Endocrinology Practice Questions

Q: A high carbohydrate diet can precipitate which of the following conditions?

Hypokalemic periodic paralysis. **Explanation:** **Hypokalemic Periodic Paralysis (HPP)** is the correct answer because of the physiological relationship between glucose, insulin, and potassium. 1. **Mechanism of the Correct Answer:** A high carbohydrate diet triggers a significant release of **insulin**. Insulin acts on the Na+/K+-ATPase pump, shifting potassium from the extracellular fluid into the intracellular compartment (skeletal muscle) [2]. In individuals with genetic mutations in calcium or sodium channels (e.g., CACNA1S or SCN4A), this shift leads to acute hypokalemia and muscle membrane inexcitability, resulting in flaccid paralysis. Common triggers include high-carb meals, strenuous exercise followed by rest, and emotional stress [1]. 2. **Analysis of Incorrect Options:** * **Hyperkalemic Periodic Paralysis:** This condition is typically precipitated by fasting, rest after exercise, or potassium intake—not high carbohydrates [1]. In fact, glucose/insulin can be used to *treat* an acute attack by lowering potassium levels. * **Hysterical Paralysis (Conversion Disorder):** This is a psychiatric manifestation of neurological symptoms without a physiological cause. It is triggered by psychological stress, not dietary intake. * **Myasthenia Gravis:** This is an autoimmune disorder involving antibodies against acetylcholine receptors. It presents with fatigable weakness (ptosis, diplopia) and is unrelated to carbohydrate metabolism or potassium shifts. **NEET-PG High-Yield Pearls:** * **Inheritance:** Most cases are Autosomal Dominant [1]. * **Thyrotoxic Periodic Paralysis (TPP):** A common secondary cause of HPP, especially in Asian males; it presents identically but is triggered by hyperthyroidism. * **Management:** Acute attacks are treated with oral potassium (preferred over IV to avoid rebound hyperkalemia). Prophylaxis includes **Acetazolamide** (a carbonic anhydrase inhibitor) and avoiding high-carb meals.

Q: Which of the following is NOT a characteristic of inappropriate ADH secretion?

Hypo-osmolar urine. **Explanation:** The hallmark of **Syndrome of Inappropriate Antidiuretic Hormone (SIADH)** is the excessive release of ADH despite low plasma osmolality. ADH acts on the V2 receptors in the renal collecting ducts, causing water reabsorption [1], [3]. **1. Why "Hypo-osmolar urine" is the correct answer:** In SIADH, the kidneys reabsorb excessive amounts of water, leading to concentrated urine. Therefore, the urine is **hyper-osmolar** (typically >100 mOsm/kg, and often greater than the plasma osmolality). **Hypo-osmolar urine** is characteristic of Diabetes Insipidus, not SIADH. **2. Analysis of incorrect options:** * **Water intoxication:** The continuous water reabsorption leads to dilutional hyponatremia, essentially a state of "water intoxication" where the body has too much water relative to sodium. * **Expanded fluid volume:** SIADH causes mild ECF volume expansion. However, it is clinically **euvolemic** [2] because the body compensates via pressure natriuresis (excreting sodium and water) to prevent overt edema or hypertension. * **Hypomagnesemia:** Chronic SIADH is frequently associated with secondary electrolyte disturbances, including hypomagnesemia and hypokalemia, due to increased urinary excretion of these ions alongside the natriuresis. **NEET-PG High-Yield Pearls:** * **Diagnosis:** Look for the triad of Hyponatremia + Low Plasma Osmolality ( 100 mOsm/kg) in a clinically euvolemic patient [2]. * **Urine Sodium:** Typically high (>40 mEq/L) due to the body's attempt to shed volume. * **Treatment:** Fluid restriction is the first-line treatment. For severe cases, use hypertonic saline (3%) but avoid rapid correction to prevent **Osmotic Demyelination Syndrome (Central Pontine Myelinolysis).** * **Drug of choice (Vaptans):** Tolvaptan (oral) or Conivaptan (IV) are vasopressin receptor antagonists used in refractory cases.

Q: Which of the following is NOT a manifestation of carcinoid syndrome?

