Endocrinology — MCQs

A 27-year-old man and his 24-year-old wife have been trying to conceive a child for 6 years. Physical examination shows he has bilateral gynecomastia, reduced testicular size, reduced body hair, and increased length between the soles of his feet and the pubic bone. A semen analysis indicates oligospermia. Laboratory studies show increased follicle-stimulating hormone level and slightly decreased testosterone level. Which of the following karyotypes is this man most likely to have?

Q57Easy

Weight gain is seen in all of the following conditions except:

Q58Medium

Food-dependent Cushing's syndrome is a result of the aberrant expression of which of the following?

Q59Medium

A 54-year-old man presents with 7 weeks of facial flushing and diarrhea. His symptoms began intermittently but are becoming more constant. A 24-hour urine collection reveals an elevated level of 5-hydroxyindoleacetic acid (5-HIAA), a metabolite of serotonin. An abdominal CT scan shows a 2-cm mesenteric mass in the ileum and likely metastatic tumors in the liver. What is the likely diagnosis?

Q60Easy

Type I diabetes mellitus is associated with which of the following?

Endocrinology Indian Medical PG Practice Questions and MCQs

Question 51: A 17-year-old girl presents with weight gain, hair loss, constipation, and weakness. Her free T4 level is low and TSH is increased. Which of the following is the most likely diagnosis?

A. Graves' disease
B. McCune-Albright syndrome
C. TSH-secreting pituitary adenoma
D. Hashimoto's thyroiditis (Correct Answer)

Explanation: ### Explanation **1. Why Hashimoto’s Thyroiditis is Correct:** The clinical presentation of weight gain, hair loss, constipation, and weakness is classic for **hypothyroidism** [1]. The laboratory findings of a **low free T4** and an **increased TSH** confirm **primary hypothyroidism**. In a 17-year-old female, the most common cause of primary hypothyroidism is Hashimoto’s thyroiditis (Chronic Lymphocytic Thyroiditis). It is an autoimmune destruction of the thyroid gland, often characterized by the presence of anti-TPO and anti-thyroglobulin antibodies. **2. Why the Other Options are Incorrect:** * **Graves' Disease:** This is the most common cause of *hyperthyroidism*. Patients typically present with weight loss, tachycardia, heat intolerance, and low TSH levels [1]. * **McCune-Albright Syndrome:** This is a triad of polyostotic fibrous dysplasia, café-au-lait spots, and autonomous endocrine hyperfunction (most commonly **precocious puberty**, not hypothyroidism). * **TSH-secreting Pituitary Adenoma:** This is a rare cause of *secondary hyperthyroidism*. It would present with **elevated** free T4 levels and an inappropriately normal or elevated TSH. **3. High-Yield Clinical Pearls for NEET-PG:** * **Gold Standard Diagnosis:** Histopathology showing **Hurthle cells** (Askanazy cells) and lymphocytic infiltration with germinal centers. * **Antibody Profile:** Anti-TPO (Antimicrosomal) antibodies are the most sensitive marker (found in >90% of cases). * **Associated Risk:** Hashimoto’s thyroiditis increases the risk of **Primary Thyroid B-cell Lymphoma**. * **Wolff-Chaikoff Effect:** Hashimoto’s patients are uniquely sensitive to iodine loads, which can precipitate or worsen hypothyroidism.

Question 52: What is the recommended target HbA1c to minimize the risk of vascular complications in a diabetic individual?

