Endocrinology Practice Questions

Q: The provided diagram shows the adrenal gland. Identify the hormone produced from the area labeled 'A'.

Aldosterone. ***Aldosterone*** - Area 'A' represents the **zona glomerulosa**, the outermost layer of the adrenal cortex, which specifically produces **aldosterone**. - **Aldosterone** is a **mineralocorticoid** that regulates **sodium** and **potassium** balance and **blood pressure**. *Cortisol* - **Cortisol** is produced by the **zona fasciculata**, the middle layer of the adrenal cortex, not area 'A'. - This **glucocorticoid** primarily regulates **glucose metabolism** and **stress response**. *Epinephrine* - **Epinephrine** (adrenaline) is produced by the **adrenal medulla**, the innermost part of the adrenal gland. - This **catecholamine** is involved in the **fight-or-flight response** and **sympathetic nervous system** activation. *Androgen* - **Androgens** (like **DHEA**) are produced by the **zona reticularis**, the innermost cortical layer. - These **sex hormones** are precursors to **testosterone** and **estrogen**, not produced in area 'A'.

Q: Which of the following is both synthesized and stored in the hypothalamus?

Somatostatin. **Explanation:** The correct answer is **Somatostatin**. To answer this question correctly, one must distinguish between hormones that are merely produced in the hypothalamus and those that are both produced and stored there. **1. Why Somatostatin is Correct:** Somatostatin (Growth Hormone Inhibiting Hormone) is a regulatory hormone **synthesized** in the periventricular nucleus of the hypothalamus. It is **stored** in the median eminence (the inferior-most portion of the hypothalamus) before being released into the hypophyseal portal system to inhibit the secretion of Growth Hormone and TSH from the anterior pituitary. **2. Why the other options are incorrect:** * **ADH (Antidiuretic Hormone):** While ADH is **synthesized** in the hypothalamus (supraoptic and paraventricular nuclei), it is **stored** and released from the **posterior pituitary** (neurohypophysis). * **TSH and LH:** These are trophic hormones **synthesized and stored** in the **anterior pituitary** (adenohypophysis) by thyrotropes and gonadotropes, respectively. Their release is controlled by hypothalamic "releasing hormones" (TRH and GnRH). **Clinical Pearls for NEET-PG:** * **The "Two-Site" Rule:** Remember that ADH and Oxytocin are hypothalamic hormones by origin but **pituitary hormones by storage**. * **Somatostatin Locations:** It is found in three main areas: the Hypothalamus (inhibits GH), Delta cells of the Pancreas (inhibits insulin/glucagon), and D cells of the GI tract (inhibits gastrin). * **Octreotide:** A high-yield synthetic analog of somatostatin used clinically to treat acromegaly, carcinoid syndrome, and esophageal varices.

Q: Obesity is ordinarily associated with low ghrelin levels. Which of the following conditions is an exception where obesity is associated with high ghrelin levels?

Prader-Willi syndrome. ### Explanation **Core Concept: The Ghrelin Paradox** Ghrelin is an orexigenic (appetite-stimulating) hormone secreted primarily by the P-cells of the gastric fundus. In normal physiology, ghrelin levels follow an inverse relationship with Body Mass Index (BMI). In common obesity, ghrelin levels are **low** because the body attempts to suppress further food intake in response to positive energy balance. **Why Prader-Willi Syndrome (PWS) is the Exception:** Prader-Willi Syndrome is a genetic disorder (deletion of the paternal 15q11-q13 locus) characterized by hyperphagia and early-onset morbid obesity. Unlike common obesity, PWS is uniquely associated with **markedly elevated fasting ghrelin levels**. This hyperghrelinemia is believed to drive the insatiable hunger and lack of satiety characteristic of the syndrome, making it a classic "exception to the rule" in endocrinology. **Analysis of Incorrect Options:** * **A. Hypothyroidism:** Associated with weight gain due to a low metabolic rate, but ghrelin levels are typically normal or decreased, following the standard inverse relationship with BMI. * **C. Hypoadrenalism (Addison’s Disease):** Usually presents with weight loss and anorexia, not obesity. * **D. Insulinoma:** Causes hypoglycemia leading to increased appetite and weight gain. However, the hyperinsulinemia typically suppresses ghrelin levels. **High-Yield Clinical Pearls for NEET-PG:** * **Ghrelin vs. Leptin:** Ghrelin is the "Hunger Hormone" (levels rise before meals); Leptin is the "Satiety Hormone" (secreted by adipocytes). * **Sleep Deprivation:** Associated with increased ghrelin and decreased leptin, contributing to obesity. * **Post-Gastric Bypass:** Ghrelin levels significantly **decrease** after Roux-en-Y gastric bypass, which contributes to the surgery's success in weight loss. * **PWS Triad:** Hypotonia (infancy), Hyperphagia/Obesity, and Hypogonadism.

