Endocrinology Practice Questions

Q: SIADH secretion is seen in all of the following conditions except?

Interstitial Nephritis. The Syndrome of Inappropriate Antidiuretic Hormone (SIADH) is characterized by the excessive release of ADH from the posterior pituitary [1] or an ectopic source, leading to water retention and dilutional hyponatremia [2]. **Why Interstitial Nephritis is the correct answer:** Interstitial nephritis is a primary renal parenchymal disease. It often leads to **Nephrogenic Diabetes Insipidus (NDI)** rather than SIADH. In NDI, the renal tubules become resistant to ADH [3], leading to the inability to concentrate urine and resulting in polyuria and hypernatremia. Therefore, it is physiologically opposite to SIADH. **Analysis of Incorrect Options:** * **Meningitis:** Central Nervous System (CNS) disorders (meningitis, encephalitis, trauma, or tumors) are classic causes of SIADH. Any irritation or pressure on the hypothalamus/pituitary axis can trigger unregulated ADH release [4]. * **Hypothyroidism:** Severe hypothyroidism (Myxedema) is a well-known cause of SIADH. The mechanism involves decreased cardiac output and glomerular filtration rate (GFR), which triggers non-osmotic release of ADH. * **Lung Cancer:** Specifically, **Small Cell Carcinoma of the Lung** is the most common ectopic source of ADH. It is a classic paraneoplastic syndrome frequently tested in NEET-PG. **High-Yield Clinical Pearls for NEET-PG:** 1. **Diagnosis:** SIADH is a diagnosis of exclusion. Criteria include: Euvolemic hyponatremia, low serum osmolality ( 100 mOsm/kg). 2. **Drug Causes:** Common triggers include Carbamazepine, Cyclophosphamide, and SSRIs. 3. **Treatment:** Fluid restriction is the first-line treatment. For chronic management, Vaptans (Vasopressin antagonists) or Demeclocycline may be used. 4. **Caution:** Rapid correction of hyponatremia can lead to **Osmotic Demyelination Syndrome** (Central Pontine Myelinolysis).

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 gene is NOT associated with Diabetes Mellitus?

PDGF-R. The correct answer is **D. PDGF-R** (Platelet-Derived Growth Factor Receptor). This receptor is primarily involved in cell growth, proliferation, and angiogenesis. While it plays a role in wound healing and atherosclerosis (complications of diabetes), it is not a genetic locus associated with the pathogenesis or susceptibility of Diabetes Mellitus itself. **Analysis of Options:** * **PPARγ (Peroxisome Proliferator-Activated Receptor Gamma):** This is a nuclear receptor essential for adipocyte differentiation and glucose metabolism. Mutations in the *PPARG* gene are strongly associated with **Type 2 Diabetes (T2DM)** and insulin resistance. It is the molecular target for Thiazolidinediones (e.g., Pioglitazone). * **KCNJ11:** This gene encodes the Kir6.2 subunit of the ATP-sensitive potassium (K-ATP) channel in pancreatic beta cells. Mutations in this gene are a well-known cause of **Neonatal Diabetes Mellitus** and are associated with an increased risk of T2DM. * **CTLA4 (Cytotoxic T-Lymphocyte Associated Protein 4):** This is an immune checkpoint molecule. Polymorphisms in the *CTLA4* gene are associated with autoimmune susceptibility, specifically **Type 1 Diabetes Mellitus (T1DM)**, as well as Graves' disease and Addison’s disease [1]. **High-Yield Clinical Pearls for NEET-PG:** * **MODY Type 3:** The most common form of Maturity-Onset Diabetes of the Young, caused by mutations in the **HNF1A** gene. * **MODY Type 2:** Caused by **Glucokinase (GCK)** mutations; usually presents with mild, stable fasting hyperglycemia. * **HLA Association:** T1DM is most strongly linked to **HLA-DR3 and HLA-DR4** [2]. * **TCF7L2:** Currently considered the strongest common genetic risk factor for Type 2 Diabetes in various ethnic groups.

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

SIADH secretion is seen in all of the following conditions except?

Accepted Answer

Interstitial Nephritis

Answer

Meningitis

Answer

Hypothyroidism

Answer

Lung cancer

Question 2

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

Accepted Answer

Hypoglycemia

Answer

Dilutional hyponatremia

Answer

Increased bleeding tendency

Answer

Pancreatitis

Question 3

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 4

What is the earliest presentation of hypopituitarism in adults?

Accepted Answer

Hypogonadism

Answer

Growth failure

Answer

Anosmia

Answer

Visual field defects

Question 5

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 6

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 7

Which gene is NOT associated with Diabetes Mellitus?

Accepted Answer

PDGF-R

Answer

PPARγ

Answer

KCNJ11

Answer

CTLA4

Question 8

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

Question 9

All of the following are true about hyperparathyroidism, except?

Accepted Answer

None of the above

Answer

Commonly occurs after thyroidectomy

Answer

May cause hypercalcemia

Answer

Solitary adenoma is the most common cause

Question 10

Which of the following is true about Conn's syndrome?

Accepted Answer

Decreased K+

Answer

Increased K+

Answer

Proximal myopathy

Answer

Decreased plasma renin activity

Endocrinology — MCQs

Endocrinology — MCQs

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