A. 10% or more
B. 8%
C. 7% or less (Correct Answer)
D. 9%

Explanation: The primary goal of diabetes management is to prevent chronic complications. Large-scale clinical trials (such as **UKPDS** for Type 2 DM and **DCCT** for Type 1 DM) have conclusively demonstrated that maintaining an **HbA1c of ≤ 7%** significantly reduces the risk of **microvascular complications** (retinopathy, nephropathy, and neuropathy) [1]. While the impact on macrovascular outcomes (stroke, MI) is more evident over long-term follow-up (the "legacy effect"), the 7% threshold remains the standard recommendation for most non-pregnant adults [2]. **Analysis of Options:** * **Option C (Correct):** An HbA1c < 7% balances the benefits of complication prevention with the risks of hypoglycemia. * **Options A, B, and D (Incorrect):** HbA1c levels of 8%, 9%, or 10% are associated with a progressive and exponential increase in the risk of tissue damage due to advanced glycation end-products (AGEs) and oxidative stress. **Clinical Pearls for NEET-PG:** 1. **Individualization:** While < 7% is the general target, a more stringent goal (**< 6.5%**) may be suggested for young patients with short disease duration and no CVD [1]. Conversely, a less stringent goal (**< 8%**) is preferred for elderly patients, those with limited life expectancy, or those with a history of severe hypoglycemia. 2. **Diagnosis:** An HbA1c **≥ 6.5%** is diagnostic of Diabetes Mellitus. 3. **The 3-Month Rule:** HbA1c reflects average glycemia over the preceding 8–12 weeks (the lifespan of an RBC). 4. **False Lows:** HbA1c may be falsely low in conditions with high RBC turnover (e.g., hemolytic anemia, pregnancy, or recent blood transfusion).

Question 53: A 3cm adrenal mass is found incidentally on CT scan. Which of the following investigations is NOT indicated?

A. Adrenalectomy (Correct Answer)
B. Dexamethasone suppression test
C. Measurement of urinary or plasma catecholamines
D. Midnight plasma cortisol measurement

Explanation: ### Explanation The management of an **Adrenal Incidentaloma** (an adrenal mass ≥1 cm found incidentally on imaging) follows a strict protocol: first, determine if the mass is **hormonally active**, and second, assess its **malignant potential** [1]. **Why Adrenalectomy is the correct answer:** Surgery is a **treatment**, not an investigation. An adrenalectomy is only indicated if the mass is functional (hormone-secreting), shows suspicious radiological features (e.g., size >4 cm, high Hounsfield units), or shows significant growth on follow-up [1]. A 3 cm non-functional mass with benign imaging characteristics is typically managed with observation, not immediate surgery. **Why the other options are incorrect (Investigations that ARE indicated):** * **Dexamethasone Suppression Test (1 mg overnight):** This is the primary screening tool to rule out **Autonomous Cortisol Secretion (Subclinical Cushing’s)** [3]. * **Urinary or Plasma Catecholamines/Metanephrines:** Essential to rule out **Pheochromocytoma**, even in asymptomatic patients, as a biopsy or surgery on an undiagnosed pheochromocytoma can trigger a lethal hypertensive crisis [1], [4]. * **Midnight Plasma/Salivary Cortisol:** Along with 24-hour urinary free cortisol, these are alternative or confirmatory tests for hypercortisolism [3]. **High-Yield Clinical Pearls for NEET-PG:** 1. **Size Cut-off:** Masses **>4 cm** are generally considered for resection due to increased risk of adrenocortical carcinoma [1]. 2. **Hounsfield Units (HU):** On non-contrast CT, **<10 HU** suggests a lipid-rich benign adenoma [1]. 3. **Hypertension Screening:** If the patient is hypertensive, you must also check the **Aldosterone-to-Renin Ratio (ARR)** to rule out Primary Aldosteronism [2]. 4. **Biopsy Rule:** Never biopsy an adrenal mass until a Pheochromocytoma has been biochemically ruled out [1].

Question 54: A diabetic patient in hypoglycemia does not regain consciousness despite blood glucose restoration to normal. Which one of the following is a not likely condition or explanation?

