Endocrinology Practice Questions

Q: Rapid infusion of insulin causes which of the following electrolyte imbalances?

Hypokalemia. **Explanation:** **Mechanism of Action (Why B is Correct):** Insulin plays a critical role in electrolyte homeostasis by stimulating the **Na⁺-K⁺ ATPase pump** located on the cell membranes of skeletal muscle and liver cells. When insulin levels rise rapidly (as in rapid infusion), it increases the activity of this pump, which pumps 3 Na⁺ ions out of the cell and **2 K⁺ ions into the cell**. This shift of potassium from the extracellular fluid (ECF) into the intracellular fluid (ICF) leads to a decrease in serum potassium levels, resulting in **Hypokalemia**. **Analysis of Incorrect Options:** * **A. Hyperkalemia:** This is the opposite of insulin’s effect. Hyperkalemia is often seen in insulin deficiency (e.g., Diabetic Ketoacidosis) because potassium shifts out of cells. * **C & D. Hypernatremia/Hyponatremia:** While insulin affects the Na⁺-K⁺ pump, its primary and most immediate clinical impact is on potassium. Insulin does not have a direct, significant effect on total body sodium levels that would typically manifest as acute hyper- or hyponatremia in this context. **High-Yield Clinical Pearls for NEET-PG:** * **Therapeutic Use:** Because insulin shifts potassium into cells, a combination of **Insulin + Glucose** (to prevent hypoglycemia) is a standard emergency treatment for **Hyperkalemia**. * **DKA Management:** In Diabetic Ketoacidosis (DKA), patients may have high serum potassium initially, but total body potassium is depleted. Starting insulin will cause a rapid drop in K⁺; therefore, **potassium supplementation** is often required even if initial serum levels appear normal. * **Other drugs causing Hypokalemia:** Beta-2 agonists (Salbutamol) and Diuretics (Thiazides/Loop).

Q: Which of the following is NOT an action of glucagon?

None of the above. **Explanation:** Glucagon is a peptide hormone secreted by the **alpha cells of the pancreas**. Its primary physiological role is to prevent hypoglycemia by acting as a "hormone of starvation," increasing blood glucose and fuel availability. **Why "None of the above" is correct:** All three listed actions (Gluconeogenesis, Lipolysis, and Ketogenesis) are primary physiological effects of glucagon. Since the question asks which is NOT an action, and all are indeed actions, "None of the above" is the correct choice. * **Option A: Gluconeogenic:** Glucagon is a potent stimulator of gluconeogenesis (forming glucose from non-carbohydrate sources like amino acids and glycerol) in the liver. It also stimulates glycogenolysis (breakdown of glycogen). * **Option B: Lipolytic:** Glucagon activates hormone-sensitive lipase in adipose tissue, leading to the breakdown of triglycerides into free fatty acids and glycerol, providing alternative fuel sources. * **Option C: Ketogenic:** By increasing the delivery of fatty acids to the liver and shifting hepatic metabolism toward fatty acid oxidation (via inhibition of Malonyl-CoA), glucagon promotes the formation of ketone bodies (acetoacetate and beta-hydroxybutyrate). **High-Yield NEET-PG Pearls:** 1. **Mechanism of Action:** Glucagon acts via a **G-protein coupled receptor (Gs)**, which activates Adenylyl Cyclase to increase **cAMP** levels. 2. **The Insulin/Glucagon Ratio:** The metabolic state of the body is determined more by the ratio of these two hormones than by the absolute concentration of either. 3. **Clinical Use:** Glucagon is used as an emergency treatment for severe hypoglycemia and as an antidote for **Beta-blocker poisoning** (due to its ability to increase cAMP in cardiac myocytes bypassing the beta-receptor). 4. **Inhibitor:** Somatostatin (from delta cells) inhibits the secretion of both insulin and glucagon.

Q: Parathormone secretion is stimulated by?

