Endocrinology Practice Questions

Q: Which of the following drugs is NOT used in the management of SIADH?

Desmopressin. The Syndrome of Inappropriate Antidiuretic Hormone (SIADH) is characterized by excessive release of ADH (Vasopressin), leading to water retention, dilutional hyponatremia, and concentrated urine. **Why Desmopressin is the Correct Answer:** Desmopressin (dDAVP) is a **synthetic analogue of ADH** [1]. Since SIADH is a state of ADH excess, administering Desmopressin would worsen water retention and exacerbate life-threatening hyponatremia. Desmopressin is actually the treatment of choice for *Diabetes Insipidus*, which is the physiological opposite of SIADH [1]. **Analysis of Incorrect Options:** * **Hypertonic Saline (3% NaCl):** Used in the emergency management of severe or symptomatic hyponatremia in SIADH to acutely raise serum sodium levels. * **Demeclocycline:** An antibiotic that acts as an ADH antagonist at the renal collecting duct (induces nephrogenic diabetes insipidus) [2]. It is used in chronic SIADH management when fluid restriction fails [2]. * **Fludrocortisone:** A mineralocorticoid that increases sodium reabsorption in the distal tubule. It is sometimes used off-label in SIADH to help limit urinary sodium loss and maintain sodium balance. **NEET-PG High-Yield Pearls:** 1. **First-line treatment** for SIADH is always **Fluid Restriction** (<800ml/day) [2]. 2. **Vaptans (Tolvaptan, Conivaptan):** These are "Aquaretics" (V2 receptor antagonists) and are now preferred over Demeclocycline for chronic SIADH. 3. **Correction Rate:** In symptomatic hyponatremia, do not exceed a sodium rise of **8–10 mEq/L in 24 hours** to avoid **Osmotic Demyelination Syndrome (Central Pontine Myelinolysis)** [2].

Q: What is the most likely diagnosis in a full-term neonate with electrolyte abnormalities and specific exam findings?

Congenital adrenal hyperplasia. ***Congenital adrenal hyperplasia*** - Classic **21-hydroxylase deficiency** presents with **salt-wasting** electrolyte abnormalities (**hyponatremia**, **hyperkalemia**) and **ambiguous genitalia** in virilized females. - **Elevated 17-hydroxyprogesterone** levels and **decreased cortisol** and **aldosterone** production confirm the diagnosis in full-term neonates. *Hypospadias with cryptorchidism* - These are **isolated genital anomalies** in males that do not cause **electrolyte disturbances** or systemic metabolic abnormalities. - **Normal adrenal function** is maintained, so **salt-wasting** and **hyperkalemia** would not be present. *Preterm ovarian hyperstimulation syndrome* - This condition occurs in **reproductive-age women** undergoing **fertility treatments**, not in **neonates**. - Presents with **ovarian enlargement** and **fluid retention**, completely unrelated to neonatal electrolyte abnormalities. *Turner syndrome* - Typically presents with **normal female external genitalia** and **streak gonads**, not **virilized ambiguous genitalia**. - Associated with **cardiac defects** and **lymphedema**, but does not cause **salt-wasting** electrolyte abnormalities in neonates.

Q: A 72-year-old man is prescribed hydrochlorothiazide for hypertension. Which of the following is the most likely symptomatic side effect?

Sexual impotence. Thiazide diuretics, such as hydrochlorothiazide (HCTZ), are a cornerstone of hypertension management but are associated with several metabolic and symptomatic side effects [3]. Among the options provided, **sexual impotence (erectile dysfunction)** is a well-documented symptomatic side effect of thiazides [1]. While the exact mechanism is multifactorial, it is attributed to decreased peripheral vascular resistance and the depletion of zinc, which is essential for testosterone production [2]. **Analysis of Options:** * **A. Increased serum potassium:** Incorrect. Thiazides cause **hypokalemia** (decreased potassium) [4] by increasing sodium delivery to the distal tubule, which enhances potassium excretion. * **B. Metabolic acidosis:** Incorrect. Thiazides typically cause **metabolic alkalosis** (contraction alkalosis) [4] due to the loss of hydrogen ions and chloride alongside potassium. * **D. Respiratory alkalosis:** Incorrect. This is a primary respiratory pathology (hyperventilation) and is not a direct metabolic consequence of diuretic therapy. **High-Yield Clinical Pearls for NEET-PG:** * **Mnemonic for Thiazide Side Effects (Hyper-GLUC):** Hyper**G**lycemia (impaired insulin release), Hyper**L**ipidemia, Hyper**U**ricemia (can precipitate Gout), and Hyper**C**alcemia (useful in patients with osteoporosis/nephrolithiasis). * **Electrolyte Profile:** Hypokalemia, Hyponatremia, and Hypomagnesemia. * **Clinical Note:** If a patient develops erectile dysfunction on a thiazide, switching to an ACE inhibitor or ARB may be beneficial, as these classes are generally "neutral" or even positive regarding sexual function.

