Endocrinology Indian Medical PG Practice Questions and MCQs
Practice Indian Medical PG questions for Endocrinology. These multiple choice questions (MCQs) cover important concepts and help you prepare for your exams.
Endocrinology Indian Medical PG Question 1: What is the initial drug of choice for a suspected case of acute adrenal insufficiency?
- A. Norepinephrine
- B. Hydrocortisone (Correct Answer)
- C. Dexamethasone
- D. Fludrocortisone
Endocrinology Explanation: ***Hydrocortisone***
- This is the initial drug of choice due to its **combined mineralocorticoid and glucocorticoid activity**, which effectively replaces the deficient hormones in acute adrenal insufficiency.
- It also has a **rapid onset of action** crucial for stabilizing patients in an adrenal crisis.
*Norepinephrine*
- This is a **vasopressor** used to manage **severe hypotension or shock** by increasing peripheral vascular resistance.
- While hypotension is a feature of adrenal insufficiency, norepinephrine does not address the underlying hormonal deficiency directly and is not the primary treatment.
*Dexamethasone*
- Dexamethasone is a **potent glucocorticoid** and can be used in adrenal insufficiency, but it lacks significant **mineralocorticoid activity**.
- Its longer half-life might make it less ideal for immediate, titratable replacement compared to hydrocortisone in an acute setting.
*Fludrocortisone*
- Fludrocortisone is a **pure mineralocorticoid** primarily used for long-term replacement therapy to manage sodium and potassium balance in adrenal insufficiency.
- It does not have sufficient glucocorticoid activity to address the immediate, life-threatening aspects of acute adrenal crisis.
Endocrinology Indian Medical PG Question 2: All are examples of negative feedback except
- A. Regulation of blood CO2 level
- B. Regulation of pituitary hormones
- C. Regulation of blood pressure
- D. Coagulation of the blood (Correct Answer)
Endocrinology Explanation: ***Coagulation of the blood***
- **Blood coagulation** is a classic example of **positive feedback**, where the initial clotting process amplifies itself until bleeding stops
- Platelets aggregate and release factors that promote further platelet aggregation and activation of the clotting cascade, thereby **accelerating the response** rather than diminishing it
- This is the exception among the options, as it represents positive feedback while all others are negative feedback
*Regulation of blood CO2 level*
- The regulation of **blood CO2 levels** is a vital example of **negative feedback**, where an increase in CO2 stimulates breathing to expel excess CO2
- This mechanism works to return the blood CO2 concentration to its homeostatic set point, thus **counteracting the initial stimulus**
- Central and peripheral chemoreceptors detect elevated CO2 and trigger increased ventilation
*Regulation of pituitary hormones*
- The regulation of **pituitary hormones** involves **negative feedback loops**, where high levels of target gland hormones inhibit the release of stimulating hormones from the pituitary and hypothalamus
- For example, high thyroid hormone levels inhibit TSH release from the pituitary and TRH from the hypothalamus
- This effectively **reduces the initial stimulus** and maintains hormonal balance
*Regulation of blood pressure*
- The regulation of **blood pressure** is primarily controlled by **negative feedback mechanisms** involving baroreceptors, which detect changes in pressure
- If blood pressure rises, baroreceptors in the carotid sinus and aortic arch signal the medulla to reduce heart rate and dilate blood vessels
- This response **lowers the pressure back to the set point**, maintaining cardiovascular homeostasis
Endocrinology Indian Medical PG Question 3: Which of the following is correct regarding obesity and infertility?
- A. It is always associated with endometrial atrophy
- B. It is associated with hypergonadotropic hypogonadism
- C. There is no change in HPO axis
- D. It is associated with hypogonadotropic hypogonadism (Correct Answer)
Endocrinology Explanation: ***It is associated with hypogonadotropic hypogonadism***
- **Obesity-related infertility** in men often leads to **decreased testosterone** levels and **impaired spermatogenesis**, driven by altered adipose tissue function affecting the **hypothalamic-pituitary-gonadal (HPG) axis**.
- Adipose tissue in obese individuals produces more **estrogen** and **inflammatory cytokines**, which can suppress **gonadotropin-releasing hormone (GnRH)**, leading to reduced LH and FSH levels from the pituitary and subsequently lower testosterone production by the testes.
*It is always associated with endometrial atrophy*
- While obesity can affect endometrial health, it is more commonly associated with **endometrial hyperplasia** due to increased **estrogen production** from peripheral fat, leading to unopposed estrogen stimulation.
- **Endometrial atrophy** is typically seen in states of severe chronic estrogen deficiency, such as post-menopause or severe hypogonadism not directly related to obese states.
