Endocrinology Practice Questions

Q: Dilutional hyponatremia is seen in:

Addison's disease. **Explanation** In **Addison’s disease** (Primary Adrenocortical Insufficiency), dilutional hyponatremia occurs through two primary mechanisms: 1. **Mineralocorticoid Deficiency:** A lack of aldosterone leads to renal sodium wasting and volume depletion [4]. This hypovolemia triggers the non-osmotic release of **Antidiuretic Hormone (ADH)** [3]. 2. **Glucocorticoid Deficiency:** Cortisol normally exerts a negative feedback on ADH. In its absence, ADH levels rise significantly. The resulting excess ADH causes free water retention in the renal collecting ducts via AQP-2 channel insertion [1]. This water retention, combined with the underlying sodium loss, results in **dilutional hyponatremia** [2]. **Analysis of Incorrect Options:** * **B. Diabetes Insipidus:** This condition is characterized by a deficiency of ADH (Central) or resistance to it (Nephrogenic). It leads to excessive water loss (polyuria), resulting in **hypernatremia**, not hyponatremia. * **C. Diuretic Therapy:** While diuretics (especially Thiazides) commonly cause hyponatremia, it is primarily classified as **depletional hyponatremia** due to the direct loss of sodium in the urine, rather than pure water dilution [2]. **High-Yield Clinical Pearls for NEET-PG:** * **Classic Electrolyte Triad in Addison’s:** Hyponatremia, Hyperkalemia, and Metabolic Acidosis (due to lack of aldosterone). * **Cortisol vs. ADH:** Cortisol is a physiological inhibitor of ADH. Therefore, any cause of hypocortisolism (including secondary adrenal insufficiency) can lead to SIADH-like dilutional hyponatremia. * **Diagnosis:** The gold standard is the ACTH stimulation test (Cosyntropin test) [4].

Q: The laboratory investigation of a patient shows T4 and TSH levels. Which of the following is the most likely diagnosis?

Hashimoto's disease. ***Hashimoto's disease*** - **Low T4** and **high TSH** indicates **primary hypothyroidism**, where thyroid gland dysfunction leads to compensatory TSH elevation through negative feedback. - **Anti-thyroglobulin (TgAb)** and **anti-thyroid peroxidase (TPO)** antibodies are typically positive, confirming autoimmune thyroid destruction. *Grave's disease* - Presents with **high T4** and **low TSH** due to **TSH receptor antibodies** stimulating excessive thyroid hormone production. - Associated with **hyperthyroid symptoms** like weight loss, tachycardia, and exophthalmos, opposite to the laboratory pattern shown. *Pituitary failure* - Results in **secondary hypothyroidism** with **low T4** and **low or normal TSH** due to inadequate pituitary TSH production. - **TSH levels would not be elevated** as the pituitary cannot respond appropriately to low thyroid hormone levels. *Hypothalamic failure* - Causes **tertiary hypothyroidism** with **low T4** and **low TSH** due to deficient **TRH (thyrotropin-releasing hormone)** production. - **TRH stimulation test** would show blunted TSH response, distinguishing it from primary thyroid dysfunction.

Q: A diabetic patient in the waiting room develops giddiness, sweating, and confusion. What is the most likely condition?

