Endocrinology — MCQs

Endocrinology Indian Medical PG Practice Questions and MCQs

Question 41: Which of the following is seen in 95% of patients with diabetes mellitus?

A. HLAB27
B. HLAB3-B4
C. HLA DR3-DR4 (Correct Answer)
D. HLAA3

Explanation: ### Explanation **Correct Option: C. HLA DR3-DR4** The association between Human Leukocyte Antigens (HLA) and Type 1 Diabetes Mellitus (T1DM) is one of the strongest in medical genetics [2]. Approximately **95% of Caucasians with T1DM** express either **HLA-DR3 or HLA-DR4**, compared to about 40% of the general population. Specifically, the inheritance of the **DR3/DR4 heterozygote** genotype confers the highest genetic risk for the development of the disease. These MHC Class II molecules are responsible for presenting islet autoantigens to T-helper cells, triggering the autoimmune destruction of pancreatic beta cells. **Explanation of Incorrect Options:** * **A. HLA-B27:** This is a Class I MHC antigen strongly associated with **Seronegative Spondyloarthropathies**, most notably Ankylosing Spondylitis (90% association), Reiter’s syndrome, and Psoriatic arthritis. * **B. HLA B3-B4:** These are not standard high-yield HLA associations for diabetes. While various B-locus alleles (like B8 and B15) show some linkage disequilibrium with DR3/DR4, they are not the primary diagnostic markers. * **D. HLA-A3:** This allele is classically associated with **Hereditary Hemochromatosis**. **High-Yield Clinical Pearls for NEET-PG:** * **T1DM Risk:** If one sibling has T1DM, the risk to another sibling is 5%; if they share the same HLA haplotype, the risk increases to 10–20% [1]. * **Protective Allele:** While DR3/DR4 increases risk, **HLA-DQB1*0602** is known to provide potent protection against T1DM. * **Other HLA-DR Associations:** * **DR2:** Multiple Sclerosis, SLE, Goodpasture Syndrome. * **DR3:** T1DM, SLE, Graves' Disease, Celiac Disease [1]. * **DR4:** T1DM, Rheumatoid Arthritis. * **DR5:** Hashimoto Thyroiditis.

Question 42: In which of the following conditions do Total T3, Total T4, and TSH all decrease?

A. Primary hypothyroidism
B. Hypopituitarism (Correct Answer)
C. Nephrotic syndrome
D. Pregnancy

Explanation: ### Explanation **Correct Option: B. Hypopituitarism** In **Hypopituitarism**, there is a failure of the anterior pituitary gland to secrete **Thyroid Stimulating Hormone (TSH)** [2]. This leads to **Secondary Hypothyroidism**, where the lack of TSH results in decreased stimulation of the thyroid gland, subsequently causing a drop in **Total T4 and Total T3** [2]. This pattern—low TSH accompanied by low thyroid hormones—is the hallmark of central (pituitary or hypothalamic) endocrine failure. **Analysis of Incorrect Options:** * **A. Primary Hypothyroidism:** The defect is in the thyroid gland itself. While T3 and T4 are low, the pituitary responds to the lack of negative feedback by significantly **increasing TSH** levels [1]. * **C. Nephrotic Syndrome:** This condition involves massive urinary loss of **Thyroid Binding Globulin (TBG)**. While **Total T4 and T3** decrease (due to loss of carrier proteins), the **Free T4/T3 and TSH remain normal** (euthyroid state). * **D. Pregnancy:** High estrogen levels stimulate the liver to increase TBG production. This leads to an **increase in Total T4 and T3**, while Free T4 and TSH typically remain within normal physiological limits. **High-Yield NEET-PG Pearls:** * **Sick Euthyroid Syndrome:** Can also present with low T3, low T4, and low/normal TSH during severe systemic illness. It is distinguished from hypopituitarism by clinical context and elevated **Reverse T3 (rT3)**. * **TSH is the most sensitive screening test** for primary thyroid disorders, but it is **unreliable** in suspected pituitary disease; in such cases, Free T4 must be measured. * **Rule of Thumb:** If TSH and T4 move in the **opposite** direction, the problem is **Primary** [1]. If they move in the **same** direction, the problem is **Central/Secondary** [2].

