Endocrinology Practice Questions

Q: Thyroid function tests performed on serum from a 33-year-old woman reveal increased TSH, decreased total T4, decreased free T4, and decreased T3 uptake. Which of the following clinical features would be most likely to be seen in this patient?

Weight gain. ### Explanation **Analysis of Thyroid Function Tests (TFTs):** The patient’s lab results—**increased TSH** and **decreased free T4**—are diagnostic of **Primary Hypothyroidism** [1]. The decreased T3 uptake further confirms a low thyroid hormone state (as there are more vacant binding sites on Thyroid Binding Globulin). In hypothyroidism, the basal metabolic rate (BMR) decreases significantly, leading to the clinical manifestations described. **Why Weight Gain is Correct:** In primary hypothyroidism, the deficiency of thyroid hormones leads to a generalized slowing of metabolic processes. **Weight gain** occurs due to a combination of a decreased metabolic rate and the accumulation of glycosaminoglycans (myxedema), which causes fluid retention. This is a classic "hypometabolic" symptom. **Why Other Options are Incorrect:** * **A. Diarrhea:** Hypothyroidism causes decreased gastrointestinal motility, leading to **constipation**. Diarrhea is a feature of hyperthyroidism. * **B. Heat intolerance:** Patients with hypothyroidism feel cold due to low thermogenesis (**cold intolerance**). Heat intolerance is seen in hyperthyroidism [2]. * **C. Hyperactivity:** Hypothyroidism is characterized by psychomotor retardation, fatigue, and lethargy. Hyperactivity and tremors are hallmarks of thyrotoxicosis [2]. **NEET-PG High-Yield Pearls:** * **Most common cause:** Worldwide, iodine deficiency is the leading cause; however, in iodine-sufficient areas (and frequently in exams), **Hashimoto’s Thyroiditis** (autoimmune) is the most common cause. * **Early Sign:** An elevated TSH is the most sensitive initial marker for primary hypothyroidism [1]. * **Wolff-Chaikoff Effect:** Transient hypothyroidism caused by the ingestion of a large amount of iodine (e.g., amiodarone or contrast dye). * **Clinical Sign:** Delayed relaxation of deep tendon reflexes (Hungry-bomb sign) is a highly specific physical finding.

Q: Increased intracellular insulin is characterized by all of the following EXCEPT:

Increased glucagon secretion. **Explanation:** The physiological effects of insulin are primarily anabolic and occur in response to high blood glucose levels [1], [2]. To understand this question, one must recognize the **reciprocal relationship** between insulin and glucagon [4]. **Why "Increased glucagon secretion" is the correct answer:** Insulin and glucagon act as counter-regulatory hormones [3]. When insulin levels are high (hyperinsulinemia), insulin acts directly on the alpha cells of the pancreas to **inhibit** the secretion of glucagon [1], [4]. Therefore, increased insulin is characterized by *decreased* glucagon secretion, making Option B the false statement. **Analysis of Incorrect Options:** * **A. Increased insulin secretion:** This is a direct cause of increased intracellular insulin signaling. In states like insulinoma or post-prandial surges, high circulating insulin leads to increased cellular uptake [2]. * **C. Hypoglycemia:** Insulin promotes glucose uptake into skeletal muscle and adipose tissue via GLUT-4 translocation and inhibits hepatic gluconeogenesis [1], [5]. An excess of insulin inevitably leads to a drop in blood glucose [2], [4]. * **D. Hypokalemia:** Insulin stimulates the **Na+/K+ ATPase pump**, driving potassium from the extracellular fluid into the intracellular compartment [5]. This is the physiological basis for using insulin-glucose infusions to treat hyperkalemia [5]. **NEET-PG High-Yield Pearls:** * **The "Shift" Rule:** Insulin shifts three things into cells: Glucose, Potassium ($K^+$), and Magnesium ($Mg^{2+}$). * **Paracrine Inhibition:** Within the Islets of Langerhans, insulin (from Beta cells) inhibits glucagon (from Alpha cells), and somatostatin (from Delta cells) inhibits both [4]. * **Clinical Correlation:** In Diabetic Ketoacidosis (DKA) management, always check potassium levels before starting insulin, as insulin will further worsen hypokalemia [5].