A. Cerebral edema
B. Alcohol intoxication (Correct Answer)
C. Post-ictal state
D. Cerebral haemorrhage

Explanation: In a patient with hypoglycemia, the failure to regain consciousness despite the normalization of blood glucose levels (euglycemia) indicates that the neurological deficit is no longer due to a lack of substrate, but rather due to secondary complications or an alternative underlying pathology. **Explanation of the Correct Answer:** **B. Alcohol intoxication:** Alcohol is a common cause of hypoglycemia (due to inhibition of gluconeogenesis), but it does not typically prevent a patient from regaining their baseline consciousness once glucose is restored, unless the blood alcohol levels are at a lethal/comatose range [3]. More importantly, alcohol intoxication is a *cause* of hypoglycemia, not a *consequence* of it. If a patient remains unconscious after glucose correction, we look for structural or metabolic damage caused by the hypoglycemic insult itself. **Explanation of Incorrect Options:** * **A. Cerebral edema:** Severe or prolonged hypoglycemia can lead to an influx of water into the intracellular space, causing cerebral edema. This increased intracranial pressure prevents immediate recovery of consciousness despite glucose correction. * **C. Post-ictal state:** Hypoglycemia is a potent trigger for seizures [2]. Even after glucose is normalized, the patient may remain in a prolonged post-ictal state of altered consciousness [2]. * **D. Cerebral hemorrhage:** Hypoglycemia can mimic or trigger cerebrovascular accidents. Furthermore, the physiological stress and sympathetic surge during a hypoglycemic episode can lead to acute hypertension, potentially resulting in an intracranial bleed. **High-Yield Clinical Pearls for NEET-PG:** * **Whipple’s Triad:** (1) Symptoms of hypoglycemia, (2) Low plasma glucose, (3) Relief of symptoms after glucose administration. * **Neuroglycopenic symptoms** (confusion, coma, seizures) usually occur when blood glucose falls below **40–50 mg/dL** [1]. * If a patient remains unconscious after glucose correction, the first step is often a **Non-Contrast CT (NCCT) Head** to rule out structural changes like edema or hemorrhage.

Question 55: A 17-year-old female patient presents with hirsutism, hyperglycemia, obesity, muscle wasting, and increased circulating levels of ACTH. What is the most likely cause of her symptoms?

A. Primary adrenocortical insufficiency
B. Primary overproduction of ACTH (Correct Answer)
C. Exogenous steroids
D. Hypophysectomy

Explanation: ### Explanation The patient presents with classic features of **Cushing’s Syndrome**: central obesity, muscle wasting (due to protein catabolism), hyperglycemia (due to gluconeogenesis), and hirsutism (due to excess adrenal androgens) [1]. **1. Why Option B is Correct:** The key finding is **increased circulating levels of ACTH**. In a patient with hypercortisolism, high ACTH indicates an **ACTH-dependent** cause [2]. This most commonly results from a pituitary adenoma (Cushing’s Disease) or ectopic ACTH production [2]. The high ACTH stimulates the adrenal cortex to produce excess cortisol and androgens, leading to the clinical triad of metabolic derangement, physical changes, and virilization/hirsutism [1]. **2. Why the Other Options are Incorrect:** * **Option A (Primary adrenocortical insufficiency):** Also known as Addison’s disease, this presents with weight loss, hypotension, and hypoglycemia—the exact opposite of this patient’s symptoms. * **Option C (Exogenous steroids):** This is the most common cause of Cushingoid features overall. However, exogenous glucocorticoids suppress the pituitary-adrenal axis via negative feedback, leading to **low (suppressed) ACTH levels**, not high [3]. * **Option D (Hypophysectomy):** Surgical removal of the pituitary gland would result in a deficiency of ACTH, leading to secondary adrenal insufficiency (low cortisol). **High-Yield NEET-PG Pearls:** * **Screening Test:** The best initial screening test for Cushing’s syndrome is the 24-hour urinary free cortisol or the Overnight Dexamethasone Suppression Test (ONDST) [4]. * **Localization:** If ACTH is high, the next step is a High-Dose Dexamethasone Suppression Test (HDDST). Suppression >50% suggests a pituitary source (Cushing’s Disease); no suppression suggests an ectopic source (e.g., Small Cell Lung Cancer). * **Hyperpigmentation:** High ACTH levels often lead to hyperpigmentation because ACTH is derived from POMC, which also produces Melanocyte-Stimulating Hormone (MSH).

