Endocrinology Practice Questions

Q: All of the following are true about osteomalacia EXCEPT:

Raised serum calcium. **Explanation:** Osteomalacia is a metabolic bone disease characterized by **defective mineralization** of the organic bone matrix (osteoid) [1], most commonly due to Vitamin D deficiency. **Why "Raised serum calcium" is the correct answer (The Exception):** In osteomalacia, serum calcium is typically **low or low-normal**, never raised [1]. The pathophysiology involves a primary deficiency in Vitamin D, leading to decreased intestinal calcium absorption. This triggers **Secondary Hyperparathyroidism** (increased PTH), which attempts to normalize calcium levels by mobilizing it from bones and increasing renal phosphate excretion [1]. Consequently, the classic biochemical profile shows low/normal calcium, low phosphorus, and elevated Alkaline Phosphatase (ALP) [1]. **Analysis of other options:** * **A. Vitamin D deficiency:** This is the most common cause of osteomalacia in adults [1], leading to inadequate calcium and phosphate availability for bone mineralization. * **B. Proximal myopathy:** A hallmark clinical feature [1]. Patients often present with a "waddling gait" and difficulty rising from a chair or climbing stairs due to Vitamin D deficiency affecting muscle metabolism and secondary hyperparathyroidism. * **D. Bone biopsy:** Histologically, osteomalacia is defined by an **increased thickness of osteoid seams** (demineralized matrix) and an increased osteoid volume [1], as the matrix is formed but cannot be mineralized. **NEET-PG High-Yield Pearls:** * **Radiological Sign:** **Looser’s zones** (Pseudofractures/Milkman’s fractures) are pathognomonic—translucent bands perpendicular to the bone cortex [1]. * **Biochemical Triad:** ↓ Serum Calcium/Phosphate + ↑ ALP + ↑ PTH [1]. * **Gold Standard Diagnosis:** Bone biopsy with tetracycline labeling (though rarely done clinically) [1].

Q: According to the American Diabetes Association, which of the following criteria indicates a prediabetic condition?

Fasting plasma glucose between 100 to 125 mg/dL. According to the **American Diabetes Association (ADA)**, prediabetes is a high-risk state where blood glucose levels are higher than normal but do not yet meet the threshold for a diagnosis of Type 2 Diabetes Mellitus [1]. ### **Explanation of Options:** * **Option A (Correct):** Fasting Plasma Glucose (FPG) between **100 mg/dL and 125 mg/dL** is defined as **Impaired Fasting Glucose (IFG)** [1]. This is a hallmark criteria for prediabetes. * **Option B (Incorrect):** A 2-hour plasma glucose (post 75g OGTT) must be between **140 mg/dL and 199 mg/dL** to be classified as **Impaired Glucose Tolerance (IGT)**. A value of 100 mg/dL is considered within the normal range (<140 mg/dL). * **Option C (Incorrect):** An **HbA1c ≥ 6.5%** is the diagnostic threshold for **Diabetes Mellitus**. For prediabetes, the HbA1c range is **5.7% to 6.4%**. * **Option D (Incorrect):** Since options B and C represent normal and diabetic ranges respectively, "All of the above" is incorrect. ### **High-Yield Clinical Pearls for NEET-PG:** | Category | Normal | Prediabetes | Diabetes | | :--- | :--- | :--- | :--- | | **Fasting (FPG)** | < 100 mg/dL | 100–125 mg/dL | ≥ 126 mg/dL | | **2-hr OGTT** | < 140 mg/dL | 140–199 mg/dL | ≥ 200 mg/dL | | **HbA1c** | < 5.7% | 5.7–6.4% | ≥ 6.5% | * **Random Plasma Glucose:** A value of **≥ 200 mg/dL** in a patient with classic symptoms of hyperglycemia (polyuria, polydipsia, weight loss) is also diagnostic of Diabetes [1]. * **Screening:** ADA recommends screening all adults starting at age 35, or earlier in asymptomatic individuals with a BMI ≥ 25 kg/m² and additional risk factors.

