Endocrinology Practice Questions

Q: A 25-year-old man requests cholesterol screening due to a family history of premature coronary artery disease (CAD). His lipid levels reveal elevated total and LDL cholesterol, with normal HDL and triglyceride values. His physical examination is normal. What is the most common cause of genetic dyslipidemia?

Familial combined hyperlipidemia. FCHL is the **most common genetic dyslipidemia**, affecting approximately 1 in 100 to 200 individuals [1]. It is characterized by an overproduction of Apolipoprotein B-100 (ApoB), leading to increased VLDL and LDL. The clinical presentation is highly variable; within the same family (or even the same patient over time), one may see elevated LDL, elevated triglycerides, or both [1]. In this case, the patient presents with isolated LDL elevation and a strong family history of premature CAD, which is a classic presentation of FCHL. **2. Why the other options are incorrect:** * **B. Familial Hypercholesterolemia (FH):** While a major cause of premature CAD, it is less common than FCHL (prevalence ~1 in 250 for heterozygotes) [1]. FH typically presents with much higher LDL levels (>190 mg/dL) and often features physical signs like tendon xanthomas, which are absent here [1]. * **C. Familial Defective Apo B-100:** This involves a mutation in the ligand-binding domain of ApoB-100 [1]. It mimics FH clinically but is significantly rarer. * **D. Apo C-II Deficiency:** This leads to Familial Chylomicronemia Syndrome (Type I Hyperlipoproteinemia). It presents with severe hypertriglyceridemia, eruptive xanthomas, and pancreatitis, rather than isolated high LDL and premature CAD. **Clinical Pearls for NEET-PG:** * **Most common genetic cause of CAD:** Familial Combined Hyperlipidemia. * **Fredrickson Classification:** FCHL is usually Type IIa, IIb, or IV. * **Physical Exam:** Unlike FH (Tendon xanthomas) or Type III (Palmar xanthomas), FCHL usually has **no pathognomonic physical findings** on examination [1]. * **Screening:** Always screen first-degree relatives of patients with premature CAD (Men <55y, Women <65y).

Q: Which of the following skin findings is associated with pheochromocytoma?

Cafe-au-lait spots. **Explanation:** The correct answer is **Cafe-au-lait spots**. This association is rooted in the genetic syndromes linked to pheochromocytoma, specifically **Neurofibromatosis Type 1 (NF1)**. Approximately 1–5% of patients with NF1 develop pheochromocytoma. Cafe-au-lait spots are hyperpigmented macules that serve as a hallmark cutaneous marker for NF1, alongside Lisch nodules and neurofibromas. **Analysis of Options:** * **Cafe-au-lait spots (Correct):** Associated with NF1, which is part of the familial clusters of pheochromocytoma (alongside MEN 2A/2B and Von Hippel-Lindau disease). * **Vitiligo:** An autoimmune destruction of melanocytes. While associated with autoimmune polyendocrine syndromes (APS), it has no direct link to pheochromocytoma. * **Ash leaf spots:** These are hypopigmented macules characteristic of **Tuberous Sclerosis**, not pheochromocytoma. * **Acanthosis nigricans:** A marker of **insulin resistance**, often seen in Type 2 Diabetes, PCOS, or gastric malignancy, but not catecholamine-secreting tumors. **Clinical Pearls for NEET-PG:** * **Rule of 10s:** Pheochromocytoma is 10% bilateral, 10% malignant, 10% pediatric, and 10% extra-adrenal (Paraganglioma). * **Genetic Associations:** Remember the mnemonic **"MVN"** for familial cases: **M**EN 2A/2B (RET gene), **V**on Hippel-Lindau (VHL gene), and **N**F1 (NF1 gene) [1]. * **Triad:** The classic clinical triad includes episodic headache, sweating (diaphoresis), and tachycardia. * **Diagnosis:** The best initial screening test is 24-hour urinary fractionated metanephrines or plasma free metanephrines [1].

Q: Thyrotoxic periodic paralysis leads to extreme muscle weakness due to?