Question 43: Which of the following conditions can present with eye signs?

A. Primary toxic goitre. (Correct Answer)
B. Secondary toxic goitre.
C. Thyrotoxicosis.
D. All of the above.

Explanation: **Explanation:** The presence of infiltrative ophthalmopathy (true eye signs) is a hallmark feature of **Graves' Disease**, also known as **Primary Toxic Goitre** [1]. **1. Why Option A is Correct:** Primary toxic goitre (Graves' Disease) is an autoimmune disorder caused by TSH-receptor antibodies (TRAb) [1]. These antibodies react with receptors not only in the thyroid but also in the retro-orbital tissues. This leads to inflammation, accumulation of glycosaminoglycans, and adipogenesis, resulting in **Exophthalmos** (proptosis), chemosis, and ophthalmoplegia [1]. These are "true" infiltrative eye signs. **2. Why Options B and C are Incorrect:** * **Secondary Toxic Goitre (Toxic Multinodular Goitre):** This condition occurs when a pre-existing simple goitre becomes autonomous. It is a purely hypermetabolic state without an autoimmune component; therefore, it lacks infiltrative ophthalmopathy. * **Thyrotoxicosis:** This is a general clinical syndrome of excess thyroid hormone. While it can cause "lid lag" and "lid retraction" (due to sympathetic overactivity affecting the Levator palpebrae superioris), these are **non-infiltrative** signs. True proptosis and extraocular muscle involvement are exclusive to the autoimmune pathology of Graves', not thyrotoxicosis itself [1]. **Clinical Pearls for NEET-PG:** * **Dalrymple’s Sign:** Widened palpebral fissures (staring look). * **Von Graefe’s Sign:** Lid lag on downward gaze. * **Stellwag’s Sign:** Infrequent or incomplete blinking. * **Smoking** is the most significant modifiable risk factor for the progression of Graves' ophthalmopathy. * **Treatment:** Severe cases are managed with IV Methylprednisolone or orbital decompression surgery [1].

Question 44: Characteristic feature of the urine in diabetes insipidus include the following EXCEPT?

A. No proteins
B. No sugar
C. Specific gravity > 1.020 (Correct Answer)
D. No casts

Explanation: Diabetes Insipidus (DI) is a clinical syndrome characterized by the excretion of large volumes of dilute urine (polyuria) due to either a deficiency of Antidiuretic Hormone (ADH) (Central DI) or resistance to its action (Nephrogenic DI) [2]. **Why Option C is the correct answer:** The hallmark of DI is the inability of the kidneys to concentrate urine [1]. In a normal physiological state, ADH acts on the collecting ducts to reabsorb water [2]. In DI, the lack of ADH effect leads to the excretion of highly dilute urine. Consequently, the **urinary specific gravity is characteristically low**, typically **< 1.005**, and urine osmolality is usually < 200 mOsm/kg. A specific gravity of > 1.020 indicates concentrated urine, which is physiologically inconsistent with a diagnosis of DI. **Why other options are incorrect:** * **Options A, B, and D:** Diabetes Insipidus is a disorder of water homeostasis, not a glomerular or tubular inflammatory disease. Therefore, the urine is "bland." It typically contains **no protein, no sugar (glucose), and no casts**. The presence of sugar would suggest Diabetes Mellitus, while proteins or casts would suggest underlying renal parenchymal disease. **High-Yield Clinical Pearls for NEET-PG:** * **Water Deprivation Test:** The gold standard for diagnosis [1]. In DI, urine remains dilute despite dehydration. * **Desmopressin (DDAVP) Trial:** Used to differentiate Central DI (urine osmolality increases by >50%) from Nephrogenic DI (no significant increase) [1]. * **Treatment:** Central DI is treated with **Desmopressin** [1]; Nephrogenic DI is treated with **Thiazide diuretics**, Amiloride, or NSAIDs (Indomethacin). * **Triphasic Response:** May occur after pituitary surgery (Transient DI → SIADH → Permanent DI).

Question 45: Which of the following conditions is associated with autonomic disturbances?

