Endocrinology Practice Questions

Q: All of the following are features of VIPoma, except?

Hypocalcemia. VIPoma is a rare neuroendocrine tumor, usually located in the pancreas, that secretes excessive amounts of **Vasoactive Intestinal Peptide (VIP)** [1]. It is classically associated with **WDHA syndrome**: Watery Diarrhea, Hypokalemia, and Achlorhydria (also known as Verner-Morrison syndrome). **Why Hypocalcemia is the correct answer:** Hypocalcemia is **not** a feature of VIPoma. In fact, **Hypercalcemia** is seen in approximately 25-50% of cases. This occurs either due to the direct bone-resorbing effect of VIP or because VIPomas are frequently associated with **Multiple Endocrine Neoplasia type 1 (MEN1)**, where primary hyperparathyroidism coexists. **Analysis of incorrect options:** * **A. Hypokalemia:** Massive secretory diarrhea leads to significant fecal loss of potassium, resulting in profound hypokalemia, which can cause muscle weakness and arrhythmias. * **B. Hypochlorhydria:** VIP inhibits gastric acid secretion by parietal cells. This leads to low gastric acid (hypochlorhydria) or a total absence of it (achlorhydria). * **C. Flushing:** VIP is a potent vasodilator. Excess levels cause systemic vasodilation, leading to episodes of cutaneous flushing in about 20% of patients [1]. **High-Yield Clinical Pearls for NEET-PG:** * **Classic Presentation:** "Tea-colored" watery diarrhea that persists even during fasting (secretory diarrhea), often exceeding 3 liters/day. * **Diagnosis:** Elevated fasting serum VIP levels (>200 pg/mL). * **Localization:** Most are found in the **tail of the pancreas** [1]. * **Management:** Initial stabilization requires aggressive fluid and electrolyte replacement. **Octreotide** (somatostatin analog) is the drug of choice to control symptoms by inhibiting VIP release.

Q: At what value of a one-hour glucose challenge test would you recommend a standard glucose tolerance test?

140 mg/dL. This question pertains to the screening protocol for **Gestational Diabetes Mellitus (GDM)** using the two-step approach (Carpenter-Coustan criteria). ### **Explanation** The screening process typically begins between **24 and 28 weeks of gestation** with a **50g Glucose Challenge Test (GCT)** [1]. This is a non-fasting test where plasma glucose is measured one hour after glucose ingestion [1]. * **The Threshold:** A value of **≥140 mg/dL (7.8 mmol/L)** is the standard cutoff used to identify women at high risk. If the GCT result meets or exceeds this value, the test is considered "positive" (abnormal), and the patient must proceed to the diagnostic **100g, 3-hour Oral Glucose Tolerance Test (OGTT)**. * *Note:* Some clinicians use a lower cutoff of 130 mg/dL to increase sensitivity, but 140 mg/dL remains the most widely tested standard in medical examinations. ### **Analysis of Incorrect Options** * **A. 120 mg/dL:** This value is too low and falls within the normal postprandial range for many individuals; using this would result in an excessive number of false positives. * **C. 150 mg/dL & D. 160 mg/dL:** While these values are certainly abnormal, they are too high to serve as a primary screening cutoff [2]. Using these would miss a significant percentage of women with GDM (low sensitivity). ### **High-Yield Clinical Pearls for NEET-PG** * **DIPSI Guidelines:** In India, the DIPSI (Diabetes in Pregnancy Study Group India) recommends a **single-step** procedure: 75g glucose load regardless of fasting status. A 2-hour value **≥140 mg/dL** is diagnostic of GDM. * **O'Sullivan's Criteria:** If the 1-hour GCT is **>200 mg/dL**, GDM is diagnosed directly without needing a follow-up OGTT [2]. * **Risk Factors:** Screening should be done at the **first prenatal visit** if the patient is obese, has a history of GDM, or has a strong family history of Type 2 Diabetes.

Q: A patient presents with shock and is suspected to have hypoglycemia. What is the primary basis for treatment?

