Endocrinology Practice Questions

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.

Q: Serum prolactin levels are highest

During third trimester of pregnancy. ***Correct: During third trimester of pregnancy*** - **Serum prolactin levels reach their absolute highest** during the **third trimester of pregnancy**, rising progressively from normal levels (5-25 ng/mL) to peak values of **200-400 ng/mL** near term. - This represents the **highest physiological prolactin levels** observed in humans. - Despite these high levels, **lactation does not occur** during pregnancy because **estrogen and progesterone** block prolactin's action on mammary tissue. - The high prolactin prepares the breast for lactation but milk secretion is inhibited until delivery. *Incorrect: 24 hrs after parturition* - After delivery, prolactin levels actually begin to **decline** from their pregnancy peak, though they remain elevated (around 200 ng/mL). - While **lactogenesis II** (copious milk production) begins 24-72 hours postpartum, this is due to the **removal of estrogen/progesterone inhibition**, not because prolactin levels peak at this time. - The confusion arises from conflating **functional milk production** with **peak hormone levels**. *Incorrect: REM sleep* - Prolactin exhibits **circadian variation** with nocturnal rise during sleep, peaking in early morning hours. - However, these sleep-related peaks (typically 25-40 ng/mL) are **much lower** than pregnancy levels. - This physiological variation is unrelated to reproductive function. *Incorrect: In actively lactating mothers* - During established lactation, basal prolactin levels gradually decline over weeks to months. - Each **suckling episode** causes transient prolactin surges (2-10 fold increase), but these peaks are still **lower than third trimester levels**. - By 6 months postpartum, basal prolactin may return near pre-pregnancy levels despite continued lactation.

Q: In females, the adrenal glands are the exclusive source for secretion of?

DHEAS. ***DHEAS*** - **Dehydroepiandrosterone sulfate (DHEAS)** is almost exclusively produced by the **adrenal glands** in both males and females. - Its levels are often used as a marker of **adrenal androgen production**, making it unique in terms of its exclusive adrenal source in women. *Testosterone* - While the adrenal glands produce small amounts of androgens, the primary source of **testosterone** in females is the **ovaries** and peripheral conversion of adrenal precursors. - Testes are the primary source in males, and it is not exclusively from the adrenal glands in females. *Estrogen* - **Estrogen** is primarily produced by the **ovaries** in females, particularly estradiol. - Peripheral conversion of androgens in adipose tissue also contributes to estrogen levels, and the adrenal glands do not secrete significant amounts directly. *Progesterone* - **Progesterone** is predominantly produced by the **corpus luteum** in the ovary after ovulation and by the placenta during pregnancy. - The adrenal glands produce only minor amounts of progesterone.

Q: What effect does insulin have on GLUT4 receptors in muscle cells?

Promotes their translocation to cell membrane. ***Promotes their translocation to cell membrane*** - Insulin **stimulates the movement of GLUT4 vesicles** from the intracellular compartment to the plasma membrane. - This translocation increases the number of **GLUT4 transporters** on the cell surface, facilitating glucose uptake. *Inhibits their activity* - Insulin does not inhibit the activity of GLUT4 receptors; rather, it **enhances their role** in glucose transport. - Inhibition would lead to **reduced glucose uptake**, which is contrary to insulin's primary function in muscle cells. *Decreases glucose transport* - This statement is incorrect as insulin's main function in muscle cells is to **increase glucose uptake** to lower blood glucose levels. - Insulin promotes glucose transport by **increasing the availability** of GLUT4 transporters at the cell surface. *Activates lipolysis* - Insulin is a powerful **anabolic hormone** that generally inhibits lipolysis (fat breakdown) and promotes lipogenesis (fat synthesis). - Lipolysis is primarily activated by hormones like **glucagon and catecholamines**, not insulin.

Q: All of the following are true about the adrenal gland EXCEPT:

Medulla produces mineralocorticoids. ***Medulla produces mineralocorticoids*** - The **adrenal medulla** primarily produces **catecholamines** (epinephrine and norepinephrine), not mineralocorticoids. - **Mineralocorticoids** (like aldosterone) are secreted by the **zona glomerulosa** in the adrenal cortex. *Zona fasciculata secretes cortisol* - The **zona fasciculata** is the middle and largest layer of the adrenal cortex. - Its primary function is the secretion of **glucocorticoids**, mainly **cortisol**, which is crucial for stress response and metabolism. *Zona glomerulosa produces aldosterone* - The **zona glomerulosa** is the outermost layer of the adrenal cortex. - It is responsible for producing **mineralocorticoids**, with **aldosterone** being the most significant. *Zona reticularis secretes androgens* - The **zona reticularis** is the innermost layer of the adrenal cortex, adjacent to the medulla. - It primarily secretes **adrenal androgens** (like DHEA and androstenedione), which are precursors to sex hormones.

Question 1

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 2

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 3

The hormone which helps in milk secretion:

Accepted Answer

Prolactin

Answer

FSH

Answer

Oxytocin

Answer

Growth hormone

Question 4

Following organs/tissues have proven endocrine function/capability except

Accepted Answer

Salivary gland

Answer

Adipocytes

Answer

Stomach

Answer

Heart

Question 5

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 6

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

Question 7

Serum prolactin levels are highest

Accepted Answer

During third trimester of pregnancy

Answer

24 hrs after parturition

Answer

REM sleep

Answer

In actively lactating mothers

Question 8

In females, the adrenal glands are the exclusive source for secretion of?

Accepted Answer

DHEAS

Answer

Testosterone

Answer

Estrogen

Answer

Progesterone

Question 9

What effect does insulin have on GLUT4 receptors in muscle cells?

Accepted Answer

Promotes their translocation to cell membrane

Answer

Inhibits their activity

Answer

Decreases glucose transport

Answer

Activates lipolysis

Question 10

All of the following are true about the adrenal gland EXCEPT:

Accepted Answer

Medulla produces mineralocorticoids

Answer

Zona fasciculata secretes cortisol

Answer

Zona glomerulosa produces aldosterone

Answer

Zona reticularis secretes androgens

Endocrinology — MCQs

Endocrinology — MCQs

On this page

Practice by Chapter

Want unlimited practice?