Endocrinology Practice Questions

Q: Which type of thyroid carcinoma is associated with hypocalcemia?

Medullary carcinoma. **Explanation:** **Medullary Thyroid Carcinoma (MTC)** is the correct answer because of its unique cellular origin. Unlike other thyroid cancers that arise from follicular cells, MTC originates from the **Parafollicular C-cells** of the thyroid gland. These cells are responsible for the secretion of **Calcitonin**. In MTC, there is a pathological hypersecretion of Calcitonin. Calcitonin acts as a physiological antagonist to Parathyroid Hormone (PTH); it lowers serum calcium levels by inhibiting bone resorption (osteoclast activity) and increasing renal calcium excretion. While clinical hypocalcemia is rare in MTC patients due to compensatory mechanisms, the biochemical association with calcium-lowering hormones makes it the characteristic answer for this question. **Why other options are incorrect:** * **Papillary and Follicular Carcinoma:** These are "Differentiated Thyroid Cancers" (DTC) arising from follicular cells. They secrete Thyroglobulin, not Calcitonin, and have no direct effect on calcium metabolism. * **Anaplastic Carcinoma:** This is an undifferentiated, highly aggressive tumor. While it can cause local invasion (leading to hoarseness or dysphagia), it does not produce hormones that regulate calcium. **High-Yield Clinical Pearls for NEET-PG:** * **Tumor Marker:** Calcitonin is used for both diagnosis and monitoring recurrence in MTC. Carcinoembryonic Antigen (CEA) is also often elevated. * **Genetics:** Approximately 25% of MTC cases are familial, associated with **MEN 2A and 2B** syndromes (RET proto-oncogene mutation). * **Amyloid Stroma:** Histologically, MTC is characterized by polygonal cells with **amyloid deposits** (derived from pro-calcitonin) that stain with Congo Red. * **Spread:** MTC spreads via both lymphatic and hematogenous routes.

Q: What is the most likely complication of insulin therapy in ketoacidosis?

Hypoglycemia. **Explanation:** The management of Diabetic Ketoacidosis (DKA) involves aggressive fluid resuscitation and continuous intravenous insulin infusion. **Hypoglycemia** is the most common complication of insulin therapy in this setting [1]. This occurs because insulin promotes glucose uptake into cells and inhibits hepatic gluconeogenesis. If the insulin infusion rate is not adjusted or if dextrose is not added to the intravenous fluids once blood glucose levels drop below **200–250 mg/dL**, the patient’s blood sugar can plummet rapidly. **Analysis of Options:** * **A. Dilutional Hyponatremia:** This is incorrect. In DKA, patients often have "pseudohyponatremia" due to the osmotic effect of hyperglycemia [2]. As insulin therapy lowers blood glucose, water shifts back into cells, and the serum sodium concentration typically **rises**. * **C. Increased Bleeding Tendency:** There is no direct physiological link between insulin therapy and coagulopathy or platelet dysfunction. * **D. Pancreatitis:** While acute pancreatitis can be a *trigger* for DKA (due to metabolic stress), it is not a complication caused by insulin therapy itself. **NEET-PG High-Yield Pearls:** 1. **The "Big Three" Complications:** The most common complications of DKA management are **Hypoglycemia** [1], **Hypokalemia** (due to insulin shifting K+ into cells), and **Cerebral Edema** (most common in children due to rapid fluid shifts) [3]. 2. **Protocol Tip:** To prevent hypoglycemia, switch from Normal Saline to **5% Dextrose (D5NS)** when plasma glucose reaches **200 mg/dL**, while continuing the insulin infusion to resolve the underlying ketosis. 3. **Potassium Rule:** Never start insulin if the serum potassium is **<3.3 mEq/L**, as insulin will further worsen the hypokalemia, potentially leading to fatal arrhythmias.

Q: Which of the following statements about MODY is false?