Measure blood glucose levels.. **Explanation:** In any patient presenting with altered sensorium or shock, **hypoglycemia** is a critical "can't-miss" diagnosis. The primary basis for treatment is the **biochemical confirmation of low blood glucose levels.** [1] 1. **Why Option C is Correct:** According to **Whipple’s Triad**, the diagnosis of hypoglycemia requires: (1) Symptoms consistent with hypoglycemia, (2) A low plasma glucose concentration, and (3) Relief of symptoms after the glucose level is raised. In an emergency setting, a rapid bedside capillary blood glucose (CBG) test is the standard of care to confirm the diagnosis before or during the initiation of therapy to avoid unnecessary glucose loading or misdiagnosis. [1] 2. **Why Other Options are Incorrect:** * **Option A:** While IV glucose is the treatment, administering it *before* any assessment or confirmation can be counterproductive if the shock is due to other causes (e.g., intracranial hemorrhage), where hyperglycemia might worsen neuronal injury. * **Option B:** Urine sugar is irrelevant in hypoglycemia; it is used to screen for glycosuria in hyperglycemia/diabetes. * **Option D:** Establishing IV access is a supportive step, but it is not the "basis for treatment" or the diagnostic priority. **Clinical Pearls for NEET-PG:** * **Whipple’s Triad:** Essential for diagnosing true hypoglycemia. * **Neuroglycopenic symptoms:** Occur at glucose levels <50–55 mg/dL (confusion, seizure, coma). * **Drug of Choice:** In an unconscious patient, **100 ml of 25% Dextrose** or **50 ml of 50% Dextrose** IV is the standard emergency bolus. [2] * **Glucagon:** Can be given IM/SC if IV access is unavailable, but it is ineffective in starved patients or those with liver disease (depleted glycogen stores).

Q: Which of the following is NOT a feature of tumour lysis syndrome?

Hypernatremia. Explanation: Tumor Lysis Syndrome (TLS) is a metabolic emergency caused by the rapid breakdown of malignant cells, typically following chemotherapy for high-grade hematologic malignancies (e.g., Burkitt lymphoma, ALL). When cells lyse, they release their intracellular contents into the systemic circulation. Why Hypernatremia is the Correct Answer: Hypernatremia is not a feature of TLS. Sodium is the primary extracellular cation; therefore, the destruction of cells does not significantly increase serum sodium levels. In fact, aggressive hydration (the mainstay of TLS management) may sometimes lead to dilutional hyponatremia [1], but hypernatremia is not part of the classic metabolic triad. Why the other options are incorrect (Features of TLS): * Hyperuricemia (A): Catabolism of purines from released nucleic acids leads to high uric acid levels [2], which can cause acute kidney injury (urate nephropathy). * Hyperphosphatemia (C): Malignant cells contain significantly higher concentrations of intracellular phosphorus than normal cells. Rapid release leads to hyperphosphatemia. * Hypocalcemia (B): This is a secondary phenomenon. Excess phosphorus binds to serum calcium, forming calcium-phosphate crystals that deposit in soft tissues and the kidneys, leading to a drop in ionized calcium. * Hyperkalemia: (Though not an option, it is a hallmark) Release of intracellular potassium can lead to life-threatening arrhythmias. Clinical Pearls for NEET-PG: * Cairo-Bishop Definition: Used to classify laboratory vs. clinical TLS. * Prophylaxis: Aggressive IV hydration and Allopurinol (xanthine oxidase inhibitor). * Treatment of Choice for Hyperuricemia: Rasburicase (recombinant urate oxidase) which converts uric acid to the highly soluble allantoin. * The "TLS Triad + 1": Hyperkalemia, Hyperphosphatemia, Hyperuricemia, and Hypocalcemia.

Q: What is the single best test for the diagnosis of hypothyroidism?

