Endocrinology — MCQs

A 40-year-old woman presents with lipid investigations suggestive of familial hypercholesterolemia, characterized by increased cholesterol, increased low-density lipoprotein, and normal triglycerides. This condition is associated with an increased risk for premature atherosclerosis and the presence of tuberous and tendon xanthomas. Before diagnosing familial hypercholesterolemia, secondary causes must be ruled out. Which of the following conditions is most likely to cause secondary hyperlipidemia?

Q479Medium

The triad of diabetes mellitus, gallstones, and steatorrhea is associated with which of the following tumors?

Q480Easy

All are features of Cushing's syndrome except?

Endocrinology Indian Medical PG Practice Questions and MCQs

Question 471: Primary hyperaldosteronism (Conn's syndrome) is characterized by:

A. High renin, high aldosterone
B. Low renin, high aldosterone (Correct Answer)
C. Low renin, low aldosterone
D. High renin, low aldosterone

Explanation: **Explanation:** Primary hyperaldosteronism (Conn’s syndrome) is a condition where the adrenal cortex (usually due to an adrenal adenoma or bilateral hyperplasia) autonomously secretes excessive **aldosterone**. 1. **Why Option B is correct:** In primary hyperaldosteronism, the excess aldosterone acts on the distal tubules of the kidney to increase sodium reabsorption and water retention. This leads to volume expansion and hypertension. The increased blood pressure and volume provide **negative feedback** to the juxtaglomerular apparatus, suppressing the secretion of **renin**. Thus, the hallmark is a high Aldosterone-to-Renin Ratio (ARR). 2. **Why other options are incorrect:** * **Option A (High Renin, High Aldosterone):** This characterizes **Secondary Hyperaldosteronism** (e.g., Renal artery stenosis, CHF, or Cirrhosis), where renin is high due to perceived low renal perfusion, which then stimulates aldosterone. * **Option C (Low Renin, Low Aldosterone):** This occurs in conditions mimicking mineralocorticoid excess, such as **Liddle Syndrome** or exogenous mineralocorticoid intake (e.g., Licorice ingestion). * **Option D (High Renin, Low Aldosterone):** This is seen in **Primary Adrenal Insufficiency (Addison’s disease)**, where the adrenal gland fails to produce aldosterone despite high renin stimulation. **NEET-PG High-Yield Pearls:** * **Classic Triad:** Hypertension, Hypokalemia, and Metabolic Alkalosis. * **Screening Test:** Aldosterone-to-Renin Ratio (ARR > 20-30 is suggestive). * **Confirmatory Test:** Saline infusion test (failure to suppress aldosterone) or Oral Salt Loading test. * **Management:** Surgical excision for unilateral adenoma; **Spironolactone** or Eplerenone (Aldosterone antagonists) for bilateral adrenal hyperplasia.

Question 472: What is the first drug to be started in Sheehan's syndrome?

A. Gonadotropins
B. Estrogen
C. Thyroxine
D. Corticosteroids (Correct Answer)

Explanation: Sheehan’s syndrome is postpartum hypopituitarism caused by ischemic necrosis of the pituitary gland due to severe obstetric hemorrhage [1]. This results in a deficiency of multiple anterior pituitary hormones (Panhypopituitarism). **Why Corticosteroids are the first choice:** In panhypopituitarism, both the adrenal axis (ACTH) and the thyroid axis (TSH) are often compromised. **Corticosteroids must always be started before Thyroxine.** If thyroxine is administered first, it increases the metabolic rate and the clearance of the already low levels of circulating cortisol [1]. This can precipitate an **acute adrenal crisis**, which is life-threatening. Therefore, ensuring adequate glucocorticoid levels is the absolute clinical priority. **Analysis of Incorrect Options:** * **Thyroxine (C):** While thyroid replacement is necessary, starting it before steroids is contraindicated due to the risk of adrenal crisis. * **Estrogen (B) & Gonadotropins (A):** These are used to manage infertility and secondary amenorrhea. While important for long-term quality of life and bone health, they are not life-saving and are addressed only after the adrenal and thyroid axes are stabilized [1]. **High-Yield Clinical Pearls for NEET-PG:** * **Earliest Sign:** Failure of lactation (due to prolactin deficiency) and failure to resume menses. * **Diagnosis:** Gold standard is the Insulin Tolerance Test (to check GH and ACTH), but clinically, low target organ hormones with low/normal pituitary hormones are diagnostic. * **MRI Finding:** "Empty Sella" is often seen in the chronic phase. * **Electrolyte Clue:** Unlike primary Addison’s disease, hyperkalemia is usually absent in Sheehan’s because the mineralocorticoid (aldosterone) axis is regulated by Renin-Angiotensin, not the pituitary [1].