Q: All of the following are true about neuropeptide Y EXCEPT:

It decreases food intake.. **Explanation:** Neuropeptide Y (NPY) is a 36-amino acid peptide widely distributed in the central and peripheral nervous systems. It is one of the most potent **orexigenic** (appetite-stimulating) peptides known. **Why Option D is the Correct Answer (The Exception):** NPY **increases** food intake; it does not decrease it. It is synthesized in the arcuate nucleus of the hypothalamus and acts on the paraventricular nucleus to stimulate hunger and promote weight gain. Substances that decrease food intake are called anorexigenic (e.g., Leptin, POMC, and CART). **Analysis of Other Options:** * **Option A:** NPY is indeed a polypeptide consisting of **36 amino acids**. It belongs to the same family as Peptide YY (PYY) and Pancreatic Polypeptide (PP). * **Option B:** While NPY is a potent vasoconstrictor in many vascular beds, it is known to cause **vasodilation** in specific tissues (like the heart and brain) under certain physiological conditions, often through the release of nitric oxide or by modulating sympathetic tone. (Note: In many textbooks, it is primarily highlighted as a co-transmitter with norepinephrine causing vasoconstriction, but its multifaceted role includes complex vascular regulation). * **Option C:** NPY acts as a **neurotransmitter** and neuromodulator. It is often co-stored and co-released with Norepinephrine in postganglionic sympathetic neurons. **High-Yield Clinical Pearls for NEET-PG:** * **Hypothalamic Control:** NPY/AgRP neurons are inhibited by **Leptin** and **Insulin** (satiety signals) and stimulated by **Ghrelin** (the hunger hormone). * **Location:** Highest concentrations are found in the **Arcuate Nucleus** of the Hypothalamus. * **Functions:** Beyond appetite, NPY is involved in regulating circadian rhythms, reducing anxiety (anxiolytic), and modulating cardiovascular function.

Q: Which of the following hormones is not secreted by the kidney?

Angiotensin I. **Explanation:** The kidney functions as both an excretory and an endocrine organ. The correct answer is **Angiotensin I** because it is not secreted by the kidney; rather, it is **produced in the circulating blood.** 1. **Why Angiotensin I is the correct answer:** The kidney secretes the enzyme **Renin**. Renin acts on **Angiotensinogen** (a plasma protein synthesized by the liver) to cleave it into **Angiotensin I**. Therefore, Angiotensin I is a product of an enzymatic reaction occurring in the plasma, not a direct secretion from renal cells. 2. **Analysis of incorrect options:** * **Renin:** Secreted by the **Juxtaglomerular (JG) cells** of the afferent arteriole in response to low blood pressure or low chloride delivery to the macula densa. * **Erythropoietin (EPO):** Produced by **interstitial cells (peritubular capillaries)** in the renal cortex. it stimulates RBC production in the bone marrow in response to hypoxia. * **1, 25-dihydroxycholecalciferol (Calcitriol):** The kidney contains the enzyme **1-alpha-hydroxylase** (in the proximal convoluted tubule), which converts inactive 25-hydroxyvitamin D into the active form, Calcitriol. **High-Yield NEET-PG Pearls:** * **Site of ACE:** Angiotensin I is converted to Angiotensin II primarily in the **lungs** by Angiotensin-Converting Enzyme (ACE) located on the vascular endothelium. * **Thrombopoietin:** While primarily produced in the liver, a small amount is also synthesized in the kidney. * **Prostaglandins:** The kidney also produces PGE2 and PGI2 (vasodilators) which help maintain renal blood flow.