Hypokalemia. **Thyrotoxic Periodic Paralysis (TPP)** is a rare but life-threatening complication of hyperthyroidism characterized by sudden episodes of extreme muscle weakness and **hypokalemia**. **Why Hypokalemia is the correct answer:** The pathophysiology involves an intracellular shift of potassium rather than a total body deficit. Excess thyroid hormones increase the activity of the **Na+/K+-ATPase pump**, which drives potassium from the extracellular fluid into the muscle cells. This leads to hyperpolarization of the muscle membrane, making it non-excitable and resulting in acute flaccid paralysis. This shift is often triggered by high carbohydrate meals (insulin also stimulates the Na+/K+ pump) or strenuous exercise. **Why other options are incorrect:** * **Hypocalcemia:** Typically presents with tetany, carpopedal spasm, and Chvostek/Trousseau signs, rather than periodic flaccid paralysis. * **Hypomagnesemia:** Often co-exists with hypokalemia but is not the primary driver of the paralytic episodes in thyrotoxicosis. * **Hyponatremia:** Usually presents with neurological symptoms like confusion, seizures, or coma due to cerebral edema, not focal or global muscle paralysis. **High-Yield Clinical Pearls for NEET-PG:** * **Demographics:** Most common in **Asian males**, despite hyperthyroidism being more common in females. * **Triggers:** High-carb meals, alcohol, and rest after heavy exercise. * **Management:** Propranolol (non-selective beta-blocker) is the treatment of choice as it reverses the overactivity of the Na+/K+ pump [1]. * **Caution:** Be careful with aggressive K+ replacement; as the episode resolves, potassium shifts back out of cells, leading to a risk of **rebound hyperkalemia**.

Q: Which of the following is false about viral thyroiditis?

Initial hypothyroid state. **Explanation:** Viral thyroiditis, also known as **De Quervain’s thyroiditis** or Subacute Granulomatous Thyroiditis, typically follows a viral upper respiratory tract infection. **Why Option C is False (The Correct Answer):** The hallmark of subacute thyroiditis is a **triphasic clinical course**. It begins with an **initial hyperthyroid state**, not hypothyroid. This occurs because the viral inflammation causes destruction of thyroid follicles, leading to the "leakage" of preformed thyroid hormones (T3 and T4) into the circulation. This is followed by a transient euthyroid phase, then a temporary hypothyroid phase as hormone stores are depleted, and finally, a return to normal function. **Analysis of Other Options:** * **Option A (Self-limiting):** Most cases resolve spontaneously within weeks to months. Treatment is usually supportive with NSAIDs or steroids for pain. * **Option B (Painful):** This is a classic clinical feature. Patients present with a **tender, painful thyroid gland**, often radiating to the jaw or ears. * **Option D (Raised ESR):** A markedly elevated Erythrocyte Sedimentation Rate (often >50–100 mm/hr) is a highly characteristic laboratory finding in De Quervain’s. **High-Yield Clinical Pearls for NEET-PG:** * **Radioactive Iodine Uptake (RAIU):** Characteristically **low/depressed** during the initial hyperthyroid phase (due to follicular damage and TSH suppression). * **Histology:** Features **multinucleated giant cells** and granulomatous inflammation. * **Treatment of choice:** NSAIDs for mild cases; Prednisone for severe pain. Beta-blockers can be used for thyrotoxic symptoms; antithyroid drugs (PTU/Methimazole) are **not** indicated as there is no excess synthesis.

Q: Syndrome of apparent mineralocorticoid excess is due to?

Lack of inactivation of cortisol to cortisone. Syndrome of Apparent Mineralocorticoid Excess (SAME) is a genetic or acquired condition characterized by hypertension, hypokalemia, and metabolic alkalosis, despite having low plasma renin and low aldosterone levels. 1. Why the correct answer is right: The mineralocorticoid receptor (MR) in the distal tubule has an equal affinity for both aldosterone and cortisol. Under normal physiological conditions, the enzyme 11β-hydroxysteroid dehydrogenase type 2 (11β-HSD2) converts active cortisol into inactive cortisone [1]. This ensures that only aldosterone can activate the MR. In SAME, there is a deficiency or inhibition of 11β-HSD2. Consequently, cortisol is not inactivated; it floods the MR, mimicking the effects of aldosterone (mineralocorticoid excess) despite aldosterone levels being suppressed. 2. Why other options are wrong: * A & B: In SAME, aldosterone levels are actually suppressed (low) due to the negative feedback loop caused by the cortisol-induced volume expansion and hypertension. * C: Increased cortisol production is characteristic of Cushing’s Syndrome. While severe Cushing’s can overwhelm the 11β-HSD2 enzyme, SAME specifically refers to the failure of the inactivation process rather than primary overproduction. 3. NEET-PG High-Yield Pearls: * Etiology: Autosomal recessive mutation in the HSD11B2 gene or acquired via Licorice ingestion (Glycyrrhetinic acid inhibits 11β-HSD2). * Biochemical Marker: An increased ratio of Urinary Cortisol to Urinary Cortisone (THF+αTHF/THE). * Treatment: Potassium-sparing diuretics (Spironolactone or Eplerenone) or low-dose glucocorticoids (to suppress ACTH and endogenous cortisol production). * Differential: Liddle’s Syndrome also presents with low renin/aldosterone but is due to a gain-of-function mutation in the ENaC channel.

Q: In thyrotoxicosis, which of the following is NOT controlled by beta-blockers?

