Endocrinology — MCQs

Endocrinology Indian Medical PG Practice Questions and MCQs

Question 821: Alkaline phosphatase is found in all organs, except:

A. Bone
B. Heart (Correct Answer)
C. Placenta
D. Lungs

Explanation: **Explanation:** Alkaline Phosphatase (ALP) is a group of isoenzymes that catalyze the hydrolysis of organic phosphate esters at an alkaline pH. It is primarily associated with tissues involved in high metabolic activity or transport across membranes. **Why Heart is the Correct Answer:** The heart does not contain significant amounts of Alkaline Phosphatase. Cardiac muscle damage is instead characterized by the release of specific markers like **Troponins (I and T)** and **CK-MB**. ALP is notably absent from cardiac tissue, making it a useful negative marker when differentiating causes of enzyme elevations. **Analysis of Other Options:** * **Bone (Option A):** Bone contains the **B-ALP isoenzyme**, produced by osteoblasts. It is a marker of bone formation and is elevated in Rickets, Osteomalacia, Paget’s disease, and bone metastasis [2]. * **Placenta (Option C):** The **Regan isoenzyme** (heat-stable ALP) is produced by the placenta. It rises during the third trimester of pregnancy. * **Lungs (Option D):** ALP is present in the lungs, specifically within the vascular endothelium and alveolar type II cells [1]. While not a primary diagnostic source, it is histologically present. **High-Yield Clinical Pearls for NEET-PG:** 1. **Major Sources:** The primary sources of serum ALP are **Liver** (canalicular membrane) and **Bone** (osteoblasts) [1]. 2. **Isoenzymes & Heat Stability:** Remember the mnemonic *"Lungs/Liver are Least stable, Bone is Bad, Placenta is Persistent (Stable)"* regarding heat stability (at 56°C). 3. **Biliary Obstruction:** ALP is the most sensitive marker for obstructive jaundice (cholestasis). 4. **Zinc Dependency:** ALP is a zinc-metalloenzyme; deficiency in Zinc can lead to abnormally low ALP levels.

Question 822: Regarding non-ketotic hyperglycemia hyperosmolar state (HHS), consider the following statements:

A. It is common in the second and third decades of life.
B. It is typically seen in Type 2 diabetes mellitus. (Correct Answer)
C. Blood sugar is usually above 500 mg/dl.
D. It is seen in DKA.

Explanation: Hyperosmolar Hyperglycemic State (HHS) is a life-threatening metabolic complication characterized by extreme hyperglycemia, hyperosmolality, and profound dehydration without significant ketoacidosis. **1. Why Option B is Correct:** HHS is **typically seen in Type 2 Diabetes Mellitus (T2DM)**, particularly in elderly patients. The underlying pathophysiology involves a relative insulin deficiency [1]. Unlike Type 1 DM, patients with T2DM have enough endogenous insulin to inhibit lipolysis and prevent ketogenesis, but not enough to prevent severe hyperglycemia. **2. Analysis of Incorrect Options:** * **Option A:** HHS is most common in the **elderly (6th–7th decades)**, often triggered by infections (like pneumonia or UTI) or cardiovascular events. In contrast, DKA is more common in the 2nd and 3rd decades. * **Option C:** While blood sugar is high, the diagnostic threshold for HHS is typically **>600 mg/dL**. Values often exceed 1000 mg/dL, leading to the characteristic hyperosmolality. * **Option D:** HHS and DKA are distinct ends of the hyperglycemic emergency spectrum. While "overlap syndromes" exist, HHS is defined by the **absence** of significant ketoacidosis (pH >7.30, Bicarbonate >18 mEq/L) [1]. **3. High-Yield Clinical Pearls for NEET-PG:** * **Diagnostic Triad for HHS:** Plasma glucose >600 mg/dL, Serum osmolality >320 mOsm/kg, and absence of significant ketoacidosis. * **Fluid Deficit:** HHS involves a much higher free water deficit (8–12 Liters) compared to DKA (3–6 Liters). * **Mental Status:** Altered sensorium or coma is directly proportional to the serum osmolality [1]. * **Management Priority:** Aggressive fluid resuscitation (Normal Saline) is the most critical initial step [1].

Question 823: Which of the following biochemical features is true in osteomalacia?

