Endocrinology Practice Questions

Q: Which of the following hormonal concentrations decreases with age?

Growth hormone. **Explanation:** The correct answer is **Growth Hormone (GH)**. This phenomenon is known as **somatopause**. GH secretion peaks during puberty and undergoes a progressive decline starting in the third decade of life (approximately 14% decrease per decade). This decline is primarily due to decreased hypothalamic GHRH secretion and increased somatostatin tone, contributing to age-related changes like decreased muscle mass (sarcopenia) and increased visceral fat. **Analysis of Options:** * **A. Parathormone (PTH):** PTH levels typically **increase** with age. This is often a secondary response to declining Vitamin D levels, reduced calcium absorption in the gut, and declining renal function in the elderly. * **B. FSH (Follicle-Stimulating Hormone):** FSH levels **increase** significantly with age, particularly in females during menopause. As ovarian follicles deplete, the loss of negative feedback from estrogen and inhibin leads to a compensatory rise in FSH and LH. * **D. Norepinephrine:** Plasma levels of norepinephrine generally **increase** with age due to increased sympathetic nervous system activity and reduced clearance from the synaptic cleft. **High-Yield NEET-PG Pearls:** * **Hormones that Decrease with Age:** Growth Hormone, Melatonin, DHEA (Dehydroepiandrosterone), Testosterone, and Estrogen. * **Hormones that Increase with Age:** PTH, FSH, LH, Norepinephrine, and Vasopressin (ADH). * **Hormones that remain relatively Constant:** Thyroid hormones (T3/T4) and Cortisol (though the circadian rhythm of cortisol may flatten). * **Somatopause Clinical Correlation:** The decline in GH/IGF-1 axis is a major contributor to the "frailty syndrome" in the elderly.

Q: Which of the following is NOT an endocrine function associated with the kidney?

Natriuretic peptide secretion. The kidney is a vital endocrine organ, but it is not the primary source of natriuretic peptides. ### **Why Option B is Correct** **Natriuretic peptides** (specifically ANP and BNP) are primarily secreted by the **heart**. Atrial Natriuretic Peptide (ANP) is secreted by the atrial myocytes, and Brain Natriuretic Peptide (BNP) is secreted by ventricular myocytes in response to stretch (volume overload). While the kidney is the *target* organ for these peptides (where they promote sodium excretion), it does not secrete them. ### **Why Other Options are Incorrect** * **A. Erythropoietin (EPO):** Approximately 90% of EPO is synthesized by the **peritubular interstitial cells** of the renal cortex in response to hypoxia. It stimulates RBC production in the bone marrow. * **C. 1,25-dihydroxycholecalciferol (Calcitriol):** The kidney performs the final, rate-limiting step of Vitamin D activation. The enzyme **1-alpha-hydroxylase** (located in the proximal convoluted tubule) converts 25-hydroxyvitamin D into the active form, Calcitriol. * **D. Renin:** Renin is secreted by the **Juxtaglomerular (JG) cells** of the afferent arteriole. It is the initiating enzyme of the Renin-Angiotensin-Aldosterone System (RAAS), crucial for blood pressure regulation. ### **High-Yield NEET-PG Pearls** * **Urodilatin:** A rare natriuretic peptide that *is* produced by the distal tubule, but "Natriuretic Peptide" as a general term refers to the cardiac hormones ANP/BNP. * **Chronic Kidney Disease (CKD):** Patients develop anemia primarily due to **EPO deficiency** and secondary hyperparathyroidism due to **Calcitriol deficiency**. * **Prostaglandins:** The kidney also produces PGE2 and PGI2, which act as local vasodilators to maintain renal blood flow.

Q: Sex hormone-binding globulin (SHBG) levels are decreased in which of the following conditions?