*It is associated with hypergonadotropic hypogonadism*
- **Hypergonadotropic hypogonadism** is characterized by low testosterone (or estrogen) with **elevated LH and FSH levels**, indicating primary gonadal failure (e.g., testicular failure or ovarian failure) where the pituitary is overproducing gonadotropins in an attempt to stimulate the failing gonads.
- In obesity, the issue is often at the level of the hypothalamus or pituitary (central), leading to **reduced** rather than elevated gonadotropins.
*There is no change in HPO axis*
- Obesity significantly impacts the **hypothalamic-pituitary-ovarian (HPO)** axis in women and the **hypothalamic-pituitary-testicular (HPT)** axis in men.
- Alterations include increased **leptin** and **insulin resistance**, leading to changes in **GnRH pulsatility**, which disrupts LH and FSH secretion and subsequent gonadal steroid production, thereby affecting fertility.
Endocrinology Indian Medical PG Question 4: By which mechanism do LH and FSH primarily return to baseline levels after ovulation?
- A. Negative feedback on GnRH from testosterone
- B. LH surge
- C. Negative feedback on GnRH by estradiol
- D. Negative feedback on gonadotropin-releasing hormone (GnRH) by progesterone (Correct Answer)
Endocrinology Explanation: ***Negative feedback on GnRH by progesterone***
- After ovulation, the **corpus luteum** secretes **progesterone** (and estradiol), which exerts powerful **negative feedback** on the hypothalamus and pituitary
- **Progesterone** is the **dominant hormone** in the **luteal phase** that suppresses **GnRH** pulsatility, leading to decreased secretion of both **LH** and **FSH** to baseline levels
- This negative feedback maintains low gonadotropin levels throughout the luteal phase until corpus luteum regression
*Negative feedback on GnRH by estradiol*
- **Estradiol** does provide negative feedback, particularly in the **early-mid follicular phase**, where it primarily suppresses **FSH** secretion
- In the luteal phase, estradiol works **synergistically with progesterone**, but **progesterone is the dominant feedback signal** for returning both LH and FSH to baseline after ovulation
- Estradiol alone (without progesterone) triggers the **LH surge** via positive feedback at high concentrations
*Negative feedback on GnRH from testosterone*
- This mechanism is specific to **males**, where **testosterone** from Leydig cells provides negative feedback to regulate **GnRH**, **LH**, and **FSH** secretion
- In females, testosterone plays only a minor role in feedback regulation of the hypothalamic-pituitary-gonadal axis
*LH surge*
- The **LH surge** is a **positive feedback** phenomenon triggered by high **estradiol** levels in the late follicular phase
- This represents the **peak** of LH secretion that triggers ovulation, not a mechanism for returning LH and FSH to **baseline** levels
- After the surge, LH falls due to negative feedback from progesterone and estradiol during the luteal phase
Endocrinology Indian Medical PG Question 5: A patient presents with symptoms of hyperthyroidism. Thyroid function tests would probably reveal:
- A. Increased T4, Increased T3, decreased TSH (Correct Answer)
- B. Increased T4, normal T3, and increased TSH
- C. Increased T3, T4, and increased TSH
- D. Decreased T3 and T4, increased TSH
Endocrinology Explanation: ***Increased T4, Increased T3, decreased TSH***
- In **primary hyperthyroidism**, the thyroid gland overproduces thyroid hormones (**T3 and T4**), leading to elevated levels [1].
- The high levels of T3 and T4 then **feedback negatively** on the pituitary gland, suppressing the release of **TSH** [1].
*Increased T4, normal T3, and increased TSH*
- This pattern is inconsistent with primary hyperthyroidism, as elevated T3 and T4 should suppress TSH.
- An isolated increase in T4 with normal T3 can occur in **subclinical hyperthyroidism** or **thyroxine (T4) resistance**, but increased TSH would suggest pituitary dysfunction or resistance to thyroid hormones.
*Increased T3, T4, and increased TSH*
- Elevated T3 and T4 accompanied by **increased TSH** is a rare presentation, usually indicating **TSH-secreting pituitary adenoma** (secondary hyperthyroidism) or **thyroid hormone resistance** [1], [2].
- In typical hyperthyroidism, high thyroid hormone levels would suppress TSH.
*Decreased T3 and T4, increased TSH*
- This profile is characteristic of **primary hypothyroidism**, where an underactive thyroid gland produces insufficient T3 and T4 [1].
- The low thyroid hormone levels stimulate the pituitary to release **more TSH** in an attempt to stimulate thyroid hormone production [1].
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