Hypoglycemia. **Explanation:** The clinical presentation of **giddiness, sweating, and confusion** in a diabetic patient is a classic triad of **Hypoglycemia**. This occurs when blood glucose levels fall below 70 mg/dL [1]. The symptoms are divided into two categories: 1. **Autonomic (Neurogenic):** Sweating, palpitations, tremors, and anxiety (due to catecholamine release) [3]. 2. **Neuroglycopenic:** Confusion, giddiness, behavioral changes, and seizures (due to glucose deprivation in the brain) [4]. **Why other options are incorrect:** * **Diabetic Ketoacidosis (DKA):** Typically presents with hyperglycemia, dehydration, Kussmaul breathing (deep, rapid respirations), and an acetone (fruity) breath odor [2]. It develops over hours to days, not suddenly in a waiting room. * **Non-ketotic Hyperosmolar Syndrome (HHS):** Characterized by extreme hyperglycemia (>600 mg/dL) and profound dehydration, usually in Type 2 diabetics [1]. It lacks the acute autonomic symptoms like sweating. * **Hypertension:** While it can cause headaches or dizziness, it does not typically cause acute confusion and profuse sweating unless in a hypertensive emergency, which is less common than hypoglycemia in a treated diabetic. **High-Yield NEET-PG Pearls:** * **Whipple’s Triad:** 1. Symptoms of hypoglycemia, 2. Low plasma glucose, 3. Relief of symptoms after glucose administration. * **Beta-blockers** can mask hypoglycemic symptoms (except sweating), making it dangerous for diabetic patients. * **Management:** If conscious, give 15g of rapid-acting carbohydrates (Rule of 15). If unconscious, IV 25% or 50% Dextrose is the treatment of choice.

Q: Diabetic ketoacidosis (DKA) mimics acute pancreatitis in all the following findings except?

Elevated lipase. Diabetic Ketoacidosis (DKA) and Acute Pancreatitis (AP) frequently present with overlapping clinical and biochemical features, making the differentiation challenging. However, **Serum Lipase** is the key biochemical marker that distinguishes the two. **1. Why "Elevated Lipase" is the correct answer:** In DKA, **Serum Amylase** is frequently elevated (up to 80% of cases) due to non-pancreatic sources like the salivary glands or decreased renal clearance. Conversely, **Serum Lipase** is much more specific to the pancreas. While minor elevations of lipase can occur in DKA, a significant rise (usually >3 times the upper limit of normal) is highly specific for Acute Pancreatitis. Therefore, DKA mimics the amylase elevation but typically does **not** mimic the significant lipase elevation seen in pancreatitis. **2. Why other options are incorrect:** * **Elevated Amylase:** As noted, this is a common finding in DKA (non-specific elevation), thus DKA "mimics" pancreatitis in this regard. * **Abdominal Pain:** Severe abdominal pain and guarding are classic symptoms of DKA (likely due to delayed gastric emptying and metabolic acidosis), mimicking an "acute abdomen" or pancreatitis [1]. * **Hyperglycemia:** While hyperglycemia is the hallmark of DKA, it is also frequently seen in Acute Pancreatitis due to stress-induced glucagon release and transient islet cell dysfunction [2]. **Clinical Pearls for NEET-PG:** * **The "Rule of 3":** In a patient with DKA, only suspect co-existing Acute Pancreatitis if the **Lipase is >3x normal** or if abdominal pain persists after the metabolic acidosis is corrected. * **CT Scan:** The gold standard for diagnosing pancreatitis when biochemical markers are ambiguous in DKA. * **Hypertriglyceridemia:** Severe DKA can cause massive elevation of triglycerides, which itself is a known trigger for Acute Pancreatitis.

Q: A 55-year-old obese woman presents with frequent vaginal yeast infections in the past 2 months, recent weight loss despite a large appetite, and nocturia. She has a history of hypertension treated with ramipril. What is the most likely diagnosis?

