Endocrinology Practice Questions

Q: What is the primary biochemical marker for primary hyperparathyroidism?

Hypercalcemia. **Explanation:** **Primary Hyperparathyroidism (PHPT)** is most commonly caused by a solitary parathyroid adenoma (85%), leading to the autonomous overproduction of Parathyroid Hormone (PTH). **1. Why Hypercalcemia is the correct answer:** PTH is the chief regulator of calcium homeostasis. In PHPT, elevated PTH levels act on three main targets to increase serum calcium: * **Bone:** Increases osteoclastic resorption, releasing calcium into the ECF. * **Kidneys:** Increases distal tubular reabsorption of calcium. * **Intestines:** Stimulates the synthesis of 1,25-dihydroxyvitamin D (Calcitriol) in the kidneys, which enhances intestinal calcium absorption. **Hypercalcemia** is the biochemical hallmark and often the first clinical sign detected on routine screening. **2. Analysis of Incorrect Options:** * **B. Hypophosphatemia:** While PTH decreases renal phosphate reabsorption (leading to phosphaturia), hypophosphatemia is a *secondary* finding and is not present in all patients. Hypercalcemia remains the primary diagnostic marker. * **C. Increased Alkaline Phosphatase (ALP):** ALP levels are only elevated in cases with significant bone involvement (Osteitis fibrosa cystica). Many modern PHPT patients are asymptomatic with normal ALP. * **D. Increased ACTH:** ACTH is related to adrenal/pituitary axis disorders (e.g., Cushing’s disease) and has no direct role in parathyroid pathology. **High-Yield Clinical Pearls for NEET-PG:** * **Classic Triad:** Hypercalcemia, elevated PTH, and low-to-normal phosphate. * **Mnemonic for Symptoms:** "Stones (renal calculi), Bones (aches/fractures), Groans (abdominal pain/peptic ulcers), and Psychic Moans (depression/confusion)." * **Urinary Finding:** Hypercalciuria (despite PTH increasing reabsorption, the filtered load of calcium exceeds the renal threshold). * **X-ray Finding:** Subperiosteal resorption of phalanges and "Salt and pepper" appearance of the skull.

Q: Which of the following is not a characteristic feature of Graves' disease?

Late diastolic murmur. **Explanation:** **Graves’ disease** is an autoimmune condition characterized by hyperthyroidism due to TSH-receptor antibodies [1]. The correct answer is **Late diastolic murmur**, as this is typically associated with mitral stenosis, not hyperthyroidism. **1. Why "Late diastolic murmur" is the correct answer:** Hyperthyroidism induces a hyperdynamic circulatory state. Cardiovascular findings in Graves' disease include tachycardia, palpitations, and a wide pulse pressure [3]. While a **systolic murmur** (flow murmur) is common due to increased cardiac output, a diastolic murmur is not a feature of thyrotoxicosis. Occasionally, a "Means-Lerman scratch" (a systolic sound mimicking a friction rub) may be heard, but never a late diastolic murmur. **2. Analysis of incorrect options:** * **Hyperreflexia:** Excess thyroid hormone increases neuromuscular excitability and shortens the contraction/relaxation time of muscles, leading to "brisk" deep tendon reflexes. * **Chorea:** Though rare, thyrotoxicosis can manifest as movement disorders, including chorea or tremors, due to increased sensitivity of dopamine receptors in the basal ganglia. * **Lid lag sign (Griffith’s sign):** This is a classic sympathetic overactivity sign where the upper eyelid fails to follow the downward movement of the iris [3]. **Clinical Pearls for NEET-PG:** * **Specific to Graves’:** Exophthalmos (proptosis), Pretibial Myxedema (dermopathy), and Thyroid Acropachy (clubbing) are unique to Graves' and not seen in other forms of hyperthyroidism [1]. * **Cardiac complication:** Atrial Fibrillation is the most common arrhythmia in elderly patients with thyrotoxicosis [2]. * **Diagnosis:** Low TSH, High Free T4, and diffuse uptake on Radionuclide scan [3].

