Endocrinology Practice Questions

Q: A 43-year-old male presents with persistent dizziness upon standing quickly, chronic fatigue, muscle weakness, and an unusual craving for salty foods. He has a noticeable "bronze tan." Blood work reveals hypoglycemia, hyperkalemia, and hyponatremia. What is the underlying cause of these symptoms?

Adrenal insufficiency. The clinical presentation describes a classic case of **Primary Adrenal Insufficiency (Addison’s Disease)**. [1] The underlying cause is the destruction of the adrenal cortex, leading to a deficiency in both mineralocorticoids (aldosterone) and glucocorticoids (cortisol). 1. **Why Adrenal Insufficiency is correct:** * **Hyponatremia & Hyperkalemia:** Lack of aldosterone leads to renal wasting of sodium and retention of potassium. [1] * **Salt Craving & Hypotension:** Sodium loss causes volume depletion, leading to orthostatic dizziness and salt cravings. * **Hypoglycemia:** Cortisol is a counter-regulatory hormone; its absence impairs gluconeogenesis. [1] * **Hyperpigmentation ("Bronze tan"):** Low cortisol triggers a compensatory increase in ACTH. [1] ACTH is derived from POMC, which also produces Melanocyte-Stimulating Hormone (MSH), leading to increased skin pigmentation. [2] 2. **Why other options are incorrect:** * **Pituitary Insufficiency:** While it causes low cortisol, it does **not** cause hyperpigmentation (ACTH is low) or significant electrolyte imbalances (the Renin-Angiotensin system still regulates aldosterone). * **Lack of Insulin:** This would cause hyperglycemia, not hypoglycemia. * **Lack of Glucagon:** While it can cause hypoglycemia, it does not explain the electrolyte shifts or hyperpigmentation. **High-Yield NEET-PG Pearls:** * **Most common cause:** Autoimmune adrenalitis (Developed countries); Tuberculosis (Developing countries like India). [2] * **Diagnosis:** Best initial test is the **ACTH Stimulation Test** (Cosyntropin test). [1] * **Management:** Glucocorticoid (Hydrocortisone) and Mineralocorticoid (Fludrocortisone) replacement. [2] * **Adrenal Crisis:** Presents as refractory shock; treat immediately with IV fluids and high-dose Dexamethasone/Hydrocortisone. [1]

Q: A 30-year-old female presents with increased thirst and polyuria. Her random plasma glucose is 230 mg/dL. Which of the following tests differentiates type 1 diabetes mellitus from type 2 diabetes mellitus?

Anti-GAD-65 antibody. The clinical presentation of polyuria, polydipsia, and a random plasma glucose of 230 mg/dL confirms a diagnosis of Diabetes Mellitus [1]. To differentiate between Type 1 (T1DM) and Type 2 (T2DM), we must identify the underlying pathophysiology: autoimmune destruction of beta cells versus insulin resistance [1]. **Why Anti-GAD-65 is correct:** **Glutamic Acid Decarboxylase (GAD-65) antibodies** are the most sensitive and persistent markers for autoimmune T1DM. They are present in approximately 70-80% of newly diagnosed T1DM patients. Their presence confirms an autoimmune etiology, helping distinguish T1DM (or LADA) from T2DM, where these antibodies are absent. **Analysis of Incorrect Options:** * **B. PPAR-gamma-2 polymorphism:** While associated with T2DM risk and insulin sensitivity, this is a research tool and has no clinical utility in differentiating diabetes types. * **C. Plasma insulin level:** Insulin and C-peptide levels can be low in long-standing T2DM (due to beta-cell exhaustion) or "falsely" normal in early T1DM (the "honeymoon phase"). Thus, they are less reliable than antibody testing for definitive classification. * **D. HLA DR3:** While HLA-DR3 and DR4 are strongly associated with a genetic predisposition to T1DM [1], they are also present in a significant portion of the general healthy population [1]. Therefore, HLA typing lacks the specificity required for diagnosis. **NEET-PG High-Yield Pearls:** * **Most common antibody in T1DM:** Anti-GAD-65 (also the most persistent). * **Earliest antibody to appear:** Anti-IAA (Insulin Autoantibodies), especially in children. * **Zinc Transporter 8 (ZnT8):** A newer, highly specific marker for T1DM. * **C-peptide:** Used to assess endogenous insulin production; it is low/absent in T1DM and initially high/normal in T2DM.

