Endocrinology Practice Questions

Q: A 56-year-old lady, a known case of lung cancer, presents with vomiting, headache, and seizures. Investigations reveal a serum osmolarity of 265 mosm/L (normal is 285-295 mosm/L), a serum sodium level of 125 mEq/L (normal value is 136-152 mEq/L), and urine osmolarity greater than 100 mOsm/L. She has normal water intake. Which of the following drugs is useful for this patient?

Tolvaptan. ### Explanation **Diagnosis: SIADH (Syndrome of Inappropriate Antidiuretic Hormone)** The patient presents with **hypotonic hyponatremia** (Serum Na+ 125 mEq/L, Osmolarity 265 mOsm/L) and inappropriately concentrated urine (Urine Osmolarity >100 mOsm/L) in the setting of lung cancer (likely Small Cell Lung Cancer, a common cause of ectopic ADH). The neurological symptoms (seizures, headache) indicate severe/symptomatic hyponatremia [2]. **Why Tolvaptan is Correct:** Tolvaptan is a **selective oral Vasopressin V2-receptor antagonist** (an "Aquaretic"). It works by blocking the action of ADH at the collecting ducts, leading to the excretion of electrolyte-free water [1]. It is specifically indicated for euvolemic hyponatremia (SIADH) when fluid restriction is insufficient or the patient is symptomatic. **Why Other Options are Incorrect:** * **Acetazolamide (A):** A carbonic anhydrase inhibitor used for glaucoma and altitude sickness. It can actually worsen hyponatremia by increasing sodium excretion. * **Hydrochlorothiazide (B):** Thiazide diuretics are a **common cause** of hyponatremia [2]. They inhibit sodium reabsorption in the distal tubule while preserving the medullary gradient, leading to water retention. * **Triamterene (C):** A potassium-sparing diuretic that acts on ENaC channels. It does not address the underlying pathophysiology of ADH excess and is not used to treat SIADH. **Clinical Pearls for NEET-PG:** * **Small Cell Lung Cancer** is the most common malignancy associated with SIADH. * **Management Strategy:** * *Mild/Asymptomatic:* Fluid restriction [1]. * *Moderate/Chronic:* Vaptans (Tolvaptan, Conivaptan) or Demeclocycline [1]. * *Severe/Emergency (Seizures/Coma):* Hypertonic saline (3% NaCl). * **Caution:** Always correct sodium slowly (<8–10 mEq/L in 24 hours) to avoid **Osmotic Demyelination Syndrome** (Central Pontine Myelinolysis) [1].

Q: Dawn phenomenon refers to what?

Early morning hyperglycemia. **Explanation:** The **Dawn Phenomenon** refers to an abnormal early morning increase in blood glucose levels (hyperglycemia), typically occurring between 4:00 AM and 8:00 AM, in patients with diabetes. **1. Why the Correct Answer is Right:** The underlying mechanism is the physiological surge of counter-regulatory hormones—primarily **Growth Hormone (GH)**, but also cortisol, glucagon, and epinephrine—secreted in the early morning hours. These hormones increase hepatic glucose production (gluconeogenesis and glycogenolysis) and decrease peripheral insulin sensitivity [1]. In patients with diabetes, the body cannot compensate with increased insulin secretion, resulting in **early morning hyperglycemia**. **2. Analysis of Incorrect Options:** * **Option B (Early morning hypoglycemia):** This is the opposite of the Dawn phenomenon. It may occur due to excessive evening insulin or skipped meals but is not a named physiological phenomenon. * **Option C (Hypoglycemia followed by hyperglycemia):** This describes the **Somogyi Effect** (Rebound Hyperglycemia). In this case, nocturnal hypoglycemia (often due to too much evening insulin) triggers a massive counter-regulatory hormone surge, leading to high fasting glucose [2]. * **Option D (High insulin levels):** In the Dawn phenomenon, insulin levels are relatively or absolutely deficient compared to the rising glucose levels. **3. NEET-PG High-Yield Pearls:** * **Differentiating Dawn vs. Somogyi:** To distinguish them, check blood glucose at **3:00 AM**. * If 3 AM glucose is **High/Normal** $\rightarrow$ Dawn Phenomenon (Management: Increase evening insulin dose). * If 3 AM glucose is **Low** $\rightarrow$ Somogyi Effect (Management: Decrease evening insulin dose or add a bedtime snack) [2]. * **Growth Hormone** is considered the primary driver of the Dawn phenomenon.

Q: A patient with cushingoid features presents with hemoptysis. The patient shows no response to a dexamethasone suppression test. What is the most likely diagnosis?

