Endocrinology — MCQs

Endocrinology Indian Medical PG Practice Questions and MCQs

Question 411: Which of the following causative factors is not involved in the pathogenesis of diabetic gangrene?

A. Infection
B. Myelopathy (Correct Answer)
C. Atherosclerosis
D. Osteoarthropathy

Explanation: The pathogenesis of diabetic gangrene and foot ulcers is multifactorial, primarily driven by a "triad" of **Ischemia, Neuropathy, and Infection** [1]. **Why Myelopathy is the Correct Answer:** **Myelopathy** refers to a pathological condition of the spinal cord (e.g., cervical spondylotic myelopathy). While diabetes can cause peripheral neuropathy (affecting distal nerves) [2], it does not typically cause myelopathy as a direct mechanism for limb gangrene. Therefore, it is not involved in the local pathogenesis of diabetic foot complications. **Analysis of Other Options:** * **Atherosclerosis (Ischemia):** Diabetes accelerates macrovascular disease. Atherosclerosis of the infra-popliteal arteries leads to peripheral arterial disease (PAD), causing decreased blood supply, tissue hypoxia, and eventually dry or wet gangrene [1]. * **Infection:** Hyperglycemia impairs leukocyte function (chemotaxis and phagocytosis). Once the skin barrier is breached (often due to unnoticed trauma), polymicrobic infections spread rapidly in the nutrient-rich, ischemic tissue, leading to gangrene [3]. * **Osteoarthropathy:** Specifically **Charcot’s Joint**, this results from motor and sensory neuropathy [1]. Loss of joint position sense and repetitive microtrauma lead to joint destruction and foot deformities (e.g., rocker-bottom foot). These deformities create abnormal pressure points, leading to ulcers that progress to gangrene. **NEET-PG High-Yield Pearls:** * **The Most Common Cause** of diabetic foot ulcers is **Peripheral Neuropathy** (Sensory > Motor > Autonomic) [1]. * **Autonomic Neuropathy** leads to decreased sweating (anhidrosis), causing dry, fissured skin that acts as a portal for infection [4]. * **Motor Neuropathy** causes atrophy of intrinsic foot muscles, leading to "claw toe" or "hammer toe" deformities [1]. * **Investigation of Choice** for assessing vascularity in diabetic gas gangrene/ischemia: **Duplex Ultrasound** or **CT Angiography** [3].

Question 412: Maximum amount of alkaline phosphatase is seen in which of the following?

A. Semen (Correct Answer)
B. Placenta
C. CSF
D. Plasma

Explanation: Alkaline Phosphatase (ALP) is a group of isoenzymes that catalyze the hydrolysis of phosphate esters at an alkaline pH. While ALP is commonly associated with the liver and bone in clinical practice, its highest concentration in the human body is found in **semen**. **1. Why Semen is Correct:** Semen contains exceptionally high levels of ALP, primarily secreted by the **prostate gland**. The concentration in seminal fluid is approximately **500 to 1000 times higher** than that found in normal serum. In forensic medicine, the detection of high ALP levels is used as a presumptive test to identify seminal stains [1]. **2. Analysis of Incorrect Options:** * **Placenta:** The placenta produces a specific heat-stable isoenzyme (Regan isoenzyme). While levels rise significantly during the third trimester of pregnancy, the total concentration does not reach the levels found in seminal fluid. * **CSF:** Normal Cerebrospinal Fluid contains negligible amounts of ALP. An increase in CSF-ALP is usually a pathological marker for certain germ cell tumors (like germinomas) or leptomeningeal metastasis. * **Plasma:** In healthy adults, plasma ALP originates mainly from the liver and bone. Normal reference ranges (approx. 40–140 U/L) are significantly lower than the concentrations found in the male reproductive tract [2]. **Clinical Pearls for NEET-PG:** * **Isoenzymes of ALP:** Remember the mnemonic **"BLP"** (Bone, Liver, Placenta) for the major sources. * **Heat Stability:** Placental ALP is the most heat-stable, while Bone ALP is the most heat-labile (**"Bone burns"**). * **Clinical Marker:** Elevated ALP with normal GGT suggests a **bone origin** (e.g., Paget’s disease, where ALP is markedly high). If both ALP and GGT are elevated, it suggests a **hepatobiliary origin**. * **Forensic Significance:** Along with Acid Phosphatase (ACP) and Prostate-Specific Antigen (PSA), ALP is a key marker for identifying semen in medico-legal cases [2].

Question 413: Which of the following is NOT true about dyshormonogenesis?

