Endocrinology Practice Questions

Q: A 55-year-old extremely obese man reports weakness, sweating, tachycardia, confusion, and headache whenever he fasts for more than a few hours. He has prompt relief of symptoms when he eats. These symptoms are most suggestive of which of the following disorders?

Insulinoma. ### Explanation The clinical presentation described is a classic manifestation of **Whipple’s Triad**, which is the hallmark of an **Insulinoma**. **1. Why Insulinoma is Correct:** An insulinoma is a rare neuroendocrine tumor of the pancreatic beta cells that secretes insulin autonomously, regardless of blood glucose levels. The patient exhibits the three components of Whipple’s Triad: * **Symptoms of hypoglycemia:** Neuroglycopenic (confusion, headache, weakness) and autonomic (sweating, tachycardia) symptoms triggered by fasting [1]. * **Low plasma glucose:** Occurring during these episodes. * **Relief of symptoms:** Prompt recovery upon administration of glucose/eating. The association with obesity is common, as patients often eat frequently to avoid unpleasant hypoglycemic episodes. **2. Why the Other Options are Incorrect:** * **A. Diabetes Mellitus:** Typically presents with hyperglycemia (polyuria, polydipsia). While hypoglycemia can occur in diabetics, it is almost always a side effect of medication (insulin or sulfonylureas), not the disease itself [3]. * **C. Zollinger-Ellison Syndrome:** A gastrin-secreting tumor (Gastrinoma) leading to severe peptic ulcers and diarrhea, not hypoglycemia. * **D. Carcinoid Syndrome:** Characterized by flushing, diarrhea, and wheezing due to serotonin release; it does not cause fasting hypoglycemia [2]. **3. NEET-PG High-Yield Pearls:** * **Diagnosis:** The gold standard is the **72-hour supervised fast**. * **Biochemical Profile:** High Insulin, High C-peptide, and High Pro-insulin levels during hypoglycemia. (Note: Exogenous insulin intake would show high insulin but *low* C-peptide) [1]. * **Localization:** Most insulinomas are small, benign, and solitary. Endoscopic ultrasound (EUS) is highly sensitive for localization. * **Rule of 10s:** Approximately 10% are malignant, 10% are multiple, and 10% are associated with **MEN-1 syndrome**.

Q: What is the most common hormone, other than gastrin, found in a gastric secreting islet cell tumor?

ACTH. Explanation: Gastrinomas (Zollinger-Ellison Syndrome) are neuroendocrine tumors (NETs) that primarily secrete gastrin. However, these tumors are frequently plurihormonal, meaning they can synthesize and secrete multiple peptide hormones simultaneously. Why ACTH is correct: Among the non-gastrin hormones produced by pancreatic or duodenal islet cell tumors, ACTH (Adrenocorticotropic Hormone) is the most common [2]. When a gastrinoma secretes ACTH, it can lead to ectopic Cushing syndrome [1]. This is a high-yield association, particularly in the context of Multiple Endocrine Neoplasia type 1 (MEN1), where gastrinomas are the most common functional pancreatic NET. Analysis of Incorrect Options: * B. Glucagon: While glucagon is secreted by alpha-cell tumors (glucagonomas), it is less frequently co-secreted by gastrin-secreting tumors compared to ACTH. * C. Melanocyte Stimulating Hormone (MSH): MSH can be elevated as a byproduct of ACTH synthesis (both derived from POMC), but ACTH itself is the primary hormone identified in these clinical scenarios. * D. Growth Hormone Releasing Factor (GHRF): GHRF secretion can occur in pancreatic NETs (leading to acromegaly), but it is statistically rarer than ACTH co-secretion. NEET-PG High-Yield Pearls: * Most common site for Gastrinoma: The Gastrinoma Triangle (Passaro’s Triangle)—bounded by the junction of the cystic/common bile duct, the junction of the 2nd and 3rd parts of the duodenum, and the neck of the pancreas. * MEN1 Association: 25% of gastrinomas are associated with MEN1 (3 Ps: Pituitary, Parathyroid, Pancreas). * Clinical Clue: If a patient with ZES develops hypokalemia and hypertension, suspect ectopic ACTH secretion.

Q: Which of the following statements about Diabetic Ketoacidosis is true?