Question 56: A 27-year-old man and his 24-year-old wife have been trying to conceive a child for 6 years. Physical examination shows he has bilateral gynecomastia, reduced testicular size, reduced body hair, and increased length between the soles of his feet and the pubic bone. A semen analysis indicates oligospermia. Laboratory studies show increased follicle-stimulating hormone level and slightly decreased testosterone level. Which of the following karyotypes is this man most likely to have?

A. 46, X, i(Xq)
B. 47, XYY
C. 47, XXY (Correct Answer)
D. 46, XX/47, XX, +21

Explanation: The clinical presentation of infertility, bilateral gynecomastia, small testes, and eunuchoid body habitus (increased sole-to-pubis length) is classic for **Klinefelter Syndrome (47, XXY)** [1]. **Why 47, XXY is correct:** Klinefelter syndrome is the most common cause of primary hypogonadism in males. The extra X chromosome leads to **dysgenesis of seminiferous tubules** (causing low inhibin and high FSH) and **atrophy of Leydig cells** (causing low testosterone and high LH) [1]. The high LH/FSH ratio and peripheral conversion of androgens to estrogens result in gynecomastia [3]. The "eunuchoid" habitus occurs because testosterone is required to close the epiphyseal plates; its deficiency leads to delayed closure and disproportionately long limbs [1]. **Analysis of Incorrect Options:** * **46, X, i(Xq):** This represents an isochromosome X, a variant of **Turner Syndrome** [2]. This would present in a phenotypic female with short stature and primary amenorrhea. * **47, XYY:** Known as **Jacob’s Syndrome**. These individuals are usually phenotypically normal, very tall, and may have severe acne or behavioral issues, but they typically have normal fertility and testosterone levels. * **46, XX/47, XX, +21:** This is a mosaic form of **Down Syndrome**. While it can cause hypogonadism, it is characterized by distinct facies, intellectual disability, and Simian creases, which are absent here. **High-Yield Clinical Pearls for NEET-PG:** * **Most common genotype:** 47, XXY (due to maternal meiotic non-disjunction). * **Key Lab Findings:** ↑ FSH, ↑ LH, ↓ Testosterone, ↑ Estrogen [1]. * **Histology:** Hyalinization and fibrosis of seminiferous tubules [1]. * **Increased Risks:** Breast cancer (20x higher than normal males), extragonadal germ cell tumors, and autoimmune diseases (SLE) [3]. * **Semen Analysis:** Usually shows **azoospermia** (complete absence) or severe oligospermia [1].

Question 57: Weight gain is seen in all of the following conditions except:

