Endocrinology Practice Questions

Q: Which of the following is not seen after removal of testis in an adult?

Decrease FSH. ***Decrease FSH*** - Removal of the testes (orchiectomy) in an adult leads to a **decrease in testosterone production** and the **loss of inhibin B**, which normally suppress FSH secretion. - This reduction in negative feedback on the pituitary gland results in a **marked rise in FSH and LH levels**, not a decrease. - Therefore, "decrease FSH" is **NOT seen** after testicular removal - FSH actually **increases**. *Impotence* - The testes are the primary site of **testosterone production**, which is crucial for erectile function. - Their removal substantially reduces testosterone, leading to **erectile dysfunction (impotence)**. *Loss of libido* - **Testosterone** plays a vital role in maintaining sexual desire and libido in males. - Orchiectomy causes a significant drop in testosterone, leading to a **marked decrease or loss of libido**. *Muscle weakness* - **Testosterone** has anabolic effects, promoting muscle growth and strength. - Its removal leads to a chronic state of **hypogonadism**, often resulting in **muscle atrophy and weakness** over time.

Q: Which of the following is the primary physiological stimulus for prolactin release?

Nipple stimulation. ***Nipple stimulation*** - **Nipple stimulation** (e.g., during breastfeeding or suckling) is the **primary physiological stimulus** for prolactin release. - It activates neural pathways from the nipple to the hypothalamus, which **inhibit dopamine release**. - Since dopamine acts as **prolactin-inhibiting hormone (PIH)**, reduced dopamine leads to **disinhibition** of prolactin secretion from the anterior pituitary lactotroph cells. - This is the most clinically important mechanism for maintaining lactation. *Increased sleep duration* - Prolactin levels do exhibit a **circadian rhythm** with elevated levels during sleep (nocturnal surge). - However, sleep is not considered a primary or acute stimulus for prolactin release. - **Suckling/nipple stimulation** and **stress** are much more potent stimuli. *Reduction in dopamine levels* - This represents the **biochemical mechanism** underlying prolactin release rather than a physiological stimulus. - Dopamine from the hypothalamus tonically **inhibits** prolactin secretion. - Various physiological stimuli (like nipple stimulation, stress, or pregnancy) work by reducing dopamine tone. - When asking for a "stimulus," we refer to the **initiating event** (e.g., suckling), not the intermediate biochemical step. *Elevated blood glucose levels* - **Elevated blood glucose** primarily stimulates **insulin release** from pancreatic beta cells. - There is no direct physiological link between blood glucose and prolactin secretion. - Prolactin is not involved in glucose homeostasis.

Q: Appetite is stimulated by all except

Melanocyte stimulating hormone. ***Melanocyte stimulating hormone*** - **Alpha-melanocyte stimulating hormone (α-MSH)** is a catabolic hormone that acts to reduce appetite and increase energy expenditure. - It is an **anorexigenic peptide** that suppresses feeding by binding to central melanocortin receptors, primarily MC4R. *Neuropeptide Y* - **Neuropeptide Y (NPY)** is a potent **orexigenic peptide** that stimulates appetite and food intake. - It plays a crucial role in regulating energy balance and is increased during fasting states. *Agouti related peptide* - **Agouti-related peptide (AgRP)** is a strong **orexigenic peptide** that increases food intake. - It acts as an **antagonist** at the MC3R and MC4R melanocortin receptors, counteracting the appetite-suppressing effects of α-MSH. *Melanocyte concentrating hormone* - **Melanin-concentrating hormone (MCH)** is an **orexigenic neuropeptide** that stimulates feeding behavior. - It is primarily expressed in the lateral hypothalamus and plays a significant role in promoting appetite and weight gain.

Q: Systemic factor which is responsible for bone remodeling :

PTH. ***PTH*** - **Parathyroid hormone (PTH)** is a major systemic regulator of bone remodeling, primarily influencing **calcium and phosphate homeostasis**. - High levels of PTH, particularly prolonged or continuous elevation, stimulate **osteoclasts** directly or indirectly, leading to increased **bone resorption**. *Cytokines (e.g., IL-1, IL-6)* - These are primarily **local humoral factors** that regulate bone remodeling in a specific area, often in response to inflammation or injury. - While they can influence bone metabolism, their action is generally more localized, unlike the widespread systemic effects of PTH. *Prostaglandin E2 (PGE2)* - **PGE2** is another **local mediator** involved in bone remodeling, produced by various cells including osteoblasts and osteocytes. - It plays a role in both bone formation and resorption depending on concentration and context, but its effects are typically paracrine or autocrine rather than systemic endocrine control. *Transforming Growth Factor-beta (TGF-β)* - **TGF-β** is a potent **local growth factor** stored within the bone matrix and released during bone resorption. - It regulates proliferation and differentiation of osteoblasts and osteoclasts, primarily acting as a local regulator of bone formation and repair rather than a systemic hormone.