Steatorrhea. Explanation: Carcinoid syndrome results from the systemic release of vasoactive substances (primarily **serotonin**, histamine, and bradykinin) by neuroendocrine tumors, typically after they have metastasized to the liver [1]. **Why Steatorrhea is the Correct Answer:** Steatorrhea is **not** a direct manifestation of the syndrome itself. In fact, the diarrhea in carcinoid syndrome is **secretory** in nature (due to increased intestinal motility and fluid secretion caused by serotonin). However, steatorrhea can occur as a **side effect of treatment** with Somatostatin analogs (like Octreotide), which inhibit pancreatic enzyme secretion. It is not a primary clinical feature of the disease process. **Analysis of Other Options:** * **Retroperitoneal Fibrosis & Peyronie’s Disease:** High levels of serotonin stimulate fibroblast proliferation. This leads to **fibrotic complications**, including right-sided endocardial fibrosis, retroperitoneal fibrosis, and Peyronie’s disease (fibrosis of the corpus cavernosum). * **Occlusion of Mesenteric Arteries:** The intense local fibrotic reaction (desmoplastic reaction) in the mesentery can lead to kinking of the bowel and vascular compromise, potentially causing mesenteric ischemia or occlusion. **NEET-PG High-Yield Pearls:** * **Classic Triad:** Flushing (most common), Secretory Diarrhea, and Right-sided heart failure (Tricuspid regurgitation/Pulmonary stenosis) [1]. * **Diagnosis:** Best initial screening test is **24-hour urinary 5-HIAA** (metabolite of serotonin). * **Localization:** Somatostatin receptor scintigraphy (OctreoScan) or 68Ga-DOTATATE PET/CT. * **Pellagra Connection:** Serotonin is synthesized from Tryptophan. Excessive production can deplete Tryptophan stores, leading to **Niacin (Vitamin B3) deficiency** and Pellagra (Dermatitis, Dementia, Diarrhea).

Q: Non-pitting edema is seen in which of the following conditions?

Myxedema. **Explanation:** **Correct Answer: B. Myxedema** The hallmark of hypothyroidism (specifically severe cases or "myxedema") is **non-pitting edema**. This occurs due to the excessive deposition of **glycosaminoglycans** (primarily hyaluronic acid and chondroitin sulfate) in the dermis. These molecules are osmotic and trap water, but because they are bound in a mucopolysaccharide matrix, the fluid cannot be displaced by manual pressure, resulting in a firm, non-pitting surface [1]. This is most commonly seen in the pretibial area and periorbital tissues. **Incorrect Options:** * **A, C, and D (CCF, Liver Failure, Renal Failure):** These conditions cause **pitting edema**. The underlying mechanism is a disturbance in Starling forces—either an increase in capillary hydrostatic pressure (Heart Failure) or a decrease in plasma oncotic pressure due to hypoalbuminemia (Liver Cirrhosis and Nephrotic Syndrome). In these cases, the edema consists of free-moving interstitial fluid that is easily displaced upon pressure, leaving a "pit." **NEET-PG High-Yield Pearls:** * **Pretibial Myxedema:** Despite the name, this is actually a feature of **Graves' disease** (Hyperthyroidism), caused by thyroid-stimulating antibodies reacting with TSH receptors on fibroblasts [1]. It is also non-pitting. * **Lymphedema:** Another classic cause of non-pitting edema (e.g., in Filariasis or post-mastectomy) due to impaired lymphatic drainage and subsequent fibrosis. * **Stem Clue:** If a question mentions "puffy face," "macroglossia," and "non-pitting edema," always think of **Hypothyroidism**.

Q: A 25-year-old man presents with diabetes for the past year, which is well-controlled on oral hypoglycemic agents. He also has a family history of diabetes in young individuals. What is the most likely diagnosis?

Maturity Onset Diabetes in the Young (MODY). **Explanation:** The clinical presentation of a young patient (under 25 years) with a strong family history of diabetes and good glycemic control on oral hypoglycemic agents (OHAs) is classic for **Maturity Onset Diabetes in the Young (MODY)** [1]. **Why MODY is the correct answer:** MODY is a group of monogenic disorders characterized by an autosomal dominant inheritance pattern (affecting multiple generations) and primary defects in insulin secretion [1]. Unlike Type 1 DM, patients are typically non-obese, lack autoantibodies, and have preserved beta-cell function, allowing many subtypes (especially MODY 1 and 3) to be managed effectively with low-dose sulfonylureas rather than insulin. **Why other options are incorrect:** * **Type 1 Diabetes Mellitus:** Usually presents with an absolute insulin deficiency, ketosis-proneness, and requires lifelong insulin [2]. It is not typically controlled with oral agents. * **Type 2 Diabetes Mellitus:** While increasing in youth, it is usually associated with obesity, acanthosis nigricans, and insulin resistance [3]. The strong multi-generational history in a young, non-obese male points more specifically toward a monogenic cause. * **Type A Insulin Resistance:** This is a rare syndrome characterized by severe insulin resistance, acanthosis nigricans, and hyperandrogenism (in females), often due to insulin receptor mutations. **High-Yield Clinical Pearls for NEET-PG:** * **MODY 3 (HNF-1α mutation):** The most common subtype worldwide. * **MODY 2 (Glucokinase mutation):** Presents with mild, stable fasting hyperglycemia; often requires no treatment. * **Inheritance:** Autosomal Dominant (50% chance of transmission) [1]. * **Diagnostic Clue:** Absence of islet autoantibodies and detectable C-peptide levels 3–5 years after diagnosis [3].

Q: Which of the following is NOT seen in non-ketotic hyperosmolar coma?