Decreased Bicarbonate. **Explanation:** **Diabetic Ketoacidosis (DKA)** is a life-threatening complication of diabetes characterized by the triad of hyperglycemia, ketosis, and metabolic acidosis [1], [2]. **1. Why Decreased Bicarbonate is Correct:** In DKA, an absolute or relative insulin deficiency leads to increased lipolysis and the production of ketoacids (acetoacetate and $\beta$-hydroxybutyrate) [4]. These are strong organic acids that dissociate, releasing hydrogen ions ($H^+$). To maintain physiological pH, the body’s primary buffer, **Bicarbonate ($HCO_3^-$)**, reacts with these excess $H^+$ ions. This consumption leads to a significant **decrease in serum bicarbonate levels** (typically $<18$ mEq/L), resulting in a high anion gap metabolic acidosis. **2. Why the other options are incorrect:** * **Increased Lactate:** While DKA can coexist with lactic acidosis (due to dehydration/sepsis), the primary pathology is the accumulation of **ketoacids**, not lactate. * **Normal Anion Gap:** DKA is a classic cause of **High Anion Gap Metabolic Acidosis (HAGMA)**. The "unmeasured anions" are the ketoacids. * **Glucose 250$ mg/dl**. **High Yield Clinical Pearls for NEET-PG:** * **The "Gap":** Anion Gap $= Na^+ - (Cl^- + HCO_3^-)$. Normal is $12 \pm 2$. * **Potassium Paradox:** Total body potassium is **depleted**, but serum potassium may appear **normal or high** due to the extracellular shift caused by acidosis and insulin deficiency [3]. * **Management Priority:** The first step in management is aggressive **Normal Saline (0.9% NaCl)** rehydration, followed by an insulin infusion [1]. * **Monitoring:** The best indicator of resolution is the **closure of the anion gap**, not just the normalization of blood glucose.

Q: Which one of the following features may not be seen in hypothyroidism?

Pretibial myxedema. Explanation: The correct answer is **Pretibial myxedema**. This is a classic "trap" question in NEET-PG, as it tests the distinction between hypothyroidism and Graves' disease. **Why Pretibial Myxedema is the correct answer:** Pretibial myxedema (localized dermopathy) is a characteristic feature of **Graves' disease (Hyperthyroidism)**, not hypothyroidism [1]. It occurs due to the deposition of glycosaminoglycans in the dermis, triggered by the same autoimmune process (TSH-receptor antibodies) that causes Graves' ophthalmopathy. While "myxedema" is a term used to describe the generalized non-pitting edema of severe hypothyroidism, the specific *pretibial* distribution is unique to Graves' disease [1]. **Analysis of incorrect options:** * **Cold intolerance:** A hallmark of hypothyroidism. Low levels of thyroid hormone decrease the basal metabolic rate (BMR) and thermogenesis, making patients sensitive to cold. * **Deafness:** Sensorineural or conductive hearing loss can occur in hypothyroidism. It is notably seen in **Pendred syndrome** (congenital hypothyroidism with goiter and deafness). * **Pericardial effusion:** Hypothyroidism causes increased capillary permeability and decreased lymphatic drainage, leading to protein-rich fluid accumulation in serous cavities (pleural, pericardial, or peritoneal). It is usually asymptomatic as it accumulates slowly. **High-Yield Clinical Pearls for NEET-PG:** * **Wolff-Chaikoff Effect:** Inhibition of thyroid hormone synthesis by high iodine levels (can lead to hypothyroidism). * **Most common cause:** Hashimoto’s thyroiditis (in iodine-sufficient areas). * **ECG in Hypothyroidism:** Low voltage complexes, sinus bradycardia, and flattened T-waves. * **Myxedema Coma:** The most severe form of hypothyroidism, characterized by hypothermia, bradycardia, and altered mental status.

Q: According to the American Diabetes Association, what is the target HbA1c level for diabetes patients under good control?

<7%. The **American Diabetes Association (ADA)** recommends a glycemic target of **HbA1c <7%** for most non-pregnant adults with diabetes. This target is based on landmark trials like the **UKPDS** and **DCCT**, which demonstrated that maintaining an HbA1c below 7% significantly reduces the risk of microvascular complications (retinopathy, nephropathy, and neuropathy) [1]. HbA1c reflects the average blood glucose over the preceding 2-3 months (the lifespan of an erythrocyte). **Analysis of Options:** * **Option A (4-6%):** This is the normal physiological range for non-diabetic individuals. While ideal, targeting this range in diabetics often increases the risk of life-threatening hypoglycemia. * **Option B ( 8%):** These levels indicate suboptimal control. However, a less stringent goal (e.g., <8%) may be appropriate for patients with a history of severe hypoglycemia, limited life expectancy, or advanced macrovascular complications [1]. **High-Yield Clinical Pearls for NEET-PG:** * **Individualization:** The ADA emphasizes "individualized" targets. Tight control (<6.5%) may be sought in young patients with short disease duration, while relaxed targets (<8%) are for the elderly or comorbid [1]. * **Diagnosis:** HbA1c **≥6.5%** is diagnostic for Diabetes Mellitus; **5.7-6.4%** is diagnostic for Pre-diabetes. * **Falsely Low HbA1c:** Seen in conditions with high red cell turnover (e.g., Hemolytic anemia, pregnancy, recent blood transfusion). * **Falsely High HbA1c:** Seen in Iron deficiency anemia (due to increased erythrocyte lifespan).

