Endocrinology — MCQs

Endocrinology Indian Medical PG Practice Questions and MCQs

Question 1021: Which of the following is the most likely clinical feature associated with high prolactin levels causing sexual dysfunction?

A. Loss of sexual desire
B. Failure of erection with absent nocturnal penile tumescence (NPT) (Correct Answer)
C. Absence of emission
D. Absence of orgasm with normal libido and erectile function

Explanation: Hyperprolactinemia is a common cause of secondary hypogonadism. High prolactin levels inhibit the pulsatile secretion of **Gonadotropin-Releasing Hormone (GnRH)** from the hypothalamus, leading to decreased LH and FSH, and subsequently, low testosterone levels [1]. ### **Explanation of the Correct Option** **B. Failure of erection with absent nocturnal penile tumescence (NPT):** In males, hyperprolactinemia leads to **hypogonadotropic hypogonadism**. Low testosterone levels result in organic erectile dysfunction [2]. A hallmark of organic (hormonal or neurovascular) impotence is the **absence of Nocturnal Penile Tumescence (NPT)**. In contrast, psychogenic impotence typically maintains normal NPT. Hyperprolactinemia is a recognized endocrine cause of impotence and sterility [3]. ### **Explanation of Incorrect Options** * **A. Loss of sexual desire:** While decreased libido is a common symptom of high prolactin, it is a subjective symptom. The question asks for the "clinical feature" specifically associated with the physiological dysfunction (erectile failure) caused by the hormonal axis disruption. * **C. Absence of emission:** Emission is primarily mediated by the sympathetic nervous system and is usually preserved unless there is significant autonomic neuropathy (e.g. Diabetes) or surgical trauma. * **D. Absence of orgasm with normal libido:** Hyperprolactinemia typically affects the "arousal" and "desire" phases due to low testosterone; it does not cause isolated anorgasmia while leaving libido intact. ### **NEET-PG High-Yield Pearls** * **Mechanism:** Prolactin $\uparrow$ $\rightarrow$ GnRH $\downarrow$ $\rightarrow$ LH/FSH $\downarrow$ $\rightarrow$ Testosterone $\downarrow$ [1]. * **Clinical Triad in Men:** Erectile dysfunction, decreased libido, and infertility (oligospermia). Galactorrhea is rare in men (<10%) [1]. * **Drug-Induced:** Antipsychotics (Risperidone) and Metoclopramide are common causes due to D2 receptor antagonism [1]. * **Gold Standard Test for NPT:** Rigiscan (helps differentiate organic from psychogenic ED).

Question 1022: Which of the following is NOT true about Hashimoto's thyroiditis?

A. Patients can present with hyperthyroidism or hypothyroidism.
B. It is an autoimmune disease.
C. It is commoner in males. (Correct Answer)
D. Antithyroglobulin antibodies are characteristic.

Explanation: **Explanation:** Hashimoto’s thyroiditis (Chronic Lymphocytic Thyroiditis) is the most common cause of hypothyroidism in iodine-sufficient regions. **1. Why Option C is the correct answer (The False Statement):** Autoimmune thyroid diseases, including Hashimoto’s, are significantly **more common in females** than in males (ratio approximately 10:1 to 20:1). This is a high-yield epidemiological fact for NEET-PG; most autoimmune endocrine disorders show a strong female predilection. **2. Analysis of Incorrect Options (True Statements):** * **Option A:** While it typically leads to permanent hypothyroidism, patients can initially present with **"Hashitoxicosis"**—a transient hyperthyroid phase caused by the inflammatory destruction of thyroid follicles and the subsequent leak of stored thyroid hormones into the circulation [1]. * **Option B:** It is a classic **autoimmune disease** involving both cell-mediated (T-cell) and humoral (B-cell) immunity, leading to the destruction of thyroid tissue. * **Option C:** Diagnosis is supported by high titers of **Antithyroglobulin (anti-Tg)** and **Antithyroid peroxidase (anti-TPO)** antibodies [1]. Anti-TPO is generally more sensitive (present in >90% of cases). **Clinical Pearls for NEET-PG:** * **Histology:** Look for **Hurthle cells** (Askanazy cells)—large eosinophilic follicular cells—and dense lymphocytic infiltrates with **germinal centers**. * **Risk Factor:** It is associated with HLA-DR3 and HLA-DR5. * **Complication:** Patients have an increased risk of developing **Primary Thyroid Lymphoma** (typically B-cell type). * **Goiter:** Usually presents as a painless, diffuse, firm goiter.

