Endocrinology

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].

Endocrinology Indian Medical PG Question 6: Which of the following conditions is least likely to be associated with diabetes mellitus?

• A. Noonan syndrome
• B. Ataxia telengiectasia
• C. Fanconi syndrome (Correct Answer)
• D. Myotonic dystrophy

Endocrinology Explanation: ***Fanconi syndrome*** - This syndrome primarily involves a generalized defect in **proximal renal tubular function**, leading to excessive excretion of glucose, amino acids, phosphate, and bicarbonate. - While it can be inherited or acquired, it is **not directly linked** to the pathogenesis or common complications of diabetes mellitus. *Noonan syndrome* - Individuals with Noonan syndrome are at an **increased risk of developing diabetes mellitus**, often due to insulin resistance and impaired glucose tolerance. - This genetic disorder, characterized by distinctive facial features, short stature, and cardiac defects, includes **endocrine abnormalities** that predispose to metabolic dysfunction. *Ataxia telangiectasia* - This rare, **autosomal recessive immune deficiency disorder** is associated with an increased incidence of diabetes mellitus [1]. - Patients often present with **insulin resistance** and impaired glucose homeostasis, making diabetes a recognized comorbidity [2]. *Myotonic dystrophy* - Myotonic dystrophy, particularly type 1, is frequently associated with **endocrine abnormalities**, including a high prevalence of **insulin resistance** and impaired glucose tolerance, often progressing to diabetes mellitus [2]. - This inherited neuromuscular disorder can manifest with a variety of systemic complications, with diabetes being a common one.

Endocrinology Indian Medical PG Question 7: An adolescent with type 1 diabetes returns for a follow-up visit after his annual check-up last week. You note that his serum glucose is elevated, and his glycosylated hemoglobin (hemoglobin A1C) is 16.7%. This finding suggests poor control of his diabetes over at least which of the following time-periods?

• A. 1 month
• B. 2 months (Correct Answer)
• C. 8 hours
• D. 1 week

Endocrinology Explanation: ***2 months*** - **Hemoglobin A1c** reflects the average blood glucose levels over the preceding **2-3 months**, as it measures glycated hemoglobin within red blood cells. - Red blood cells have a lifespan of approximately 120 days, so this test provides a good indication of long-term glycemic control. [2] *1 month* - While recent glucose levels contribute to A1c, a 1-month period is generally too short to reflect the full averaging effect of the test. - A 1-month period would not fully capture the complete lifespan of red blood cells, which is central to A1c's utility as a long-term marker. *8 hours* - An 8-hour period is far too short to be reflected by hemoglobin A1c, which assesses average glucose over weeks to months. - This timeframe is more relevant for **fasting glucose** or immediate postprandial glucose levels, not long-term control. [1] *1 week* - Similar to a 1-month period, 1 week is insufficient to reflect the long-term glucose control captured by **hemoglobin A1c**. - **Fructosamine** levels are a better indicator for glucose control over a 1-2 week period, as it reflects glycated proteins with a shorter half-life.

Endocrinology Indian Medical PG Question 8: A 25-year-old woman presents with intermittent double vision and fatigue. Her symptoms are worse at the end of the day. She reports no other focal muscle weakness or sensory symptoms. On examination her eye movements, motor strength, and reflexes in the upper and lower limbs are normal. Repetitive handgrip exercises cause loss of strength in the grip. A CXR reveals an anterior mediastinal mass. Which of the following is the most likely diagnosis of the anterior mediastinal mass?

• A. lymphoma
• B. teratoma
• C. thymoma (Correct Answer)
• D. thyroid

Endocrinology Explanation: ***thymoma*** - The patient's symptoms of **intermittent double vision** and **fatigue, worsening at the end of the day**, are highly suggestive of **myasthenia gravis** [1]. - Approximately 15-20% of patients with myasthenia gravis have a **thymoma**, which is typically found as an **anterior mediastinal mass** on CXR [2]. *lymphoma* - While lymphoma can present as an anterior mediastinal mass, it is not typically associated with the specific neurological symptoms of **myasthenia gravis**. - Lymphoma often presents with systemic symptoms like **fever, night sweats, and weight loss**, which are not described here. *teratoma* - A teratoma is a germ cell tumor that can occur in the anterior mediastinum but does not typically cause **neuromuscular symptoms** like those seen in myasthenia gravis. - They can sometimes be associated with paraneoplastic syndromes, but not usually with symptoms directly pointing to **acetylcholine receptor antibodies** [2]. *thyroid* - An ectopic thyroid gland or thyroid mass in the mediastinum is rare and would not explain the patient's **myasthenic symptoms** [2]. - Thyroid masses are usually asymptomatic unless they cause **compression symptoms** or are hormonally active.