Question 473: Addison's disease typically:

A. Causes hypertension
B. Causes hypopigmentation
C. Is an autoimmune disease (Correct Answer)
D. Steroids are contraindicated

Explanation: **Explanation:** **Addison’s Disease (Primary Adrenocortical Insufficiency)** occurs due to the destruction of the adrenal cortex, leading to a deficiency of cortisol, aldosterone, and adrenal androgens [3]. 1. **Why Option C is correct:** In developed countries and increasingly in urban India, **autoimmune adrenalitis** is the most common cause of Addison’s disease (accounting for ~80% of cases). It involves the destruction of the adrenal cortex by 21-hydroxylase antibodies [1]. (Note: In rural India, Tuberculosis remains a significant infectious cause) [4]. 2. **Why the other options are incorrect:** * **Option A:** Addison’s causes **hypotension** (specifically postural hypotension) due to the loss of aldosterone, leading to sodium wasting and volume depletion. * **Option B:** It causes **hyperpigmentation**, not hypopigmentation. Low cortisol triggers a compensatory increase in ACTH [1]. Since ACTH and Melanocyte-Stimulating Hormone (MSH) share a common precursor (POMC), high ACTH levels stimulate melanocytes, especially in skin creases, scars, and buccal mucosa. * **Option D:** Steroids are the **mainstay of treatment**, not contraindicated. Patients require lifelong replacement of glucocorticoids (Hydrocortisone/Prednisolone) and mineralocorticoids (Fludrocortisone) [1]. **High-Yield Clinical Pearls for NEET-PG:** * **Electrolyte Triad:** Hyponatremia, Hyperkalemia, and Metabolic Acidosis [2]. * **Diagnosis:** The screening test of choice is the **ACTH Stimulation Test** (Cosyntropin test) [2]. A failure of cortisol to rise above 18-20 µg/dL confirms the diagnosis. * **Adrenal Crisis:** An acute emergency characterized by shock unresponsive to vasopressors; it requires immediate IV Hydrocortisone and saline resuscitation [2].

Question 474: Which of the following is most likely to be raised in patients with atypical carcinoids?

A. 5-HIAA
B. 5-HTP (Correct Answer)
C. VMA
D. Metanephrines

Explanation: The correct answer is **5-HTP (5-Hydroxytryptophan)**. **Understanding the Concept:** Carcinoid tumors are neuroendocrine tumors derived from enterochromaffin cells [3]. They are classified based on their embryological origin: **Foregut** (bronchial/atypical, stomach, duodenum), **Midgut** (ileum, jejunum), and **Hindgut** (rectum) [1]. Atypical carcinoids (Foregut tumors) often lack the enzyme **DOPA decarboxylase** (also known as aromatic L-amino acid decarboxylase). In the normal serotonin pathway, Tryptophan is converted to 5-HTP, which is then converted by DOPA decarboxylase into Serotonin (5-HT) [3]. Because atypical carcinoids lack this enzyme, they cannot convert 5-HTP to Serotonin. Consequently, these tumors secrete large amounts of **5-HTP** into the bloodstream, which is the hallmark biochemical marker for foregut/atypical carcinoids. **Analysis of Incorrect Options:** * **A. 5-HIAA:** This is the end-metabolite of serotonin. While it is the standard screening marker for **Midgut carcinoids** (which possess DOPA decarboxylase), it is often normal or only slightly elevated in atypical/foregut carcinoids. * **C & D. VMA and Metanephrines:** These are breakdown products of catecholamines (epinephrine/norepinephrine) [2]. They are used to diagnose **Pheochromocytoma** and Neuroblastoma, not carcinoid tumors. **NEET-PG High-Yield Pearls:** * **Foregut Carcinoids:** Often associated with **MEN-1**; may cause "Atypical Carcinoid Syndrome" (characterized by bright red, patchy, geographic flushing) [1]. * **Midgut Carcinoids:** Most common site is the **Ileum**; most likely to cause classic Carcinoid Syndrome (diarrhea, wheezing, right-sided heart failure) [1]. * **Diagnostic Gold Standard:** 24-hour urinary 5-HIAA (for Midgut); Plasma Chromogranin A (general marker) [1]. * **Treatment:** Somatostatin analogues (Octreotide/Lanreotide) are the mainstay for symptomatic relief.