Question 1023: Multiple Endocrine Neoplasia (MEN) Type-I is also known as:

A. Wermer's Syndrome (Correct Answer)
B. Sipple Syndrome
C. Weber's Syndrome
D. Morrison Syndrome

Explanation: **Multiple Endocrine Neoplasia Type 1 (MEN1)** is an autosomal dominant disorder caused by a mutation in the *MEN1* gene on chromosome 11q13, which encodes the protein **menin**. It is characterized by the "3 Ps": **P**arathyroid hyperplasia (the most common feature), **P**ancreatic islet cell tumors (e.g., Gastrinoma, Insulinoma), and **P**ituitary adenomas (most commonly Prolactinoma). **Why Option A is correct:** **Wermer’s Syndrome** is the eponymous name for MEN1, named after Paul Wermer, who first described the familial occurrence of these specific endocrine tumors in 1954. **Analysis of Incorrect Options:** * **B. Sipple Syndrome:** This is the eponym for **MEN Type 2A**, characterized by Medullary Thyroid Carcinoma (MTC), Pheochromocytoma, and Parathyroid hyperplasia. * **C. Weber’s Syndrome:** This is a neurological condition (Superior Alternating Hemiplegia) involving a midbrain stroke affecting the CN III nerve fibers and the cerebral peduncle. * **D. Morrison Syndrome:** Also known as Verner-Morrison Syndrome, this refers specifically to **VIPoma** (Watery Diarrhea, Hypokalemia, Achlorhydria or WDHA syndrome), which can be a component of MEN1 but is not the name of the syndrome itself. **High-Yield Clinical Pearls for NEET-PG:** * **MEN 2A (Sipple Syndrome):** MTC + Pheochromocytoma + Parathyroid. * **MEN 2B (Wagenmann-Froboese Syndrome):** MTC + Pheochromocytoma + Mucosal Neuromas + Marfanoid habitus. * **Most common initial presentation of MEN1:** Primary Hyperparathyroidism (seen in >95% of patients by age 30). * **Screening:** Genetic testing for *MEN1* mutations is the gold standard for family members.

Question 1024: Somatostatin is produced by:

A. A cell
B. B cell
C. D cell (Correct Answer)
D. F cell

Explanation: **Explanation:** The Islets of Langerhans in the pancreas are composed of several distinct endocrine cell types, each secreting specific hormones that regulate glucose metabolism [1]. **Correct Answer: C. D cell (Delta cells)** Somatostatin is synthesized and secreted by the **D cells** of the pancreatic islets (as well as by cells in the gastrointestinal tract and the hypothalamus). In the pancreas, somatostatin acts primarily as a potent **inhibitor** [2]. It functions via paracrine signaling to inhibit the secretion of both Insulin and Glucagon, thereby modulating the glycemic response [1], [3]. **Analysis of Incorrect Options:** * **A. A cell (Alpha cells):** These cells comprise about 20% of the islet and are responsible for secreting **Glucagon**, which increases blood glucose levels via glycogenolysis and gluconeogenesis [1]. * **B. B cell (Beta cells):** These are the most numerous cells (approx. 65-70%) and secrete **Insulin**, which lowers blood glucose, and **Amylin**. * **D. F cell (PP cells):** These cells secrete **Pancreatic Polypeptide**, which plays a role in regulating exocrine pancreatic secretions and gallbladder contraction [2]. **High-Yield Clinical Pearls for NEET-PG:** * **Somatostatinoma:** A rare neuroendocrine tumor of D cells characterized by the "Inhibitory Syndrome": Diabetes mellitus (low insulin), Cholelithiasis (low CCK/gallbladder motility), and Steatorrhea (low pancreatic enzymes). * **Octreotide:** A synthetic long-acting analog of somatostatin used clinically to treat acromegaly, carcinoid syndrome, and acute variceal bleeding. * **Universal Inhibitor:** Remember Somatostatin as the "Great Inhibitor"—it decreases GH, TSH, Insulin, Glucagon, and Gastrin [3].

Question 1025: A progressive increase in mandibular length and in mandibular interdental spacing in an adult patient is characteristic of which condition?