Q: Jod-Basedow phenomenon is seen in all of the following, EXCEPT:

Normal thyroid gland. The **Jod-Basedow phenomenon** refers to iodine-induced hyperthyroidism. It occurs when an excess load of iodine is administered to a patient with an underlying thyroid abnormality, leading to the unregulated overproduction of thyroid hormones. [2] ### Why "Normal Thyroid Gland" is the Correct Answer: In a **normal thyroid gland**, the body utilizes a protective mechanism called the **Wolff-Chaikoff effect**. When exposed to high iodine levels, a healthy gland temporarily shuts down iodine organification to prevent hyperthyroidism. Therefore, the Jod-Basedow phenomenon **cannot** occur in a normal gland because its autoregulatory mechanisms are intact. ### Explanation of Incorrect Options: * **Amiodarone:** This anti-arrhythmic drug contains 37% iodine by weight. It can trigger Jod-Basedow (Type 1 Amiodarone-Induced Thyrotoxicosis), especially in patients with underlying multinodular goiter or latent Graves' disease. * **Iodine-containing contrast agents:** Used in CT scans and angiography, these agents provide a massive acute load of iodine, which can trigger thyrotoxicosis in susceptible individuals. [1] * **Iodine in seafood:** While rare, excessive dietary intake of iodine (e.g., kelp or seaweed) can precipitate hyperthyroidism in patients living in iodine-deficient areas who have developed autonomous thyroid nodules. ### High-Yield Clinical Pearls for NEET-PG: * **Wolff-Chaikoff Effect:** Iodine-induced **hypo**thyroidism (The gland "shuts off"). * **Jod-Basedow Phenomenon:** Iodine-induced **hyper**thyroidism (The gland "runs wild"). * **Risk Factors:** Most commonly seen in patients with **Endemic Goiter, Multinodular Goiter (MNG), or Graves' Disease.** * **Clinical Note:** Unlike Graves' disease, Jod-Basedow typically presents with **low/absent radioactive iodine uptake (RAIU)** because the gland is already saturated with exogenous iodine. [1], [2]

Q: Which of the following statements is NOT true regarding Insulinoma?

Weight loss. **Explanation:** Insulinoma is the most common functional neuroendocrine tumor (NET) of the pancreas [2]. It is characterized by the autonomous secretion of insulin, leading to fasting hypoglycemia. **Why Weight Loss is NOT true:** The hallmark of insulinoma is **weight gain**, not weight loss. This occurs for two primary reasons: 1. **Anabolic Effect:** Insulin is a potent anabolic hormone that promotes lipogenesis and inhibits lipolysis [3]. 2. **Increased Caloric Intake:** Patients frequently overeat or consume high-calorie snacks to prevent or relieve the distressing symptoms of neuroglycopenia. **Analysis of Other Options:** * **Hypoglycemic attacks:** These are the cardinal clinical feature [1]. Patients present with **Whipple’s Triad**: (1) Symptoms of hypoglycemia, (2) Low plasma glucose (<55 mg/dL), and (3) Relief of symptoms after glucose administration. * **Usually solitary tumor:** Over 90% of insulinomas occur as single, isolated lesions. Multiple tumors are rare and often associated with **MEN-1 syndrome**. * **Mostly benign tumor:** Approximately 90% of insulinomas are benign. Only about 5-10% show features of malignancy (metastasis to liver or regional lymph nodes). **High-Yield Clinical Pearls for NEET-PG:** * **Diagnosis:** The "Gold Standard" is the **72-hour fasting test**. Diagnostic findings include elevated Insulin (≥3 μU/mL), elevated C-peptide (≥0.6 ng/mL), and absent sulfonylurea in the urine/plasma during hypoglycemia [1]. * **Localization:** Endoscopic Ultrasound (EUS) is highly sensitive for preoperative localization. * **Treatment:** Surgical resection (enucleation) is the treatment of choice. Medical management includes **Diazoxide** (inhibits insulin release) or Octreotide.

Q: A 45-year old woman is admitted to the hospital following a head injury. She has severe polyuria (producing 1 L of urine every 2 hours) and polydipsia (drinking 3 to 4 glasses of water every hour). During a 24-hour period in the hospital, the woman produces 10 L of urine, containing no glucose. She is placed on overnight water restriction for further evaluation. The following morning, she is weak and confused. Her serum osmolarity is 330 mOsm/L, her serum sodium is 164 mEq/L, and her urine osmolarity is 70 mOsm/L. She is treated with dDAVP by nasal spray. Within 24 hours of initiating the treatment, her serum osmolarity is 295 mOsm/L and her urine osmolarity is 620 mOsm/L. What is the most likely diagnosis?