A. Hyperthyroidism
B. Diabetes mellitus (Correct Answer)
C. Hyperaldosteronism
D. Hyperparathyroidism

Explanation: **Explanation:** **Diabetes Mellitus (DM)** is the most common cause of **Diabetic Autonomic Neuropathy (DAN)**. [1] The underlying pathophysiology involves chronic hyperglycemia leading to the accumulation of sorbitol (polyol pathway), increased oxidative stress, and advanced glycation end-products (AGEs). These processes cause microvascular damage to the *vasa nervorum*, resulting in ischemia and axonal degeneration of the autonomic nerve fibers. [1] * **Autonomic Disturbances in DM:** These manifest across multiple systems: [2] * **Cardiovascular:** Resting tachycardia, orthostatic hypotension, and painless myocardial infarction. [2] * **Gastrointestinal:** Gastroparesis (delayed emptying) and diabetic diarrhea. [2] * **Genitourinary:** Neurogenic bladder and erectile dysfunction. [2] * **Sudomotor:** Anhidrosis of the feet with compensatory gustatory sweating. [2] **Why other options are incorrect:** * **Hyperthyroidism:** While it presents with symptoms mimicking sympathetic overactivity (tachycardia, tremors), these are due to increased sensitivity/density of beta-adrenergic receptors, not structural autonomic nerve damage. * **Hyperaldosteronism:** Primarily presents with hypertension and hypokalemia (muscle weakness/polyuria); it does not typically involve the autonomic nervous system. * **Hyperparathyroidism:** Characterized by the "stones, bones, abdominal groans, and psychic overtones" (hypercalcemia symptoms), but lacks primary autonomic dysfunction. **High-Yield NEET-PG Pearls:** * **Cardiac Autonomic Neuropathy (CAN):** The earliest sign is often a **loss of Heart Rate Variability (HRV)** during deep breathing. [2] * **Hypoglycemia Unawareness:** A critical autonomic complication where the warning sympathetic surge (sweating, palpitations) is lost. [3] * **Treatment:** Tight glycemic control is the only way to slow progression; symptomatic relief includes Metoclopramide for gastroparesis and Fludrocortisone for orthostatic hypotension. [2]

Question 46: Osteoporosis is commonly associated with which of the following conditions?

A. Turner's syndrome
B. Klinefelter's syndrome
C. Cushing's syndrome due to steroids
D. All of the above (Correct Answer)

Explanation: Osteoporosis is a systemic skeletal disorder characterized by low bone mass and micro-architectural deterioration [1]. It can be primary or secondary to various endocrine and systemic conditions. **1. Turner’s Syndrome (45, XO):** Patients have primary hypogonadism (streak ovaries), leading to **estrogen deficiency**. Estrogen is crucial for inhibiting osteoclast activity; its absence results in increased bone resorption and failure to achieve peak bone mass [1]. **2. Klinefelter’s Syndrome (47, XXY):** This is a common cause of primary hypogonadism in males. **Testosterone deficiency** leads to decreased bone turnover and uncoupling of bone resorption from bone formation, as androgens are essential for maintaining bone mineral density (BMD) in men [1]. **3. Cushing’s Syndrome (Exogenous Steroids):** Glucocorticoid-induced osteoporosis is the most common cause of secondary osteoporosis [1]. Steroids decrease bone formation (inhibiting osteoblasts), increase bone resorption (stimulating osteoclasts), and decrease intestinal calcium absorption while increasing renal calcium excretion [1]. **Clinical Pearls for NEET-PG:** * **Most common cause of secondary osteoporosis:** Glucocorticoid use [1]. * **Gold Standard Investigation:** DEXA Scan (Dual-Energy X-ray Absorptiometry). * **T-score:** $\leq -2.5$ SD defines Osteoporosis; $-1$ to $-2.4$ SD defines Osteopenia. * **First-line treatment:** Bisphosphonates (e.g., Alendronate), which act by inhibiting osteoclasts. * **Teriparatide:** A recombinant PTH analogue; it is the only anabolic agent that stimulates new bone formation.

Question 47: A lady presents with central obesity and abdominal skin showing purple striae. What is the most likely diagnosis?