A. Periodontosis
B. Hypothyroidism
C. Hyperpituitarism (Correct Answer)
D. Hypoadrenalism

Explanation: The clinical presentation described—progressive increase in mandibular length (**prognathism**) and widening of spaces between the teeth (**diastema**) in an adult—is a classic hallmark of **Acromegaly**, which results from **Hyperpituitarism** (specifically, a growth hormone-secreting adenoma) [1]. **Why Hyperpituitarism is correct:** In adults, after the epiphyseal plates have fused, excess Growth Hormone (GH) cannot increase height but instead causes **acral overgrowth** and soft tissue hypertrophy [1]. The mandible is particularly sensitive; its enlargement leads to a "lantern jaw" appearance. As the bone expands, the fixed number of teeth become separated, leading to increased interdental spacing. **Why the other options are incorrect:** * **Periodontosis:** While this can cause tooth mobility and spacing due to bone loss, it does not cause an increase in mandibular length or systemic bony overgrowth. * **Hypothyroidism:** In adults (Myxedema), this typically presents with macroglossia (enlarged tongue) and non-pitting edema, but it does not cause bony enlargement of the jaw. * **Hypoadrenalism (Addison’s Disease):** This is characterized by hyperpigmentation, hypotension, and electrolyte imbalances, with no effect on bone growth or dental spacing [3]. **NEET-PG High-Yield Pearls:** * **Best Initial Test:** Serum IGF-1 levels (more stable than GH) [2]. * **Gold Standard Diagnostic Test:** Oral Glucose Tolerance Test (OGTT) showing failure to suppress GH levels below 1 ng/mL [2]. * **Most Common Cause:** Somatotroph adenoma of the anterior pituitary [4]. * **Associated Comorbidities:** Sleep apnea, bitemporal hemianopia (due to optic chiasm compression), and increased risk of colorectal polyps/carcinoma [2].

Question 1026: A patient presents with fasting blood sugar of 167 mg/dl, skin pigmentation, and hypogonadism. Liver enzymes show SGOT as 670 and SGPT as 690. Which of the following is the most likely diagnosis?

A. Alpha-1 Antitrypsin Deficiency
B. Wilson's Disease
C. Hemochromatosis (Correct Answer)
D. Glycogen Storage Disease

Explanation: **Explanation:** The clinical triad of **Diabetes Mellitus** (fasting blood sugar 167 mg/dl), **Skin Pigmentation** (often described as "bronzed"), and **Cirrhosis/Liver Dysfunction** (elevated SGOT/SGPT) is the classic presentation of **Hereditary Hemochromatosis**, often referred to as **"Bronze Diabetes."** [1] **Why Hemochromatosis is correct:** Hemochromatosis is an iron-overload disorder where excessive iron (hemosiderin) deposits in various organs: * **Pancreas:** Damage to islet cells leads to secondary Diabetes Mellitus. [1] * **Skin:** Iron deposition and increased melanin production cause hyperpigmentation. [1] * **Liver:** Iron accumulation leads to hepatomegaly, elevated enzymes, and eventually cirrhosis. [1] * **Pituitary/Gonads:** Iron deposition in the pituitary leads to hypogonadotropic **hypogonadism** (presenting as decreased libido or impotence). [1] **Why other options are incorrect:** * **Alpha-1 Antitrypsin Deficiency:** Primarily presents with panacinar emphysema and liver cirrhosis, but does not typically cause diabetes or significant skin pigmentation. * **Wilson's Disease:** A disorder of copper metabolism. While it causes liver disease, it is characterized by neuropsychiatric symptoms and **Kayser-Fleischer (KF) rings**, not diabetes and bronzing. * **Glycogen Storage Disease:** These typically present in childhood with hypoglycemia, hepatomegaly, and growth retardation, rather than the adult-onset triad of diabetes and pigmentation. **NEET-PG High-Yield Pearls:** * **Gene Mutation:** Most commonly the **HFE gene** (C282Y mutation) on Chromosome 6. [1] * **Screening Test:** Transferrin saturation (best initial test; >45% is suggestive). * **Gold Standard Diagnosis:** Liver biopsy with Prussian Blue staining (Perl’s stain). * **Treatment:** Therapeutic phlebotomy is the mainstay of management. * **Cardiac Involvement:** Can lead to restrictive or dilated cardiomyopathy.

Question 1027: Which of the following is true about Cushing's syndrome?