Diabetes mellitus. **Explanation:** The clinical presentation is classic for **Type 2 Diabetes Mellitus (T2DM)**. The patient exhibits the hallmark "3 Ps": polyphagia (large appetite), polyuria (nocturia), and weight loss [1]. In T2DM, insulin resistance or deficiency leads to hyperglycemia; once blood glucose exceeds the renal threshold (~180 mg/dL), glucose is excreted in the urine (glycosuria), causing osmotic diuresis and nocturia [1], [4]. The weight loss despite polyphagia occurs because the body cannot utilize glucose for energy and begins breaking down fat and muscle [1], [4]. Furthermore, hyperglycemia creates an environment conducive to fungal overgrowth, explaining the recurrent **vaginal candidiasis** [3]. **Analysis of Incorrect Options:** * **B. Diabetes Insipidus:** While it causes polyuria and nocturia, it is due to ADH deficiency or resistance. It does not present with weight loss, polyphagia, or yeast infections. * **C. Vaginitis and Cystitis:** These are localized infections. While they explain the yeast infections and urinary frequency, they do not account for systemic symptoms like weight loss and polyphagia. * **D. Myxedema (Hypothyroidism):** This typically presents with weight gain, constipation, and cold intolerance, which contradicts this patient’s weight loss and increased appetite. **NEET-PG High-Yield Pearls:** * **Screening:** The ADA recommends screening all adults with BMI ≥25 kg/m² who have additional risk factors (e.g., hypertension). * **Diagnostic Criteria:** Fasting Plasma Glucose ≥126 mg/dL, 2-hour OGTT ≥200 mg/dL, or HbA1c ≥6.5% [2]. * **Clinical Clue:** Recurrent vulvovaginal candidiasis is often the first clinical sign of undiagnosed T2DM in women [3].

Q: Which of the following obesity-related syndromes is associated with hypogonadism in males but not in females?

Ahlstrom's syndrome. **Explanation:** The correct answer is **Alström’s syndrome**. This rare autosomal recessive ciliopathy is characterized by childhood obesity, progressive cone-rod dystrophy (leading to blindness), sensorineural hearing loss, and Type 2 Diabetes Mellitus. **Why Alström’s syndrome is the correct answer:** The endocrine profile of Alström’s syndrome is unique among obesity syndromes. In **males**, it consistently presents with **hypogonadotropic hypogonadism** (low testosterone and gonadotropins). However, **females** typically have normal pubertal development and are often fertile, though they may develop polycystic ovary syndrome (PCOS) or hyperandrogenism later in life. **Analysis of Incorrect Options:** * **Prader-Willi Syndrome (PWS):** This is the most common genetic cause of obesity [1]. It is characterized by neonatal hypotonia and hyperphagia. Unlike Alström’s, hypogonadism in PWS affects **both sexes** (undescended testes in males; primary amenorrhea/clitomegaly in females). * **Laurence-Moon-Bardet-Biedl (LMBB) Syndrome:** This ciliopathy presents with obesity, retinitis pigmentosa, and polydactyly [1]. Hypogonadism is a cardinal feature that affects **both males and females**. * **Cohen’s Syndrome:** Characterized by truncal obesity, intellectual disability, microcephaly, and "cherubic" facial features. While it involves developmental delays, it does not show the sex-specific sparing of the gonadal axis seen in Alström’s. **High-Yield Clinical Pearls for NEET-PG:** * **Alström’s vs. LMBB:** Both have obesity and retinal degeneration, but **polydactyly** is present in LMBB and **absent** in Alström’s. * **Cardiac involvement:** Dilated cardiomyopathy is a frequent and severe complication specific to Alström’s syndrome. * **Genetics:** Alström’s is caused by mutations in the *ALMS1* gene.

Q: Which of the following is NOT a primary cause of hypogonadism?