Q: A middle aged man noticed that he can no longer fit in his shoes and that his jaw was protruding and phalanges were enlarged. These effects are likely to be mediated by

IGF-1. ***IGF-1*** - The described symptoms (increased shoe size, jaw protrusion, enlarged phalanges) are characteristic of **acromegaly**, a condition caused by excessive growth hormone (GH) secretion in adults. - **Insulin-like Growth Factor 1 (IGF-1)** is primarily responsible for mediating the growth-promoting effects of GH on various tissues, leading to the clinical manifestations seen in this patient. *TRH* - **Thyrotropin-releasing hormone (TRH)** stimulates the release of thyroid-stimulating hormone (TSH) from the pituitary, which in turn regulates thyroid hormone production. - Excess TRH would lead to hyperthyroidism symptoms like weight loss, heat intolerance, and tachycardia, not acromegalic features. *ACTH* - **Adrenocorticotropic hormone (ACTH)** stimulates the adrenal glands to produce cortisol. - Excessive ACTH causes **Cushing's syndrome**, characterized by central obesity, moon facies, striae, and muscle weakness, which are different from the presented symptoms. *TGF Beta* - **Transforming growth factor beta (TGF-beta)** is a pleiotropic cytokine involved in cell growth, differentiation, apoptosis, and immune regulation. - While it plays a role in tissue remodeling and fibrosis, it is not the direct mediator of the generalized growth and skeletal changes seen in acromegaly.

Q: The hormone which helps in milk secretion:

Prolactin. **Prolactin** - **Prolactin** is the primary hormone responsible for **milk production** (lactogenesis) in the mammary glands after childbirth. - It stimulates the alveolar cells to synthesize and secrete milk components. *FSH* - **Follicle-stimulating hormone (FSH)** is involved in the development of **ovarian follicles** and **sperm production**, not milk secretion. - Its main actions are on the gonads to regulate reproductive cycles. *Oxytocin* - **Oxytocin** is responsible for **milk ejection** (milk let-down reflex), causing contraction of myoepithelial cells, but it does not directly stimulate milk production. - It also plays a role in uterine contractions during labor. *Growth hormone* - **Growth hormone (GH)** primarily promotes **growth** and **metabolism** throughout the body. - While it can have some metabolic effects that indirectly support lactation, it is not the main hormone for milk *secretion* itself.

Q: Following organs/tissues have proven endocrine function/capability except

Salivary gland. ***Salivary gland*** - Salivary glands are primarily **exocrine glands**, producing saliva which contains enzymes and lubricants for digestion. - While they contribute to oral health, they do not have a recognized **endocrine function** of secreting hormones directly into the bloodstream to regulate distant organs. *Adipocytes* - **Adipocytes** (fat cells) are known to have significant **endocrine function**, secreting hormones like **leptin**, adiponectin, and resistin, which play roles in metabolism, appetite regulation, and inflammation. - These hormones act on various target tissues throughout the body, influencing energy homeostasis and insulin sensitivity. *Stomach* - The stomach contains specialized cells that secrete various hormones, such as **gastrin**, ghrelin, somatostatin, and histamine. - **Gastrin** stimulates gastric acid secretion, while **ghrelin** promotes hunger, demonstrating its important endocrine role in digestion and appetite regulation. *Heart* - The heart, particularly the atria, produces and secretes **atrial natriuretic peptide (ANP)**. - **ANP** acts as a hormone to regulate blood pressure and fluid balance by promoting sodium and water excretion by the kidneys.

Q: In which of the following conditions would the cortisol level be highest?

Normal person in the early morning. ***Normal person in the early morning*** - Cortisol secretion follows a **circadian rhythm**, with levels naturally peaking in the early morning (typically between 6-8 AM) to prepare the body for the day's activities. - This **diurnal variation** is a key physiological characteristic of cortisol, regulated by the **hypothalamic-pituitary-adrenal (HPA) axis**. *Normal person after receiving dexamethasone* - **Dexamethasone** is a potent synthetic glucocorticoid that **suppresses ACTH secretion** via negative feedback, leading to a significant **reduction in endogenous cortisol production**. - This is the principle behind the **dexamethasone suppression test**, used to diagnose Cushing's syndrome (failure of suppression). *Normal person in the late evening* - Cortisol levels are typically at their **lowest point** in the late evening (around midnight to early morning hours) as part of the normal **circadian rhythm**. - This nadir reflects the body's decreased need for metabolic and stress response hormones during rest. *Addison's disease* - **Addison's disease** is characterized by **primary adrenal insufficiency**, meaning the adrenal glands are unable to produce sufficient amounts of cortisol. - Patients with Addison's disease have **chronically low cortisol levels** due to glandular damage, often accompanied by high ACTH levels.

