Endocrinology Practice Questions

Q: Which of the following statements regarding hormones and their metabolic actions are correct? A. Insulin increases protein synthesis B. Thyroxine decreases basal metabolic rate C. Insulin decreases blood glucose levels D. Epinephrine increases glycogenolysis E. Glucagon increases gluconeogenesis

A, C, D and E only. ### ***A, C, D and E only*** - **Insulin** acts as a potent anabolic hormone, stimulating amino acid uptake and intracellular **protein synthesis**, while simultaneously lowering **blood glucose levels** by facilitating glucose uptake into tissues like skeletal muscle and adipose tissue. - **Epinephrine** stimulates glycogen breakdown (**glycogenolysis**) in the liver and muscle for rapid energy, while **Glucagon** elevates blood glucose by promoting **gluconeogenesis** and glycogenolysis, primarily in the liver. *A, B and C only* - This option includes **Thyroxine**, which is incorrect because thyroid hormones are key regulators that **increase the basal metabolic rate (BMR)**, not decrease it. - Therefore, any set containing statement B is fundamentally incorrect. *A, C and D only* - While A, C, and D are correct, this combination is incomplete because statement **E (Glucagon increases gluconeogenesis)** is medically accurate. - Omitting statement E makes this option inferior to the fully comprehensive answer. *All of the above* - This option is incorrect because it includes statement B, which contradicts the established physiological role of **Thyroxine**. - Thyroxine is calorigenic and consistently acts to raise the body's **metabolic rate**.

Q: If a patient is on testosterone therapy, what changes can one see in LH and FSH levels?

Decreased LH, decreased FSH. ***Decreased LH, decreased FSH*** - Exogenous **testosterone** exerts strong **negative feedback** on the **hypothalamic-pituitary-gonadal (HPG) axis**. - This suppression leads to reduced secretion of **Gonadotropin-Releasing Hormone (GnRH)**, which subsequently lowers the release of both **Luteinizing Hormone (LH)** and **Follicle-Stimulating Hormone (FSH)** from the anterior pituitary. *Increased LH, decreased FSH* - **LH** levels would not increase because **testosterone** suppresses the pituitary's output of gonadotropins rather than stimulating it. - This pattern does not correspond to the physiological effect of testosterone administration on the feedback loop. *Decreased LH, increased FSH* - While **LH** would indeed decrease due to negative feedback, **FSH** would also be concurrently suppressed, not increased. - There is no mechanism in this context for isolated **FSH** increase while receiving androgen therapy. *Increased LH, increased FSH* - This pattern is characteristic of **primary hypogonadism**, where the testes fail to produce testosterone, thus removing the negative feedback on the pituitary. - With exogenous **testosterone** administration, the opposite effect occurs (suppression rather than elevation).

Q: Following a bolus administration of insulin, which of the following occurs?

Glucose uptake into muscle via GLUT 4. ***Glucose uptake into muscle via GLUT 4*** - Insulin stimulates the translocation of **GLUT 4** glucose transporters to the plasma membrane in **skeletal muscle** and adipose tissue cells. - This mechanism significantly increases cellular **glucose uptake** and utilization following a meal or an insulin bolus. *Glucose uptake into the liver via GLUT 4* - The liver does not express the **GLUT 4** transporter; it relies primarily on **GLUT 2** for glucose transport. - Hepatic glucose regulation is influenced by insulin but mediated through enzymatic pathways rather than transporter translocation. *Glucose uptake into muscle via GLUT 2* - **GLUT 2** is a high-capacity, insulin-independent transporter primarily found in the liver, pancreas, and intestine, not skeletal muscle. - Muscles utilize **GLUT 4**, which is the primary **insulin-sensitive** glucose transporter in these tissues. *Glucose uptake into the liver via GLUT 2* - While the liver does use **GLUT 2**, this transporter is **insulin-independent** and facilitates bidirectional glucose movement based on concentration gradients. - Although insulin affects hepatic glucose metabolism (e.g., via **glycogen synthase**), it does not control the *process of uptake* via GLUT 2 translocation.

Q: Which adrenergic or muscarinic receptor subtype is coupled to the Gs protein?

Beta adrenergic receptor. ***Beta adrenergic receptor*** - The **beta-adrenergic receptors** (β1, β2, and β3) are classical G protein-coupled receptors that stimulate the enzyme **adenylyl cyclase** via the **Gs protein**. - Activation leads to an increase in intracellular **cyclic AMP (cAMP)**, resulting in physiological effects such as increased heart rate and bronchodilation. *M1 receptor* - This muscarinic receptor subtype is coupled to the **Gq protein**, which activates **phospholipase C**. - Its activation primarily leads to an increase in intracellular **calcium** and activation of **protein kinase C**. *M2 receptor* - The M2 muscarinic receptor is coupled to the **Gi protein**. - This leads to the **inhibition of adenylyl cyclase**, thereby decreasing levels of **cAMP** within the cell. *Alpha adrenergic receptor* - Alpha-1 receptors are coupled to the **Gq protein**, while alpha-2 receptors are coupled to the **Gi protein**. - Neither of these major alpha-receptor subtypes is linked to the **Gs protein** signaling pathway.