A. Elevated serum calcium level
B. Elevated serum phosphate level
C. Elevated serum alkaline phosphatase (Correct Answer)
D. Elevated 25-hydroxyvitamin D3

Explanation: Explanation: Osteomalacia is a metabolic bone disease characterized by **defective mineralization** of the organic bone matrix (osteoid), most commonly due to Vitamin D deficiency [1]. **Why Option C is Correct:** In osteomalacia, the lack of mineralization leads to structural weakness of the bone [1]. This triggers **osteoblastic activity** as a compensatory mechanism to lay down more osteoid. Alkaline Phosphatase (ALP) is a byproduct of osteoblast activity; therefore, serum ALP levels are characteristically **elevated** in these patients [1]. **Analysis of Incorrect Options:** * **A & B (Serum Calcium and Phosphate):** Vitamin D is essential for the intestinal absorption of calcium and phosphate. In osteomalacia, levels of calcium and phosphate are typically **low or low-normal** [1]. If calcium levels drop, secondary hyperparathyroidism occurs, which further lowers serum phosphate by increasing renal excretion [1]. * **D (25-hydroxyvitamin D3):** Since the most common cause of osteomalacia is Vitamin D deficiency (due to poor diet, lack of sun exposure, or malabsorption), the serum levels of 25(OH)D3 are typically **decreased**, not elevated [1]. **NEET-PG High-Yield Pearls:** * **Radiological Hallmark:** **Looser’s zones** (pseudofractures) are pathognomonic—transverse radiolucent lines often seen in the femoral neck, ribs, or scapula [1]. * **Biochemical Profile Summary:** ↓/N Calcium, ↓/N Phosphate, **↑ ALP**, ↑ PTH (Secondary Hyperparathyroidism), and ↓ 24-hour urinary calcium. * **Clinical Presentation:** Diffuse bone pain, muscle weakness (proximal myopathy), and a "waddling gait" [1]. * **Rickets vs. Osteomalacia:** Rickets occurs in children (before epiphyseal closure); Osteomalacia occurs in adults (after epiphyseal closure) [1].

Question 824: A 50-year-old man with a history of recurrent renal stones and peptic ulcer disease presents with difficulty in peripheral vision. He has been taking a proton pump inhibitor (PPI) as prescribed without relief. Which of the following laboratory workups is required in the evaluation of this patient?

A. Gastrin
B. Parathyroid hormone (PTH)
C. Prolactin
D. All of the above (Correct Answer)

Explanation: ### Explanation This clinical vignette describes a classic presentation of **Multiple Endocrine Neoplasia Type 1 (MEN1)**, also known as Wermer Syndrome. MEN1 is characterized by the "3 Ps": **P**arathyroid, **P**ancreas, and **P**ituitary tumors. **Why "All of the Above" is correct:** The patient exhibits symptoms pointing toward all three components of MEN1: 1. **Recurrent Renal Stones:** Suggests primary hyperparathyroidism (the most common feature of MEN1), necessitating a **Parathyroid hormone (PTH)** and Calcium workup [1], [3]. 2. **Refractory Peptic Ulcer Disease:** Peptic ulcers unresponsive to PPIs strongly suggest a Gastrinoma (Zollinger-Ellison Syndrome), a common pancreatic neuroendocrine tumor in MEN1 [1], [4]. This requires checking serum **Gastrin** levels. 3. **Visual Field Defects:** "Difficulty in peripheral vision" (bitemporal hemianopia) indicates optic chiasm compression by a pituitary tumor (most commonly a **Prolactinoma**). Measuring **Prolactin** is essential to evaluate pituitary involvement [2]. **Analysis of Options:** * **A (Gastrin):** Necessary to diagnose Gastrinoma in the setting of refractory ulcers. * **B (PTH):** Necessary to diagnose hyperparathyroidism causing renal calculi [3]. * **C (Prolactin):** Necessary to evaluate the pituitary mass causing visual symptoms. Since the patient shows clinical evidence for all three, a comprehensive workup is mandatory. **High-Yield Clinical Pearls for NEET-PG:** * **Inheritance:** MEN1 is Autosomal Dominant; the gene is located on **Chromosome 11q13** (codes for the protein Menin). * **Most Common Initial Presentation:** Hyperparathyroidism (seen in >95% of patients by age 30) [3]. * **Most Common Pituitary Tumor:** Prolactinoma. * **Most Common Pancreatic Tumor:** Gastrinoma (though Insulinomas are also frequent). * **Rule of 3Ps:** Parathyroid (90%), Pancreas (60-70%), Pituitary (30-50%).

Question 825: Hypoglycemic unawareness that occurs in diabetic patients when transferred from oral hypoglycemics to insulin, is due to what?