A. It follows autosomal dominant inheritance. (Correct Answer)
B. The most common abnormality is with thyroid peroxidase activity.
C. Young patients may present with euthyroid goiter.
D. Pendred syndrome is a classic example of dyshormonogenesis due to TPO deficiency.

Explanation: **Explanation:** **Dyshormonogenesis** refers to a group of genetic defects in the enzymatic pathways required for thyroid hormone synthesis [1]. 1. **Why Option A is the Correct Answer (The False Statement):** Dyshormonogenesis follows an **autosomal recessive** inheritance pattern, not autosomal dominant [1]. Most cases result from loss-of-function mutations in both alleles of genes encoding enzymes like TPO, thyroglobulin, or the sodium-iodide symporter. 2. **Analysis of Other Options:** * **Option B:** The most common biochemical defect in dyshormonogenesis is a deficiency or dysfunction of the **Thyroid Peroxidase (TPO)** enzyme, which impairs the organification of iodide [1]. * **Option C:** In mild enzymatic defects, increased TSH levels can compensate for the biosynthetic block, leading to a **euthyroid goiter**. However, severe defects typically present as congenital hypothyroidism (cretinism) [1]. * **Option D:** **Pendred Syndrome** is a classic example caused by mutations in the *SLC26A4* gene (encoding pendrin). It is characterized by a triad of sensorineural hearing loss, goiter, and a positive perchlorate discharge test (indicating an organification defect/TPO dysfunction). **High-Yield Clinical Pearls for NEET-PG:** * **Perchlorate Discharge Test:** Used to diagnose iodide organification defects (positive if >10-15% of the tracer is discharged). * **Goiter:** Unlike thyroid agenesis, dyshormonogenesis typically presents with a goiter due to chronic TSH overstimulation. * **Most common cause of Congenital Hypothyroidism:** Thyroid Dysgenesis (80-85%); Dyshormonogenesis accounts for the remaining 10-15% [1].

Question 414: Which of the following conditions is associated with pheochromocytoma?

A. Von Hippel-Lindau syndrome (Correct Answer)
B. Multiple endocrine neoplasia type I (MEN-I)
C. Neurofibromatosis
D. Insulinomas

Explanation: **Explanation:** Pheochromocytoma is a catecholamine-secreting tumor of the adrenal medulla. While most cases are sporadic, approximately 30-40% are associated with hereditary syndromes. **1. Why Option A is Correct:** **Von Hippel-Lindau (VHL) Syndrome** (Type 2) is strongly associated with pheochromocytoma. It is caused by a mutation in the *VHL* tumor suppressor gene on chromosome 3p. In VHL Type 2, patients develop pheochromocytomas alongside hemangioblastomas (CNS and retinal) and clear cell renal cell carcinoma. **2. Analysis of Incorrect Options:** * **Option B (MEN-I):** Also known as Wermer’s syndrome, it is characterized by the "3 Ps": **P**arathyroid hyperplasia, **P**ituitary adenoma, and **P**ancreatic islet cell tumors. It is **not** associated with pheochromocytoma. (Note: MEN-2A and 2B *are* associated with pheochromocytoma). * **Option C (Neurofibromatosis):** While Neurofibromatosis Type 1 (NF1) is associated with pheochromocytoma, the option simply states "Neurofibromatosis." In the context of NEET-PG, if VHL is an option, it is often the preferred specific association. However, note that NF1 carries a ~1-5% risk of pheochromocytoma. * **Option D (Insulinomas):** These are functional neuroendocrine tumors of the pancreas, commonly seen in MEN-I, but they have no direct syndromic link to pheochromocytoma. **High-Yield Clinical Pearls for NEET-PG:** * **Rule of 10s (Traditional):** 10% bilateral, 10% malignant, 10% pediatric, 10% extra-adrenal (Paragrangliomas). * **Genetic Associations:** Remember the mnemonic **"V-M-N"**: **V**HL, **M**EN-2A/2B (RET proto-oncogene), and **N**F-1. * **Triad of Symptoms:** Episodic headache, sweating (diaphoresis), and tachycardia. * **Diagnosis:** Best initial screening test is **24-hour urinary fractionated metanephrines** or plasma free metanephrines. * **Pre-op Management:** Always give **Alpha-blockers first** (e.g., Phenoxybenzamine) followed by Beta-blockers to prevent a hypertensive crisis.

Question 415: An obese patient presented with random blood sugar 400 mg%, urine sugar +++, and ketones. Which drug is most useful in management?