Diabetes mellitus. **Explanation:** The core concept in this question is the distinction between **Primary Hypogonadism (Hypergonadotropic)**, where the defect lies in the testes, and **Secondary Hypogonadism (Hypogonadotropic)**, where the defect lies in the Hypothalamic-Pituitary axis. **Why Diabetes Mellitus is the correct answer:** Diabetes Mellitus is a metabolic disorder that typically causes **Secondary Hypogonadism**. Chronic hyperglycemia and insulin resistance disrupt the pulsatile secretion of GnRH from the hypothalamus and LH/FSH from the pituitary [1]. Additionally, obesity (often comorbid with Type 2 DM) increases aromatase activity, converting testosterone to estrogen, further suppressing the HPO axis [1]. It is not a direct "primary" testicular failure. **Analysis of Incorrect Options (Primary Causes):** * **A. Klinefelter Syndrome (47, XXY):** The most common genetic cause of primary hypogonadism [3]. It involves dysgenesis of seminiferous tubules and Leydig cell dysfunction, leading to low testosterone and high gonadotropins [3]. * **B. Cryptorchidism:** Undescended testes lead to heat-induced damage of the germinal epithelium and Leydig cells, resulting in primary testicular failure if not corrected early [1]. * **C. Mumps Orchitis:** A common viral cause of acquired primary hypogonadism [3]. It causes direct inflammatory destruction of the testicular parenchyma (usually post-pubertal) [3]. **High-Yield Clinical Pearls for NEET-PG:** * **Primary Hypogonadism:** Testosterone ↓, LH/FSH ↑ (e.g., Turner’s, Noonan syndrome, Irradiation) [3]. * **Secondary Hypogonadism:** Testosterone ↓, LH/FSH ↓ or inappropriately Normal (e.g., Kallmann syndrome, Prolactinoma, Pituitary adenoma) [1], [2]. * **Kallmann Syndrome:** Look for the triad of hypogonadotropic hypogonadism, **anosmia**, and midline defects (cleft palate) [2].

Question 1

Dilutional hyponatremia is seen in:

Accepted Answer

Addison's disease

Answer

Diabetes insipidus

Answer

Diuretic therapy

Answer

None of the above

Question 2

The laboratory investigation of a patient shows T4 and TSH levels. Which of the following is the most likely diagnosis?

Accepted Answer

Hashimoto's disease

Answer

Grave's disease

Answer

Pituitary failure

Answer

Hypothalamic failure

Question 3

A diabetic patient in the waiting room develops giddiness, sweating, and confusion. What is the most likely condition?

Accepted Answer

Hypoglycemia

Answer

Hypertension

Answer

Diabetic ketoacidosis

Answer

Non-ketotic hyperosmolar syndrome

Question 4

Diabetic ketoacidosis (DKA) mimics acute pancreatitis in all the following findings except?

Accepted Answer

Elevated lipase

Answer

Elevated amylase

Answer

Abdominal pain

Answer

Hyperglycemia

Question 5

A 55-year-old obese woman presents with frequent vaginal yeast infections in the past 2 months, recent weight loss despite a large appetite, and nocturia. She has a history of hypertension treated with ramipril. What is the most likely diagnosis?

Accepted Answer

Diabetes mellitus

Answer

Diabetes insipidus

Answer

Vaginitis and cystitis

Answer

Myxedema

Question 6

Which of the following is the LEAST likely symptom of hyperthyroidism in a 77-year-old man?

Accepted Answer

Tremor

Answer

Atrial fibrillation

Answer

Confusion

Answer

Weakness

Question 7

Which of the following obesity-related syndromes is associated with hypogonadism in males but not in females?

Accepted Answer

Ahlstrom's syndrome

Answer

Prader Willi syndrome

Answer

Laurence Moon Biedl syndrome

Answer

Cohen's syndrome

Question 8

A child underwent bilateral adrenalectomy. Later, the child developed headache, visual field defect, and hyperpigmentation of the skin. What is the most probable diagnosis?

Accepted Answer

Nelson syndrome

Answer

Pituitary adenoma

Answer

Allgrove syndrome

Answer

Wolman syndrome

Question 9

All of the following are true of cerebral salt wasting syndrome, except:

Accepted Answer

Low uric acid in serum

Answer

Increased urine output

Answer

Low intravascular volume

Answer

Decreased vasopressin levels

Question 10

Which of the following is NOT a primary cause of hypogonadism?

Accepted Answer

Diabetes mellitus

Answer

Klinefelter syndrome

Answer

Cryptorchidism

Answer

Mumps orchitis

Endocrinology — MCQs

Endocrinology — MCQs

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