Central Diabetes Insipidus. ### Explanation **1. Why Central Diabetes Insipidus (CDI) is the Correct Answer:** The patient presents with the classic triad of **polyuria, polydipsia, and hypernatremic dehydration** following a head injury (a common cause of damage to the hypothalamus or posterior pituitary). * **Water Deprivation Test:** The patient’s urine remains dilute (70 mOsm/L) despite high serum osmolarity (330 mOsm/L), indicating a failure to concentrate urine. This confirms Diabetes Insipidus (DI). * **Response to dDAVP (Desmopressin):** This is the "gold standard" for differentiation. In this case, administering dDAVP (an ADH analogue) caused a dramatic increase in urine osmolarity (from 70 to 620 mOsm/L). This significant response (>50% increase) proves that the kidneys are sensitive to ADH, but the body is not producing it. Thus, the diagnosis is **Central Diabetes Insipidus**. **2. Why Other Options are Incorrect:** * **Options A & B (Diabetes Mellitus):** While DM causes polyuria and polydipsia, it is characterized by **glycosuria** and osmotic diuresis. The question explicitly states there is "no glucose" in the urine. * **Option D (Juvenile Diabetes Insipidus):** This is not a standard clinical classification for this presentation. CDI can occur at any age, and in this case, it is clearly secondary to trauma. **3. NEET-PG High-Yield Pearls:** * **Etiology:** Head trauma, pituitary surgery (Sheehan syndrome), or idiopathic are common causes of CDI. * **Nephrogenic DI:** If the urine osmolarity had remained low after dDAVP, the diagnosis would be Nephrogenic DI (ADH resistance), often caused by Lithium or mutations in V2 receptors. * **Diagnostic Cut-off:** A urine osmolarity increase of **>50%** after desmopressin indicates Central DI; an increase of **<10%** indicates Nephrogenic DI. * **Normal Serum Osmolarity:** 275–295 mOsm/L. This patient’s 330 mOsm/L indicates severe dehydration.

Q: Hypertension with hyperkalemia is seen in which of the following conditions?

Gordon's syndrome. **Explanation:** The combination of **hypertension and hyperkalemia** is a classic "high-yield" clinical scenario. Most hypertensive endocrine disorders involve excess mineralocorticoids, which typically cause hypokalemia [1]. **1. Why Gordon’s Syndrome is correct:** Also known as **Pseudohypoaldosteronism Type II**, this is a rare genetic disorder caused by mutations in WNK kinases. This leads to overactivity of the **Na-Cl cotransporter (NCC)** in the distal convoluted tubule. The increased reabsorption of sodium and chloride causes volume expansion (hypertension). Because less sodium reaches the collecting duct, there is decreased secretion of potassium and hydrogen ions, resulting in **hyperkalemia** and metabolic acidosis, despite low or normal aldosterone levels. **2. Why the other options are incorrect:** * **Conn’s Syndrome (Primary Hyperaldosteronism):** Characterized by hypertension with **hypokalemia** (due to aldosterone-mediated potassium wasting) [2]. * **Addison’s Disease:** While it features hyperkalemia (due to aldosterone deficiency), it is characterized by **hypotension**, not hypertension. * **Renal Failure:** While advanced renal failure causes hyperkalemia and hypertension, Gordon’s syndrome is the specific endocrine/genetic "spot diagnosis" tested in this context, especially when renal function (GFR) is otherwise relatively preserved. **Clinical Pearls for NEET-PG:** * **Gordon’s Syndrome** is essentially the "mirror image" of Gitelman syndrome. * **Treatment:** It responds remarkably well to **Thiazide diuretics**, which block the overactive NCC transporter. * **Liddle’s Syndrome:** Another cause of hypertension, but it causes **hypokalemia** (due to overactive ENaC channels). * **Rule of Thumb:** Hypertension + Hyperkalemia = Think Gordon’s Syndrome or Renal Artery Stenosis with Renal Failure.

Q: Which of the following is NOT used in the diagnosis of insulinoma?