A. Glibenclamide
B. Troglitazone
C. Insulin (Correct Answer)
D. Metformin

Explanation: **Explanation:** The patient presents with significant hyperglycemia (RBS 400 mg/dL), glycosuria, and **ketonuria**. This clinical triad is highly suggestive of **Diabetic Ketoacidosis (DKA)** [3] or severe insulin deficiency. **Why Insulin is the Correct Choice:** Insulin is the definitive treatment for any patient presenting with ketosis. In the presence of ketones, there is an absolute or relative deficiency of insulin leading to lipolysis and ketone body formation. Insulin is required to: 1. Inhibit further ketogenesis by suppressing lipolysis. 2. Facilitate glucose uptake into cells. 3. Correct the metabolic acidosis [5]. Oral hypoglycemic agents (OHAs) are ineffective and contraindicated in the management of acute ketosis or DKA. **Why Other Options are Incorrect:** * **Glibenclamide (Sulfonylurea):** It works by stimulating insulin release from pancreatic beta cells [4]. In an acute state of ketosis, the pancreas cannot produce enough insulin to overcome the crisis, and the onset of action is too slow. * **Troglitazone (Thiazolidinedione):** These are insulin sensitizers that take weeks to reach maximum effect. Furthermore, Troglitazone was withdrawn globally due to severe hepatotoxicity. * **Metformin (Biguanide):** It is the first-line drug for stable Type 2 Diabetes but is **contraindicated** in states of severe dehydration or metabolic acidosis (like DKA) due to the risk of worsening lactic acidosis. **High-Yield Clinical Pearls for NEET-PG:** * **DKA Diagnosis:** Look for the "D-K-A" triad: Diabetes (Glucose >250 mg/dL), Ketones (positive in urine/serum), and Acidosis (pH <7.3 or Bicarbonate <18 mEq/L) [1]. * **Management Priority:** The first step in DKA management is aggressive fluid resuscitation (Normal Saline), followed by intravenous regular insulin [2]. * **Insulin Choice:** Regular (Short-acting) insulin is the preparation of choice for managing acute hyperglycemic emergencies [2].

Question 416: A patient, after bilateral adrenalectomy, develops gradual loss of vision, hyperpigmentation of the skin, and headache. What is the likely cause of these symptoms?

A. Addison's disease
B. Nelson's syndrome (Correct Answer)
C. Cushing's disease
D. Harrison's syndrome

Explanation: ### Explanation **Nelson’s Syndrome** is the correct diagnosis. It is a clinical condition characterized by the rapid enlargement of a pre-existing ACTH-secreting pituitary adenoma following **bilateral adrenalectomy** (usually performed to treat Cushing’s disease). [1] **Pathophysiology:** When the adrenals are removed, the negative feedback mechanism of cortisol on the hypothalamus and pituitary is lost [1]. In the absence of cortisol, the pituitary adenoma grows aggressively and secretes massive amounts of **ACTH** and **POMC** (Pro-opiomelanocortin). * **Hyperpigmentation:** High levels of ACTH/MSH (Melanocyte Stimulating Hormone) stimulate melanocytes. * **Vision Loss & Headache:** The expanding pituitary tumor causes mass effect, compressing the **optic chiasm** (leading to bitemporal hemianopia) and increasing intracranial pressure. [1] --- ### Why the other options are incorrect: * **Addison’s Disease:** This is primary adrenal insufficiency. While it causes hyperpigmentation, it does not involve a pituitary tumor; therefore, it would not cause vision loss or headaches due to mass effect. [1] * **Cushing’s Disease:** This refers to the state of hypercortisolism caused by a pituitary adenoma *before* treatment. The patient in the stem has already undergone adrenalectomy, which resolves the hypercortisolism but triggers Nelson's syndrome. * **Harrison’s Syndrome:** This is a distracter term (often confused with Harrison’s textbook or Harrison’s sulcus in rickets) and is not a recognized endocrine syndrome related to adrenalectomy. --- ### High-Yield Clinical Pearls for NEET-PG: * **Classic Triad:** Hyperpigmentation + High ACTH levels + Enlarging pituitary mass (post-bilateral adrenalectomy). * **Investigation of Choice:** MRI of the Brain/Pituitary to visualize the adenoma. * **Prevention:** Prophylactic pituitary radiation or careful monitoring of ACTH levels and MRI post-adrenalectomy can help in early detection. * **Visual Field Defect:** The most common finding is **Bitemporal Hemianopia**. [1]

Question 417: All are causes of hypercalcemia, except?