Question 1

Which of the following statements regarding hormones and their metabolic actions are correct?

A. Insulin increases protein synthesis
B. Thyroxine decreases basal metabolic rate
C. Insulin decreases blood glucose levels
D. Epinephrine increases glycogenolysis
E. Glucagon increases gluconeogenesis

Accepted Answer

A, C, D and E only

Answer

A, B and C only

Answer

A, C and D only

Answer

All of the above

Question 2

If a patient is on testosterone therapy, what changes can one see in LH and FSH levels?

Accepted Answer

Decreased LH, decreased FSH

Answer

Increased LH, decreased FSH

Answer

Decreased LH, increased FSH

Answer

Increased LH, increased FSH

Question 3

Following a bolus administration of insulin, which of the following occurs?

Accepted Answer

Glucose uptake into muscle via GLUT 4

Answer

Glucose uptake into the liver via GLUT 4

Answer

Glucose uptake into muscle via GLUT 2

Answer

Glucose uptake into the liver via GLUT 2

Question 4

Which adrenergic or muscarinic receptor subtype is coupled to the Gs protein?

Accepted Answer

Beta adrenergic receptor

Answer

Alpha adrenergic receptor

Answer

M1 receptor

Answer

M2 receptor

Question 5

A 55-year-old man with type 1 diabetes for 30 years is hospitalized for pneumonia. Despite appropriate antibiotic therapy, his insulin requirements have tripled. Blood glucose ranges from 250-400 mg/dL. He develops hypotension unresponsive to fluid resuscitation. Cortisol level is 2 μg/dL (normal 5-25), and ACTH is 320 pg/mL (normal 10-60). Evaluate the endocrine complication and synthesize the pathophysiological connection to his primary disease.

Accepted Answer

Autoimmune polyglandular syndrome type 2 with adrenal insufficiency complicating stress response

Answer

Isolated aldosterone deficiency from diabetic nephropathy

Answer

Pituitary apoplexy from infection causing secondary adrenal insufficiency

Answer

Medication-induced suppression of adrenal function from chronic steroid use

Answer

Sepsis-induced adrenal hemorrhage causing acute adrenal crisis

Question 6

A 42-year-old woman presents with tremor, anxiety, and weight loss. TSH is 0.02 mIU/L, free T4 is 3.2 ng/dL, and T3 is 280 ng/dL (normal 80-180). Radioactive iodine uptake scan shows uniformly increased uptake of 45% at 24 hours (normal 10-30%). Thyroid-stimulating immunoglobulin is positive. Analyze the feedback mechanism disruption occurring in this patient's hypothalamic-pituitary-thyroid axis.

Accepted Answer

Antibody-mediated TSH receptor activation bypassing normal feedback inhibition

Answer

Defective thyroid hormone receptor in the pituitary causing inappropriate TSH release

Answer

Peripheral resistance to thyroid hormone at target tissues requiring higher levels

Answer

Pituitary adenoma autonomously secreting TSH despite elevated thyroid hormones

Answer

Loss of negative feedback at the hypothalamus causing increased TRH secretion

Question 7

A 35-year-old woman undergoes total thyroidectomy for papillary thyroid cancer. Two hours post-operatively, she develops perioral numbness and carpopedal spasm. Trousseau's sign is positive. Serum calcium is 6.8 mg/dL (normal 8.5-10.5). Analyze the pathophysiological mechanism linking the surgical procedure to her current presentation.

Accepted Answer

Inadvertent removal of parathyroid glands causing decreased PTH and impaired calcium mobilization

Answer

Postoperative hypomagnesemia causing functional hypoparathyroidism

Answer

Surgical stress-induced calcitonin release causing calcium deposition in bone

Answer

Thyroid hormone withdrawal causing decreased intestinal calcium absorption

Answer

Acute vitamin D deficiency from loss of thyroid conversion enzymes

Question 8

A 28-year-old woman with Addison's disease presents to the emergency department with severe vomiting and diarrhea for 2 days. She ran out of her medications 3 days ago. Blood pressure is 85/50 mmHg, heart rate 118/min. Laboratory results show sodium 128 mEq/L, potassium 6.2 mEq/L, glucose 65 mg/dL. Apply your understanding of adrenal physiology to determine the immediate hormonal deficiency causing her presentation.

Accepted Answer

Combined cortisol and aldosterone deficiency with loss of mineralocorticoid and glucocorticoid effects

Answer

Primary epinephrine deficiency from adrenal medulla dysfunction

Answer

ACTH excess causing direct renal sodium wasting

Answer

Isolated cortisol deficiency with intact mineralocorticoid function

Answer

Isolated aldosterone deficiency causing electrolyte abnormalities only

Question 9

Insulin is secreted along with which of the following molecules in a 1:1 molar ratio?

Accepted Answer

GLP-1

Answer

Pancreatic polypeptide

Answer

Glucagon

Answer

Somatostatin

Question 10

Aldosterone regulates extracellular volume and potassium homeostasis by binding to its receptors present in all, EXCEPT:

Accepted Answer

Liver

Answer

Colon

Answer

Hippocampus

Answer

Distal nephron

Endocrinology — MCQs

Endocrinology — MCQs

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