Q: A 22-year-old female presents with diarrhea, palpitations, anxiety, and abdominal pain, reporting weight loss. She mentions taking an unknown medication prescribed to someone else. Which of the following drugs is most likely responsible for her presentation?

Levothyroxine. ### **Explanation** **Correct Option: D. Levothyroxine** The patient is presenting with classic signs of **thyrotoxicosis** (hyperthyroidism): palpitations, anxiety, weight loss, and diarrhea. The history of taking an "unknown medication prescribed to someone else" points toward **Factitious Thyrotoxicosis** (exogenous ingestion of thyroid hormone). Levothyroxine (T4) is a synthetic thyroid hormone used for hypothyroidism; when taken by a euthyroid individual, it induces a hypermetabolic state mimicking Graves' disease, but notably without goiter or exophthalmos. **Why Incorrect Options are Wrong:** * **A & C (Propylthiouracil & Methimazole):** These are **anti-thyroid drugs (Thionamides)**. They inhibit thyroid hormone synthesis by blocking thyroid peroxidase. Overdose or misuse of these drugs would lead to **hypothyroidism** (bradycardia, weight gain, constipation), the exact opposite of this patient's presentation. * **B (Iodide):** High doses of Iodide (Lugol’s iodine) generally cause a transient inhibition of thyroid hormone release (the **Wolff-Chaikoff effect**). While it can rarely cause hyperthyroidism in patients with underlying nodules (Jod-Basedow phenomenon), it is not a common medication "prescribed to someone else" that would typically cause this acute presentation in a young female. **NEET-PG High-Yield Pearls:** * **Factitious Thyrotoxicosis:** Characterized by high T4/T3 levels, low TSH, and **suppressed (low) serum thyroglobulin** levels. * **Radioactive Iodine Uptake (RAIU):** In exogenous ingestion (Levothyroxine), the RAIU will be **low/absent** because the thyroid gland is suppressed. * **Propylthiouracil (PTU):** Preferred in the **1st trimester** of pregnancy and thyroid storm (inhibits peripheral conversion of T4 to T3). * **Methimazole:** Preferred in the 2nd and 3rd trimesters; associated with **Aplasia Cutis** if used in the 1st trimester.

Q: A 36-year-old female presents with symptoms of hyperparathyroidism, a tumor in the pancreas, adrenal cortical hyperplasia, pituitary adenomas, an islet cell tumor, and cutaneous angiofibromas. What is the diagnosis?

Multiple Endocrine Neoplasia type 1 (MEN 1). The patient presents with the classic triad of **MEN 1 (Wermer Syndrome)**, often remembered by the **"3 Ps"**: **P**arathyroid hyperplasia (leading to hyperparathyroidism), **P**ancreatic islet cell tumors (e.g., gastrinomas, insulinomas), and **P**ituitary adenomas (most commonly prolactinomas) [1]. The presence of **cutaneous angiofibromas**, collagenomas, and lipomas are recognized dermatological manifestations specific to MEN 1. While adrenal cortical hyperplasia can occur in MEN 1, it is less common than the primary triad but helps differentiate it from other syndromes. The condition is caused by a mutation in the **MEN1 gene** on chromosome **11q13**, which encodes the protein **menin**. **Why other options are incorrect:** * **MEN 2A (Sipple Syndrome):** Characterized by Medullary Thyroid Carcinoma (MTC), Pheochromocytoma, and Parathyroid hyperplasia. It lacks pituitary and pancreatic involvement. * **MEN 2B:** Characterized by MTC, Pheochromocytoma, and distinct physical features like **Mucosal neuromas** and a **Marfanoid habitus**. It does not involve the parathyroid or pancreas. * **MEN 2C:** This is an obsolete term sometimes previously used to describe familial medullary thyroid carcinoma without other endocrine features; it is not a standard diagnosis in modern classification. **NEET-PG High-Yield Pearls:** * **Most common initial presentation of MEN 1:** Primary Hyperparathyroidism (seen in >90% of patients by age 40). * **Most common pancreatic tumor in MEN 1:** Gastrinoma (Zollinger-Ellison Syndrome). * **Inheritance:** All MEN syndromes are **Autosomal Dominant** [1]. * **MEN 2 Association:** Both 2A and 2B are associated with mutations in the **RET proto-oncogene**.