Decreased serum calcium. **Explanation:** The secretion of **Parathyroid Hormone (PTH)** is primarily regulated by a negative feedback loop involving ionized serum calcium levels. **Why Option B is Correct:** The chief cells of the parathyroid gland possess **Calcium-Sensing Receptors (CaSR)** on their surface. When serum ionized calcium levels drop (**Hypocalcemia**), these receptors are less stimulated, which triggers the rapid release of pre-formed PTH and increases the synthesis of new hormone. PTH then acts to restore calcium levels by increasing bone resorption, enhancing renal calcium reabsorption, and stimulating the synthesis of Calcitriol (Vitamin D3) to increase intestinal absorption. **Why Other Options are Incorrect:** * **Option A:** Increased serum calcium (**Hypercalcemia**) activates the CaSR, which inhibits PTH secretion to prevent further calcium rise. * **Options C & D:** Serum potassium levels do not have a direct regulatory effect on PTH secretion. Potassium is primarily regulated by Aldosterone and Insulin. **High-Yield Clinical Pearls for NEET-PG:** * **Magnesium’s Role:** While hypocalcemia is the primary stimulus, **mild hypomagnesemia** also stimulates PTH. However, **severe, chronic hypomagnesemia** actually inhibits PTH release and causes PTH resistance, leading to refractory hypocalcemia. * **Phosphate:** Hyperphosphatemia indirectly stimulates PTH by lowering ionized calcium and inhibiting Vitamin D activation. * **Target Organs:** PTH acts directly on the **Bone** (RANKL pathway) and **Kidney** (distal tubule), but its effect on the **Intestine** is indirect (via Vitamin D). * **PTH and Phosphorus:** Remember the phrase: *"PTH stands for Phosphate Trashing Hormone"* because it decreases renal phosphate reabsorption (causing phosphaturia).

Q: Which of the following is characteristic of a hyperthyroid state?

Lipolysis. **Explanation:** Thyroid hormones ($T_3$ and $T_4$) are the primary regulators of the body’s Basal Metabolic Rate (BMR). In a hyperthyroid state, the body enters a **hypermetabolic phase** characterized by the rapid breakdown of energy stores. **Why Lipolysis is Correct:** Thyroid hormones stimulate **lipolysis** by increasing the activity of hormone-sensitive lipase in adipose tissue. This leads to the mobilization of free fatty acids and glycerol into the plasma. While thyroid hormones also stimulate lipogenesis, the rate of lipid catabolism (lipolysis) significantly outweighs synthesis in hyperthyroidism, leading to a decrease in fat stores and body weight. **Analysis of Incorrect Options:** * **A. Increased protein synthesis:** While physiological levels of thyroid hormone are anabolic, **excessive** levels (hyperthyroidism) are **catabolic**. This leads to increased protein breakdown (proteolysis), resulting in negative nitrogen balance and muscle wasting (thyrotoxic myopathy). * **B. Decreased glycolysis:** Hyperthyroidism **increases** all aspects of carbohydrate metabolism, including glycolysis, gluconeogenesis, and glucose absorption from the GI tract, to meet the high energy demands. * **D. Increased cholesterol:** Thyroid hormones increase the expression of **LDL receptors** in the liver. In hyperthyroidism, this leads to rapid clearance of cholesterol from the blood, resulting in **hypocholesterolemia**. **High-Yield Clinical Pearls for NEET-PG:** * **Weight Loss despite Polyphagia:** A classic hallmark of hyperthyroidism due to increased BMR. * **Cholesterol Paradox:** Hypocholesterolemia is seen in hyperthyroidism, while hypercholesterolemia is a key diagnostic marker for hypothyroidism. * **Beta-Adrenergic Sensitivity:** Thyroid hormones increase the number and sensitivity of $\beta$-adrenergic receptors, explaining the tachycardia and tremors treated with Propranolol.

Q: Which hormone increases with age?

FSH. **Explanation:** The correct answer is **FSH (Follicle-Stimulating Hormone)**. **1. Why FSH increases with age:** As individuals age, there is a progressive decline in gonadal function (menopause in females and andropause in males). In females, the depletion of ovarian follicles leads to a significant decrease in **Estrogen and Inhibin**. Since Inhibin and Estrogen normally exert negative feedback on the anterior pituitary and hypothalamus, their absence leads to a compensatory, marked rise in **FSH** (and to a lesser extent, LH). FSH levels >40 mIU/mL are a diagnostic hallmark of menopause. **2. Why the other options are incorrect:** * **GH (Growth Hormone):** GH levels peak during puberty and decline steadily with age (somatopause), contributing to reduced muscle mass and increased adiposity in the elderly. * **Prolactin:** Prolactin levels generally remain stable or slightly decrease with age, particularly in postmenopausal women due to the lack of estrogenic stimulation of lactotrophs. * **Insulin:** While insulin *resistance* often increases with age (leading to Type 2 Diabetes), the actual basal insulin secretion and the pancreatic beta-cell response to glucose typically **decrease** or remain impaired due to islet cell atrophy. **3. High-Yield Clinical Pearls for NEET-PG:** * **Hormones that Decrease with Age:** GH, Melatonin, DHEA (Adrenopause), Testosterone, Estrogen, and Aldosterone. * **Hormones that Increase with Age:** FSH, LH, PTH (due to Vitamin D deficiency/renal decline), and Norepinephrine. * **Stable Hormones:** Thyroid hormones (T3/T4) generally remain stable, though the risk of hypothyroidism increases. * **Key Fact:** FSH is the most sensitive marker for the onset of menopause.

Q: Which of the following is NOT an action of GLP-1?