A. Adrenomedullary hyperplasia in association with MEN syndrome is a common cause.
B. Bronchial and mediastinal carcinoids can cause Cushing's syndrome. (Correct Answer)
C. It is diagnosed by hypokalemia in association with increased adrenal secretion.
D. It is often fatal due to coronary and cerebrovascular accidents.

Explanation: **Explanation:** **Cushing’s Syndrome (CS)** results from chronic exposure to excess glucocorticoids [2]. The correct answer is **Option B** because bronchial and mediastinal carcinoids are classic causes of **Ectopic ACTH Syndrome**. These tumors secrete ACTH autonomously, leading to bilateral adrenal hyperplasia and hypercortisolism [2]. Ectopic production accounts for approximately 10-15% of ACTH-dependent CS. **Analysis of Incorrect Options:** * **Option A:** MEN (Multiple Endocrine Neoplasia) syndromes are associated with the adrenal **cortex** (e.g., adenomas in MEN1) or the adrenal **medulla** (Pheochromocytoma in MEN2) [1]. Adrenomedullary hyperplasia is a precursor to pheochromocytoma, which secretes catecholamines, not cortisol. * **Option C:** While hypokalemia is a common feature (especially in ectopic ACTH due to mineralocorticoid effects of high cortisol), it is a **biochemical finding**, not the diagnostic criteria. Diagnosis requires demonstrating hypercortisolism via 24-hour urinary free cortisol, Low-Dose Dexamethasone Suppression Test (LDDST), or late-night salivary cortisol [3]. * **Option D:** While CS increases cardiovascular risk, it is rarely "acutely fatal" due to accidents. The most common causes of mortality in untreated Cushing’s are **infections** (due to immunosuppression) and complications of vascular disease over time. **High-Yield Pearls for NEET-PG:** * **Most common cause overall:** Iatrogenic (Exogenous steroids). * **Most common endogenous cause:** Cushing’s Disease (Pituitary adenoma) [2]. * **Ectopic ACTH Clue:** Rapid onset, severe hypertension, profound hypokalemia, and hyperpigmentation (due to high ACTH/MSH). * **Screening Test of Choice:** Overnight Dexamethasone Suppression Test (ODST) [3]. * **Gold Standard for localization:** Inferior Petrosal Sinus Sampling (IPSS) to differentiate Pituitary vs. Ectopic sources.

Question 1028: Zollinger-Ellison syndrome is characterized by the following except?

A. Profound gastric hypersecretion
B. Large diarrhea with occasional steatorrhea
C. Hypocalcemia (Correct Answer)
D. Hypergastrinemia

Explanation: **Explanation:** Zollinger-Ellison Syndrome (ZES) is caused by a gastrin-secreting neuroendocrine tumor (gastrinoma), typically located in the "gastrinoma triangle." **Why Hypocalcemia is the Correct Answer:** Hypocalcemia is **not** a feature of ZES. In fact, approximately 25% of ZES cases occur as part of **Multiple Endocrine Neoplasia type 1 (MEN1)**. In these patients, ZES is associated with primary hyperparathyroidism, which leads to **hypercalcemia**, not hypocalcemia. Hypercalcemia can further stimulate gastrin release, worsening the symptoms. **Analysis of Incorrect Options:** * **Profound gastric hypersecretion:** Gastrinomas secrete excessive gastrin, which acts on parietal cells to produce massive amounts of hydrochloric acid. This leads to refractory peptic ulcers. * **Large diarrhea with occasional steatorrhea:** The high acid volume overwhelms the small intestine. Steatorrhea occurs because the low pH inactivates pancreatic lipases and causes the precipitation of bile acids, leading to fat malabsorption. * **Hypergastrinemia:** This is the biochemical hallmark of ZES. Elevated fasting serum gastrin levels (typically >1000 pg/mL) in the presence of gastric acid (pH <2) confirm the diagnosis. **High-Yield Clinical Pearls for NEET-PG:** 1. **Diagnosis:** The most sensitive and specific provocative test is the **Secretin Stimulation Test** (Secretin causes a paradoxical rise in gastrin in ZES). 2. **Location:** Most gastrinomas are found in the **Gastrinoma Triangle** (bounded by the cystic duct, junction of the 2nd/3rd parts of the duodenum, and the neck of the pancreas). 3. **MEN1 Association:** Always screen for Hyperparathyroidism and Pituitary adenomas if ZES is diagnosed. 4. **Treatment:** High-dose Proton Pump Inhibitors (PPIs) and surgical resection of the tumor.