Lung cancer with ectopic ACTH production. The patient presents with **Cushing syndrome** (cushingoid features) and **hemoptysis**, which is a classic "red flag" for underlying pulmonary pathology [4]. **1. Why Option C is Correct:** The key to this diagnosis is the combination of ectopic ACTH production and the failure of the **High-Dose Dexamethasone Suppression Test (HDDST)**. In **Ectopic ACTH Syndrome** (most commonly caused by **Small Cell Lung Cancer**), the tumor cells produce ACTH autonomously [1]. Unlike pituitary adenomas, these ectopic sources do not possess glucocorticoid receptors that respond to feedback inhibition; therefore, cortisol levels remain high despite dexamethasone administration. The hemoptysis points directly to a lung malignancy as the source [4]. **2. Why Other Options are Incorrect:** * **Pituitary Microadenoma (Cushing’s Disease):** While this is the most common cause of endogenous Cushing syndrome, these tumors usually retain some sensitivity to negative feedback. They typically show **>50% suppression** of cortisol during an HDDST. * **Adrenal Adenoma/Hyperplasia:** These are primary adrenal causes where ACTH levels would be **suppressed** (low) due to autonomous cortisol production by the adrenal gland itself [3]. The question implies an ACTH-dependent process given the context of ectopic production. **3. NEET-PG High-Yield Pearls:** * **Small Cell Lung Carcinoma** is the most common cause of rapid-onset Ectopic ACTH [1]. * **Bronchial Carcinoid** is another ectopic source but usually presents with a more chronic course. * **Hyperpigmentation and Hypokalemia** are more common in ectopic ACTH than in Cushing’s disease due to very high ACTH levels (cross-reactivity with MSH receptors) and mineralocorticoid effects of high cortisol. * **Localization:** If HDDST fails to suppress cortisol, the next step is a **CT Chest/Abdomen** to locate the ectopic tumor [2].

Q: Which one of the following features may NOT be seen in hypocalcemia/tetany?

Clotting defects. The correct answer is **Clotting defects**. While calcium (Factor IV) is essential for the coagulation cascade, clinical hypocalcemia does not manifest as bleeding or clotting disorders. This is because the level of ionized calcium required for blood clotting is significantly lower than the level required to sustain life; a patient would succumb to fatal tetany or cardiac arrest long before calcium levels dropped low enough to impair coagulation. **Analysis of other options:** * **Prolongation of QT interval:** This is a classic ECG finding in hypocalcemia [1]. It occurs due to the lengthening of Phase 2 (the plateau phase) of the cardiac action potential. * **Cataract formation:** Chronic hypocalcemia (often seen in hypoparathyroidism) leads to the formation of subcapsular cataracts. Low calcium levels in the aqueous humor interfere with the metabolic pumps of the lens, leading to hydration and opacification. * **Intestinal and biliary colic:** Hypocalcemia increases neuromuscular irritability [1], which can lead to spasms of smooth muscles in the gastrointestinal and biliary tracts, manifesting as abdominal pain or colic. **High-Yield Clinical Pearls for NEET-PG:** * **Neuromuscular Signs:** Look for **Chvostek’s sign** (facial twitching on tapping the facial nerve) and **Trousseau’s sign** (carpal spasm after inflating a BP cuff). Trousseau’s is more specific. * **ECG:** Hypocalcemia = Long QT; Hypercalcemia = Short QT [1]. * **Basal Ganglia Calcification:** Chronic hypocalcemia can lead to ectopic calcification in the brain, often presenting as extrapyramidal symptoms. * **Emergency Management:** IV Calcium Gluconate (10%) is the preferred treatment for symptomatic tetany.

Q: A 27-year-old woman complains of pain in her left shin. X-rays of the leg reveal a stress fracture of the tibia, decreased cortical bone density, and increased radiolucency. She is suspected of having osteomalacia (impaired mineralization of bone matrix). Which of the following is the most common biochemical manifestation of osteomalacia?

Decreased vitamin D. **Explanation:** Osteomalacia is a metabolic bone disease characterized by **impaired mineralization of the osteoid (bone matrix)** [1], most commonly due to a deficiency in Vitamin D. **1. Why Vitamin D deficiency is the correct answer:** Vitamin D is essential for the intestinal absorption of calcium and phosphorus. In its absence, serum calcium levels drop, triggering the parathyroid glands to release Parathyroid Hormone (PTH). This **Secondary Hyperparathyroidism** attempts to maintain serum calcium by mobilizing it from bones and increasing renal phosphorus excretion [1]. Consequently, low Vitamin D is the primary biochemical driver and the most common finding in these patients. **2. Analysis of Incorrect Options:** * **A. Hyperphosphatemia:** Incorrect. Due to secondary hyperparathyroidism, PTH increases renal phosphate excretion, leading to **hypophosphatemia**, not hyperphosphatemia [1]. * **B. Hypoparathyroidism:** Incorrect. Osteomalacia typically presents with **Secondary Hyperparathyroidism** (elevated PTH) as a compensatory mechanism for low serum calcium [1]. * **D. Hypercalcemia:** Incorrect. Patients are usually **hypocalcemic** or have low-normal calcium levels [1]. Hypercalcemia would suggest primary hyperparathyroidism or malignancy. **3. NEET-PG High-Yield Pearls:** * **Biochemical Profile:** ↓/Normal Calcium, ↓ Phosphate, **↑ Alkaline Phosphatase (ALP)**, ↑ PTH, and ↓ 25(OH) Vitamin D. * **Radiological Signs:** Look for **Looser’s zones** (pseudofractures/Milkman’s lines), which are pathognomonic—transverse lucent bands perpendicular to the bone cortex [2]. * **Clinical Presentation:** Diffuse bone pain, muscle weakness (proximal myopathy), and "waddling gait" [1]. * **Histology:** Characterized by an **increased thickness of unmineralized osteoid seams** [2].