Q: Which of the following laboratory findings is characteristic of primary hypothyroidism?

Decreased T3, decreased T4, increased TSH. ### Explanation **Correct Answer: A. Decreased T3, decreased T4, increased TSH** **Understanding the Concept:** Primary hypothyroidism occurs due to a failure of the thyroid gland itself (most commonly Hashimoto’s thyroiditis). When the thyroid gland cannot produce sufficient thyroid hormones (**T4 and T3**), the negative feedback loop to the pituitary gland is lost [1]. In response, the anterior pituitary increases the secretion of **Thyroid Stimulating Hormone (TSH)** to "force" the thyroid to work [2]. Therefore, the hallmark of primary hypothyroidism is a **high TSH** accompanied by **low free T4** [1]. **Analysis of Incorrect Options:** * **Option B (Decreased T3, increased T4, decreased TSH):** This pattern is physiologically inconsistent. High T4 would typically suppress TSH, not occur alongside a low TSH unless there is an exogenous source, but T3 would not be low. * **Option C (Normal T3, normal T4, increased TSH):** This is the characteristic profile of **Subclinical Hypothyroidism**. The pituitary is sensing a mild deficiency and compensating by raising TSH to keep T4/T3 within the normal range. * **Option D (Decreased T3, decreased T4, normal/low TSH):** This indicates **Secondary (Central) Hypothyroidism**, where the pathology lies in the pituitary or hypothalamus. The thyroid is capable of working, but the "stimulus" (TSH) is missing. **NEET-PG High-Yield Pearls:** 1. **TSH is the most sensitive screening test** for thyroid dysfunction. 2. **T4 vs. T3:** T4 is the primary secretory product of the thyroid; T3 is often the last to fall in hypothyroidism because peripheral conversion of T4 to T3 is maintained. 3. **Hashimoto’s Thyroiditis:** The most common cause of primary hypothyroidism in iodine-sufficient areas; associated with **Anti-TPO antibodies**. 4. **Wolff-Chaikoff Effect:** Hypothyroidism induced by a large load of iodine (e.g., amiodarone).

Q: Early morning hyperglycemia with increased blood glucose at 3:00 AM suggests:

Insufficient insulin. This question tests the ability to differentiate between the three primary causes of early morning hyperglycemia in diabetic patients. The key to the diagnosis lies in the **3:00 AM blood glucose reading**. ### **1. Why "Insufficient Insulin" is Correct** Early morning hyperglycemia with an **elevated** 3:00 AM glucose level indicates that the basal insulin dose administered the previous evening was inadequate to cover the body's needs throughout the night. Since glucose is high at 3:00 AM and continues to rise until morning, it reflects a simple deficiency of insulin (waning effect) [1]. ### **2. Why the Other Options are Incorrect** * **Dawn Phenomenon:** This is a physiological rise in blood glucose between 4:00 AM and 8:00 AM caused by the nocturnal surge of counter-regulatory hormones (Growth Hormone, Cortisol, and Glucagon). Crucially, in Dawn Phenomenon, the **3:00 AM glucose is normal or slightly elevated**, not low. * **Somogyi Effect:** This is **rebound hyperglycemia**. It occurs when excessive evening insulin causes hypoglycemia in the middle of the night (around 3:00 AM) [2]. The body responds by releasing stress hormones (epinephrine, glucagon) that cause a spike in morning glucose. In Somogyi effect, the **3:00 AM glucose must be low (<70 mg/dL)**. ### **3. Clinical Pearls for NEET-PG** * **The "3 AM Rule":** To distinguish these conditions, always check the 3:00 AM blood sugar [2]. * **Low at 3 AM:** Somogyi Effect (Management: Decrease evening insulin or add a bedtime snack). * **High/Normal at 3 AM:** Dawn Phenomenon or Insufficient Insulin (Management: Increase evening insulin). * **Dawn Phenomenon** is most common in Type 1 Diabetics during puberty due to high Growth Hormone levels. * **Management Summary:** If glucose is high at 3 AM, you need **more** insulin; if it is low at 3 AM, you need **less** insulin.