Q: Prolactin levels are highest in which of the following?

After nipple stimulation. ***After nipple stimulation*** - Nipple stimulation is a powerful physiological stimulus for **prolactin release** from the anterior pituitary. - This reflex is essential for **lactation** and milk let-down, as suckling signals directly enhance prolactin secretion. *After 24 hrs of ovulation* - Prolactin levels do not peak significantly 24 hours after ovulation; while some fluctuation occurs during the menstrual cycle, the highest levels are not seen at this time. - **Luteinizing hormone (LH)** and **follicle-stimulating hormone (FSH)** are the primary hormones exhibiting surges related to ovulation. *After 24 hours of parturition* - While prolactin levels are elevated throughout the third trimester and immediately postpartum, they tend to **decline somewhat** if breastfeeding is not initiated within the first 24-48 hours. - Post-partum, prolactin levels are primarily sustained by **frequent nipple stimulation** from breastfeeding. *Just before parturition* - Prolactin levels are **chronically elevated** during the third trimester of pregnancy, but the **acute highest surge** or peak is typically in response to specific triggers like nipple stimulation, rather than just the state of being immediately pre-partum. - High prolactin during late pregnancy prepares the breasts for lactation but is not necessarily the **absolute peak** that nipple stimulation can elicit.

Question 1

Which of the following is not seen after removal of testis in an adult?

Accepted Answer

Decrease FSH

Answer

Impotence

Answer

Loss of libido

Answer

Muscle weakness

Question 2

Which of the following is the primary physiological stimulus for prolactin release?

Accepted Answer

Nipple stimulation

Answer

Increased sleep duration

Answer

Reduction in dopamine levels

Answer

Elevated blood glucose levels

Question 3

Appetite is stimulated by all except

Accepted Answer

Melanocyte stimulating hormone

Answer

Neuropeptide Y

Answer

Agouti related peptide

Answer

Melanocyte concentrating hormone

Question 4

Systemic factor which is responsible for bone remodeling :

Accepted Answer

PTH

Answer

Cytokines (e.g., IL-1, IL-6)

Answer

Prostaglandin E2 (PGE2)

Answer

Transforming Growth Factor-beta (TGF-β)

Question 5

A middle aged man noticed that he can no longer fit in his shoes and that his jaw was protruding and phalanges were enlarged. These effects are likely to be mediated by

Accepted Answer

IGF-1

Answer

TRH

Answer

ACTH

Answer

TGF Beta

Question 6

Two normal, healthy subjects volunteer for a study on insulin secretion. In Patient 1, blood glucose is increased to 150 mg/dL by direct intravenous infusion. In Patient 2, blood glucose is increased to 150 mg/dL by ingestion of oral glucose. The peak plasma insulin concentration produced in Patient 1 is 70 uU/mL while in Patient 2, it is 95 uU/mL. Which of the following best explains the higher insulin concentration in Patient 2?

Accepted Answer

Ingested glucose increases duodenal secretion of gastric inhibitory peptide (GIP), increasing beta cell release of insulin

Answer

Intravenous glucose increases islet cell secretion of somatostatin, inhibiting beta cell release of insulin

Answer

Intravenous glucose increases islet cell secretion of glucagon, inhibiting beta cell release of insulin

Answer

Ingested glucose activates a sympathetic reflex that increases beta cell release of insulin

Question 7

The hormone which helps in milk secretion:

Accepted Answer

Prolactin

Answer

FSH

Answer

Oxytocin

Answer

Growth hormone

Question 8

Following organs/tissues have proven endocrine function/capability except

Accepted Answer

Salivary gland

Answer

Adipocytes

Answer

Stomach

Answer

Heart

Question 9

In which of the following conditions would the cortisol level be highest?

Accepted Answer

Normal person in the early morning

Answer

Normal person after receiving dexamethasone

Answer

Normal person in the late evening

Answer

Addison's disease

Question 10

Prolactin levels are highest in which of the following?

Accepted Answer

After nipple stimulation

Answer

After 24 hrs of ovulation

Answer

After 24 hours of parturition

Answer

Just before parturition

Endocrinology — MCQs

Endocrinology — MCQs

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