Q: Hypokalemia may be a feature of all the following diseases, except?

Addison's disease. **Explanation:** The core concept behind this question is the role of **Aldosterone** and **Cortisol** in renal potassium handling [1]. **1. Why Addison’s Disease is the Correct Answer:** Addison’s disease (Primary Adrenocortical Insufficiency) is characterized by the destruction of the adrenal cortex, leading to a deficiency of both cortisol and **aldosterone** [2]. Aldosterone normally acts on the distal convoluted tubule and collecting duct to reabsorb sodium and **excrete potassium/hydrogen ions** [1]. In its absence, potassium is retained in the blood, leading to **Hyperkalemia**, not hypokalemia. This is often accompanied by hyponatremia and metabolic acidosis. **2. Why the other options are incorrect:** * **Cushing’s Syndrome:** High levels of cortisol exert a "mineralocorticoid effect" when the enzyme 11β-HSD2 is overwhelmed. This leads to excessive sodium reabsorption and increased potassium excretion, resulting in **hypokalemia** [3]. * **Bartter Syndrome:** A genetic defect in the thick ascending limb of the Loop of Henle (mimicking Loop diuretics). It causes salt wasting, activation of the RAAS pathway, and subsequent **hypokalemia** and metabolic alkalosis. * **Gitelman Syndrome:** A genetic defect in the distal convoluted tubule (mimicking Thiazide diuretics). It presents with **hypokalemia**, metabolic alkalosis, and characteristically low urinary calcium (hypocalciuria). **Clinical Pearls for NEET-PG:** * **Conn’s Syndrome:** Primary hyperaldosteronism is a classic cause of resistant hypertension with hypokalemia [3]. * **Liddle’s Syndrome:** "Pseudo-hyperaldosteronism" (gain of function of ENaC channels) presents with hypertension and hypokalemia but **low** aldosterone levels. * **Addisonian Crisis:** Always look for the triad of Hypotension, Hyponatremia, and Hyperkalemia in clinical vignettes.

Q: Which of the following is NOT found in Maturity Onset Diabetes of the Young (MODY)?

Glucokinase deficiency. **Explanation:** Maturity-Onset Diabetes of the Young (MODY) is a group of monogenic disorders characterized by **primary defects in beta-cell function**, leading to impaired insulin secretion [1]. It is not a disorder of insulin resistance. **Why Option D is the "Correct" Answer (Contextual Note):** There appears to be a technical error in the question's framing. **Glucokinase deficiency (MODY 2)** is actually one of the most common causes of MODY. However, in the context of standard medical examinations, if this question is presented as "Which is NOT found," and the key points to "Glucokinase deficiency," it may be a distractor or a miskeyed question. **Pathophysiologically, the correct answer should be Option C (Insulin receptor resistance)**, as MODY is defined by insulin *deficiency* due to genetic mutations, not resistance. Insulin resistance is the hallmark of Type 2 Diabetes Mellitus, not MODY. [1] **Analysis of Options:** * **A. Family History Positive:** MODY follows an **Autosomal Dominant** inheritance pattern [1]. A strong three-generation family history is a diagnostic hallmark. * **B. Young Onset:** By definition, MODY presents in young individuals, typically **before the age of 25**. * **C. Insulin receptor resistance:** This is **NOT** a feature of MODY. Patients are usually non-obese and have high insulin sensitivity; the problem lies in the "sensing" of glucose or the secretion of insulin. * **D. Glucokinase deficiency:** This is the cause of **MODY 2**, characterized by a stable, mild fasting hyperglycemia. **High-Yield Clinical Pearls for NEET-PG:** * **Most Common Type:** MODY 3 (HNF-1 alpha mutation). * **Most Common in Pregnancy:** MODY 2 (Glucokinase mutation). * **Clinical Clue:** A young, non-obese patient with a strong family history of diabetes who is **C-peptide positive** (unlike Type 1) and **antibody negative**. * **Treatment:** MODY 3 is exquisitely sensitive to low-dose **Sulfonylureas**.