Kussmaul's breathing. ### Explanation **Hyperosmolar Hyperglycemic State (HHS)**, formerly known as non-ketotic hyperosmolar coma, is a metabolic complication of Diabetes Mellitus characterized by extreme hyperglycemia and hyperosmolality without significant ketoacidosis. **Why Kussmaul’s breathing is NOT seen:** Kussmaul’s breathing (deep, rapid, labored respiration) is a compensatory mechanism for **metabolic acidosis**. It occurs in Diabetic Ketoacidosis (DKA) to "blow off" CO2 and increase blood pH. In HHS, there is enough endogenous insulin to suppress lipolysis and prevent the formation of ketone bodies. Since there is no significant ketosis or acidosis, Kussmaul’s breathing is absent. **Analysis of other options:** * **Insidious onset:** Unlike DKA, which develops over hours, HHS develops over days to weeks. The slow progression allows for extreme dehydration and glucose levels often exceeding 600 mg/dL. * **Seen in elderly:** HHS typically affects older patients with Type 2 DM, often triggered by infections (like pneumonia or UTI), stroke, or myocardial infarction. * **Seen in Type 2 DM:** While DKA is the hallmark of Type 1 DM, HHS is the classic emergency associated with Type 2 DM, where residual insulin prevents ketogenesis but cannot control hyperglycemia. **High-Yield Clinical Pearls for NEET-PG:** * **Diagnostic Criteria for HHS:** Plasma glucose >600 mg/dL, Serum osmolality >320 mOsm/kg, and pH >7.3 (absence of acidosis). * **Neurological Symptoms:** HHS presents with more profound neurological deficits (coma, focal signs, seizures) than DKA due to extreme hyperosmolality. * **Management:** The priority in HHS is **aggressive fluid resuscitation** (Normal Saline) to correct the massive free water deficit, followed by insulin.

Question 1

A 55-year-old man has experienced increasing lethargy for the past 7 months. Physical examination shows hyperpigmentation of the skin. Vital signs include a temperature of 36.9°C, pulse of 70/min, respirations of 14/min, and blood pressure of 95/65 mm Hg. Laboratory studies include a serum cortisol level of 3 mg/mL at 8:00 A.M. with a serum corticotropin level of 65 pg/mL. Which of the following diseases most often occurs in patients with this disorder?

Accepted Answer

Hashimoto thyroiditis

Answer

Type 2 diabetes mellitus

Answer

Classic polyarteritis nodosa

Answer

Systemic lupus erythematosus

Question 2

A high carbohydrate diet can precipitate which of the following conditions?

Accepted Answer

Hypokalemic periodic paralysis

Answer

Hyperkalemic periodic paralysis

Answer

Hysterical paralysis

Answer

Myasthenia gravis

Question 3

Which of the following is NOT a characteristic of inappropriate ADH secretion?

Accepted Answer

Hypo-osmolar urine

Answer

Water intoxication

Answer

Expanded fluid volume

Answer

Hypomagnesemia

Question 4

Which of the following is NOT a manifestation of carcinoid syndrome?

Accepted Answer

Steatorrhea

Answer

Retroperitoneal fibrosis

Answer

Peyronie's disease of the penis

Answer

Occlusion of the mesenteric arteries

Question 5

Non-pitting edema is seen in which of the following conditions?

Accepted Answer

Myxedema

Answer

Congestive cardiac failure

Answer

Liver failure

Answer

Renal failure

Question 6

Which of the following is a definitive treatment for Graves' thyrotoxicosis?

Accepted Answer

Radioiodine therapy

Answer

Carbimazole

Answer

Steroids

Answer

Hemithyroidectomy

Question 7

A 29-year-old male on oral hypoglycemic drugs has never had ketonuria. His BMI is 20.5. His grandfather had diabetes, and his father, who was his grandfather's only son, also had the disease. Which type of diabetes mellitus is this person most likely to have?

Accepted Answer

Maturity-onset diabetes of the young (MODY)

Answer

Pancreatic diabetes

Answer

Type I diabetes mellitus

Answer

Type II diabetes mellitus

Question 8

A 58-year-old man is referred for evaluation of a 2-cm adrenal mass discovered incidentally on a CT scan performed for abdominal pain. The patient has no history of malignancy and denies erectile dysfunction. Physical examination reveals a blood pressure of 122/78 mmHg with no gynecomastia or evidence of Cushing syndrome. His serum potassium is normal. What is the next step in determining whether this patient's adrenal mass should be resected?

Accepted Answer

Plasma metanephrines and dexamethasone-suppressed cortisol level

Answer

Plasma aldosterone/renin ratio

Answer

Estradiol level

Answer

Testosterone level

Question 9

A 25-year-old man presents with diabetes for the past year, which is well-controlled on oral hypoglycemic agents. He also has a family history of diabetes in young individuals. What is the most likely diagnosis?

Accepted Answer

Maturity Onset Diabetes in the Young (MODY)

Answer

Type 1 Diabetes mellitus

Answer

Type 2 Diabetes mellitus

Answer

Type A insulin resistance

Question 10

Which of the following is NOT seen in non-ketotic hyperosmolar coma?

Accepted Answer

Kussmaul's breathing

Answer

Insidious onset

Answer

Seen in elderly

Answer

Seen in type 2 DM

Endocrinology — MCQs

Endocrinology — MCQs

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