A. Cushing's syndrome
B. Hypothyroidism
C. Pheochromocytoma (Correct Answer)
D. Insulinoma

Explanation: **Explanation:** The correct answer is **Pheochromocytoma**. This condition is characterized by the hypersecretion of catecholamines (epinephrine and norepinephrine), which are potent catabolic hormones. Catecholamines increase the basal metabolic rate (BMR) and promote glycogenolysis and lipolysis [2]. Furthermore, they inhibit insulin secretion, leading to a hypermetabolic state that typically results in **weight loss**, despite a normal or increased appetite [5]. **Analysis of Incorrect Options:** * **Cushing’s Syndrome:** Characterized by hypercortisolism, which promotes adipogenesis and redistribution of fat. This leads to progressive weight gain and "centripetal obesity" (moon facies, buffalo hump, and truncal obesity) [3]. * **Hypothyroidism:** A deficiency in thyroid hormones leads to a significant decrease in BMR and the accumulation of glycosaminoglycans (myxedema), which causes water retention and weight gain [1]. * **Insulinoma:** This beta-cell tumor secretes excessive insulin, leading to recurrent hypoglycemia. Patients often experience weight gain due to the anabolic effects of insulin and "defensive eating" (frequent snacking to prevent or treat hypoglycemic symptoms). **NEET-PG High-Yield Pearls:** * **Pheochromocytoma Triad:** Episodic headache, sweating, and tachycardia (often associated with hypertension). * **Rule of 10s:** Historically associated with Pheochromocytoma (10% bilateral, 10% malignant, 10% extra-adrenal, 10% pediatric). * **Weight Gain Differential:** Always consider PCOS, Metabolic Syndrome, and drugs (Steroids, Sulfonylureas, TCAs, and Valproate) in clinical vignettes [4].

Question 58: Food-dependent Cushing's syndrome is a result of the aberrant expression of which of the following?

A. Gastric inhibitory polypeptide (Correct Answer)
B. Somatostatin
C. Substance P
D. Tachykinins

Explanation: **Explanation:** **Food-dependent Cushing’s syndrome** is a rare form of ACTH-independent macronodular adrenal hyperplasia (AIMAH). The underlying pathophysiology involves the **aberrant expression of receptors for Gastric Inhibitory Polypeptide (GIP)** on the adrenal cortex [1]. 1. **Why GIP is correct:** Normally, GIP is a hormone secreted by the K-cells of the small intestine in response to food intake. In this pathological state, the adrenal glands ectopically express GIP receptors. Consequently, every time the patient eats, the postprandial rise in GIP stimulates the adrenal glands to secrete cortisol, leading to hypercortisolism that is specifically triggered by meals [1]. 2. **Why other options are incorrect:** * **Somatostatin:** Generally acts as an inhibitory hormone in the endocrine system; its receptors are often targets for treatment (e.g., octreotide), not the cause of food-dependent Cushing’s. * **Substance P and Tachykinins:** These are neuropeptides involved in pain transmission and smooth muscle contraction; they do not have a recognized role in the postprandial regulation of adrenal cortisol secretion. **High-Yield Clinical Pearls for NEET-PG:** * **Diagnosis:** Characterized by low morning (fasting) cortisol levels and high postprandial cortisol levels. * **ACTH Levels:** ACTH will be suppressed (ACTH-independent) because the cortisol excess is driven by GIP, not the pituitary [1]. * **Other Ectopic Receptors:** Besides GIP, AIMAH can also be caused by aberrant expression of receptors for **Beta-adrenergic agonists**, **Vasopressin (V1)**, or **LH/hCG** [1]. * **Treatment:** Often involves bilateral adrenalectomy or, in some GIP-dependent cases, octreotide to suppress GIP release.

Question 59: A 54-year-old man presents with 7 weeks of facial flushing and diarrhea. His symptoms began intermittently but are becoming more constant. A 24-hour urine collection reveals an elevated level of 5-hydroxyindoleacetic acid (5-HIAA), a metabolite of serotonin. An abdominal CT scan shows a 2-cm mesenteric mass in the ileum and likely metastatic tumors in the liver. What is the likely diagnosis?