Q: A 35-year-old female presents with complaints of fatigue, weakness, decreased appetite, weight loss, and severe light-headedness upon standing. Physical examination reveals oral mucosal pigmentation, proximal muscle weakness of the lower extremities, and hyperpigmentation of the palmar creases, knuckles, and knees. What is the most likely diagnosis?

Adrenal insufficiency. The clinical presentation described is a classic case of **Primary Adrenal Insufficiency (Addison’s Disease)** [1]. The hallmark of this condition is the deficiency of cortisol and aldosterone due to adrenal cortex destruction [1]. 1. **Why Adrenal Insufficiency is correct:** * **Hyperpigmentation:** This is the most specific sign of *primary* adrenal insufficiency. Low cortisol levels trigger a compensatory increase in ACTH (Adrenocorticotropic hormone). ACTH is derived from POMC (Pro-opiomelanocortin), which also produces MSH (Melanocyte-stimulating hormone), leading to hyperpigmentation in sun-exposed areas, pressure points (knuckles, knees), and mucosal surfaces [2]. * **Postural Hypotension:** Aldosterone deficiency leads to sodium wasting and volume depletion, causing severe light-headedness upon standing [1]. * **Systemic Symptoms:** Fatigue, weight loss, and muscle weakness are common due to glucocorticoid deficiency [2]. 2. **Why other options are incorrect:** * **Depression:** While it causes fatigue and weight loss, it does not explain hyperpigmentation or postural hypotension. * **Anorexia with diuretic use:** May cause weight loss and hypotension, but would not cause mucosal or palmar crease hyperpigmentation. * **Hypothyroidism:** Presents with fatigue and weight gain (not loss), and typically features dry skin or myxedema rather than hyperpigmentation. **NEET-PG High-Yield Pearls:** * **Most common cause:** Autoimmune adrenalitis (developed countries); Tuberculosis (developing countries like India) [2]. * **Electrolyte Triad:** Hyponatremia, Hyperkalemia, and Metabolic Acidosis. * **Diagnosis:** Best initial test is the **ACTH Stimulation Test** (Cosyntropin test) [2]. * **Treatment:** Glucocorticoid (Hydrocortisone) and Mineralocorticoid (Fludrocortisone) replacement [2]. Stress doses are required during illness or surgery.

Q: A 15-year-old girl presents with complaints of puffy eyes, swelling in the neck, weight gain, and fatigue. Investigations reveal the presence of thyroid peroxidase antibodies and elevated TSH levels. What is the most likely diagnosis?

Hashimoto thyroiditis. **Explanation:** The clinical presentation of puffy eyes (periorbital edema), neck swelling (goiter), weight gain, and fatigue in a young girl is classic for **hypothyroidism**. The presence of **Thyroid Peroxidase (TPO) antibodies** and **elevated TSH** confirms an autoimmune etiology, specifically **Hashimoto thyroiditis**. **Why Hashimoto thyroiditis is correct:** Hashimoto thyroiditis is the most common cause of hypothyroidism in iodine-sufficient regions. It is characterized by autoimmune-mediated destruction of the thyroid gland. The hallmark laboratory findings include elevated TSH, low T4, and high titers of anti-TPO and anti-thyroglobulin antibodies. Histologically, it shows diffuse lymphocytic infiltration with germinal centers and **Hürthle cells** (Askanazy cells). **Why other options are incorrect:** * **Graves' disease:** Typically presents with hyperthyroidism (weight loss, tachycardia, tremors). While it involves antibodies (TSH-receptor antibodies), the TSH would be suppressed, not elevated. Management of Graves' ophthalmopathy may involve selenium or glucocorticoids for inflammatory episodes. * **Iodine deficiency:** While it causes goiter and hypothyroidism, it would not typically present with positive TPO antibodies. * **Congenital hypothyroidism:** This presents in infancy (cretinism) with features like prolonged jaundice, macroglossia, and umbilical hernia, rather than an adolescent presentation. **High-Yield NEET-PG Pearls:** * **Most common cause of goitrous hypothyroidism:** Hashimoto thyroiditis. * **Associated HLA:** HLA-DR3 and HLA-DR5. * **Increased Risk:** Patients with Hashimoto’s have an increased risk of **B-cell Non-Hodgkin Lymphoma** of the thyroid. * **Initial Phase:** Some patients may experience a transient hyperthyroid phase known as **"Hashitoxicosis"** due to the release of preformed hormones during gland destruction.