Q: Which one of the following is not a feature of Klinefelter's syndrome?

Short 4th metacarpal. **Explanation:** **Klinefelter’s Syndrome (47, XXY)** is the most common cause of primary hypogonadism in males. [1] The correct answer is **Short 4th metacarpal**, as this is a classic clinical feature of **Turner’s Syndrome (45, XO)** and Pseudohypoparathyroidism, not Klinefelter’s. [2] **Analysis of Options:** * **Short 4th metacarpal (Correct Answer):** Also known as **Archibald’s sign**, this is a skeletal deformity associated with Turner’s syndrome. [2] In Klinefelter’s, skeletal findings typically involve increased limb length rather than shortening of metacarpals. [1] * **Gynecomastia:** Present in approximately 40-50% of cases due to an increased estrogen-to-androgen ratio. It also carries a significantly higher risk of male breast cancer. [3] * **Eunuchoid habitus:** Characterized by tall stature, long legs (lower segment > upper segment), and a decreased arm span-to-height ratio. [1] This occurs because testosterone deficiency leads to delayed epiphyseal closure. * **Hypogonadism:** Patients exhibit primary testicular failure characterized by small, firm testes (usually <2 cm), azoospermia (infertility), and low testosterone levels with compensatory elevations in LH and FSH. [1] **High-Yield Clinical Pearls for NEET-PG:** * **Karyotype:** Most commonly 47, XXY due to meiotic non-disjunction. * **Histology:** Testicular biopsy shows **hyalinization and fibrosis of seminiferous tubules** and Leydig cell hyperplasia. [1] * **Lab Findings:** ↓ Testosterone, ↑ FSH, ↑ LH, ↑ Estradiol. [1] * **Associated Risks:** Increased risk of Germ Cell Tumors (especially mediastinal), Breast Cancer, and autoimmune diseases (SLE). [3] * **Psychosocial:** Often associated with mild intellectual disability or learning delays. [1]

Q: The classic triad of pheochromocytoma includes episodes of all of the following except:

Hypertension. The correct answer is **Hypertension**. ### **Explanation** While **hypertension** is the most common clinical sign of pheochromocytoma (present in >90% of cases), it is **not** part of the "classic symptomatic triad." The triad refers specifically to the paroxysmal symptoms experienced by the patient during a catecholamine surge. The classic clinical triad consists of: 1. **Headache** (most common symptom) 2. **Sweating** (diaphoresis) 3. **Palpitations** (tachycardia) The presence of all three symptoms plus hypertension has a specificity of over 90% for pheochromocytoma. However, because hypertension is a physical finding (sign) rather than a symptom in the triad, it is the "except" in this question. ### **Analysis of Options** * **A, B, and C (Palpitations, Headache, Sweating):** These constitute the classic triad. They occur in paroxysms ("spells") due to the episodic release of epinephrine and norepinephrine from the adrenal medulla tumor. * **D (Hypertension):** Although it is the most common feature, it is categorized as a **clinical sign**. Hypertension in pheochromocytoma can be sustained (60%) or paroxysmal (40%). ### **NEET-PG High-Yield Pearls** * **Rule of 10s:** 10% bilateral, 10% malignant, 10% pediatric, 10% extra-adrenal (Paraganglioma), and 10% familial. * **Best Screening Test:** Plasma free metanephrines (high sensitivity). * **Best Confirmatory Test:** 24-hour urinary fractionated metanephrines and catecholamines (high specificity). * **Pre-operative Management:** Always give **Alpha-blockers first** (e.g., Phenoxybenzamine) followed by Beta-blockers to avoid a hypertensive crisis (unopposed alpha-stimulation). * **Genetic Associations:** MEN 2A, MEN 2B, VHL syndrome, and NF-1.