Q: Which of the following hormones increases during sleep?

GH. **Explanation:** The correct answer is **GH (Growth Hormone)**. Growth hormone secretion follows a distinct pulsatile and circadian rhythm, with its most significant peak occurring during sleep. **1. Why GH is correct:** GH secretion is maximal during **Slow-Wave Sleep (Stage N3/Deep Sleep)**, typically occurring within the first 90 minutes after sleep onset. This surge is mediated by an increase in GHRH (Growth Hormone Releasing Hormone) and a decrease in Somatostatin. In children and adolescents, this sleep-associated peak is crucial for linear growth and metabolic repair. **2. Why other options are incorrect:** * **ACTH and Glucocorticoids (Cortisol):** These follow a diurnal rhythm but are at their **lowest** levels during the early part of the night (around midnight). Their levels begin to rise in the early morning hours (3 AM – 4 AM) and peak just before awakening (the "dawn phenomenon"). * **Insulin:** Insulin levels are primarily regulated by blood glucose levels (post-prandial). During sleep (a fasting state), insulin levels generally decrease to allow for glucagon-mediated glycogenolysis and gluconeogenesis to maintain basal glucose levels. **High-Yield Clinical Pearls for NEET-PG:** * **Sleep Stages:** GH peaks specifically during **Stage 3 (N3) NREM sleep**. If sleep is deprived or fragmented, GH secretion is significantly blunted. * **Other Hormones that increase during sleep:** Prolactin, Melatonin, and TSH (TSH peaks just before sleep onset). * **Somatomedins:** While GH is pulsatile, IGF-1 (Somatomedin C) levels remain stable throughout the day and are used for the clinical screening of Acromegaly. * **Inhibitors of GH:** Hyperglycemia, Free Fatty Acids, and Somatostatin.

Q: Which of the following statements about the hormone leptin is FALSE?

Leptin stimulates appetite.. ### Explanation **Correct Answer: D. Leptin stimulates appetite.** **Why Option D is the correct (False) statement:** Leptin is an **anorexigenic** hormone, meaning it **suppresses appetite**. It is often referred to as the "satiety hormone." Leptin acts on the arcuate nucleus of the hypothalamus to inhibit Neuropeptide Y (NPY) and Agouti-related peptide (AgRP)—which are hunger stimulants—while simultaneously stimulating Pro-opiomelanocortin (POMC) neurons to promote satiety and increase energy expenditure. **Analysis of Incorrect Options:** * **Option A:** In most cases of human obesity, leptin levels are high. However, obese individuals often suffer from **leptin resistance**, where the brain fails to respond to the satiety signal despite high circulating levels. * **Option B:** The primary site of action for leptin is the **Hypothalamus** (specifically the arcuate nucleus), where it regulates long-term energy balance and body weight. * **Option C:** Leptin is a peptide hormone primarily synthesized and secreted by **white adipose tissue** (adipocytes). The amount of leptin secreted is directly proportional to the total body fat mass. **High-Yield NEET-PG Pearls:** * **Gene Association:** Leptin is encoded by the *ob* (obese) gene; its receptor is encoded by the *db* (diabetes) gene. * **Thermoregulation:** Leptin increases metabolic rate and heat production by stimulating sympathetic activity and upregulating **uncoupling protein-1 (UCP1/Thermogenin)** in brown adipose tissue. * **Opposing Hormone:** **Ghrelin**, produced by the stomach (P/D1 cells), is the "hunger hormone" and acts as the physiological antagonist to leptin. * **Reproduction:** Leptin is necessary for the onset of puberty; very low levels (as seen in anorexia or extreme exercise) can lead to hypothalamic amenorrhea.

Q: Which of the following inhibits the secretion of Growth Hormone (GH)?

