common cause:** Hashimoto’s Thyroiditis (look for anti-TPO antibodies). * **Cardiac findings:** Bradycardia, pericardial effusion (low voltage ECG), and muffled heart sounds. * **Dermatological findings:** Non-pitting edema (Myxedema) and loss of the outer one-third of eyebrows (Queen Anne’s sign). * **Metabolic:** Hypercholesterolemia and hyponatremia are common laboratory findings [2].

Question 227: Which of the following statements is FALSE regarding Nelson's syndrome?

A. Skin pigmentation
B. Pituitary tumor
C. High ACTH levels
D. None of the above (Correct Answer)

Explanation: ### Explanation: Nelson’s Syndrome **Concept Overview:** Nelson’s syndrome refers to the development of an aggressive, ACTH-secreting pituitary adenoma following a **bilateral adrenalectomy** (usually performed to treat Cushing’s disease) [1]. The underlying mechanism is the loss of negative feedback inhibition by cortisol on the hypothalamus and pituitary gland. Without cortisol to "brake" the system, pre-existing corticotroph microadenomas undergo rapid expansion and hypersecretion. **Why "None of the above" is correct:** All the options provided (A, B, and C) are classic, defining features of Nelson’s syndrome. Since the question asks for the **FALSE** statement, and all listed statements are true, "None of the above" is the correct choice. * **Pituitary tumor (Option B):** The hallmark of the syndrome is the enlargement of a corticotroph adenoma. These tumors are often locally invasive and can cause mass effect symptoms like bitemporal hemianopia. * **High ACTH levels (Option C):** Due to the lack of glucocorticoid feedback and the presence of a functional adenoma, ACTH levels are extremely elevated [1]. * **Skin pigmentation (Option A):** High levels of ACTH (and its precursor POMC) stimulate melanocortin-1 receptors on melanocytes, leading to progressive, intense hyperpigmentation. **NEET-PG High-Yield Pearls:** * **Trigger:** Occurs only after **bilateral adrenalectomy** [1]. * **Clinical Presentation:** Hyperpigmentation + Visual field defects + Headache. * **Diagnosis:** Rising plasma ACTH levels and MRI evidence of an enlarging pituitary mass. * **Prevention:** Modern management of Cushing’s disease (Pituitary surgery/Radiotherapy) has made Nelson’s syndrome rare. * **Treatment:** Surgical resection of the pituitary tumor or radiotherapy.

Question 228: Which clinical features are characteristic of congenital adrenal hyperplasia?

A. Female pseudohermaphroditism
B. Hypertension
C. Electrolyte imbalance
D. All of the above (Correct Answer)

Explanation: **Explanation:** Congenital Adrenal Hyperplasia (CAH) is a group of autosomal recessive disorders caused by a deficiency in enzymes required for cortisol synthesis [1]. The clinical presentation depends on the specific enzyme deficiency, most commonly **21-hydroxylase deficiency (90% of cases)**. 1. **Female Pseudohermaphroditism (Option A):** In 21-hydroxylase and 11̢β-hydroxylase deficiencies, the blockage of the cortisol pathway shunts precursors toward androgen production. Excess adrenal androgens in utero lead to virilization of female fetuses (ambiguous genitalia), while internal female organs (ovaries/uterus) remain normal. 2. **Hypertension (Option B):** While 21-hydroxylase deficiency causes hypotension, **11β-hydroxylase** and **17α-hydroxylase** deficiencies lead to the accumulation of mineralocorticoid precursors (like 11-deoxycorticosterone). This causes sodium retention and hypertension. 3. **Electrolyte Imbalance (Option C):** In the "salt-wasting" form of 21-hydroxylase deficiency, the lack of aldosterone leads to hyponatremia, hyperkalemia, and metabolic acidosis. Conversely, in hypertensive forms, hypokalemia may occur. Since CAH encompasses various enzymatic defects that can manifest with any of these features, **"All of the above"** is the correct choice. **High-Yield NEET-PG Pearls:** * **Most Common Cause:** 21-hydroxylase deficiency (Marker: Elevated **17-OH Progesterone**). * **The "Rule of 1s":** If the enzyme starts with **1** (11β, 17α), it causes hypertension. If it ends with **1** (21, 11β), it causes virilization (except 17α, which causes sexual infantilism). * **Treatment:** Glucocorticoids (to suppress ACTH and reduce androgen production) and mineralocorticoids if salt-wasting is present.