Q: Which of the following statements regarding the lipid abnormalities seen in patients with type 2 diabetes mellitus is incorrect?

Elevated levels of plasma LDL cholesterol. The characteristic pattern of dyslipidemia in Type 2 Diabetes Mellitus (T2DM) is known as "Diabetic Dyslipidemia." It is primarily driven by insulin resistance rather than a simple elevation of total cholesterol. In T2DM, the absolute level of LDL cholesterol is typically not significantly elevated compared to the general population. Instead, the abnormality lies in the quality of the LDL particles. Due to high triglyceride levels, LDL particles undergo remodeling to become small, dense LDL (sdLDL) [1]. These particles are more atherogenic because they easily penetrate the arterial wall and are more susceptible to oxidation [1]. Insulin resistance leads to increased lipolysis in adipose tissue, flooding the liver with free fatty acids [3]. This stimulates the overproduction of VLDL (rich in triglycerides), leading to hypertriglyceridemia [1]. High VLDL levels trigger an exchange where HDL loses cholesterol and gains triglycerides via CETP [1]. These triglyceride-rich HDL particles are rapidly cleared by hepatic lipase, resulting in low plasma HDL levels [1]. Reduced activity of Lipoprotein Lipase (LPL) in insulin-deficient states contributes to decreased clearance of VLDL and chylomicrons [2].

Question 1

A 56-year-old lady, a known case of lung cancer, presents with vomiting, headache, and seizures. Investigations reveal a serum osmolarity of 265 mosm/L (normal is 285-295 mosm/L), a serum sodium level of 125 mEq/L (normal value is 136-152 mEq/L), and urine osmolarity greater than 100 mOsm/L. She has normal water intake. Which of the following drugs is useful for this patient?

Accepted Answer

Tolvaptan

Answer

Acetazolamide

Answer

Hydrochlorothiazide

Answer

Triamterene

Question 2

What is the most appropriate management of diabetic ketoacidosis?

Accepted Answer

500ml of 0.9% Saline over 15 minutes with potassium chloride and a fixed rate insulin infusion

Answer

500ml of 0.9% Saline over 15 minutes and a fixed rate insulin infusion

Answer

500ml of 0.9% Saline over 30 minutes with potassium chloride and a rapid acting subcutaneous insulin injection

Answer

500ml of 0.9% Saline over 30 minutes and a rapid acting subcutaneous insulin injection

Question 3

An 18-year-old woman develops weakness, weight gain, amenorrhea, abdominal striae, and behavioral abnormalities. Physical examination reveals lateral visual field loss. Which of the following is the most likely diagnosis?

Accepted Answer

A functional pituitary tumor

Answer

Adrenal hyperplasia

Answer

Anorexia nervosa with bulimia

Answer

Glioblastoma multiforme

Question 4

Dawn phenomenon refers to what?

Accepted Answer

Early morning hyperglycemia

Answer

Early morning hypoglycemia

Answer

Hypoglycemia followed by hyperglycemia

Answer

High insulin levels

Question 5

A patient with cushingoid features presents with hemoptysis. The patient shows no response to a dexamethasone suppression test. What is the most likely diagnosis?

Accepted Answer

Lung cancer with ectopic ACTH production

Answer

Adrenal hyperplasia

Answer

Adrenal adenoma

Answer

Pituitary microadenoma

Question 6

Which one of the following features may NOT be seen in hypocalcemia/tetany?

Accepted Answer

Clotting defects

Answer

Prolongation of QT interval

Answer

Cataract formation

Answer

Intestinal and biliary colic

Question 7

A 27-year-old woman complains of pain in her left shin. X-rays of the leg reveal a stress fracture of the tibia, decreased cortical bone density, and increased radiolucency. She is suspected of having osteomalacia (impaired mineralization of bone matrix). Which of the following is the most common biochemical manifestation of osteomalacia?

Accepted Answer

Decreased vitamin D

Answer

Hyperphosphatemia

Answer

Hypoparathyroidism

Answer

Hypercalcemia

Question 8

Which one of the following is not a feature of Klinefelter's syndrome?

Accepted Answer

Short 4th metacarpal

Answer

Gynecomastia

Answer

Eunuchoid habitus

Answer

Hypogonadism

Question 9

The classic triad of pheochromocytoma includes episodes of all of the following except:

Accepted Answer

Hypertension

Answer

Palpitations

Answer

Headache

Answer

Sweating

Question 10

Which of the following statements regarding the lipid abnormalities seen in patients with type 2 diabetes mellitus is incorrect?

Accepted Answer

Elevated levels of plasma LDL cholesterol

Answer

Increase in hepatic VLDL production

Answer

Decrease in plasma levels of HDL cholesterol

Answer

Elevated plasma triglycerides

Endocrinology — MCQs

Endocrinology — MCQs

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