Q: A common cause of Cushing syndrome is:

Pituitary adenoma. Cushing syndrome refers to the clinical state resulting from chronic exposure to excessive glucocorticoids. When the cause is a pituitary adenoma secreting excess ACTH, it is specifically termed **Cushing Disease**. [1] **1. Why Pituitary Adenoma is Correct:** Among the endogenous causes of Cushing syndrome, **Cushing Disease (Pituitary ACTH-secreting adenoma)** is the most common, accounting for approximately **70%** of cases. [1] It typically involves a microadenoma (<10 mm) that stimulates the adrenal cortex to produce excess cortisol bilaterally. [4] **2. Why Other Options are Incorrect:** * **A. Cancer producing ectopic ACTH:** While this is a known cause of ACTH-dependent Cushing syndrome (most commonly Small Cell Carcinoma of the Lung), it is less frequent than pituitary adenomas, accounting for only about 10-15% of cases. [1] * **C. Adrenal Tuberculosis:** This is a classic cause of **Addison’s Disease** (Primary Adrenal Insufficiency), not Cushing syndrome. Tuberculosis destroys the adrenal cortex, leading to a deficiency of cortisol and aldosterone, rather than an excess. **High-Yield Clinical Pearls for NEET-PG:** * **Most Common Cause Overall:** Exogenous (Iatrogenic) administration of glucocorticoids. [1], [3] * **Most Common Endogenous Cause:** Cushing Disease (Pituitary Adenoma). * **Screening Tests:** Overnight Dexamethasone Suppression Test (ONDST), 24-hour urinary free cortisol, or Late-night salivary cortisol. [2], [3] * **Differential Diagnosis:** High-dose dexamethasone suppression test (HDDST) and CRH stimulation test typically show suppression/response in Cushing Disease but *not* in ectopic ACTH production. [4] * **Imaging:** MRI Brain (Pituitary) is the investigation of choice for Cushing Disease. [4]

Q: Hypoparathyroidism is seen in all of the following conditions except:

Chronic renal failure. **Explanation:** The core concept here is distinguishing between conditions that cause **primary hypoparathyroidism** (destruction/dysfunction of the gland) and those that cause **secondary hyperparathyroidism**. **Why Chronic Renal Failure (CRF) is the correct answer:** In CRF, there is a decrease in 1-alpha-hydroxylase activity (leading to Vitamin D deficiency) and phosphate retention [1]. Both factors result in **hypocalcemia**, which acts as a potent stimulus for the parathyroid glands [2]. This leads to **Secondary Hyperparathyroidism** (elevated PTH levels) to compensate for the low calcium [1]. Therefore, CRF is associated with high PTH, not hypoparathyroidism. **Why the other options are incorrect:** * **DiGeorge Syndrome:** A congenital dysgenesis of the 3rd and 4th pharyngeal pouches, leading to thymic hypoplasia and **parathyroid aplasia**, causing primary hypoparathyroidism. * **Wilson’s Disease:** Excessive copper deposition can occur in the parathyroid glands, leading to tissue damage and functional hypoparathyroidism. * **Hemochromatosis:** Iron overload leads to deposition in various endocrine organs; iron deposition in the parathyroid glands causes gland destruction and hypoparathyroidism. **NEET-PG High-Yield Pearls:** 1. **Magnesium Link:** Severe hypomagnesemia can cause functional hypoparathyroidism because magnesium is required for both PTH secretion and its peripheral action [2]. 2. **Hungry Bone Syndrome:** A state of profound hypocalcemia seen post-parathyroidectomy in patients with pre-existing hyperparathyroidism. 3. **DiGeorge Mnemonic (CATCH-22):** **C**ardiac defects, **A**bnormal facies, **T**hymic hypoplasia, **C**left palate, **H**ypocalcemia (due to hypoparathyroidism), **22**q11 deletion.

Q: Which of the following is a true statement about primary hyperparathyroidism?