Increased androgen levels. **Explanation:** Sex hormone-binding globulin (SHBG) is a glycoprotein produced primarily by the **liver**. It binds to sex steroids (testosterone, DHT, and estradiol) to regulate their bioavailability; only the "free" hormone is biologically active. **Why Option B is Correct:** The synthesis of SHBG in the liver is inhibited by **androgens, insulin, and obesity**. Therefore, in conditions with increased androgen levels (such as PCOS or androgen-secreting tumors), SHBG levels decrease. This creates a clinical "vicious cycle": lower SHBG leads to higher levels of free (active) testosterone, further worsening androgenic symptoms like hirsutism. **Why Other Options are Incorrect:** * **A. Hyperthyroidism:** Thyroid hormones (T3/T4) **stimulate** the hepatic production of SHBG. Thus, SHBG levels are elevated in hyperthyroidism. * **C. Increased Estrogen levels:** Estrogen is a potent stimulator of SHBG synthesis. High estrogen levels increase SHBG, which is why women generally have higher levels than men. * **D. Pregnancy:** This is a state of high endogenous estrogen production, which significantly **increases** SHBG levels (often 5–10 fold). **High-Yield Clinical Pearls for NEET-PG:** * **SHBG Increases in:** Hyperthyroidism, Pregnancy, Oral Contraceptive Pill (OCP) use, Cirrhosis, and Aging (in men). * **SHBG Decreases in:** Hypothyroidism, Obesity, PCOS, Hyperinsulinemia/Type 2 Diabetes, and Acromegaly. * **Clinical Correlation:** In **PCOS**, the combination of high androgens and hyperinsulinemia synergistically suppresses SHBG, making it a key marker for the disease.

Q: Prolactin secretion is stimulated by:

TRH. **Explanation:** Prolactin (PRL) is unique among anterior pituitary hormones because its primary regulation is **inhibitory** rather than stimulatory. Under normal physiological conditions, the hypothalamus exerts a tonic inhibitory influence on prolactin via dopamine. **Why TRH is the correct answer:** Thyrotropin-Releasing Hormone (TRH), primarily known for stimulating TSH, also acts as a potent **prolactin-releasing factor**. In states of primary hypothyroidism, the lack of negative feedback leads to elevated TRH levels. This excess TRH stimulates lactotrophs in the anterior pituitary, leading to hyperprolactinemia. This explains why patients with hypothyroidism may present with galactorrhea or menstrual irregularities. **Analysis of Incorrect Options:** * **ACTH (Adrenocorticotropic Hormone):** This is a hormone secreted *by* the anterior pituitary to stimulate the adrenal cortex; it does not regulate prolactin secretion. * **GnRH (Gonadotropin-Releasing Hormone):** This stimulates the release of LH and FSH. Interestingly, high levels of prolactin actually *inhibit* GnRH secretion, leading to hypogonadism. * **Dopamine:** This is the primary **inhibitor** of prolactin (secreted via the tuberoinfundibular pathway). Drugs that block dopamine (antipsychotics) lead to increased prolactin levels. **NEET-PG High-Yield Pearls:** * **Prolactin Inhibitory Factor (PIF):** Dopamine. * **Prolactin Releasing Factors (PRF):** TRH, VIP (Vasoactive Intestinal Peptide), and Oxytocin. * **Physiological Stimuli:** Suckling (strongest), sleep, stress, and pregnancy (estrogen). * **Clinical Correlation:** Always check TSH levels in a patient with hyperprolactinemia to rule out primary hypothyroidism before considering a prolactinoma.

Q: FSH is secreted by which of the following cells?

Basophils. **Explanation:** The anterior pituitary (adenohypophysis) contains cells classified based on their staining properties with hematoxylin and eosin (H&E). **Basophils** are cells that stain with basic dyes and are responsible for secreting the "B-FLAT" hormones: **B**asophils produce **F**SH, **L**H, **A**CTH, and **T**SH. Specifically, FSH (Follicle-Stimulating Hormone) is secreted by **gonadotrophs**, which are a subtype of basophils. **Analysis of Options:** * **Option A (Chromophobes):** These are "color-hating" cells that do not pick up significant stain. They are generally considered to be either resting/degranulated acidophils/basophils or stem cells; they do not actively secrete FSH. * **Option C (Acidophils):** These stain with acidic dyes (eosin) and secrete Growth Hormone (Somatotrophs) and Prolactin (Lactotrophs). A common mnemonic is **"GPA"** (**G**rowth hormone, **P**rolactin are **A**cidophils). * **Option D (Theca interna cells):** These are ovarian cells, not pituitary cells. While they are involved in the reproductive axis, their role is to produce androgens (androstenedione) under the influence of LH, not to secrete FSH. **High-Yield Facts for NEET-PG:** * **Mnemonic for Pituitary Staining:** **"GPA"** (Acidophils: GH, Prolactin) and **"B-FLAT"** (Basophils: FSH, LH, ACTH, TSH). * **PAS Stain:** Basophils are PAS (Periodic Acid-Schiff) positive because the hormones they secrete (FSH, LH, TSH) are glycoproteins. * **Most Numerous Cell Type:** Somatotrophs (Acidophils) are the most abundant cells in the anterior pituitary. * **FSH Function:** In females, it stimulates follicular growth; in males, it acts on Sertoli cells to support spermatogenesis.