D-xylose test. The diagnosis of **Insulinoma** (an insulin-secreting pancreatic islet cell tumor) relies on demonstrating endogenous hyperinsulinemic hypoglycemia [1]. **Why D-xylose test is the correct answer:** The **D-xylose test** is a diagnostic tool used to evaluate the absorptive capacity of the proximal small intestine. It is primarily used to differentiate between malabsorption caused by intestinal mucosal disease (e.g., Celiac disease) and malabsorption due to pancreatic enzyme deficiency. It has no physiological or clinical relevance to glucose metabolism or insulin secretion. **Analysis of other options:** * **72-hour fasting blood glucose:** This is the **gold standard** provocative test for insulinoma. Patients are fasted until they develop symptoms of hypoglycemia (Whipple’s triad), at which point blood is drawn for glucose, insulin, and C-peptide [1]. * **C-peptide levels:** Insulinomas secrete insulin and C-peptide in equimolar amounts. High C-peptide levels during hypoglycemia help distinguish insulinoma from **factitious insulin injection** (where C-peptide would be suppressed) [1]. * **Insulin/glucose ratio:** In normal individuals, insulin levels fall as glucose falls. In insulinoma, the ratio is inappropriately high (typically **>0.3**). **Clinical Pearls for NEET-PG:** * **Whipple’s Triad:** 1. Symptoms of hypoglycemia, 2. Low plasma glucose (<55 mg/dL), 3. Relief of symptoms after glucose administration. * **Biochemical Diagnosis:** Glucose <55 mg/dL, Insulin ≥3 μU/mL, C-peptide ≥0.6 ng/mL, and Proinsulin ≥5.0 pmol/L. * **Localization:** Endoscopic Ultrasound (EUS) is the most sensitive imaging modality for localizing the tumor. * **Association:** 10% of insulinomas are associated with **MEN-1 syndrome**.

Question 1

A 52-year-old man complains of impotence. On physical examination, he has an elevated jugular venous pressure, an S3 gallop, and hepatomegaly. He also appears tanned with pigmentation along the skin folds. He has joint pain and bony overgrowth primarily affecting the second and third metacarpophalangeal joints bilaterally. The plasma glucose is 250 mg/dL, and liver enzymes are elevated. Which of the following studies will help establish the diagnosis?

Accepted Answer

Determination of iron saturation

Answer

Detection of nocturnal penile tumescence

Answer

Determination of serum copper

Answer

Detection of hepatitis B surface antigen

Question 2

All of the following are true about osteomalacia EXCEPT:

Accepted Answer

Raised serum calcium

Answer

Vitamin D deficiency

Answer

Proximal myopathy

Answer

Bone biopsy shows increased demineralized bone matrix

Question 3

According to the American Diabetes Association, which of the following criteria indicates a prediabetic condition?

Accepted Answer

Fasting plasma glucose between 100 to 125 mg/dL

Answer

2-hour plasma glucose of 100 mg/dL

Answer

HbA1c greater than 6.5%

Answer

All of the above

Question 4

All of the following are true regarding idiopathic edema in women except:

Accepted Answer

It is due to estrogen-mediated sodium retention.

Answer

It is related to the menstrual cycle.

Answer

There is increased water retention in the upright position.

Answer

ACE inhibitors can be useful in some cases.

Question 5

Jod-Basedow phenomenon is seen in all of the following, EXCEPT:

Accepted Answer

Normal thyroid gland

Answer

Amiodarone

Answer

Iodine-containing contrast agents

Answer

Iodine in seafood

Question 6

Which of the following statements is NOT true regarding Insulinoma?

Accepted Answer

Weight loss

Answer

Hypoglycemic attacks

Answer

Usually solitary tumor

Answer

Mostly benign tumor

Question 7

A 45-year old woman is admitted to the hospital following a head injury. She has severe polyuria (producing 1 L of urine every 2 hours) and polydipsia (drinking 3 to 4 glasses of water every hour). During a 24-hour period in the hospital, the woman produces 10 L of urine, containing no glucose. She is placed on overnight water restriction for further evaluation. The following morning, she is weak and confused. Her serum osmolarity is 330 mOsm/L, her serum sodium is 164 mEq/L, and her urine osmolarity is 70 mOsm/L. She is treated with dDAVP by nasal spray. Within 24 hours of initiating the treatment, her serum osmolarity is 295 mOsm/L and her urine osmolarity is 620 mOsm/L. What is the most likely diagnosis?

Accepted Answer

Central Diabetes Insipidus

Answer

Diabetes Mellitus Type I

Answer

Diabetes Mellitus Type II

Answer

Juvenile Diabetes Insipidus

Question 8

Hypertension with hyperkalemia is seen in which of the following conditions?

Accepted Answer

Gordon's syndrome

Answer

Conn's syndrome

Answer

Addison's disease

Answer

Renal failure

Question 9

Which of the following is NOT used in the diagnosis of insulinoma?

Accepted Answer

D-xylose test

Answer

72-hour fasting blood glucose levels

Answer

C-peptide levels

Answer

Insulin/glucose ratio

Question 10

Dehydration in ketoacidosis is best treated with?

Accepted Answer

Normal saline

Answer

Isolyte P

Answer

Isolyte M

Answer

Molar 1/6 lactate

Endocrinology — MCQs

Endocrinology — MCQs

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