Question 475: Which of the following is not a part of the classical triad of symptoms of diabetes?

A. Polyuria
B. Polyphagia
C. Polydipsia
D. Weight loss (Correct Answer)

Explanation: The classical clinical presentation of Diabetes Mellitus is characterized by the **"3 Ps"**: Polyuria, Polydipsia, and Polyphagia [1]. While weight loss is a common clinical feature of uncontrolled diabetes (especially Type 1), it is not considered a component of the formal "classical triad" [2]. ### **Explanation of the Options:** * **Polyuria (Option A):** Hyperglycemia exceeds the renal threshold for glucose (~180 mg/dL), leading to glucosuria. This causes **osmotic diuresis**, resulting in excessive urination [2]. * **Polydipsia (Option B):** The significant loss of fluid via polyuria leads to intracellular and extracellular dehydration [3]. This stimulates the **thirst center** in the hypothalamus, causing excessive thirst [2]. * **Polyphagia (Option C):** Despite high blood glucose, the lack of insulin (or insulin resistance) prevents glucose from entering cells. This "starvation amidst plenty" triggers a catabolic state, stimulating the appetite [1]. * **Weight Loss (Correct Answer):** While weight loss occurs due to the depletion of glycogen, fat, and muscle stores (proteolysis and lipolysis), it is a **consequence** of the metabolic derangement rather than a member of the primary symptomatic triad [2]. ### **Clinical Pearls for NEET-PG:** * **Renal Threshold for Glucose:** Approximately **180 mg/dL**. Glucosuria begins once blood glucose crosses this limit. * **Type 1 vs. Type 2:** The classical triad is more acutely prominent in **Type 1 DM**. Type 2 DM is often asymptomatic for years and may present first with complications (e.g., neuropathy or candidiasis). * **Diagnostic Criteria:** Remember the ADA criteria: Fasting Plasma Glucose $\geq$ 126 mg/dL, 2-hour Post-Prandial $\geq$ 200 mg/dL, or HbA1c $\geq$ 6.5%.

Question 476: A 65-year-old lady hospitalized for cervical spondylosis was found to have a serum calcium of 12.5 mg%. Her hematocrit and KFT are normal, with a phosphate of 2.3 mg/dL. What is the most appropriate initial investigation for this patient?

A. Serum PTH (Correct Answer)
B. PTH-rP levels
C. Serum electrophoresis for M spike
D. Vitamin D3 levels

Explanation: ### Explanation The patient presents with significant **hypercalcemia** (12.5 mg/dL) and **hypophosphatemia** (2.3 mg/dL). In a clinical scenario where calcium is high and phosphate is low, the most likely diagnosis is **Primary Hyperparathyroidism (PHPT)**. **1. Why Serum PTH is the Correct Answer:** The first step in evaluating hypercalcemia is to determine if it is **PTH-mediated** or **non-PTH-mediated** [1]. * In PHPT, the parathyroid glands inappropriately secrete PTH despite high serum calcium [1]. * The combination of high calcium and low/low-normal phosphate is a classic biochemical signature of PHPT, as PTH acts on the renal tubules to reduce reabsorption of phosphate [1]. * Measuring Serum PTH is the most cost-effective and definitive initial step to confirm the source of the electrolyte imbalance [1]. **2. Why Other Options are Incorrect:** * **PTH-rP levels:** This is used to diagnose "Humoral Hypercalcemia of Malignancy." While malignancy is a differential for hypercalcemia, it usually presents with very high calcium and a more acute clinical deterioration. PTH is checked first; PTH-rP is only ordered if PTH is found to be suppressed [1]. * **Serum electrophoresis:** Used to screen for Multiple Myeloma. While myeloma causes hypercalcemia, it typically presents with normal or high phosphate (due to bone destruction) and often shows renal impairment or anemia, which are absent here. * **Vitamin D3 levels:** Vitamin D toxicity causes hypercalcemia, but it also causes **hyperphosphatemia** (as Vit D increases absorption of both), contradicting this patient's low phosphate [1]. **Clinical Pearls for NEET-PG:** * **Most common cause of hypercalcemia:** In outpatients, it is Primary Hyperparathyroidism; in hospitalized patients, it is Malignancy [1]. * **PTH-Calcium Relationship:** If Calcium is high and PTH is high/inappropriately normal, think PHPT. If Calcium is high and PTH is low (suppressed), look for malignancy or granulomatous diseases [1]. * **Localization:** Once PHPT is biochemically confirmed via PTH, the next step is localization using a **Sestamibi scan** [1].