Q: Hypercalcemia is seen in all of the following conditions EXCEPT?

Pseudohypoparathyroidism. **Explanation:** The correct answer is **Pseudohypoparathyroidism (PHP)** because it is characterized by **hypocalcemia**, not hypercalcemia [1]. **1. Why Pseudohypoparathyroidism is the correct answer:** PHP is a genetic disorder caused by **end-organ resistance to Parathyroid Hormone (PTH)** [2]. Although PTH levels are high, the kidneys and bones fail to respond to it. This leads to the biochemical triad of **hypocalcemia**, hyperphosphatemia, and elevated PTH [1]. Type 1A (Albright’s Hereditary Osteodystrophy) also presents with physical features like short stature and shortened 4th/5th metacarpals [2]. **2. Why the other options are incorrect:** * **Bone Metastasis:** This is a common cause of hypercalcemia of malignancy [1]. It occurs via direct osteolysis by tumor cells or the release of local cytokines (e.g., RANKL) that activate osteoclasts. * **Sarcoidosis:** Granulomatous diseases cause hypercalcemia because macrophages within the granulomas contain the enzyme **1-alpha-hydroxylase** [1]. This leads to uncontrolled conversion of Vitamin D to its active form (1,25-dihydroxyvitamin D), increasing intestinal calcium absorption. * **Hyperparathyroidism:** Primary hyperparathyroidism (usually due to a parathyroid adenoma) involves autonomous secretion of PTH, which directly increases bone resorption and renal calcium reabsorption, leading to hypercalcemia [3]. **High-Yield Clinical Pearls for NEET-PG:** * **Most common cause of hypercalcemia:** Outpatients = Primary Hyperparathyroidism; Inpatients = Malignancy [1]. * **PTHrP (PTH-related protein):** The most common cause of hypercalcemia in non-metastatic solid tumors (e.g., Squamous cell carcinoma of the lung). * **Pseudopseudohypoparathyroidism (PPHP):** Has the physical features of Albright’s but **normal** calcium and PTH levels (due to paternal imprinting) [2]. * **ECG in Hypercalcemia:** Look for a **shortened QT interval**.

Q: What is a characteristic physical finding of prolactinoma, besides galactorrhea?

Bitemporal hemianopia. ### Explanation **Correct Option: A. Bitemporal hemianopia** **Medical Concept:** The pituitary gland sits in the **sella turcica**, located directly beneath the **optic chiasm**. Prolactinomas, particularly **macroadenomas** (size >10 mm), can expand superiorly out of the sella [1]. This upward extension causes mechanical compression of the decussating nasal fibers of the optic nerves at the optic chiasm [2]. Since these fibers carry visual information from the temporal fields, the classic physical finding is **bitemporal hemianopia** (loss of the outer half of the visual field in both eyes) [1]. **Why the other options are incorrect:** * **B, C, and D (Anovulatory cycles, Amenorrhea, Infertility):** While these are classic clinical manifestations of hyperprolactinemia in females, they are **symptoms** (subjective complaints) rather than **physical findings** (objective signs detected by a clinician during an examination). High prolactin inhibits the pulsatile release of GnRH, leading to low LH/FSH and subsequent hypogonadism. **High-Yield Clinical Pearls for NEET-PG:** * **Most Common:** Prolactinoma is the most common secretory tumor of the anterior pituitary. * **Size vs. Gender:** Microadenomas ( 10 mm) are more common in males (presenting late with mass effect symptoms like headache and visual field defects) [1]. * **Hook Effect:** In extremely high prolactin levels, lab assays may show falsely low levels; serial dilution is required for accurate diagnosis. * **Drug of Choice:** **Cabergoline** (a dopamine agonist) is the first-line treatment for both micro and macroadenomas, unlike most other pituitary tumors which require surgery [2].

Q: A patient presents with jaw pain, elevated alkaline phosphatase, and normal serum creatinine. Which of the following tests would best confirm the diagnosis?