A. Conn's syndrome
B. Cushing's syndrome (Correct Answer)
C. Addison's disease
D. Hypothyroidism

Explanation: ### Explanation The clinical presentation of **central obesity** and **purple striae** is a classic hallmark of **Cushing’s syndrome**, which results from chronic exposure to excess glucocorticoids (hypercortisolism). [1] **Why Cushing’s Syndrome is Correct:** Excess cortisol leads to a redistribution of fat to the trunk and face (moon facies, buffalo hump), while causing protein catabolism. The **purple striae** (typically >1 cm wide) occur because cortisol inhibits fibroblasts and causes loss of collagen, making the skin thin and translucent, allowing the underlying vascularity to show through. [1] **Analysis of Incorrect Options:** * **Conn’s Syndrome (Primary Hyperaldosteronism):** Characterized by the triad of hypertension, hypokalemia, and metabolic alkalosis. It does not cause obesity or skin changes. * **Addison’s Disease (Primary Adrenal Insufficiency):** This is the opposite of Cushing’s. It presents with weight loss, hypotension, and hyperpigmentation (due to high ACTH). * **Hypothyroidism:** While it causes weight gain, it is usually generalized (not central) and associated with dry skin, bradycardia, and non-pitting edema (myxedema), rather than purple striae. **High-Yield Clinical Pearls for NEET-PG:** 1. **Screening Tests:** The best initial tests are the 24-hour urinary free cortisol, late-night salivary cortisol, or the Low-Dose Dexamethasone Suppression Test (LDDST). [2] 2. **Proximal Myopathy:** Patients often have difficulty rising from a chair due to muscle wasting. [1] 3. **Striae Distinction:** Striae in Cushing’s are typically **wide (>1 cm) and violaceous**, distinguishing them from the pale/pink striae seen in normal pregnancy or rapid weight gain. 4. **Most Common Cause:** Overall, the most common cause is iatrogenic (exogenous steroids). The most common endogenous cause is Cushing’s Disease (ACTH-secreting pituitary adenoma). [1]

Question 48: Weight gain is seen in all the following conditions except?

A. Phaeochromocytoma (Correct Answer)
B. Insulinoma
C. Myxoedema
D. Cushing's disease

Explanation: **Explanation:** The correct answer is **Phaeochromocytoma**. This condition is characterized by a catecholamine-secreting tumor (usually of the adrenal medulla). Catecholamines (epinephrine and norepinephrine) increase the basal metabolic rate (BMR) and promote glycogenolysis and lipolysis. Consequently, patients typically present with **weight loss** despite a normal or increased appetite, alongside the classic triad of episodic headaches, sweating, and palpitations [2]. **Analysis of Incorrect Options:** * **Insulinoma:** These tumors secrete excessive insulin, leading to recurrent hypoglycemia. Patients often experience "hyperphagia" (increased hunger) and consume high-calorie foods to relieve symptoms, resulting in significant **weight gain**. * **Myxoedema (Hypothyroidism):** A deficiency in thyroid hormones leads to a decreased BMR and the accumulation of glycosaminoglycans (myxedema) in the interstitial space, which causes water retention and **weight gain** [2]. * **Cushing’s Disease:** Excess cortisol promotes adipogenesis and redistribution of fat, leading to "central obesity," moon facies, and a buffalo hump [1]. Cortisol also stimulates appetite, further contributing to **weight gain** [2]. **Clinical Pearls for NEET-PG:** * **Phaeochromocytoma Rule of 10s:** 10% are bilateral, 10% are malignant, 10% are extra-adrenal (Paragangliomas), and 10% are familial. * **MEN 2A/2B:** Always screen for Phaeochromocytoma before performing surgery for Medullary Thyroid Carcinoma to prevent a hypertensive crisis. * **Diagnosis:** The most sensitive screening test is plasma free metanephrines; the most specific is 24-hour urinary catecholamines/metanephrines.

Question 49: Hyperprolactinoma causes which of the following menstrual abnormalities?