TSH. The diagnosis of hypothyroidism primarily relies on the hypothalamic-pituitary-thyroid axis [1]. **Serum TSH (Thyroid Stimulating Hormone)** is the single best, most sensitive, and most specific screening test for both primary hypothyroidism and hyperthyroidism [1], [2]. Due to the inverse logarithmic relationship between TSH and free T4, even a minor decrease in thyroid hormone levels triggers a significant compensatory rise in TSH, making it the earliest marker of thyroid dysfunction [1]. **Why other options are incorrect:** * **T4 (Thyroxine):** While Free T4 is used to confirm the diagnosis and assess severity, it is less sensitive than TSH [2]. In "Subclinical Hypothyroidism," TSH is elevated while T4 remains within the normal range [1]. * **T3 (Triiodothyronine):** This is the least useful test for hypothyroidism [1]. T3 levels often remain within the normal range until late stages of the disease due to increased peripheral conversion of T4 to T3 and preferential secretion of T3 by the failing gland. * **RAIU (Radioactive Iodine Uptake):** This test measures the metabolic activity of the gland. It is primarily used in the differential diagnosis of **hyperthyroidism** (e.g., Graves' vs. Thyroiditis) and has no role in the routine diagnosis of hypothyroidism. **High-Yield Clinical Pearls for NEET-PG:** * **Best Screening Test:** TSH. * **Best test to monitor Levothyroxine therapy:** TSH (target 0.5–2.5 mIU/L). * **Exception:** In **Secondary (Central) Hypothyroidism**, TSH is unreliable (may be low, normal, or slightly high but non-functional) [2]. Here, **Free T4** is the best test for diagnosis and monitoring [2]. * **Subclinical Hypothyroidism:** Elevated TSH with Normal Free T4 [1].

Q: Raised calcium and phosphorus are seen in which of the following conditions?

Vitamin D intoxication. ### Explanation The correct answer is **Vitamin D intoxication**. **1. Why Vitamin D Intoxication is Correct:** Vitamin D (specifically its active form, Calcitriol) acts on three main sites to regulate mineral homeostasis: [1] * **Intestine:** It significantly increases the absorption of both **Calcium and Phosphorus**. * **Bone:** In high doses, it promotes bone resorption, releasing both minerals into the ECF. * **Kidneys:** It increases the reabsorption of Calcium and Phosphorus in the distal tubules. Consequently, an excess of Vitamin D leads to simultaneous **Hypercalcemia** and **Hyperphosphatemia**, along with symptoms like thickening of long bones and calcification of soft tissues. [1] **2. Why the Other Options are Incorrect:** * **Chronic Renal Failure (CRF):** Characterized by **Hypocalcemia** (due to decreased 1-alpha-hydroxylase activity/low Calcitriol) and **Hyperphosphatemia** (due to decreased renal excretion). * **Hyperparathyroidism:** Parathyroid hormone (PTH) increases Calcium but is **phosphaturic**. It decreases proximal tubular reabsorption of phosphate, leading to **Hypercalcemia** and **Hypophosphatemia**. * **Pseudohypoparathyroidism:** This is a state of PTH resistance. It mimics hypoparathyroidism, resulting in **Hypocalcemia** and **Hyperphosphatemia**. **3. NEET-PG High-Yield Pearls:** * **The "Rule of Reciprocity":** Usually, Calcium and Phosphorus move in opposite directions (e.g., PTH action). Vitamin D is the notable exception where both move in the **same** direction. * **Sarcoidosis:** Patients with Sarcoidosis develop hypercalcemia and hyperphosphatemia because macrophages in granulomas contain 1-alpha-hydroxylase, which converts Vitamin D to its active form uncontrollably. * **Milk-Alkali Syndrome:** Another cause of high calcium and high phosphorus, often associated with metabolic alkalosis and renal failure.

Q: Which of the following urinary metabolites are most sensitive for the diagnosis of pheochromocytomas?