Q: A 75-year-old woman presents with mild congestive heart failure 6 weeks after a myocardial infarction. She has a history of neck surgery for parathyroid adenoma 5 years ago and her ECG shows slow atrial fibrillation. Her serum calcium is 13.0 mg/dL and urinary calcium is 300 mg/24 h. Examination reveals a small mass in the paratracheal region behind the right clavicle. What is the most appropriate management at this time?

Ultrasound-guided alcohol injection of the mass. The patient presents with **persistent/recurrent primary hyperparathyroidism (PHPT)** (Calcium 13.0 mg/dL) and a localized parathyroid mass. The key to this question is the patient’s **recent myocardial infarction (6 weeks ago)** and current **congestive heart failure (CHF)**. [1] 1. **Why Option D is Correct:** In patients with symptomatic hypercalcemia who are **high-risk surgical candidates** (due to recent MI and CHF), invasive surgery is contraindicated. **Ultrasound-guided percutaneous ethanol injection (PEI)** is a minimally invasive alternative to ablate the overactive parathyroid tissue. It effectively reduces PTH and calcium levels without the risks of general anesthesia or complex neck re-exploration. 2. **Why Other Options are Incorrect:** * **Option A:** Repeat neck surgery is the definitive treatment for recurrent PHPT but is contraindicated here. Surgery within 6 months of an MI carries a high risk of perioperative mortality and cardiac complications. * **Option B:** Technetium-99m (Sestamibi) is a **diagnostic imaging modality** used for localization, not a treatment. [1] Radioactive iodine is used for thyroid, not parathyroid, ablation. * **Option C:** Observation is inappropriate. A calcium level of 13.0 mg/dL is significantly elevated (hypercalcemic crisis threshold is >14) and is likely exacerbating her cardiac issues (atrial fibrillation and CHF). **Clinical Pearls for NEET-PG:** * **Surgical Criteria for PHPT:** Serum Ca >1 mg/dL above normal, age <50, T-score <-2.5, or creatinine clearance <60 mL/min. [1] * **Localization:** Sestamibi scan is the gold standard for localizing adenomas before re-operation. [1] * **Post-MI Surgery:** Elective non-cardiac surgery should ideally be delayed **6 months** post-MI to minimize risk. * **ECG in Hypercalcemia:** Characterized by a **shortened QT interval**.

Q: A woman presents with amenorrhea, headache, blurred vision, and galactorrhea. What is the most appropriate investigation?

Prolactin levels. ### Explanation The clinical presentation of **amenorrhea** and **galactorrhea** (the "amenorrhea-galactorrhea syndrome") strongly suggests **hyperprolactinemia**. The addition of **headache and blurred vision** (likely bitemporal hemianopia due to optic chiasm compression) indicates a **prolactin-secreting pituitary adenoma (Prolactinoma)**, specifically a macroadenoma (>10mm) [1]. **Why Prolactin levels are the correct investigation:** Prolactin inhibits the pulsatile release of GnRH from the hypothalamus, leading to decreased LH and FSH, which causes amenorrhea. It also directly stimulates mammary tissue to produce milk (galactorrhea) [1]. Measuring serum prolactin is the essential first step to confirm the diagnosis before proceeding to imaging (MRI Brain) [1]. **Analysis of Incorrect Options:** * **LH and FSH:** While these levels may be low or inappropriately normal in this patient (hypogonadotropic hypogonadism), they are secondary changes and do not identify the primary cause of the symptoms. * **HCG:** Although pregnancy is the most common cause of secondary amenorrhea, it does not typically present with galactorrhea, headaches, or visual field defects. HCG would be a routine test, but Prolactin is the specific investigation for the constellation of symptoms provided. **NEET-PG High-Yield Pearls:** * **Most common secretory pituitary tumor:** Prolactinoma. * **Drug-induced hyperprolactinemia:** Most commonly caused by antipsychotics (dopamine antagonists like Risperidone) and Metoclopramide [1]. * **Hook Effect:** In cases of extremely high prolactin (giant adenomas), lab tests may show falsely low levels; a "dilution test" is required for accurate measurement. * **Treatment of choice:** Medical management with **Dopamine agonists** (Cabergoline is preferred over Bromocriptine due to better efficacy and fewer side effects), even for large macroadenomas [1]. Surgery is reserved for refractory cases.