Hyperglycemia. **Explanation:** Growth Hormone (GH) secretion is regulated by a complex interplay of hypothalamic factors and metabolic signals. **Why Hyperglycemia is Correct:** GH is a **diabetogenic hormone**; it increases blood glucose levels by stimulating gluconeogenesis and antagonizing insulin action. According to the negative feedback principle, **Hyperglycemia** (high blood glucose) inhibits GH secretion to prevent further glucose elevation. This occurs via the stimulation of hypothalamic **Somatostatin** (Growth Hormone Inhibiting Hormone - GHIH) and the direct inhibition of the anterior pituitary. **Why Other Options are Incorrect:** * **Bromocriptine:** In healthy individuals, dopamine agonists like Bromocriptine actually *stimulate* GH release. (Note: Paradoxically, it inhibits GH in patients with Acromegaly, which is a common clinical confusion). * **Vigorous Exercise:** Physical stress and exercise are potent physiological *stimulators* of GH secretion, mediated via increased sympathetic tone and GHRH release. * **Deep Sleep:** GH is secreted in pulsatile bursts, with the largest peak occurring during **Stage 3 and 4 (NREM) deep sleep**. Sleep deprivation significantly suppresses GH levels. **High-Yield NEET-PG Pearls:** 1. **Stimulators of GH:** Hypoglycemia (most potent metabolic stimulus), fasting/starvation, Ghrelin, Arginine (amino acids), and Sleep. 2. **Inhibitors of GH:** Hyperglycemia, Free Fatty Acids (FFA), Somatostatin, and IGF-1 (via negative feedback). 3. **Clinical Correlation:** The **Oral Glucose Tolerance Test (OGTT)** is the gold standard for diagnosing Acromegaly. In a healthy person, a glucose load suppresses GH to <1 ng/mL; failure to suppress confirms the diagnosis.

Q: Excessive secretion of ACTH causes which of the following conditions?

Cushing's syndrome. **Explanation:** **1. Why Cushing’s Syndrome is Correct:** Adrenocorticotropic hormone (ACTH), secreted by the anterior pituitary, stimulates the adrenal cortex to produce cortisol. Excessive secretion of ACTH (most commonly due to a pituitary adenoma, known specifically as **Cushing’s Disease**) leads to chronic hypercortisolism. This clinical state is characterized by the classic symptoms of **Cushing’s Syndrome**, including "moon facies," "buffalo hump," central obesity, purple striae, and hypertension. **2. Why Other Options are Incorrect:** * **Addison’s Disease:** This is primary adrenocortical insufficiency (low cortisol and aldosterone). In this condition, ACTH levels are actually **elevated** as a compensatory mechanism (negative feedback), but the primary pathology is the *lack* of adrenal response, not the *excess* of ACTH itself. * **Myxoedema:** This refers to severe **hypothyroidism** in adults, caused by a deficiency of thyroid hormones (T3/T4), not ACTH. * **Thyrotoxicosis:** This is a clinical state resulting from excessive circulating **thyroid hormones**, usually associated with Grave’s disease or toxic nodular goiter. **3. NEET-PG High-Yield Pearls:** * **Cushing’s Disease vs. Syndrome:** "Cushing’s Disease" specifically refers to a pituitary tumor secreting ACTH. "Cushing’s Syndrome" is the broad term for hypercortisolism from any cause (iatrogenic, adrenal tumor, or ectopic ACTH). * **Hyperpigmentation:** Excessive ACTH causes skin hyperpigmentation because ACTH is derived from **POMC (Pro-opiomelanocortin)**, which also produces Melanocyte-Stimulating Hormone (MSH). * **Dexamethasone Suppression Test (DST):** High-dose DST is used to differentiate Cushing’s Disease (suppresses) from ectopic ACTH production (does not suppress).

Q: A patient sustains a pituitary stalk transection due to an accident. Which of the following physiological responses will NOT occur?