A. Serotonin syndrome
B. Malignant carcinoid syndrome (Correct Answer)
C. Cushing syndrome
D. Phaeochromocytoma

Explanation: ### Explanation **Correct Answer: B. Malignant carcinoid syndrome** **Pathophysiology & Diagnosis:** Carcinoid syndrome is caused by the systemic release of vasoactive substances (primarily **serotonin**, but also histamine and bradykinin) from neuroendocrine tumors [1]. These tumors most commonly arise in the **ileum** (midgut) [2]. * **The "Liver Bypass" Rule:** Serotonin produced by primary intestinal tumors is normally metabolized by the liver into **5-HIAA** (inactive) via the portal circulation. Therefore, carcinoid syndrome typically occurs only once the tumor has **metastasized to the liver**, allowing secretions to enter the systemic circulation directly via the hepatic veins [1]. * **Clinical Triad:** The classic presentation includes **episodic flushing**, **secretory diarrhea**, and wheezing. Chronic cases may develop right-sided heart failure (tricuspid regurgitation). * **Biochemical Marker:** The gold standard for screening is elevated **24-hour urinary 5-HIAA**. **Why the other options are incorrect:** * **A. Serotonin syndrome:** This is an iatrogenic drug reaction (e.g., SSRI overdose) characterized by the triad of altered mental status, autonomic instability, and **neuromuscular hyperactivity** (clonus/hyperreflexia), which are absent here. * **C. Cushing syndrome:** Caused by hypercortisolism; presents with central obesity, striae, and hypertension, not episodic flushing and diarrhea. * **D. Phaeochromocytoma:** A catecholamine-secreting tumor presenting with the "P" triad: Palpitations, Perspiration, and Pressure (headache/hypertension). While it causes flushing, it does not typically cause chronic secretory diarrhea or elevated 5-HIAA. **NEET-PG High-Yield Pearls:** * **Localization:** Most common site of carcinoid tumor is the **appendix**, but the most common site to cause *syndrome* is the **ileum**. * **Heart Involvement:** Affects the **right side** (Tricuspid Regurgitation/Pulmonary Stenosis). The left side is spared because the lungs contain monoamine oxidase (MAO) which degrades serotonin. * **Pellagra Risk:** Chronic carcinoid can lead to **Niacin (B3) deficiency** because the tumor diverts dietary tryptophan toward serotonin synthesis instead of nicotinic acid. * **Treatment:** **Octreotide** (Somatostatin analog) is the drug of choice to manage symptoms.

Question 60: Type I diabetes mellitus is associated with which of the following?

A. Insulin resistance
B. Defect in mitochondrial DNA
C. Islet cell autoantibodies (Correct Answer)
D. Beta cell dysfunction

Explanation: ### Explanation **Correct Answer: C. Islet cell autoantibodies** **Medical Concept:** Type 1 Diabetes Mellitus (T1DM) is primarily an **autoimmune disease** characterized by the T-cell-mediated destruction of pancreatic beta cells [1]. The presence of **islet cell autoantibodies** (e.g., GAD65, IA-2, Zinc transporter 8, and Insulin autoantibodies) serves as a hallmark marker of this autoimmune process [2]. These antibodies are often present years before clinical symptoms appear and are used to differentiate T1DM from Type 2 DM or Monogenic diabetes. **Analysis of Incorrect Options:** * **A. Insulin resistance:** This is the primary pathophysiological feature of **Type 2 Diabetes Mellitus (T2DM)** and metabolic syndrome. In T1DM, the problem is an absolute deficiency of insulin, not resistance to its action. * **B. Defect in mitochondrial DNA:** This is associated with **Maternally Inherited Diabetes and Deafness (MIDD)**. It follows a non-Mendelian inheritance pattern and is not the mechanism for classic T1DM. * **C. Beta cell dysfunction:** While beta cells are destroyed in T1DM, "dysfunction" (impaired secretion despite cells being present) is more characteristic of the early stages of **T2DM** or **MODY** [3]. In T1DM, there is beta-cell **destruction** leading to absolute deficiency. **High-Yield Clinical Pearls for NEET-PG:** * **HLA Association:** T1DM is strongly linked to **HLA-DR3 and HLA-DR4** [2]. * **Most Common Antibody:** **GAD65 (Glutamic Acid Decarboxylase)** antibodies are the most persistent and commonly tested. * **Honey Moon Phase:** A transient period after diagnosis where the remaining beta cells function temporarily before total exhaustion. * **Histology:** The classic finding in T1DM is **Insulitis** (lymphocytic infiltration of the islets).

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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