A. Autonomic neuropathy (Correct Answer)
B. Insulin resistance
C. Lipodystrophy
D. Somogi phenomenon

Explanation: ### Explanation **Correct Option: A. Autonomic Neuropathy** Hypoglycemic unawareness is a clinical syndrome where the early warning symptoms of hypoglycemia (adrenergic/neurogenic symptoms) are absent. 1. **Mechanism:** Normally, a drop in blood glucose triggers the sympathetic nervous system, causing the release of epinephrine. This results in **adrenergic symptoms** like tremors, palpitations, sweating, and anxiety, which alert the patient to ingest glucose [1]. 2. **The Role of Neuropathy:** In long-standing diabetes, **Autonomic Neuropathy** impairs the sympathoadrenal response [3]. When these patients are switched to insulin (which has a more potent glucose-lowering effect than oral drugs), they may experience profound hypoglycemia without the "warning" adrenergic surge. They bypass the neurogenic stage and progress directly to **neuroglycopenia** (confusion, seizures, or coma) [1]. --- ### Why Other Options are Incorrect: * **B. Insulin Resistance:** This refers to a decreased biological response to insulin (common in Type 2 DM). It leads to hyperglycemia, not a lack of awareness during hypoglycemia. * **C. Lipodystrophy:** This is a local complication at the insulin injection site (atrophy or hypertrophy). While it can cause erratic insulin absorption, it does not physiologically mask the symptoms of hypoglycemia. * **D. Somogyi Phenomenon:** This is "rebound hyperglycemia" in the morning caused by a counter-regulatory hormone surge following an undetected nocturnal hypoglycemic episode. While related to hypoglycemia, it describes the *result* (hyperglycemia), not the *lack of awareness* itself. --- ### NEET-PG High-Yield Pearls: * **First symptom masked by Beta-blockers:** Most adrenergic symptoms of hypoglycemia (except sweating, which is cholinergic) are masked by non-selective beta-blockers. * **Hypoglycemia-Associated Autonomic Failure (HAAF):** Repeated episodes of hypoglycemia lower the glycemic threshold for the next counter-regulatory response, creating a vicious cycle of unawareness [2]. * **Strict Glycemic Control:** Paradoxically, very tight HbA1c control increases the risk of hypoglycemic unawareness [2]. * **Treatment:** Awareness can often be restored by scrupulously avoiding hypoglycemia for 2–3 weeks ("Hypoglycemia holiday").

Question 826: A patient presents with wide eyes, nervousness, elevated systolic blood pressure, and weight loss. What is the most probable diagnosis?

A. Hypothyroidism
B. Hyperthyroidism (Correct Answer)
C. Hyperparathyroidism
D. Hypoparathyroidism

Explanation: ### Explanation **Correct Option: B. Hyperthyroidism** The clinical presentation described is a classic manifestation of **Hyperthyroidism**, a state of thyroid hormone excess that leads to a hypermetabolic condition [1]. * **Wide eyes (Exophthalmos/Lid lag):** Thyroid hormones increase sympathetic activity. In Graves' disease, autoimmune-mediated inflammation of retro-orbital tissues causes proptosis (wide eyes) [1]. * **Nervousness:** Excess T3/T4 increases the sensitivity of beta-adrenergic receptors, leading to irritability, tremors, and anxiety [1]. * **Elevated Systolic BP:** Thyroid hormones increase cardiac output and stroke volume. While systolic BP rises, diastolic BP often drops due to decreased peripheral vascular resistance, resulting in a **wide pulse pressure** [1]. * **Weight Loss:** Despite an increased appetite, the basal metabolic rate (BMR) is significantly elevated, leading to weight loss [1]. --- ### Why the other options are incorrect: * **A. Hypothyroidism:** This presents with the opposite clinical picture: weight gain, bradycardia, lethargy, cold intolerance, and "puffy" eyes (myxedema) rather than wide, staring eyes. * **C. Hyperparathyroidism:** Primarily affects calcium metabolism. Symptoms are summarized as "stones, bones, abdominal groans, and psychic overtones" (renal stones, bone pain, constipation, and depression), not hypermetabolic symptoms. * **D. Hypoparathyroidism:** Characterized by hypocalcemia, leading to neuromuscular irritability (tetany, Chvostek's sign, Trousseau's sign) and seizures, rather than weight loss or hypertension. --- ### NEET-PG High-Yield Pearls: 1. **Most common cause:** Graves' Disease (associated with HLA-DR3 and B8) [1]. 2. **Cardiac Finding:** Atrial Fibrillation is a common complication of hyperthyroidism in elderly patients [2], [3]. 3. **Specific Sign:** **Dalrymple Sign** refers to the widened palpebral fissures (staring look) seen in thyrotoxicosis. 4. **Diagnosis:** Low TSH with high Free T4 is the primary biochemical screen [1].