Requires insulin therapy. Maturity-Onset Diabetes of the Young (MODY) is a group of monogenic disorders characterized by non-insulin-dependent diabetes caused by mutations in genes affecting beta-cell function, rather than insulin resistance or autoimmune destruction [1]. Why Option D is the Correct Answer (False Statement): Unlike Type 1 Diabetes, MODY is primarily a defect in insulin secretion "sensing" or production, not a total absence of insulin. Most patients (especially those with MODY 1 and 3) have significant residual beta-cell function and do not require insulin therapy, at least in the early stages [1]. Many can be managed effectively with oral hypoglycemic agents or diet alone. Analysis of Incorrect Options: * Option A: MODY typically presents in adolescence or early adulthood, usually before age 25, distinguishing it from Type 2 Diabetes [1]. * Option B: The pathophysiology involves impaired insulin secretion due to genetic mutations (e.g., HNF1A, GCK), while insulin sensitivity remains normal. * Option C: Patients with MODY 3 (the most common type) and MODY 1 are exquisitely sensitive to Sulfonylureas, which is often the first-line treatment. High-Yield Clinical Pearls for NEET-PG: 1. Inheritance: Autosomal Dominant (look for a strong family history across 3 generations) [1]. 2. MODY 3 (HNF1A): Most common form; highly sensitive to low-dose sulfonylureas. 3. MODY 2 (GCK): Characterized by mild, stable fasting hyperglycemia; usually requires no treatment (diet only). 4. Diagnostic Clue: Absence of pancreatic autoantibodies (GAD, IA-2) and low/normal BMI.

Question 1

Which of the following statements about Cushing's disease is true?

Accepted Answer

A pituitary microadenoma usually is present

Answer

Serum adrenocorticotropic hormone (ACTH) levels usually are high

Answer

There is a low incidence of nonendocrine tumors

Answer

Suppression of cortisol production by the high-dose dexamethasone suppression test is a characteristic finding

Question 2

A patient presents with bilateral proptosis, heat intolerance, and palpitations. Which of the following is the most unlikely diagnosis?

Accepted Answer

Riedel's thyroiditis

Answer

Hashimoto's thyroiditis

Answer

Thyroid adenoma

Answer

Diffuse thyroid goiter

Question 3

A 55-year-old woman with a history of severe depression and radical mastectomy for breast carcinoma one year ago presents with polyuria, nocturia, and excessive thirst. Laboratory values are as follows: Serum sodium 149 mEq/L, Serum potassium 3.6 mEq/L, Serum calcium 9.5 mg/dL, Glucose 110 mg/dL, BUN 30 mg/dL, Urine osmolarity 150 mOsm/kg. What is the most likely clinical diagnosis?

Accepted Answer

Diabetes insipidus

Answer

Psychogenic polydipsia

Answer

Renal glycosuria

Answer

Hypercalcemia

Question 4

Which type of thyroid carcinoma is associated with hypocalcemia?

Accepted Answer

Medullary carcinoma

Answer

Follicular carcinoma

Answer

Anaplastic carcinoma

Answer

Papillary carcinoma

Question 5

What is the most likely complication of insulin therapy in ketoacidosis?

Accepted Answer

Hypoglycemia

Answer

Dilutional hyponatremia

Answer

Increased bleeding tendency

Answer

Pancreatitis

Question 6

A 47-year-old woman presents with increasing headaches and visual changes. On examination, her pupils are normal and reactive to light, the extraocular movements are normal, and there are visual field defects of the outer half in both eyes (bitemporal hemianopsia). Which of the following is the most likely diagnosis?

Accepted Answer

pituitary adenoma

Answer

falx meningioma

Answer

craniopharyngioma

Answer

aneurysm of the internal carotid artery

Question 7

What is the earliest presentation of hypopituitarism in adults?

Accepted Answer

Hypogonadism

Answer

Growth failure

Answer

Anosmia

Answer

Visual field defects

Question 8

What is the Chvostek sign?

Accepted Answer

Twitching of circumoral muscles on tapping of the facial nerve

Answer

Involuntary blink on tapping of the facial nerve

Answer

Inability to open the eye on tapping of the facial nerve

Answer

Inability to close the eye on tapping of the facial nerve

Question 9

An 80-year-old woman, previously in sinus rhythm, developed atrial fibrillation with rapid ventricular response during an ICU stay for sepsis. She was treated with amiodarone, converted to sinus rhythm, and was discharged on maintenance amiodarone. In the following weeks, she presented with increasing fatigue, dry skin, and constipation. Laboratory tests revealed a TSH of 25 mIU/L. What is the best management approach in this situation?

Accepted Answer

Initiate low-dose levothyroxine and repeat TSH in 6 weeks.

Answer

Discontinue amiodarone and monitor TSH and clinical symptoms.

Answer

Start a beta-blocker and gradually withdraw amiodarone.

Answer

Measure anti-thyroid peroxidase (TPO) antibodies to guide treatment.

Question 10

Which of the following statements about MODY is false?

Accepted Answer

Requires insulin therapy

Answer

Onset typically before 25 years of age

Answer

Characterized by impaired insulin secretion

Answer

Often responsive to sulfonylureas

Endocrinology — MCQs

Endocrinology — MCQs

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