Question 1

Thyroid function tests performed on serum from a 33-year-old woman reveal increased TSH, decreased total T4, decreased free T4, and decreased T3 uptake. Which of the following clinical features would be most likely to be seen in this patient?

Accepted Answer

Weight gain

Answer

Diarrhea

Answer

Heat intolerance

Answer

Hyperactivity

Question 2

Increased intracellular insulin is characterized by all of the following EXCEPT:

Accepted Answer

Increased glucagon secretion

Answer

Increased insulin secretion

Answer

Hypoglycemia

Answer

Hypokalemia

Question 3

A 40-year-old woman presents with symptoms of light-headedness, sweating, palpitations, and hunger, most pronounced when she misses a meal. Her physical examination, vital signs, and past medical history are unremarkable. During an episode, her blood glucose level was 30 mg/dL, and symptoms resolved with juice. What is the most likely diagnosis?

Accepted Answer

Tumor of the pancreatic beta-cells

Answer

Excess growth hormone

Answer

Cushing disease

Answer

Thyrotoxicosis

Question 4

A 22-year-old female presents with diarrhea, palpitations, anxiety, and abdominal pain, reporting weight loss. She mentions taking an unknown medication prescribed to someone else. Which of the following drugs is most likely responsible for her presentation?

Accepted Answer

Levothyroxine

Answer

Propylthiouracil (PTU)

Answer

Iodide

Answer

Methimazole

Question 5

A 36-year-old female presents with symptoms of hyperparathyroidism, a tumor in the pancreas, adrenal cortical hyperplasia, pituitary adenomas, an islet cell tumor, and cutaneous angiofibromas. What is the diagnosis?

Accepted Answer

Multiple Endocrine Neoplasia type 1 (MEN 1)

Answer

Multiple Endocrine Neoplasia type 2A (MEN 2A)

Answer

Multiple Endocrine Neoplasia type 2B (MEN 2B)

Answer

Multiple Endocrine Neoplasia type 2C (MEN 2C)

Question 6

Which of the following laboratory findings is characteristic of primary hypothyroidism?

Accepted Answer

Decreased T3, decreased T4, increased TSH

Answer

Decreased T3, increased T4, decreased TSH

Answer

Normal T3, normal T4, increased TSH

Answer

Decreased T3, decreased T4, normal TSH

Question 7

A 35-year-old male presents with symptoms of palpitations, tremors, nervousness, and headache. His father has a history of type 2 DM and his mother has a history of psychiatric illness. He has no chronic medical conditions and takes no medications. He appears anxious, sweaty, and shaky. His fingerstick glucose is 45 mg/dl. The patient is administered a bolus of 50% glucose which rapidly improves his symptoms. CECT abdomen shows a mass. Which of the following is likely to be seen after overnight fasting?

Accepted Answer

Serum insulin, Serum pro-insulin, C-peptide levels: Increased, Increased, Increased

Answer

Serum insulin, Serum pro-insulin, C-peptide levels: Normal, Normal, Normal

Answer

Serum insulin, Serum pro-insulin, C-peptide levels: Increased, Normal, Decreased

Answer

Serum insulin, Serum pro-insulin, C-peptide levels: Decreased, Increased, Increased

Question 8

A patient sustains a transaction of the pituitary stalk following an accident. Which of the following clinical manifestations will NOT occur?

Accepted Answer

Diabetes mellitus

Answer

Diabetes insipidus

Answer

Hyperprolactinemia

Answer

Hypothyroidism

Question 9

A patient presented with episodes of flushing and hypotension. His urinary 5HIAA levels were found to be increased. What is the diagnosis?

Accepted Answer

Carcinoid syndrome

Answer

Pheochromocytoma

Answer

Addison's disease

Answer

SIADH

Question 10

Early morning hyperglycemia with increased blood glucose at 3:00 AM suggests:

Accepted Answer

Insufficient insulin

Answer

Dawn phenomenon

Answer

Somogyi effect

Answer

None of the above

Endocrinology — MCQs

Endocrinology — MCQs

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