Q: Regarding the action of insulin, which of the following is true?

Decreased ketogenesis in the liver. **Explanation:** Insulin is the body’s primary **anabolic hormone**, secreted by the beta cells of the pancreas. Its overarching function is to promote energy storage and inhibit the mobilization of fuel reserves. **Why Option D is Correct:** Insulin **decreases ketogenesis** in the liver through two main mechanisms: 1. It inhibits **Hormone-Sensitive Lipase (HSL)** in adipose tissue, reducing the supply of free fatty acids (FFAs) to the liver. 2. It inhibits **Carnitine Palmitoyltransferase-1 (CPT-1)**, the rate-limiting enzyme for beta-oxidation, thereby preventing the conversion of fatty acids into ketone bodies. This is why insulin deficiency leads to Diabetic Ketoacidosis (DKA). **Analysis of Incorrect Options:** * **Option A:** Insulin **increases K+ uptake** into cells (muscle and adipose) by stimulating the Na+/K+ ATPase pump. This is why insulin/glucose infusion is a standard treatment for hyperkalemia. * **Option B:** Insulin is anabolic; it **increases protein synthesis** and **decreases protein catabolism** in muscle. * **Option C:** Insulin **inhibits Hormone-Sensitive Lipase (HSL)** to prevent lipolysis and instead activates **Lipoprotein Lipase (LPL)** to promote triglyceride storage in adipocytes. **High-Yield Clinical Pearls for NEET-PG:** * **GLUT-4:** The only insulin-dependent glucose transporter, found in skeletal muscle and adipose tissue. * **Enzyme Regulation:** Insulin dephosphorylates enzymes (usually activating them, except for HSL and Glycogen Phosphorylase, which are inactivated). * **Antagonism:** Glucagon, Epinephrine, Cortisol, and Growth Hormone are "counter-regulatory" hormones that oppose insulin's actions.

Q: Insulin secretion is inhibited by all of the following, EXCEPT:

Beta-ketoacids. **Explanation:** Insulin secretion from the pancreatic beta cells is a highly regulated process. To answer this question, one must distinguish between factors that inhibit insulin release and those that stimulate it. **Why Beta-ketoacids is the correct answer:** Beta-ketoacids (such as acetoacetate and beta-hydroxybutyrate) actually **stimulate** insulin secretion. This serves as a crucial physiological negative feedback loop: as ketone bodies rise (e.g., during fasting or starvation), they trigger a modest release of insulin to prevent runaway ketogenesis and the development of ketoacidosis. Therefore, they do not inhibit insulin; they promote it. **Analysis of incorrect options (Inhibitors of Insulin):** * **Somatostatin:** Known as the "universal endocrine off-switch," paracrine secretion of somatostatin from delta cells directly inhibits both insulin and glucagon release. * **Beta-adrenergic blockers:** Beta-2 receptors on pancreatic beta cells stimulate insulin release. Therefore, blocking these receptors (or alpha-adrenergic stimulation) results in the **inhibition** of insulin secretion. * **Diazoxide:** This drug is a potassium channel opener. By keeping the ATP-sensitive $K^+$ channels open, it hyperpolarizes the beta cell membrane, preventing calcium influx and thereby **inhibiting** insulin release. It is clinically used to treat hyperinsulinism. **NEET-PG High-Yield Pearls:** * **The "Incretin Effect":** Oral glucose stimulates more insulin than IV glucose due to GIP and GLP-1. * **Rate-limiting step:** The phosphorylation of glucose by **Glukokinase** is the glucose-sensor in beta cells. * **Alpha vs. Beta:** Alpha-2 adrenergic stimulation **inhibits** insulin, while Beta-2 stimulation **increases** it. In a "fight or flight" response, alpha-dominance ensures insulin is suppressed to keep blood glucose high for the brain and muscles.

Q: Which of the following statements can be regarded as the primary action of inhibin?