A. Thyrotoxicosis
B. Sarcoidosis
C. Vitamin A toxicity
D. Phenytoin toxicity (Correct Answer)

Explanation: **Explanation:** The correct answer is **Phenytoin toxicity**. Phenytoin is a well-known cause of **hypocalcemia**, not hypercalcemia [2]. It induces the Cytochrome P450 system in the liver, leading to accelerated metabolism of Vitamin D into inactive metabolites. This results in Vitamin D deficiency, reduced intestinal calcium absorption, and secondary hyperparathyroidism (osteomalacia/rickets) [2], [3]. **Analysis of Options:** * **Thyrotoxicosis:** Thyroid hormones (T3/T4) have a direct stimulating effect on osteoclasts, leading to increased bone resorption and hypercalcemia in approximately 15-20% of thyrotoxic patients [1]. * **Sarcoidosis:** This is a granulomatous disease where macrophages within the granulomas express the enzyme **1-alpha-hydroxylase**. This enzyme converts 25-hydroxyvitamin D to its active form (1,25-dihydroxyvitamin D), leading to increased intestinal calcium absorption and hypercalcemia [1]. * **Vitamin A toxicity:** Excessive Vitamin A stimulates osteoclast activity and inhibits osteoblasts, leading to increased bone turnover and elevated serum calcium levels. **High-Yield Clinical Pearls for NEET-PG:** 1. **Mnemonic for Hypercalcemia (PAM P. SCHMIDT):** Parathyroid (Primary HPT), Addison’s, Malignancy, Paget’s, Sarcoidosis, Cancer, Hyperthyroidism, Milk-alkali syndrome, Immobilization, Vitamin D/A toxicity, Thiazides [1]. 2. **Drugs causing Hypocalcemia:** Phenytoin, Phenobarbital, Bisphosphonates, Loop diuretics (Furosemide), and Calcitonin. 3. **Malignancy:** The most common cause of hypercalcemia in hospitalized patients (via PTHrP or bone metastasis), whereas **Primary Hyperparathyroidism** is the most common cause in outpatients [1]. 4. **EKG finding:** Hypercalcemia typically causes a **shortened QT interval**.

Question 418: A short metacarpal is a characteristic finding in which of the following conditions?

A. Turner's syndrome
B. Pseudohypoparathyroidism
C. Pseudopseudohypoparathyroidism
D. All of the above (Correct Answer)

Explanation: **Explanation:** The characteristic finding of a short metacarpal (specifically the **4th and 5th metacarpals**) is known as **Archibald’s sign**. This occurs due to premature epiphyseal closure and is a classic high-yield physical finding shared by several genetic and endocrine disorders. 1. **Pseudohypoparathyroidism (PHP) Type 1a:** This condition is characterized by end-organ resistance to Parathyroid Hormone (PTH). Patients present with **Albright’s Hereditary Osteodystrophy (AHO)**, a phenotype comprising short stature, round face, obesity, subcutaneous calcifications, and short 4th/5th metacarpals [2]. 2. **Pseudopseudohypoparathyroidism (PPHP):** These patients possess the same genetic mutation (GNAS1) and the same **AHO phenotype** (including short metacarpals) as PHP, but they have **normal** calcium and PTH levels because the defect is inherited paternally [2]. 3. **Turner’s Syndrome (45, XO):** While primarily a chromosomal disorder, short 4th metacarpals are a recognized skeletal feature in approximately 35% of cases, alongside short stature, webbed neck, and streak ovaries [1]. **Clinical Pearls for NEET-PG:** * **Archibald’s Sign:** To elicit this, ask the patient to make a fist; the knuckle of the 4th/5th metacarpal will be replaced by a dimple. * **Differential Diagnosis:** Other causes of short metacarpals include **Homocystinuria** and **Hereditary Multiple Exostoses**. * **Biochemical Distinction:** Remember that PHP has low calcium/high phosphate (PTH resistance), whereas PPHP has normal biochemistry despite the physical findings [2].