Question 827: All of the following are known causes of osteoporosis except:

A. Fluorosis (Correct Answer)
B. Hypogonadism
C. Hyperthyroidism
D. Hyperparathyroidism

Explanation: **Explanation:** **Osteoporosis** is characterized by a reduction in bone mass and disruption of skeletal microarchitecture, leading to increased fragility [3]. **Why Fluorosis is the Correct Answer:** Fluorosis (specifically skeletal fluorosis) is characterized by **osteosclerosis**, which is an abnormal *increase* in bone density. Chronic ingestion of high levels of fluoride stimulates osteoblasts, leading to the formation of dense but brittle bone. Unlike osteoporosis, which shows decreased radiodensity, fluorosis presents with increased radiopacity (whiter bones) on X-rays, particularly in the axial skeleton. **Why the other options are incorrect:** * **Hypogonadism:** Estrogen and testosterone are crucial for inhibiting osteoclast activity. Deficiency (e.g., menopause or Klinefelter syndrome) leads to accelerated bone resorption, making it a leading cause of osteoporosis [1]. * **Hyperthyroidism:** Excess thyroid hormone (T3/T4) shortens the bone remodeling cycle and favors bone resorption over formation, leading to a high-turnover state and loss of bone mineral density (BMD). * **Hyperparathyroidism:** Parathyroid hormone (PTH) stimulates osteoclasts via the RANKL pathway. Chronic elevation (Primary Hyperparathyroidism) results in significant cortical bone loss [2]. **High-Yield Clinical Pearls for NEET-PG:** * **Drug-induced Osteoporosis:** Glucocorticoids (most common) [1], Heparin, Phenytoin, and PPIs. * **Skeletal Fluorosis Hallmark:** "Chalky white" appearance of bones and calcification of the interosseous membrane (especially in the forearm). * **Screening:** DEXA scan is the gold standard; Osteoporosis is defined as a **T-score ≤ -2.5**. * **Secondary Causes:** Always rule out Vitamin D deficiency, Multiple Myeloma, and Malabsorption syndromes in young patients with low BMD.

Question 828: A 11-year-old boy presents with complaints of not developing secondary sexual characteristics. On examination, the child is found to have tall stature, no secondary sexual characteristics, small and firm testes, and gynecomastia. What is the most probable clinical diagnosis?

A. Klinefelter's syndrome (Correct Answer)
B. Edwards syndrome
C. Patau syndrome
D. Turner syndrome

Explanation: ### Explanation The clinical presentation of an adolescent male with tall stature, delayed puberty, and specific physical findings is classic for **Klinefelter’s Syndrome (47, XXY)** [1]. **1. Why Klinefelter’s Syndrome is Correct:** Klinefelter’s syndrome is the most common cause of **primary hypogonadism** in males. The presence of an extra X chromosome leads to dysgenesis of seminiferous tubules and hyperplasia of Leydig cells [1]. * **Small, firm testes:** This is the hallmark clinical sign (usually <2 cm or <4 mL volume) [1]. * **Tall stature:** Due to the extra copy of the *SHOX* gene on the X chromosome and delayed epiphyseal closure (low testosterone) [1]. * **Gynecomastia:** Results from an increased estrogen-to-androgen ratio. * **Infertility:** Azoospermia is almost universal due to tubular fibrosis [1]. **2. Why Other Options are Incorrect:** * **Edwards Syndrome (Trisomy 18):** Characterized by severe intellectual disability, micrognathia, low-set ears, and "rocker-bottom feet." Most patients do not survive beyond infancy. * **Patau Syndrome (Trisomy 13):** Presents with midline defects like cleft lip/palate, holoprosencephaly, polydactyly, and microphthalmia. It is usually fatal in the first year of life. * **Turner Syndrome (45, XO):** This occurs in **females** [2]. It presents with short stature (not tall), streak ovaries, webbed neck, and primary amenorrhea [2]. **3. NEET-PG High-Yield Pearls:** * **Lab Profile:** Low Testosterone, **High LH**, and **High FSH** (Hypergonadotropic hypogonadism) [1]. Inhibin B is low. * **Barr Body:** Positive on buccal smear (unlike normal males). * **Increased Risks:** Breast cancer (20x higher than normal males), extragonadal germ cell tumors, and autoimmune diseases (SLE) [3]. * **Cognitive Profile:** Often associated with mild language delays or learning disabilities, though IQ is usually within the normal range [1].