It inhibits the secretion of FSH.. ### Explanation **Correct Answer: D. It inhibits the secretion of FSH.** **Mechanism of Action:** Inhibin is a glycoprotein hormone belonging to the **transforming growth factor-beta (TGF-β) superfamily**. It is produced primarily by the **Sertoli cells** in males and the **Granulosa cells** in females. Its primary physiological role is the **selective negative feedback inhibition** of Follicle-Stimulating Hormone (FSH) secretion from the anterior pituitary. Unlike GnRH or sex steroids, inhibin does not significantly affect the secretion of Luteinizing Hormone (LH), making it a specific regulator of the FSH axis. **Analysis of Incorrect Options:** * **A & C (Prolactin and TSH):** Inhibin has no physiological role in regulating the secretion of Prolactin or Thyroid-Stimulating Hormone (TSH). These are regulated by Dopamine/TRH and TRH/Somatostatin, respectively. * **B (Estradiol Synthesis):** Inhibin does not stimulate estradiol synthesis. In fact, **Activin** (another member of the TGF-β family) is the hormone that stimulates FSH secretion and promotes granulosa cell aromatase activity, leading to increased estradiol. **High-Yield Clinical Pearls for NEET-PG:** * **Inhibin B vs. Inhibin A:** Inhibin B is the primary form in males (marker of spermatogenesis) and the early follicular phase in females. Inhibin A is dominant in the luteal phase and during pregnancy (produced by the corpus luteum and placenta). * **Clinical Marker:** Inhibin B levels are used as a clinical marker for **ovarian reserve** and **Sertoli cell function**. * **Tumor Marker:** Elevated Inhibin levels are a highly specific marker for **Granulosa Cell Tumors** of the ovary. * **The "Counter-Hormone":** Remember **Activin** as the functional antagonist to Inhibin; it stimulates FSH release.

Question 1

Which of the following hormonal concentrations decreases with age?

Accepted Answer

Growth hormone

Answer

Parathormone

Answer

FSH

Answer

Norepinephrine

Question 2

All of the following statements about adrenal glands are true EXCEPT:

Accepted Answer

The adrenal medulla normally secretes epinephrine in excess of norepinephrine.

Answer

Chromaffin granules are seen in pheochromocytoma.

Answer

Tumors of the adrenal medulla secrete epinephrine in excess of norepinephrine.

Answer

The adrenal medulla is not essential for life.

Question 3

Which of the following is NOT an endocrine function associated with the kidney?

Accepted Answer

Natriuretic peptide secretion

Answer

Erythropoietin secretion

Answer

1,25-dihydroxycholecalciferol formation

Answer

Renin secretion

Question 4

Sex hormone-binding globulin (SHBG) levels are decreased in which of the following conditions?

Accepted Answer

Increased androgen levels

Answer

Hyperthyroidism

Answer

Increased estrogen levels

Answer

Pregnancy

Question 5

Prolactin secretion is stimulated by:

Accepted Answer

TRH

Answer

ACTH

Answer

GnRH

Answer

Dopamine

Question 6

FSH is secreted by which of the following cells?

Accepted Answer

Basophils

Answer

Chromophobes

Answer

Acidophils

Answer

Theca interna cells

Question 7

All of the following short stature cases are caused by mechanisms independent of specific defects in the growth hormone axis, except?

Accepted Answer

Laron dwarfism

Answer

Gonadal dysgenesis

Answer

Kasper - Hauser syndrome

Answer

Achondroplasia

Question 8

Regarding the action of insulin, which of the following is true?

Accepted Answer

Decreased ketogenesis in the liver

Answer

Decreased K+ uptake in adipose tissue

Answer

Increased protein catabolism in muscle

Answer

Activation of hormone-sensitive lipase

Question 9

Insulin secretion is inhibited by all of the following, EXCEPT:

Accepted Answer

Beta-ketoacids

Answer

Somatostatin

Answer

Beta-adrenergic blockers

Answer

Diazoxide

Question 10

Which of the following statements can be regarded as the primary action of inhibin?

Accepted Answer

It inhibits the secretion of FSH.

Answer

It inhibits the secretion of prolactin.

Answer

It stimulates the synthesis of estradiol.

Answer

It stimulates the secretion of TSH.

Endocrinology — MCQs

Endocrinology — MCQs

On this page

Practice by Chapter

Want unlimited practice?