Q: What is the fasting blood sugar level diagnostic of overt diabetes mellitus?

126 mg/dL. The diagnosis of Diabetes Mellitus (DM) is based on specific glycemic thresholds established by the American Diabetes Association (ADA) and WHO [1]. ### **Explanation of the Correct Answer** **Option C (126 mg/dL)** is the correct threshold for diagnosing overt diabetes. Fasting is defined as no caloric intake for at least 8 hours. A **Fasting Plasma Glucose (FPG) ≥ 126 mg/dL (7.0 mmol/L)** on two separate occasions (or once with symptoms) indicates that the pancreas cannot maintain basal glucose homeostasis, confirming the diagnosis of DM [1]. ### **Analysis of Incorrect Options** * **Option A (106 mg/dL) & B (116 mg/dL):** These values fall within the **Prediabetes** range (Impaired Fasting Glucose). Prediabetes is defined as an FPG between **100–125 mg/dL** [1]. While these levels indicate increased cardiovascular risk, they do not meet the criteria for overt diabetes. * **Option D (140 mg/dL):** While this value is diagnostic of diabetes (as it is >126 mg/dL), it is not the *minimum* diagnostic threshold. Note that 140 mg/dL is the cutoff for the 2-hour value in an Oral Glucose Tolerance Test (OGTT) to define **Impaired Glucose Tolerance (140–199 mg/dL)**. ### **NEET-PG High-Yield Pearls** To diagnose Diabetes Mellitus, any **one** of the following criteria must be met: 1. **HbA1c:** ≥ 6.5% 2. **Fasting Plasma Glucose (FPG):** ≥ 126 mg/dL [1] 3. **2-hour Post-Prandial (75g OGTT):** ≥ 200 mg/dL 4. **Random Plasma Glucose:** ≥ 200 mg/dL **PLUS** classic symptoms (polyuria, polydipsia, weight loss) [1]. * **Note:** In the absence of unequivocal hyperglycemia, results should be confirmed by repeat testing. * **Screening:** In asymptomatic adults, screening should begin at age 35 (revised from 45).

Q: Which one of the following oral hypoglycemic agents is not an insulin secretagogue?

Rosiglitazone. **Explanation:** The core concept tested here is the classification of oral hypoglycemic agents (OHAs) based on their mechanism of action. **Insulin secretagogues** are drugs that stimulate the pancreas to release insulin, whereas **insulin sensitizers** improve the body's response to existing insulin. **Why Rosiglitazone is the Correct Answer:** Rosiglitazone belongs to the **Thiazolidinedione (TZD)** class. Its primary mechanism is as a selective agonist for the nuclear receptor **PPAR-γ** (Peroxisome Proliferator-Activated Receptor gamma) [3]. It works as an **insulin sensitizer**, primarily increasing glucose uptake in peripheral tissues (adipose and muscle) and decreasing hepatic glucose production [3]. It does **not** stimulate the pancreatic beta cells to secrete insulin. **Why the other options are incorrect:** * **Gliclazide & Glimepiride (Options A & B):** These are **Sulfonylureas** (Second and Third generation, respectively). They are classic secretagogues that work by closing ATP-sensitive K+ channels in the pancreatic beta-cell membrane, leading to depolarization and subsequent insulin release [1]. * **Repaglinide (Option C):** This belongs to the **Meglitinide** class. Like sulfonylureas, meglitinides are short-acting secretagogues that stimulate insulin release by binding to a distinct site on the same K+ channel complex. **High-Yield Clinical Pearls for NEET-PG:** * **TZD Side Effects:** Weight gain, peripheral edema, and increased risk of heart failure (due to fluid retention) and bone fractures [1]. * **Hypoglycemia Risk:** Secretagogues (Sulfonylureas/Meglitinides) carry a high risk of hypoglycemia [1], whereas sensitizers (Metformin/TZDs) generally do not cause hypoglycemia when used as monotherapy. * **Metformin:** The first-line drug for Type 2 DM; it is an insulin sensitizer (AMPK activator), not a secretagogue [2].