Bone scan. The clinical presentation of **jaw pain** and **isolated elevation of Alkaline Phosphatase (ALP)** with normal renal function (normal creatinine) is highly suggestive of **Paget’s Disease of Bone (Osteitis Deformans)**. In Paget’s disease, there is excessive and disorganized bone remodeling, often involving the skull and mandible, leading to bone pain and cranial nerve entrapment [1]. **Why Bone Scan is Correct:** A **Technetium-99m MDP Bone Scan** is the most sensitive test to confirm the diagnosis and determine the extent (monostotic vs. polyostotic) of the disease. It identifies areas of increased bone turnover ("hot spots") even before structural changes appear on conventional X-rays. **Analysis of Incorrect Options:** * **B. IGF-1 level:** Used to diagnose Acromegaly. While acromegaly causes jaw changes (prognathism), it typically presents with soft tissue swelling and metabolic derangements, not isolated ALP elevation. * **C. Serum Calcium:** In Paget’s disease, serum calcium and phosphate are characteristically **normal**. Calcium only rises during periods of prolonged immobilization. * **D. Abdominal Ultrasound:** This has no diagnostic value for metabolic bone diseases like Paget’s. **High-Yield Pearls for NEET-PG:** * **Hallmark Lab Finding:** Isolated elevated ALP with normal Calcium, Phosphate, and PTH. * **Radiology:** Look for "Cotton wool spots" in the skull, "Picture frame vertebrae," and cortical thickening. * **Complications:** The most feared late complication is **Osteosarcoma** (suspect if pain suddenly worsens) [1]. * **Treatment of Choice:** Bisphosphonates (specifically **Zoledronic acid**) [1].

Question 1

A 55-year-old extremely obese man reports weakness, sweating, tachycardia, confusion, and headache whenever he fasts for more than a few hours. He has prompt relief of symptoms when he eats. These symptoms are most suggestive of which of the following disorders?

Accepted Answer

Insulinoma

Answer

Diabetes mellitus

Answer

Zollinger-Ellison syndrome

Answer

Carcinoid syndrome

Question 2

What is the most common hormone, other than gastrin, found in a gastric secreting islet cell tumor?

Accepted Answer

ACTH

Answer

Glucagon

Answer

Melanocyte stimulating hormone

Answer

Growth hormone releasing factor

Question 3

Which of the following statements about Diabetic Ketoacidosis is true?

Accepted Answer

Decreased Bicarbonate

Answer

Increased Lactate

Answer

Normal anion gap

Answer

Glucose < 250 mg/dl

Question 4

Which one of the following features may not be seen in hypothyroidism?

Accepted Answer

Pretibial myxedema

Answer

Cold intolerance

Answer

Deafness

Answer

Pericardial effusion

Question 5

According to the American Diabetes Association, what is the target HbA1c level for diabetes patients under good control?

Accepted Answer

<7%

Answer

4-6%

Answer

8%

Answer

>8%

Question 6

A 49-year-old man seeks a prescription for erectile dysfunction. He is 168 cm (5 feet 6 inches) tall and weighs 93 kg (body mass index 33). On physical examination, there are bilateral carotid bruits and a midline palpable abdominal pulsatile mass. Decreased hair is noted over the lower extremities, and a 1-cm shallow ulceration is present in the skin over the right first metatarsal head. He has decreased sensation to light touch and pinprick in the lower extremities. Laboratory findings include hemoglobin, 12.9 g/dL; hematocrit, 42%; WBC count, 8950/ mm3; and creatinine, 1.7 mg/dL. Which of the following laboratory findings is most likely to be present in this man?

Accepted Answer

Hemoglobin A1c, 8.8%

Answer

Oligoclonal IgG bands in CSF

Answer

Plasma ACTH, 119 pg/mL

Answer

Plasma homocysteine, 23 mmol/L

Question 7

Hypercalcemia is seen in all of the following conditions EXCEPT?

Accepted Answer

Pseudohypoparathyroidism

Answer

Bone metastasis

Answer

Sarcoidosis

Answer

Hyperparathyroidism

Question 8

What is a characteristic physical finding of prolactinoma, besides galactorrhea?

Accepted Answer

Bitemporal hemianopia

Answer

Anovulatory cycles

Answer

Amenorrhea

Answer

Infertility

Question 9

A 31-year-old female presents with complaints of weight loss and palpitations. On examination, she has exophthalmos, tremors, a smooth goiter with a bruit, and an irregularly irregular pulse. What would the thyroid function tests likely reveal?

Accepted Answer

Increased T4, increased T3, and decreased TSH

Answer

Decreased T3, T4, and TSH

Answer

Increased T4, normal T3, and decreased TSH

Answer

Increased T3, T4, and TSH

Question 10

A patient presents with jaw pain, elevated alkaline phosphatase, and normal serum creatinine. Which of the following tests would best confirm the diagnosis?

Accepted Answer

Bone scan

Answer

Insulin-like growth factor-1 level

Answer

Serum calcium

Answer

Abdominal ultrasound

Endocrinology — MCQs

Endocrinology — MCQs

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