Increases gastric emptying. **Explanation:** Glucagon-like peptide-1 (GLP-1) is an **incretin hormone** secreted by the L-cells of the distal ileum and colon in response to food intake. Its primary physiological role is to lower postprandial blood glucose levels and promote satiety. **Why Option C is the correct answer:** GLP-1 actually **slows gastric emptying** (decreases gastric motility). By delaying the passage of food from the stomach to the duodenum, it slows the absorption of nutrients into the bloodstream, preventing rapid spikes in postprandial glucose. Therefore, "increasing gastric emptying" is physiologically incorrect. **Analysis of Incorrect Options:** * **A. Increases insulin release:** GLP-1 stimulates glucose-dependent insulin secretion from pancreatic beta cells. This is known as the "incretin effect." * **B. Decreases glucagon release:** It suppresses glucagon secretion from pancreatic alpha cells, which reduces hepatic glucose production. * **D. Reduces appetite:** GLP-1 acts on the hypothalamus to increase satiety and reduce food intake, contributing to weight loss. **High-Yield Clinical Pearls for NEET-PG:** * **Incretin Effect:** Oral glucose causes a much higher insulin response than intravenous glucose due to the release of GLP-1 and GIP. * **Degradation:** Endogenous GLP-1 is rapidly degraded by the enzyme **Dipeptidyl Peptidase-4 (DPP-4)**. * **Pharmacology:** GLP-1 agonists (e.g., Liraglutide, Semaglutide) are used to treat Type 2 Diabetes and obesity. They are contraindicated in patients with a history of Medullary Thyroid Carcinoma or MEN 2 syndrome.

Q: What is the main product of the fetal adrenal gland?

DHEA-S. **Explanation:** The fetal adrenal gland is a unique, highly active organ characterized by a massive **"fetal zone"** (comprising about 80% of the gland), which lacks the enzyme **3β-hydroxysteroid dehydrogenase (3β-HSD)**. 1. **Why DHEA-S is correct:** Due to the deficiency of 3β-HSD, the fetal adrenal cannot convert pregnenolone to progesterone. Instead, it shunts precursors toward the androgen pathway. It produces large quantities (up to 200 mg/day) of **Dehydroepiandrosterone sulfate (DHEA-S)**. This DHEA-S serves as the essential precursor for the placenta to synthesize **Estriol (E3)**, which is a key marker of fetal well-being. 2. **Why other options are incorrect:** * **Cortisol:** While the definitive zone produces some cortisol (essential for lung maturation), it is not the *main* product. Most fetal cortisol is actually derived from maternal sources or converted from cortisone. * **Testosterone:** While DHEA-S is an androgen precursor, the adrenal gland itself does not primarily secrete testosterone; this occurs mainly in the fetal Leydig cells of the testes. * **Progesterone:** The fetal adrenal cannot produce progesterone due to the lack of 3β-HSD. Progesterone is primarily supplied to the fetus by the **placenta**. **High-Yield Clinical Pearls for NEET-PG:** * **Size:** At birth, the fetal adrenal is disproportionately large (similar in size to the kidney) but undergoes rapid involution of the fetal zone post-delivery. * **Estriol (E3) Marker:** A sudden drop in maternal serum estriol indicates **fetal distress**, as its synthesis requires a functional fetal adrenal (to produce DHEA-S) and a functional fetal liver (for 16-hydroxylation). * **ACTH Control:** The fetal zone is primarily regulated by fetal ACTH and hCG.

Q: Growth hormone is not produced during which of the following conditions?

Paradoxical sleep. Growth hormone (GH) secretion is pulsatile and regulated by various physiological stimuli. Understanding the relationship between sleep architecture and metabolic states is crucial for NEET-PG. ### **Explanation of the Correct Answer** Growth hormone secretion is highly dependent on the stages of sleep. The primary surge of GH occurs during **Deep Sleep (Stage N3 of NREM sleep)**, specifically during the first few hours of the night. Conversely, during **Paradoxical Sleep (REM sleep)**, GH secretion is significantly inhibited. This is why GH levels are at their lowest during the REM phase, making Option D the correct answer. ### **Analysis of Incorrect Options** * **A. Deep Sleep:** This is the period of maximal GH secretion. The surge is linked to the onset of slow-wave sleep (SWS). * **B. Hypoglycemia:** Low blood glucose is a potent stimulator of GH. GH acts as a counter-regulatory hormone that increases blood glucose by antagonizing insulin and promoting gluconeogenesis. * **C. Low Free Fatty Acid (FFA):** GH promotes lipolysis. Therefore, a decrease in circulating FFAs acts as a stimulus for GH release, while high FFA levels inhibit it. ### **Clinical Pearls for NEET-PG** * **Stimulators of GH:** GHRH, Ghrelin (produced by the stomach), fasting/starvation, exercise, trauma, and amino acids (Arginine). * **Inhibitors of GH:** Somatostatin, Hyperglycemia, Obesity, and Somatomedins (IGF-1) via negative feedback. * **Gold Standard Test:** The Insulin Tolerance Test (ITT) is the gold standard for diagnosing GH deficiency because it induces hypoglycemia, which should normally trigger a GH surge. * **Screening Test:** IGF-1 levels are used for screening because GH levels fluctuate due to their pulsatile nature.