Question 229: Which of the following conditions is associated with hypocalcemia?

A. Medullary carcinoma of the thyroid
B. Squamous cell carcinoma of the lung
C. Tumor lysis syndrome
D. Both Medullary carcinoma of the thyroid and Tumor lysis syndrome (Correct Answer)

Explanation: **Explanation:** The correct answer is **D (Both Medullary carcinoma of the thyroid and Tumor lysis syndrome)**. **1. Why the correct options are right:** * **Medullary Carcinoma of the Thyroid (MCT):** This tumor arises from the parafollicular C-cells of the thyroid, which secrete **Calcitonin**. Calcitonin is a hormone that lowers serum calcium levels by inhibiting osteoclast activity and increasing renal calcium excretion. While clinical hypocalcemia is rare in MCT due to compensatory mechanisms, elevated calcitonin is the hallmark biochemical marker. * **Tumor Lysis Syndrome (TLS):** This is an oncologic emergency caused by the rapid breakdown of tumor cells. It leads to the release of intracellular contents, resulting in **hyperphosphatemia**. The excess phosphate binds to serum calcium, causing calcium-phosphate precipitation and subsequent **hypocalcemia**. **2. Why the incorrect option is wrong:** * **Squamous Cell Carcinoma (SCC) of the Lung:** This is a classic cause of **hypercalcemia** [1]. It often produces Parathyroid Hormone-related Protein (PTHrP), which mimics PTH action, leading to increased bone resorption and renal calcium reabsorption (Paraneoplastic syndrome) [2]. **High-Yield Clinical Pearls for NEET-PG:** * **Tumor Lysis Syndrome Tetrad:** Hyperuricemia, Hyperkalemia, Hyperphosphatemia, and **Hypocalcemia**. * **MCT Associations:** Always screen for **MEN 2A and 2B** syndromes (look for pheochromocytoma and hyperparathyroidism) [1]. * **PTHrP:** The most common cause of hypercalcemia in malignancy without bone metastases (Humoral Hypercalcemia of Malignancy) [2]. * **ECG in Hypocalcemia:** Look for **prolonged QT interval**, which can predispose to arrhythmias.

Question 230: Which of the following is NOT typically seen in hemochromatosis?

A. Hypogonadism
B. Arthropathy
C. Bronze diabetes
D. Desferrioxamine is the treatment of choice (Correct Answer)

Explanation: Hereditary Hemochromatosis (HH) is an autosomal recessive disorder characterized by excessive intestinal iron absorption, leading to iron deposition in various organs. **Why Option D is the correct answer (False statement):** The treatment of choice for hereditary hemochromatosis is **therapeutic phlebotomy**, not chelation [1]. Phlebotomy is more effective, less toxic, and cheaper for removing iron in HH. **Desferrioxamine** (an iron chelator) is reserved for patients with secondary hemochromatosis (e.g., Thalassemia major) where phlebotomy is contraindicated due to anemia, or in cases of severe iron-overload cardiomyopathy. **Analysis of Incorrect Options:** * **A. Hypogonadism:** This is the most common endocrinopathy in HH. It is usually **hypogonadotropic hypogonadism** caused by iron deposition in the anterior pituitary (gonadotrophs), leading to decreased libido and impotence [2]. * **B. Arthropathy:** Occurs in ~50% of patients. It characteristically involves the **2nd and 3rd metacarpophalangeal (MCP) joints** and is often associated with calcium pyrophosphate deposition (pseudogout). * **C. Bronze Diabetes:** This refers to the classic triad of hyperpigmentation (due to melanin and iron deposition) and diabetes mellitus (due to iron deposition in pancreatic beta cells) [2]. **High-Yield Clinical Pearls for NEET-PG:** * **Gene Mutation:** Most commonly the **HFE gene (C282Y mutation)** on Chromosome 6 [2]. * **Screening:** Best initial test is **Transferrin Saturation** (>45% is suggestive). * **Gold Standard:** Liver biopsy (to assess cirrhosis and calculate the Hepatic Iron Index) [1]. * **MRI:** MRI T2* is the non-invasive method of choice to quantify hepatic and cardiac iron [1]. * **Early Sign:** "Hook-like" osteophytes on X-ray of the MCP joints.

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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