Endocrinology Indian Medical PG Question 9: Plasma cholinesterase levels are affected by various conditions. Which of the following conditions does not typically reduce plasma cholinesterase levels?

• A. Pregnancy
• B. Liver disease
• C. Malnutrition
• D. Chronic renal failure (Correct Answer)

Endocrinology Explanation: ***Chronic renal failure*** - While chronic renal failure can cause various metabolic derangements, it does not typically lead to a significant **reduction in plasma cholinesterase levels**. - Plasma cholinesterase is primarily synthesized in the liver, and its levels are more directly impacted by conditions affecting **liver function** or **protein synthesis** [1]. *Pregnancy* - **Plasma cholinesterase levels** are known to decrease during normal pregnancy, particularly in the third trimester. - This reduction is thought to be due to **hormonal changes** and possibly increased plasma volume. *Liver disease* - Since plasma cholinesterase is synthesized in the **liver**, severe **liver disease** (e.g., cirrhosis, acute hepatitis) significantly impairs its production [1]. - This leads to a marked **reduction in circulating enzyme levels**, which can affect drug metabolism [1]. *Malnutrition* - **Severe malnutrition**, especially protein-calorie malnutrition, can lead to decreased synthesis of many proteins, including plasma cholinesterase. - This is because the body lacks the necessary **amino acids** for enzyme production.

Endocrinology Indian Medical PG Question 10: Which of the following CNS tumor shows increased growth during pregnancy?

• A. Oligodendroglioma
• B. Meningioma (Correct Answer)
• C. Craniopharyngioma
• D. Glioblastoma Multiforme

Endocrinology Explanation: ***Meningioma*** - **Meningiomas** often express receptors for **estrogen** and **progesterone**, leading to increased growth rates during the **estrogen-rich environment of pregnancy**. - This tumor's growth during pregnancy can exacerbate neurological symptoms or lead to the discovery of previously asymptomatic meningiomas. *Oligodendroglioma* - **Oligodendrogliomas** are a type of glioma that do not typically show an increased growth rate in response to hormonal changes during pregnancy. - Their growth is generally independent of **sex hormones**, and their progression is determined by other genetic and molecular factors. *Craniopharyngioma* - **Craniopharyngiomas** are benign epithelial tumors that arise from Rathke's pouch remnants and primarily affect children, though they can occur in adults. - Their growth is not significantly influenced by **hormonal changes** related to pregnancy. *Glioblastoma Multiforme* - **Glioblastoma multiforme (GBM)** is a highly aggressive and fast-growing primary brain tumor, but its growth is not directly stimulated by the hormonal changes of pregnancy. - While GBM can rapidly progress during pregnancy, this is due to its inherent aggressive nature rather than hormonal effects on tumor cells.

Endocrinology Flashcard 1 of 10

Question: The levels of TBG and total thyroid hormone are _____ with hepatic failure, steroid use, and nephrotic syndrome

Answer: decreased

Endocrinology Flashcard 2 of 10

Question: _____ is the most common hormone that is affected in the case of Sheehan syndrome.

Answer: Prolactin

Endocrinology Flashcard 3 of 10

Question: The cut-off values with a 75 g oral glucose tolerance test (OGTT) are _____ for fasting, at 1 hr and 2 hours after meals respectively.

Answer: 92,180 and 153

Endocrinology Flashcard 4 of 10

Question: What kind of shock is seen in Addisonian crisis?_____

Answer: Distributive

Endocrinology Flashcard 5 of 10

Question: Most reliable test for an insulinoma is a _____-hr fasting test

Answer: 72

Endocrinology Flashcard 6 of 10

Question: _____ is the most common endocrinopathy occurring as a paraneoplastic syndrome.

Answer: Cushing syndrome

Endocrinology Flashcard 7 of 10

Question: Secondary sexual characters appear normal in the following: No answer _____

Answer: :)

Endocrinology Flashcard 8 of 10

Question: Diagnosis of parathyroid disease summary: no answer _____

Answer: :)

Endocrinology Flashcard 9 of 10

Question: 1. Identify → _____ 2. Use → _____

Answer: Insulin Syringe

Extra Information: y

Endocrinology Flashcard 10 of 10

Question: Thyroid, Pituitary, & Adrenal _____ may be used to treat acromegaly and gigantism if symptoms persist after trans-sphenoidal resection

Answer: Octreotide (somatostatin analog)