Q: What is the primary mechanism by which catecholamines stabilize blood glucose concentration during hypoglycemia?

Stimulation of gluconeogenesis in the liver.. ### Explanation **Correct Answer: D. Stimulation of gluconeogenesis in the liver.** **Mechanism:** Catecholamines (Epinephrine and Norepinephrine) act as counter-regulatory hormones during hypoglycemia. They primarily stabilize blood glucose by stimulating **hepatic gluconeogenesis** (the synthesis of glucose from non-carbohydrate precursors like lactate and amino acids) and **hepatic glycogenolysis**. Epinephrine activates $\beta_2$ receptors in the liver, increasing cAMP levels, which activates protein kinase A, leading to the induction of key gluconeogenic enzymes. **Analysis of Incorrect Options:** * **Option A:** While catecholamines do stimulate glycogen phosphorylase in muscles, muscle tissue lacks the enzyme **Glucose-6-Phosphatase**. Therefore, muscle glycogen is broken down into lactate (via glycolysis) rather than being released directly as free glucose into the blood. * **Option B:** Catecholamines **promote** glycogenolysis (breakdown of glycogen) to increase blood sugar; inhibiting it would worsen hypoglycemia. * **Option C:** Catecholamines actually **inhibit** insulin release (via $\alpha_2$ receptors) and stimulate glucagon release. Inhibiting insulin is crucial during hypoglycemia to prevent further glucose uptake by peripheral tissues. **High-Yield NEET-PG Pearls:** * **Dual Action:** Epinephrine increases glucose production (liver) and decreases glucose utilization (peripheral tissues). * **Receptor Specificity:** Hepatic glucose production is mediated by $\beta_2$ and $\alpha_1$ receptors, while the inhibition of insulin secretion is mediated by $\alpha_2$ receptors in pancreatic beta cells. * **Hierarchy of Response:** In hypoglycemia, the first line of defense is the suppression of insulin, followed by a rise in glucagon and epinephrine. Cortisol and Growth Hormone act later (4–6 hours) to maintain glucose levels.

Question 1

Rapid infusion of insulin causes which of the following electrolyte imbalances?

Accepted Answer

Hypokalemia

Answer

Hyperkalemia

Answer

Hypernatremia

Answer

Hyponatremia

Question 2

Which of the following is NOT an action of glucagon?

Accepted Answer

None of the above

Answer

Gluconeogenic

Answer

Lipolytic

Answer

Ketogenic

Question 3

Parathormone secretion is stimulated by?

Accepted Answer

Decreased serum calcium

Answer

Increased serum calcium

Answer

Increased serum potassium

Answer

Decreased serum potassium

Question 4

Which of the following is characteristic of a hyperthyroid state?

Accepted Answer

Lipolysis

Answer

Increased protein synthesis

Answer

Decreased glycolysis

Answer

Increased cholesterol

Question 5

Which of the following statements is true about estrogen?

Accepted Answer

Estradiol is the most potent among estradiol, estriol, and estrone.

Answer

Inhibits osteoblasts.

Answer

Decreases the expression of LDL receptors.

Answer

Is a C19 steroid.

Question 6

Which hormone increases with age?

Accepted Answer

FSH

Answer

GH

Answer

Prolactin

Answer

Insulin

Question 7

Which of the following is NOT an action of GLP-1?

Accepted Answer

Increases gastric emptying

Answer

Increases insulin release

Answer

Decreases glucagon release

Answer

Reduces appetite

Question 8

What is the main product of the fetal adrenal gland?

Accepted Answer

DHEA-S

Answer

Cortisol

Answer

Testosterone

Answer

Progesterone

Question 9

Growth hormone is not produced during which of the following conditions?

Accepted Answer

Paradoxical sleep

Answer

Deep sleep

Answer

Hypoglycemia

Answer

Low free fatty acid content in the body

Question 10

What is the primary mechanism by which catecholamines stabilize blood glucose concentration during hypoglycemia?

Accepted Answer

Stimulation of gluconeogenesis in the liver.

Answer

Stimulation of glycogen phosphorylase to release glucose from muscle.

Answer

Inhibition of glycogenolysis in the liver.

Answer

Stimulation of insulin release from the pancreas.

Endocrinology — MCQs

Endocrinology — MCQs

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