Oxygen consumption. Explanation: In thyrotoxicosis, the clinical manifestations arise from two distinct mechanisms: **increased sympathetic (adrenergic) activity** and a **hypermetabolic state** caused by direct action of thyroid hormones ($T_3$ and $T_4$) on tissues. **1. Why Oxygen Consumption is the Correct Answer:** Beta-blockers (like Propranolol) act by antagonizing $\beta$-adrenergic receptors. While they effectively mitigate the symptoms of sympathetic overactivity, they have **no effect on the basal metabolic rate (BMR)** or the direct calorigenic effects of thyroid hormones [2,3]. Increased oxygen consumption is a result of thyroid hormone-induced stimulation of $Na^+/K^+$ ATPase activity and mitochondrial respiration [4]. Since this is a direct metabolic effect and not mediated by catecholamines, beta-blockers cannot control it. **2. Why the other options are incorrect:** * **Anxiety and Tremors:** These are neurological manifestations of increased $\beta$-adrenergic sensitivity [3]. Beta-blockers cross the blood-brain barrier (especially Propranolol) and block peripheral receptors to effectively reduce these symptoms [1]. * **Tachycardia:** This is driven by increased $\beta_1$ receptor expression in the myocardium [4]. Beta-blockers are the first-line treatment to rapidly control heart rate in thyrotoxic patients [1]. **Clinical Pearls for NEET-PG:** * **Drug of Choice:** Propranolol is preferred in thyrotoxic crisis (thyroid storm) because, in high doses, it also inhibits the **peripheral conversion of $T_4$ to $T_3$** (by inhibiting 5'-deiodinase). * **Contraindication:** Avoid beta-blockers in patients with thyrotoxicosis who have co-existing **asthma**; use cardioselective agents (e.g., Atenolol) or Calcium Channel Blockers (Diltiazem) instead. * **Key Concept:** Beta-blockers provide **symptomatic relief** but do not treat the underlying hyperthyroidism [1].

Question 1

A 25-year-old man requests cholesterol screening due to a family history of premature coronary artery disease (CAD). His lipid levels reveal elevated total and LDL cholesterol, with normal HDL and triglyceride values. His physical examination is normal. What is the most common cause of genetic dyslipidemia?

Accepted Answer

Familial combined hyperlipidemia

Answer

Familial hypercholesterolemia

Answer

Familial defective Apo B

Answer

Apo C-II deficiency

Question 2

A 30-year-old woman presented with secondary amenorrhea for 3 years along with galactorrhea. What is the most likely cause of her symptoms?

Accepted Answer

Prolactinoma

Answer

Craniopharyngioma

Answer

Meningioma

Answer

Subarachnoid hemorrhage

Question 3

Which of the following skin findings is associated with pheochromocytoma?

Accepted Answer

Cafe-au-lait spots

Answer

Vitiligo

Answer

Ash leaf spots

Answer

Acanthosis nigricans

Question 4

Thyrotoxic periodic paralysis leads to extreme muscle weakness due to?

Accepted Answer

Hypokalemia

Answer

Hypocalcemia

Answer

Hypomagnesemia

Answer

Hyponatremia

Question 5

Which of the following is false about viral thyroiditis?

Accepted Answer

Initial hypothyroid state

Answer

Self limiting

Answer

Painful

Answer

Raised ESR

Question 6

A 52-year-old alcoholic presents with a skin rash on his chest, diarrhea, and abdominal pain. Examination reveals a scaly and pigmented rash on sun-exposed areas, a soft abdomen, and impaired short-term memory. The patient exhibits dermatitis, diarrhea, and dementia syndrome. What is the most likely diagnosis for this patient's vitamin deficiency or excess?

Accepted Answer

niacin

Answer

thiamine

Answer

pyridoxine

Answer

vitamin C

Question 7

Tumor-induced hypoglycemia is seen in all of the following EXCEPT:

Accepted Answer

Lymphoma

Answer

Mesenchymal tumors

Answer

Hepatocellular carcinoma

Answer

Adrenal carcinoma

Question 8

Syndrome of apparent mineralocorticoid excess is due to?

Accepted Answer

Lack of inactivation of cortisol to cortisone

Answer

Increased aldosterone production

Answer

Lack of inactivation of aldosterone

Answer

Increased cortisol production

Question 9

In thyrotoxicosis, which of the following is NOT controlled by beta-blockers?

Accepted Answer

Oxygen consumption

Answer

Anxiety

Answer

Tremors

Answer

Tachycardia

Question 10

A 55-year-old diabetic man presents to the emergency room in an unresponsive state. His laboratory values show PCO2 19 mm Hg, HCO3 11 mEq/L, and pH 6.9. What is the most appropriate immediate treatment for this patient?

Accepted Answer

Administration of insulin

Answer

Administration of an oral hypoglycemic agent

Answer

Administration of bicarbonate

Answer

Close observation only

Endocrinology — MCQs

Endocrinology — MCQs

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