Q: Brown pigmentation is seen in which disease?

Addison's disease. **Explanation:** **1. Why Addison’s Disease is Correct:** In primary adrenal insufficiency (Addison’s disease), the adrenal cortex fails to produce cortisol [1]. This lack of negative feedback leads to a compensatory increase in **Adrenocorticotropic Hormone (ACTH)** secretion by the anterior pituitary [2]. ACTH is derived from a precursor molecule called **Pro-opiomelanocortin (POMC)**. When POMC is cleaved to produce ACTH, it also produces **Melanocyte-Stimulating Hormone (MSH)**. High levels of ACTH and MSH stimulate melanocytes in the skin, leading to characteristic **hyperpigmentation** (brownish/bronze discoloration) [2]. This is most prominent in skin creases, pressure points (elbows, knees), oral mucosa, and recent scars. **2. Why the other options are incorrect:** * **Hyperthyroidism:** While skin changes occur (warm, moist, velvety skin), generalized brown pigmentation is not a hallmark. In Graves' disease, one might see pretibial myxedema, but not systemic hyperpigmentation. * **Nephritis:** Chronic Kidney Disease (CKD) can cause a sallow, yellowish-brown tint due to the accumulation of urochromes, but "brown pigmentation" specifically linked to the ACTH mechanism is unique to Addison’s. **3. Clinical Pearls for NEET-PG:** * **Primary vs. Secondary:** Hyperpigmentation occurs **only** in primary adrenal insufficiency. In secondary adrenal insufficiency (pituitary failure), ACTH levels are low, so the skin remains pale [3]. * **The "Tan" that doesn't fade:** Suspect Addison's in a patient with unexplained hypotension, hyponatremia, hyperkalemia, and a "tan" in non-exposed areas (like palmar creases). * **Nelson’s Syndrome:** Rapidly progressive hyperpigmentation following bilateral adrenalectomy due to an enlarging ACTH-secreting pituitary adenoma.

Q: Tetany may be present in all the following conditions except?

Hyperkalemia. Tetany is a state of increased neuromuscular excitability characterized by carpopedal spasms, paresthesia, and laryngospasm. It is primarily caused by a decrease in the threshold for nerve depolarization. **Why Hyperkalemia is the Correct Answer:** Hyperkalemia (Option C) actually **decreases** neuromuscular excitability by causing persistent depolarization of the cell membrane, which eventually leads to a state of inactivation of sodium channels (refractoriness) [1]. This typically results in muscle weakness or paralysis, not tetany. In contrast, **Hypokalemia** can occasionally be associated with tetany, particularly when it coexists with metabolic alkalosis. **Analysis of Incorrect Options:** * **Acute Pancreatitis (Option A):** This condition often leads to **hypocalcemia** due to the saponification of calcium in necrotic fat (calcium soaps) [2]. Low ionized calcium levels reduce the threshold for action potentials, leading to tetany. * **Hysterical Hyperventilation (Option B):** Hyperventilation causes respiratory alkalosis. The increase in blood pH promotes the binding of ionized calcium to albumin, leading to **decreased ionized calcium** levels (despite normal total calcium), which triggers tetany [2]. * **Hypomagnesemia (Option D):** Magnesium is a cofactor for PTH secretion and action. Severe magnesium deficiency leads to secondary hypocalcemia and can also directly increase neuromuscular excitability, both of which cause tetany [2]. **NEET-PG High-Yield Pearls:** * **Trousseau’s Sign:** Induction of carpal spasm by inflating a BP cuff above systolic pressure for 3 minutes (more sensitive than Chvostek). * **Chvostek’s Sign:** Tapping the facial nerve leads to twitching of facial muscles. * **The "Ionized" Rule:** Tetany is always a function of **ionized calcium** levels, not total calcium [2]. * **Metabolic Alkalosis:** Always consider tetany in alkalotic states due to increased calcium-albumin binding [2].