Metanephrines. **Explanation:** The diagnosis of **Pheochromocytoma** (a catecholamine-secreting tumor of the adrenal medulla) relies on demonstrating excess catecholamine production [2]. **Why Metanephrines are the correct answer:** Metanephrines (normetanephrine and metanephrine) are the intermediate metabolites of catecholamines [2]. Within the tumor cells, the enzyme **Catechol-O-methyltransferase (COMT)** continuously converts catecholamines into metanephrines. This process occurs independently of the episodic release of hormones into the bloodstream. Consequently, metanephrines are produced and leaked into the circulation/urine continuously, making them the **most sensitive** marker (sensitivity ~97-99%) for diagnosis. **Analysis of Incorrect Options:** * **A. Vanillylmandelic acid (VMA):** VMA is the end-product of catecholamine metabolism. While highly specific, it has **low sensitivity** because its levels only rise significantly during periods of massive catecholamine release. It is no longer the first-line screening test. * **C & D. 5-HIAA and 5-HTP:** These are metabolites of **serotonin**. They are used in the diagnosis of **Carcinoid Syndrome**, not pheochromocytoma. **NEET-PG High-Yield Pearls:** * **Screening Test of Choice:** Plasma free metanephrines (highest sensitivity). * **Confirmatory Test:** 24-hour urinary fractionated metanephrines and catecholamines. * **Rule of 10s:** 10% are bilateral, 10% are malignant, 10% are extra-adrenal (Paragangliomas), and 10% occur in children. * **Clinical Triad:** Episodic headache, sweating (diaphoresis), and tachycardia/palpitations. * **Pre-operative Management:** Always give **Alpha-blockers first** (e.g., Phenoxybenzamine) followed by Beta-blockers to prevent a hypertensive crisis [1].

Question 1

All of the following are features of VIPoma, except?

Accepted Answer

Hypocalcemia

Answer

Hypokalemia

Answer

Hypochlorhydria

Answer

Flushing

Question 2

At what value of a one-hour glucose challenge test would you recommend a standard glucose tolerance test?

Accepted Answer

140 mg/dL

Answer

120 mg/dL

Answer

150 mg/dL

Answer

160 mg/dL

Question 3

What is the most common cause of Addison's disease?

Accepted Answer

Autoimmune adrenalitis

Answer

Meningococcal septicemia

Answer

Malignancy

Answer

Tuberculosis

Question 4

A patient presents with shock and is suspected to have hypoglycemia. What is the primary basis for treatment?

Accepted Answer

Measure blood glucose levels.

Answer

Administer intravenous glucose after clinical assessment.

Answer

Check for urine sugar.

Answer

Establish intravenous access.

Question 5

Which of the following is NOT a feature of tumour lysis syndrome?

Accepted Answer

Hypernatremia

Answer

Hyperuricemia

Answer

Hypocalcemia

Answer

Hyperphosphatemia

Question 6

A 23-year-old female air force officer notes a lower pitch to her voice, coarsening of her hair, an increased tendency toward weight gain, menorrhagia, and increasing intolerance to cold. Which of the following laboratory abnormalities is expected?

Accepted Answer

Increased serum TSH

Answer

Increased serum free T4

Answer

Increased serum T3 resin uptake

Answer

Increased saturation of thyroid hormone-binding sites on TBG

Question 7

What is the single best test for the diagnosis of hypothyroidism?

Accepted Answer

TSH

Answer

T3

Answer

T4

Answer

RAIU

Question 8

A 30-year-old woman is evaluated for fatigue and found to have a low serum thyroxine level. Five years ago, she was treated for Graves' disease with radioactive iodine. What is the diagnostic test of choice?

Accepted Answer

Serum TSH

Answer

Serum T3

Answer

TRH stimulation test

Answer

Radioactive iodine uptake

Question 9

Raised calcium and phosphorus are seen in which of the following conditions?

Accepted Answer

Vitamin D intoxication

Answer

Chronic renal failure (CRF)

Answer

Hyperparathyroidism

Answer

Pseudohypoparathyroidism

Question 10

Which of the following urinary metabolites are most sensitive for the diagnosis of pheochromocytomas?

Accepted Answer

Metanephrines

Answer

Vanillylmandelic acid (VMA)

Answer

5-Hydroxyindoleacetic acid (5HIAA)

Answer

5-Hydroxytryptophan (5HTP)

Endocrinology — MCQs

Endocrinology — MCQs

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