Question 1

Which statement is true regarding the treatment of hypertensive crisis with encephalopathy in a patient with a pheochromocytoma?

Accepted Answer

Treatment with phentolamine should be started with low-dose phenoxybenzamine to be titrated upward. Surgery should be done in 2 to 3 weeks once blood pressure is below 160/100 mmHg.

Answer

Immediate surgical removal of the mass is indicated.

Answer

High-dose phenoxybenzamine should be used to control blood pressure with surgery in 24 to 48 hours.

Answer

Beta blockade is contraindicated.

Question 2

Which of the following drugs is NOT used in the management of SIADH?

Accepted Answer

Desmopressin

Answer

Fludrocortisone

Answer

Demeclocycline

Answer

Hypertonic saline

Question 3

What is the most likely diagnosis in a full-term neonate with electrolyte abnormalities and specific exam findings?

Accepted Answer

Congenital adrenal hyperplasia

Answer

Hypospadias with cryptorchidism

Answer

Preterm ovarian hyperstimulation syndrome

Answer

Turner syndrome

Question 4

A 72-year-old man is prescribed hydrochlorothiazide for hypertension. Which of the following is the most likely symptomatic side effect?

Accepted Answer

Sexual impotence

Answer

Increased serum potassium

Answer

Metabolic acidosis

Answer

Respiratory alkalosis

Question 5

A patient presents to a clinic with complaints of headache and fatigue. Lab data show serum sodium, 122 mEq/L; serum osmolality, 240 mOsm/L; urine osmolality, 455 mOsm/L. Which condition best correlates with these data?

Accepted Answer

Syndrome of inappropriate antidiuretic hormone secretion (SIADH)

Answer

Neurogenic diabetes insipidus

Answer

Nephrogenic diabetes insipidus

Answer

Diabetes mellitus

Question 6

A 75-year-old woman presents with mild congestive heart failure 6 weeks after a myocardial infarction. She has a history of neck surgery for parathyroid adenoma 5 years ago and her ECG shows slow atrial fibrillation. Her serum calcium is 13.0 mg/dL and urinary calcium is 300 mg/24 h. Examination reveals a small mass in the paratracheal region behind the right clavicle. What is the most appropriate management at this time?

Accepted Answer

Ultrasound-guided alcohol injection of the mass

Answer

Repeat neck surgery

Answer

Treatment with Technetium-99

Answer

Observation and repeat serum calcium in two months

Question 7

A woman presents with amenorrhea, headache, blurred vision, and galactorrhea. What is the most appropriate investigation?

Accepted Answer

Prolactin levels

Answer

Luteinizing hormone (LH)

Answer

Follicle-stimulating hormone (FSH)

Answer

Human chorionic gonadotropin (HCG)

Question 8

What is the fasting blood sugar level diagnostic of overt diabetes mellitus?

Accepted Answer

126 mg/dL

Answer

106 mg/dL

Answer

116 mg/dL

Answer

140 mg/dL

Question 9

A 63-year-old male presented with chronic watery diarrhea associated with flushing, characterized by sudden onset deep red or violaceous erythema of the upper body, often with pruritus, lacrimation, and facial edema. The flushing was noticed to be precipitated by exercise, alcohol, stress, and cheese intake. He has a history of wheezing and clinical examination revealed pellagra-like skin lesions. Which of the following is NOT a useful step in the management of this clinical condition?

Accepted Answer

Rapamycin is useful to control symptoms.

Answer

Lanreotide can be used to control the symptoms.

Answer

Hepatic chemoembolization using doxorubicin is effective.

Answer

Interferon Alpha can be effective in controlling the symptoms.

Question 10

Which one of the following oral hypoglycemic agents is not an insulin secretagogue?

Accepted Answer

Rosiglitazone

Answer

Gliclazide

Answer

Glimiperide

Answer

Repaglinide

Endocrinology — MCQs

Endocrinology — MCQs

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