Question 477: Which of the following conditions is characterized by a pigmented lesion in the mouth but not on the skin?

A. Cushing syndrome
B. Cushing syndrome
C. Peutz-Jeghers syndrome
D. None of the above (Correct Answer)

Explanation: The correct answer is **None of the above** because the conditions listed typically present with either skin pigmentation, both skin and mucosal pigmentation, or no pigmentation at all. There is no classic endocrine or genetic syndrome characterized strictly by oral pigmentation in the absolute absence of skin lesions. **Analysis of Options:** * **Cushing Syndrome:** This condition is characterized by cortisol excess [2]. It does **not** typically cause hyperpigmentation. In contrast, **Addison’s disease** (primary adrenal insufficiency) or **Nelson’s syndrome** involves high ACTH levels [1]. Since ACTH is derived from Pro-opiomelanocortin (POMC), it stimulates melanocytes, leading to hyperpigmentation of **both** the skin (creases, pressure points) and the oral mucosa [1]. * **Peutz-Jeghers Syndrome (PJS):** This is an autosomal dominant disorder characterized by hamartomatous polyps and mucocutaneous pigmentation. Crucially, the pigmented macules (melanocytic) appear on the **lips and buccal mucosa** as well as the **perioral skin**, fingertips, and toes. It does not spare the skin. **Clinical Pearls for NEET-PG:** 1. **Addison’s Disease:** Look for "bronzing" of the skin and pigmentation of palmar creases and buccal mucosa. This is a hallmark of primary (not secondary) adrenal insufficiency [1]. 2. **Peutz-Jeghers Syndrome:** Associated with the **STK11 (LKB1)** gene mutation. The pigmentation often fades after puberty, but the mucosal lesions persist. 3. **McCune-Albright Syndrome:** Characterized by "Café-au-lait" spots with irregular borders (Coast of Maine), polyostotic fibrous dysplasia, and precocious puberty. 4. **Laugier-Hunziker Syndrome:** A rare differential for PJS that presents with mucocutaneous hyperpigmentation but **without** systemic involvement or intestinal polyposis.

Question 478: A 40-year-old woman presents with lipid investigations suggestive of familial hypercholesterolemia, characterized by increased cholesterol, increased low-density lipoprotein, and normal triglycerides. This condition is associated with an increased risk for premature atherosclerosis and the presence of tuberous and tendon xanthomas. Before diagnosing familial hypercholesterolemia, secondary causes must be ruled out. Which of the following conditions is most likely to cause secondary hyperlipidemia?

A. Cholestatic liver disease (Correct Answer)
B. Alcoholism
C. Estrogen replacement therapy
D. Malabsorption syndromes

Explanation: The patient presents with **Type IIa Hyperlipoproteinemia** (isolated elevation of LDL-C and total cholesterol), which is the hallmark of Familial Hypercholesterolemia (FH) [1]. However, secondary causes must be excluded before a genetic diagnosis is made. **1. Why Cholestatic Liver Disease is correct:** In cholestatic conditions (e.g., Primary Biliary Cholangitis), there is a significant decrease in the biliary excretion of cholesterol. This leads to the accumulation of an abnormal lipoprotein called **Lipoprotein X**, which interferes with normal lipid metabolism and causes a marked increase in total cholesterol and LDL levels [2]. This mimics the lipid profile of FH. **2. Why the other options are incorrect:** * **Alcoholism:** Typically causes **hypertriglyceridemia** (Type IV) by increasing VLDL synthesis and decreasing fatty acid oxidation. It does not cause isolated hypercholesterolemia. * **Estrogen Replacement Therapy:** Estrogens generally increase HDL and **triglycerides** (by increasing VLDL production) while lowering LDL. They do not mimic the FH profile. * **Malabsorption Syndromes:** These conditions (e.g., Celiac disease) usually lead to **hypolipidemia** due to the impaired absorption of fats and fat-soluble vitamins. **Clinical Pearls for NEET-PG:** * **High-Yield Rule:** If a question mentions isolated high LDL/Cholesterol, think **Hypothyroidism, Nephrotic Syndrome, or Cholestasis.** * **High-Yield Rule:** If a question mentions high Triglycerides, think **Diabetes Mellitus, Alcohol, or Chronic Kidney Disease.** * **Tendon Xanthomas:** These are pathognomonic for Familial Hypercholesterolemia (specifically the Achilles tendon) [1]. * **Lipoprotein X:** A specific marker for obstructive jaundice/cholestasis that causes a "pseudohypercholesterolemia" [2].