Diabetes mellitus. **Explanation:** Pituitary stalk transection (infundibular injury) disrupts the connection between the hypothalamus and the pituitary gland. This results in the loss of hypothalamic releasing hormones and the interruption of the hypothalamic-hypophyseal portal system. **Why Diabetes Mellitus is the correct answer:** Diabetes Mellitus is a metabolic disorder characterized by hyperglycemia due to insulin deficiency or resistance. It is related to the **pancreas**, not the pituitary gland. In fact, pituitary stalk transection leads to a loss of Growth Hormone (GH) and ACTH (cortisol), both of which are "diabetogenic" (insulin-antagonistic) hormones. Therefore, stalk injury would more likely lead to **increased insulin sensitivity** or hypoglycemia, rather than Diabetes Mellitus. **Analysis of Incorrect Options:** * **Diabetes Insipidus (B):** The stalk contains the axons of the supraoptic and paraventricular nuclei. Transection prevents ADH (Vasopressin) from reaching the posterior pituitary for release, leading to central diabetes insipidus. * **Hyperprolactinemia (C):** Prolactin is the only anterior pituitary hormone under tonic **inhibition** by hypothalamic dopamine. Stalk transection removes this "dopamine brake," causing prolactin levels to rise. * **Hypothyroidism (D):** Transection prevents Hypothalamic TRH from reaching the anterior pituitary, leading to secondary hypothyroidism (low TSH and T4). **NEET-PG High-Yield Pearls:** 1. **The "Rule of Prolactin":** In any hypothalamic-pituitary destructive lesion, all anterior pituitary hormones decrease **except Prolactin**, which increases. 2. **Panhypopituitarism:** Stalk injury typically causes deficiency of GH, LH/FSH, TSH, and ACTH. 3. **Houssay Phenomenon:** This refers to the spontaneous improvement of hyperglycemia in a diabetic patient who subsequently develops pituitary insufficiency (due to loss of GH and Cortisol).

Question 1

The provided diagram shows the adrenal gland. Identify the hormone produced from the area labeled 'A'.

Accepted Answer

Aldosterone

Answer

Cortisol

Answer

Epinephrine

Answer

Androgen

Question 2

Which of the following is both synthesized and stored in the hypothalamus?

Accepted Answer

Somatostatin

Answer

ADH

Answer

Thyroid-stimulating hormone (TSH)

Answer

LH

Question 3

Obesity is ordinarily associated with low ghrelin levels. Which of the following conditions is an exception where obesity is associated with high ghrelin levels?

Accepted Answer

Prader-Willi syndrome

Answer

Hypothyroidism

Answer

Hypoadrenalism

Answer

Insulinoma

Question 4

All of the following are true about neuropeptide Y EXCEPT:

Accepted Answer

It decreases food intake.

Answer

It consists of 36 amino acids.

Answer

It causes vasodilatation.

Answer

It acts as a neurotransmitter.

Question 5

Which of the following hormones is not secreted by the kidney?

Accepted Answer

Angiotensin I

Answer

Renin

Answer

Erythropoietin

Answer

1, 25-dihydroxycholecalciferol

Question 6

Which of the following hormones increases during sleep?

Accepted Answer

GH

Answer

Insulin

Answer

ACTH

Answer

Glucocorticoid

Question 7

Which of the following statements about the hormone leptin is FALSE?

Accepted Answer

Leptin stimulates appetite.

Answer

Leptin levels are typically increased in obese individuals.

Answer

Leptin exerts its primary action on the hypothalamus.

Answer

Leptin is synthesized and secreted by adipose tissue.

Question 8

Which of the following inhibits the secretion of Growth Hormone (GH)?

Accepted Answer

Hyperglycemia

Answer

Bromocriptine

Answer

Vigorous exercise

Answer

Deep sleep

Question 9

Excessive secretion of ACTH causes which of the following conditions?

Accepted Answer

Cushing's syndrome

Answer

Addison's disease

Answer

Myxoedema

Answer

Thyrotoxicosis

Question 10

A patient sustains a pituitary stalk transection due to an accident. Which of the following physiological responses will NOT occur?

Accepted Answer

Diabetes mellitus

Answer

Diabetes insipidus

Answer

Hyperprolactinemia

Answer

Hypothyroidism

Endocrinology — MCQs

Endocrinology — MCQs

On this page

Practice by Chapter

Want unlimited practice?