Question 829: Flatbush diabetes is associated with which of the following conditions?

A. Type 1 Diabetes Mellitus (Correct Answer)
B. Type 2 Diabetes Mellitus
C. Diabetes Insipidus
D. Bronze Diabetes

Explanation: **Explanation:** **Flatbush Diabetes**, also known as **Ketosis-Prone Type 2 Diabetes (KPD)** or "Idiopathic Type 1B Diabetes," is a unique clinical variant where patients present with acute ketoacidosis (typical of Type 1) but subsequently transition into a state of insulin independence (typical of Type 2). **Why Option A is Correct:** According to the **WHO classification**, Flatbush Diabetes is categorized under **Type 1 Diabetes Mellitus (specifically Type 1B - Idiopathic)** [1]. These patients lack the autoantibodies (GAD65, IA-2) found in Type 1A but suffer from episodic β-cell dysfunction. During the initial presentation, they exhibit severe insulin deficiency and ketosis; however, after the initial "glucotoxicity" is resolved with insulin therapy, the β-cells recover, allowing patients to maintain glycemic control with oral hypoglycemics or diet alone for months or years. **Why Incorrect Options are Wrong:** * **Option B (Type 2 DM):** While the long-term clinical course resembles Type 2 DM, the official classification and the acute presentation of ketoacidosis distinguish it. In exams, it is classified under the Type 1 umbrella (1B) [1]. * **Option C (Diabetes Insipidus):** This is a disorder of water metabolism caused by ADH deficiency or resistance, unrelated to glucose metabolism or ketosis. * **Option D (Bronze Diabetes):** This refers to **Hereditary Hemochromatosis**, where iron overload damages the pancreas. It is a form of secondary diabetes, not Flatbush diabetes. **High-Yield Clinical Pearls for NEET-PG:** * **Demographics:** Most commonly seen in African-American and Afro-Caribbean populations (named after the Flatbush neighborhood in Brooklyn). * **Pathophysiology:** Characterized by "Stunned β-cells" that recover after the initial crisis. * **Classification:** It follows the **Aβ classification system** (based on the presence/absence of Autoantibodies and β-cell function). Flatbush is typically **A–β+** (Antibody negative, β-cell function present after recovery).

Question 830: All of the following are associated with pheochromocytoma except:

A. Ventricular arrhythmias
B. Interstitial fibrosis
C. Hypotension (Correct Answer)
D. Ectopic ACTH production

Explanation: **Explanation:** Pheochromocytoma is a catecholamine-secreting tumor arising from the chromaffin cells of the adrenal medulla. The clinical manifestations are primarily driven by the excessive release of epinephrine and norepinephrine [3]. **Why Hypotension is the Correct Answer:** The hallmark of pheochromocytoma is **Hypertension** (persistent in 60% and paroxysmal in 40% of cases). Hypotension is highly atypical and usually only occurs in specific scenarios, such as sudden catecholamine withdrawal, severe volume depletion, or a switch to a purely epinephrine-secreting tumor (causing beta-2 mediated vasodilation). Therefore, it is not a standard association. **Analysis of Other Options:** * **Ventricular Arrhythmias:** Excess catecholamines overstimulate $\beta_1$ receptors in the heart, leading to palpitations, tachycardia, and potentially fatal ventricular arrhythmias [3]. * **Interstitial Fibrosis:** Chronic exposure to high catecholamine levels causes "Catecholamine Cardiomyopathy." This leads to focal myocardial necrosis, inflammatory cell infiltration, and eventually **interstitial fibrosis**, which can progress to heart failure. * **Ectopic ACTH Production:** Pheochromocytoma is a known cause of ectopic ACTH syndrome [2], [4]. These tumors can co-secrete peptides like ACTH or CRH, leading to Cushing’s syndrome features alongside hypertensive crises. **NEET-PG High-Yield Pearls:** 1. **Rule of 10s:** 10% bilateral, 10% malignant, 10% extra-adrenal (Paraganglioma), 10% pediatric, and 10% familial [1]. 2. **Genetic Associations:** MEN 2A, MEN 2B, von Hippel-Lindau (VHL) syndrome, and NF-1 [1]. 3. **Diagnosis:** Best initial screening test is **24-hour urinary fractionated metanephrines** or plasma free metanephrines. 4. **Management:** Always give **Alpha-blockers first** (e.g., Phenoxybenzamine) followed by Beta-blockers to avoid an unopposed alpha-mediated hypertensive crisis [1].

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

Want unlimited practice?

Get full access to all questions, explanations, and performance tracking.

Start For Free