Adenoma is the commonest cause.. Primary hyperparathyroidism (PHPT) is characterized by the autonomous overproduction of parathyroid hormone (PTH), leading to hypercalcemia [2]. **Explanation of Options:** * **A. Adenoma is the commonest cause (Correct):** Approximately **80-85%** of PHPT cases are caused by a single solitary parathyroid adenoma [1]. Other causes include four-gland hyperplasia (10-15%) and parathyroid carcinoma (<1%). * **B. Associated with low serum calcium (Incorrect):** PHPT is defined by **hypercalcemia** (elevated serum calcium) and inappropriately high or normal PTH levels [3]. Low serum calcium is seen in secondary hyperparathyroidism (usually due to chronic kidney disease) [2]. * **C. Surgery is indicated if biochemical findings are abnormal in an asymptomatic patient (Incorrect):** Surgery is not indicated for *all* asymptomatic patients. Specific criteria (Asymptomatic PHPT Guidelines) must be met, such as: Serum calcium >1 mg/dL above the upper limit of normal, T-score ≤ -2.5, age <50 years, or creatinine clearance <60 ml/min [1]. * **D. MIBG isotope is useful (Incorrect):** **99mTc-Sestamibi (MIBI)** scan is the gold standard for localizing parathyroid adenomas [1]. MIBG scans are used for neuroendocrine tumors like pheochromocytoma. **High-Yield Clinical Pearls for NEET-PG:** * **Classic Presentation:** "Stones (renal calculi), bones (osteitis fibrosa cystica), abdominal groans (peptic ulcers/pancreatitis), and psychic overtones (depression)" [1]. * **Biochemical Profile:** ↑ Calcium, ↓ Phosphate, ↑ PTH, and ↑ Urinary cAMP [2]. * **Hungry Bone Syndrome:** A common postoperative complication following parathyroidectomy, characterized by profound hypocalcemia as the "starved" bones rapidly uptake calcium. * **Association:** Always screen for **MEN 1 and MEN 2A** syndromes if multiple glands are involved [3].

Question 1

What is the primary biochemical marker for primary hyperparathyroidism?

Accepted Answer

Hypercalcemia

Answer

Hypophosphatemia

Answer

Increased alkaline phosphatase levels

Answer

Increased ACTH

Question 2

Which of the following is not a characteristic feature of Graves' disease?

Accepted Answer

Late diastolic murmur

Answer

Hyperreflexia

Answer

Chorea

Answer

Lid lag sign

Question 3

A 30-year-old female presents with palpitations, increased appetite, and significant weight loss. She also reports a large neck swelling and has abnormal thyroid function tests showing elevated T3 and T4 with suppressed TSH. Her TSH receptor antibody test is negative. Ultrasound of the neck reveals multiple nodules, and a Radioactive Iodine Uptake (RAIU) scan shows increased uptake. After achieving a euthyroid state, what is the best definitive step in management?

Accepted Answer

Near-total thyroidectomy

Answer

Continue antithyroid medication

Answer

Sub-total thyroidectomy

Answer

Radioactive iodine therapy

Question 4

A common cause of Cushing syndrome is:

Accepted Answer

Pituitary adenoma

Answer

Cancer producing ectopic ACTH

Answer

Adrenal tuberculosis

Answer

None of the above

Question 5

Diabetes mellitus is best diagnosed by which of the following criteria?

Accepted Answer

Fasting blood sugar > 126 mg/dL and postprandial blood sugar > 199 mg/dL

Answer

Fasting blood sugar > 100 mg/dL and postprandial blood sugar > 140 mg/dL

Answer

HbA1C = 5.5%

Answer

Fasting blood sugar > 70 mg/dL

Question 6

Hypoparathyroidism is seen in all of the following conditions except:

Accepted Answer

Chronic renal failure

Answer

DiGeorge syndrome

Answer

Wilson's disease

Answer

Hemochromatosis

Question 7

A 19-year-old female presents for follow-up of medical management for panhypopituitarism after brain tumor resection. Her recent reports show that her TSH is below the detection limit of the assay. What is the next step in her management?

Accepted Answer

Order a free T4 level.

Answer

Decrease levothyroxine dose to half of the current dose.

Answer

Order an MRI of her brain.

Answer

Order a thyroid uptake scan.

Question 8

A raised serum creatinine phosphokinase level is unusual in which of the following conditions?

Accepted Answer

Myopathy of Cushing's syndrome

Answer

Acute alcoholic myopathy

Answer

Viral polymyositis

Answer

Duchenne's muscular dystrophy

Question 9

Which of the following is a true statement about primary hyperparathyroidism?

Accepted Answer

Adenoma is the commonest cause.

Answer

Associated with low serum calcium.

Answer

Surgery is indicated if biochemical findings are abnormal in an asymptomatic patient.

Answer

MIBG isotope is useful in the localization of the tumor.

Question 10

A 39-year-old obese patient presents with features of a Urinary Tract Infection (UTI) and a Random Blood Sugar (RBS) of 200 mg/dL. Urine analysis shows pus cells. What is true about the management?

Accepted Answer

Insulin can be administered.

Answer

Glipizide is the drug of choice.

Answer

Ciprofloxacin is indicated.

Answer

Testing for microalbuminuria is indicated.

Endocrinology — MCQs

Endocrinology — MCQs

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