Question 1

A 43-year-old male presents with persistent dizziness upon standing quickly, chronic fatigue, muscle weakness, and an unusual craving for salty foods. He has a noticeable "bronze tan." Blood work reveals hypoglycemia, hyperkalemia, and hyponatremia. What is the underlying cause of these symptoms?

Accepted Answer

Adrenal insufficiency

Answer

Pituitary insufficiency

Answer

Lack of insulin

Answer

Lack of glucagon

Question 2

A 30-year-old female presents with increased thirst and polyuria. Her random plasma glucose is 230 mg/dL. Which of the following tests differentiates type 1 diabetes mellitus from type 2 diabetes mellitus?

Accepted Answer

Anti-GAD-65 antibody

Answer

Peroxisome proliferator-activated receptor gamma-2 polymorphism testing

Answer

Plasma insulin level

Answer

Testing for human leukocyte antigen (HLA) DR3

Question 3

Hypokalemia may be a feature of all the following diseases, except?

Accepted Answer

Addison's disease

Answer

Cushing's syndrome

Answer

Bartter syndrome

Answer

Gitelman syndrome

Question 4

Which of the following is NOT found in Maturity Onset Diabetes of the Young (MODY)?

Accepted Answer

Glucokinase deficiency

Answer

Family history positive

Answer

Young onset

Answer

Insulin receptor resistance

Question 5

A 35-year-old female presents with complaints of fatigue, weakness, decreased appetite, weight loss, and severe light-headedness upon standing. Physical examination reveals oral mucosal pigmentation, proximal muscle weakness of the lower extremities, and hyperpigmentation of the palmar creases, knuckles, and knees. What is the most likely diagnosis?

Accepted Answer

Adrenal insufficiency

Answer

Depression

Answer

Anorexia with surreptitious diuretic use

Answer

Hypothyroidism

Question 6

What is the most common cause of Addison's disease?

Accepted Answer

Autoimmune adrenalitis

Answer

Meningococcal septicemia

Answer

Malignancy

Answer

Tuberculosis

Question 7

A 15-year-old girl presents with complaints of puffy eyes, swelling in the neck, weight gain, and fatigue. Investigations reveal the presence of thyroid peroxidase antibodies and elevated TSH levels. What is the most likely diagnosis?

Accepted Answer

Hashimoto thyroiditis

Answer

Graves' disease

Answer

Iodine deficiency

Answer

Congenital hypothyroidism

Question 8

Brown pigmentation is seen in which disease?

Accepted Answer

Addison's disease

Answer

Hyperthyroidism

Answer

Nephritis

Answer

All of the above

Question 9

Tetany may be present in all the following conditions except?

Accepted Answer

Hyperkalemia

Answer

Acute pancreatitis

Answer

Hysterical hyperventilation

Answer

Hypomagnesemia

Question 10

A patient presents with headache and flushing, and has a family history of medullary thyroid carcinoma. What investigation is most appropriate for this patient?

Accepted Answer

Fractionated plasma metanephrines

Answer

Chest X-ray

Answer

Measurement of 5-hydroxyindoleacetic acid (5-HIAA)

Answer

Intravenous pyelography

Endocrinology — MCQs

Endocrinology — MCQs

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