Question 419: Glycemic control in diabetes is best assessed by:

A. HbA1c (Correct Answer)
B. Urinary glucose
C. Fasting glucose
D. Post-prandial glucose

Explanation: **Explanation:** **Why HbA1c is the Correct Answer:** HbA1c (Glycated Hemoglobin) is considered the "gold standard" for assessing long-term glycemic control. It measures the percentage of hemoglobin that has glucose non-enzymatically attached to it [1]. Since the average lifespan of a Red Blood Cell (RBC) is approximately **120 days**, HbA1c provides a weighted average of blood glucose levels over the preceding **2–3 months** [1]. Unlike plasma glucose, it is not affected by short-term factors like recent meals, exercise, or acute stress, making it the most reliable indicator of overall glycemic stability and a strong predictor of chronic diabetic complications [2]. **Why Other Options are Incorrect:** * **Urinary Glucose (B):** This is a poor marker because glucose only appears in urine when blood levels exceed the renal threshold (approx. 180 mg/dL). It cannot detect hypoglycemia or mild hyperglycemia and is influenced by the individual's renal threshold. * **Fasting (C) and Post-prandial Glucose (D):** These provide only a "snapshot" of blood glucose at a specific moment [3]. While essential for daily dose adjustments and diagnosing diabetes, they do not reflect long-term control or fluctuations occurring at other times of the day [4]. **High-Yield Clinical Pearls for NEET-PG:** * **The 6-7-8-9 Rule:** HbA1c of 6% ≈ 126 mg/dL; 7% ≈ 154 mg/dL; 8% ≈ 183 mg/dL; 9% ≈ 212 mg/dL (Every 1% rise ≈ 28-30 mg/dL increase in average glucose) [2]. * **False Low HbA1c:** Seen in conditions with high RBC turnover (e.g., Hemolytic anemia, pregnancy, recent blood transfusion, EPO therapy). * **False High HbA1c:** Seen in conditions that prolong RBC lifespan (e.g., Splenectomy, Iron deficiency anemia, Vitamin B12 deficiency). * **Fructosamine Test:** Used to assess glycemic control over the past **2–3 weeks** (useful in pregnancy or hemolytic states).

Question 420: Syndrome of inappropriate antidiuretic hormone secretion (SIADH) is diagnosed by all EXCEPT:

A. Hyponatremia
B. Decreased serum osmolality (< 280 mosm/kg)
C. Normal blood urea nitrogen (Correct Answer)
D. Normal thyroid function

Explanation: **Explanation:** The diagnosis of **SIADH** is based on the **Bartter-Schwartz criteria**. It is a condition of "euvolemic hyponatremia" where excessive ADH leads to water retention and secondary solute loss [1]. **Why Option C is the correct answer (The Exception):** In SIADH, the expansion of total body water leads to a **dilutional effect** and increased renal clearance of urea. Therefore, a characteristic finding in SIADH is a **Low Blood Urea Nitrogen (BUN <10 mg/dL)** and low serum uric acid. A "Normal" BUN (typically 10–20 mg/dL) actually points away from SIADH and suggests other causes of hyponatremia or underlying renal impairment. **Analysis of Incorrect Options:** * **A & B (Hyponatremia & Decreased Serum Osmolality):** These are the hallmarks of SIADH [2]. Excessive water reabsorption dilutes the extracellular fluid, leading to hypotonic hyponatremia (Serum Na <135 mEq/L and Osmolality <280 mOsm/kg). * **D (Normal Thyroid Function):** To diagnose SIADH, one must **exclude** other causes of euvolemic hyponatremia. Both hypothyroidism and adrenal insufficiency (glucocorticoid deficiency) can mimic SIADH; thus, normal thyroid and adrenal functions are mandatory diagnostic requirements [2]. **High-Yield Clinical Pearls for NEET-PG:** * **Urine Findings:** Urine osmolality is inappropriately high (>100 mOsm/kg, often > serum) and urine sodium is high (>40 mEq/L) due to the absence of hypovolemia. * **Volume Status:** Patients are clinically **euvolemic** (no edema, no JVP elevation) [2]. * **Treatment:** Fluid restriction is the first-line treatment. For severe cases, Vaptans (ADH antagonists) or hypertonic saline may be used. * **Caution:** Rapid correction of hyponatremia can lead to **Osmotic Demyelination Syndrome (Central Pontine Myelinolysis).**

Practice by Chapter

Diabetes Mellitus

Practice Questions

Thyroid Disorders

Practice Questions

Adrenal Gland Disorders

Practice Questions

Pituitary Disorders

Practice Questions

Calcium and Bone Metabolism

Practice Questions

Reproductive Endocrinology

Practice Questions

Lipid Disorders

Practice Questions

Endocrine Hypertension

Practice Questions

Multiple Endocrine Neoplasia

Practice Questions

Obesity and Metabolic Syndrome

Practice Questions

Neuroendocrine Tumors

Practice Questions

Endocrine Emergencies

Practice Questions

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