Question 479: The triad of diabetes mellitus, gallstones, and steatorrhea is associated with which of the following tumors?

A. Gastrinomas
B. Somatostatinomas (Correct Answer)
C. Vipomas
D. Glucagonomas

Explanation: The correct answer is **Somatostatinomas**. These are rare neuroendocrine tumors (NETs) of the pancreas or duodenum that secrete excessive amounts of somatostatin. **Why Somatostatinomas?** Somatostatin is a potent "inhibitory" hormone [1]. Its excess leads to the classic clinical triad through the following mechanisms: 1. **Diabetes Mellitus:** Somatostatin inhibits the release of insulin and glucagon [1]. 2. **Gallstones (Cholelithiasis):** It inhibits the release of Cholecystokinin (CCK) and reduces gallbladder contractility, leading to bile stasis. 3. **Steatorrhea:** It inhibits the secretion of pancreatic enzymes and bicarbonate, leading to fat malabsorption. **Incorrect Options:** * **Gastrinomas (Zollinger-Ellison Syndrome):** Characterized by excessive gastrin, leading to refractory peptic ulcers and secretory diarrhea (due to gastric acid inactivating pancreatic lipases). * **VIPomas (Verner-Morrison Syndrome):** Characterized by **WDHA syndrome**: Watery Diarrhea, Hypokalemia, and Achlorhydria (also known as "Pancreatic Cholera"). * **Glucagonomas:** Characterized by the **4Ds**: Diabetes, Dermatitis (**Necrolytic Migratory Erythema**), Deep vein thrombosis, and Depression. **High-Yield Clinical Pearls for NEET-PG:** * **Location:** Most somatostatinomas are found in the **head of the pancreas** or the **duodenum** (often associated with NF-1). * **Psammoma Bodies:** Duodenal somatostatinomas are unique among NETs for frequently showing psammoma bodies on histology. * **Diagnosis:** Elevated fasting plasma somatostatin levels. * **Management:** Surgical resection is the treatment of choice; octreotide (a somatostatin analog) can paradoxically be used for symptom control in other NETs but is not the primary treatment here.

Question 480: All are features of Cushing's syndrome except?

A. Central obesity
B. Diabetes
C. Hypotension (Correct Answer)
D. Hypokalaemia

Explanation: **Explanation:** Cushing’s syndrome is characterized by a chronic excess of glucocorticoids (cortisol). The correct answer is **Hypotension**, as cortisol excess typically leads to **Hypertension**. **1. Why Hypotension is the correct answer (The Exception):** Cortisol causes hypertension through several mechanisms: it increases the sensitivity of blood vessels to catecholamines (permissive action), inhibits vasodilators like nitric oxide, and at high levels, exerts a **mineralocorticoid effect** by binding to aldosterone receptors. This leads to sodium and water retention, expanding ECF volume and raising blood pressure. Therefore, hypotension is not a feature of Cushing's syndrome. **2. Analysis of Incorrect Options:** * **Central Obesity (A):** This is the most common clinical feature [1]. Cortisol promotes lipogenesis in the trunk and face while causing lipolysis in the extremities, leading to "buffalo hump," "moon facies," and truncal obesity [1]. * **Diabetes (B):** Cortisol is a counter-regulatory hormone that increases gluconeogenesis in the liver and decreases peripheral glucose uptake (insulin resistance), leading to "Steroid Diabetes." * **Hypokalaemia (D):** At high concentrations (especially in Ectopic ACTH syndrome), cortisol acts on the renal mineralocorticoid receptors, leading to potassium excretion in exchange for sodium reabsorption. **NEET-PG High-Yield Pearls:** * **Screening Test of Choice:** 24-hour urinary free cortisol or Overnight Dexamethasone Suppression Test (ONDST) [2]. * **Gold Standard Test:** Low-dose dexamethasone suppression test (LDDST) [2]. * **Most common cause:** Iatrogenic (exogenous steroids). * **Most common endogenous cause:** Cushing’s Disease (Pituitary adenoma) [1]. * **Clinical Sign:** Purple striae (wider than 1 cm) are highly specific for Cushing’s.

Practice by Chapter

Diabetes Mellitus

Practice Questions

Thyroid Disorders

Practice Questions

Adrenal Gland Disorders

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Pituitary Disorders

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Calcium and Bone Metabolism

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Reproductive Endocrinology

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Lipid Disorders

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Endocrine Hypertension

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Multiple Endocrine Neoplasia

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Obesity and Metabolic Syndrome

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Neuroendocrine Tumors

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Endocrine Emergencies

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