Question 1029: Which of the following is not seen in thyrotoxicosis?

A. Palpitations
B. Anxiety
C. Weight loss
D. Menorrhagia (Correct Answer)

Explanation: **Explanation:** In thyrotoxicosis, the excess of circulating thyroid hormones (T3 and T4) leads to a hypermetabolic state and increased sympathetic activity [1]. **Why Menorrhagia is the correct answer:** Thyrotoxicosis typically causes **Oligomenorrhea** (infrequent periods) or **Amenorrhea** (absence of periods), rather than Menorrhagia. This occurs because high thyroid hormone levels interfere with the hypothalamic-pituitary-ovarian axis, leading to anovulatory cycles and decreased estrogen levels. Conversely, **Menorrhagia** (heavy menstrual bleeding) is a classic hallmark of **Hypothyroidism**, where low thyroid levels lead to impaired coagulation factors and failure of LH surge. **Why the other options are incorrect:** * **Palpitations:** Thyroid hormones increase the expression of beta-adrenergic receptors in the heart, leading to increased heart rate (tachycardia) and contractility [3]. * **Anxiety:** Excess T3/T4 has a stimulatory effect on the central nervous system, commonly manifesting as irritability, nervousness, and anxiety [1]. * **Weight loss:** Despite an increased appetite (polyphagia), the basal metabolic rate (BMR) is significantly elevated, leading to the breakdown of fat and muscle stores, resulting in weight loss [1], [3]. **Clinical Pearls for NEET-PG:** * **Most common cause of thyrotoxicosis:** Graves’ Disease (associated with exophthalmos and pretibial myxedema) [1]. * **Cardiac sign:** "Apathetic hyperthyroidism" in the elderly may present only with Atrial Fibrillation [2]. * **Reflexes:** Look for "brisk" or hyperreflexia in thyrotoxicosis, whereas "hung-up" (delayed relaxation) DTRs are seen in hypothyroidism. * **Tremors:** Characteristically fine, high-frequency tremors are seen in hyperthyroidism [1].

Question 1030: In type 2 DM, increased fasting plasma glucose is predominantly due to which of the following?

A. Increased hepatic glucose output (Correct Answer)
B. Decreased peripheral utilization of glucose
C. Decreased insulin secretion
D. Decreased transport of glucose to tissues

Explanation: **Explanation:** The hallmark of Type 2 Diabetes Mellitus (T2DM) is a combination of insulin resistance and relative insulin deficiency [1]. To understand the pathophysiology of hyperglycemia, it is essential to distinguish between fasting and postprandial states. **Why Option A is Correct:** In the **fasting state**, the liver is the primary source of blood glucose. Under normal physiological conditions, insulin suppresses hepatic gluconeogenesis and glycogenolysis [2]. In T2DM, the liver becomes resistant to insulin and is exposed to high levels of glucagon. This leads to **unrestrained hepatic glucose output**, which is the primary driver of elevated **Fasting Plasma Glucose (FPG)** [1]. Research indicates a direct correlation between the rate of hepatic glucose production and the severity of fasting hyperglycemia [3]. **Why Other Options are Incorrect:** * **Option B & D:** Decreased peripheral glucose utilization (primarily in skeletal muscle) and decreased tissue transport (via GLUT-4) are the dominant mechanisms for **postprandial (after-meal) hyperglycemia**, rather than fasting hyperglycemia [2]. * **Option C:** While decreased insulin secretion (beta-cell dysfunction) is a core component of T2DM progression, it is the *consequence* of insulin resistance at the liver that specifically fails to "turn off" glucose production during the night, leading to high FPG. **NEET-PG High-Yield Pearls:** * **The "Ominous Octet":** This refers to the eight pathophysiological mechanisms in T2DM, including the liver (increased glucose production), muscle (decreased uptake), and pancreas (decreased insulin/increased glucagon). * **Metformin’s Mechanism:** Metformin is the first-line drug for T2DM because its primary action is to **decrease hepatic glucose output**, directly targeting the cause of fasting hyperglycemia. * **Dawn Phenomenon:** A surge in growth hormone and cortisol in the early morning leads to increased hepatic glucose output, further elevating FPG in diabetics.

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

Practice Questions

Endocrine Hypertension

Practice Questions

Multiple Endocrine Neoplasia

Practice Questions

Obesity and Metabolic Syndrome

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Neuroendocrine Tumors

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Endocrine Emergencies

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