A. Intermenstrual bleeding
B. Prolonged menstruation
C. Oligomenorrhea (Correct Answer)
D. Polymenorrhea

Explanation: ### Explanation **Underlying Medical Concept** Hyperprolactinemia (whether from a prolactinoma or other causes) leads to menstrual abnormalities primarily through the **suppression of Gonadotropin-Releasing Hormone (GnRH)** [1]. High levels of prolactin inhibit the pulsatile secretion of GnRH from the hypothalamus [2]. This results in decreased secretion of Luteinizing Hormone (LH) and Follicle-Stimulating Hormone (FSH) from the anterior pituitary. The resulting "hypogonadotropic hypogonadism" leads to impaired follicular development, anovulation, and low estrogen levels, clinically manifesting as **Oligomenorrhea** (infrequent cycles) or **Amenorrhea** (absence of cycles) [2]. **Analysis of Options** * **C. Oligomenorrhea (Correct):** This is the classic presentation. The suppression of the HPO (Hypothalamic-Pituitary-Ovarian) axis prevents regular ovulation, leading to cycles longer than 35 days. * **A. Intermenstrual bleeding:** This is typically associated with local pathology (polyps, fibroids) or hormonal fluctuations (ovulatory spotting), not the systemic suppression seen in hyperprolactinemia. * **B. Prolonged menstruation (Menorrhagia):** Hyperprolactinemia causes a thin, atrophic endometrium due to low estrogen; it does not typically cause heavy or prolonged bleeding. * **D. Polymenorrhea:** This refers to frequent cycles (<21 days). Prolactin excess slows down the cycle or stops it entirely; it does not shorten the interval. **High-Yield Clinical Pearls for NEET-PG** * **Clinical Triad:** In females, look for the triad of **Amenorrhea, Galactorrhea, and Infertility** [2]. * **Drug-Induced:** Always rule out drugs (Antipsychotics, Metocolopramide, Methyldopa) which cause hyperprolactinemia by blocking Dopamine (the Prolactin Inhibiting Factor) [1]. * **Hook Effect:** In very large macroadenomas, extremely high prolactin levels may read as falsely low/normal unless the serum is diluted. * **Treatment:** Medical management with **Dopamine agonists (Cabergoline > Bromocriptine)** is the first-line treatment, even for large macroprolactinomas [3]. Surgery is reserved for refractory cases.

Question 50: Whipple's triad is seen in which of the following conditions?

A. Islet cell tumor (Correct Answer)
B. Carcinoma head of pancreas
C. Argentaffinoma
D. Cholangiocarcinoma

Explanation: **Explanation:** Whipple’s triad is the classic clinical diagnostic criteria for **Insulinoma**, which is a functional **Islet cell tumor** of the pancreas [1]. It consists of three components: 1. Symptoms of hypoglycemia (e.g., sweating, palpitations, confusion) triggered by fasting or exertion. 2. Documentation of low blood glucose (<50 mg/dL) at the time of symptoms [3]. 3. Immediate relief of symptoms following the administration of glucose. **Why the other options are incorrect:** * **Carcinoma head of pancreas:** Typically presents with painless obstructive jaundice, weight loss, and a palpable gallbladder (Courvoisier’s law), not hypoglycemia. * **Argentaffinoma (Carcinoid Tumor):** These neuroendocrine tumors secrete serotonin, leading to Carcinoid syndrome (flushing, diarrhea, and wheezing) [2]. They do not typically cause hypoglycemia. * **Cholangiocarcinoma:** This is a malignancy of the bile ducts presenting with biliary obstruction and jaundice; it has no association with insulin secretion or Whipple’s triad. **NEET-PG High-Yield Pearls:** * **Insulinoma** is the most common endogenous cause of hyperinsulinemic hypoglycemia in adults. * **Rule of 10s:** 10% are malignant, 10% are multiple, and 10% are associated with **MEN-1 syndrome**. * **Diagnosis:** The gold standard is the **72-hour supervised fast**. * **Lab findings:** High Insulin, High C-peptide, and High Pro-insulin levels (unlike exogenous insulin intake where C-peptide is suppressed) [1]. * **Localization:** Endoscopic Ultrasound (EUS) is highly sensitive for detecting these small tumors.

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

Practice Questions

Neuroendocrine Tumors

Practice Questions

Endocrine Emergencies

Practice Questions

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