Endocrinology — MCQs

A 52-year-old man complains of impotence. On physical examination, he has an elevated jugular venous pressure, an S3 gallop, and hepatomegaly. He also appears tanned with pigmentation along the skin folds. He has joint pain and bony overgrowth primarily affecting the second and third metacarpophalangeal joints bilaterally. The plasma glucose is 250 mg/dL, and liver enzymes are elevated. Which of the following studies will help establish the diagnosis?

Q273Easy

Hyperaldosteronism is characterized by which acid-base disturbance?

Q274Easy

Which of the following plays an important role in the treatment of Diabetic Ketoacidosis?

Q275Easy

All of the following are true about osteomalacia EXCEPT:

Q276Easy

According to the American Diabetes Association, which of the following criteria indicates a prediabetic condition?

Q277Easy

What is the most common cause of chronic renal failure?

Q278Medium

All of the following are true regarding idiopathic edema in women except:

Q279Medium

Jod-Basedow phenomenon is seen in all of the following, EXCEPT:

Q280Medium

What changes are seen in the early stage of type-2 diabetes mellitus?

Endocrinology Indian Medical PG Practice Questions and MCQs

Question 271: What are the typical laboratory values for a patient with central diabetes insipidus (Urinary Osmolality & Serum Osmolality)?

A. Urinary Osmolality: 50 mOsm/kg, Serum Osmolality: 300 mOsm/kg (Correct Answer)
B. Urinary Osmolality: 500 mOsm/kg, Serum Osmolality: 260 mOsm/kg
C. Urinary Osmolality: 50 mOsm/kg, Serum Osmolality: 260 mOsm/kg
D. Urinary Osmolality: 500 mOsm/kg, Serum Osmolality: 100 mOsm/kg

Explanation: ### Explanation **1. Understanding the Core Concept** Diabetes Insipidus (DI) is characterized by a deficiency of Antidiuretic Hormone (ADH) in Central DI or resistance to it in Nephrogenic DI. ADH normally acts on the V2 receptors in the renal collecting ducts to reabsorb water [3]. In its absence, the kidneys cannot concentrate urine, leading to the excretion of large volumes of dilute urine (**Polyuria**) and a subsequent rise in serum concentration (**Hypernatremia/Hyperosmolality**) [1], [2]. **2. Why Option A is Correct** * **Urinary Osmolality (50 mOsm/kg):** Because water is not being reabsorbed, the urine remains extremely dilute. Typical DI values are <200 mOsm/kg (often as low as 50–100). * **Serum Osmolality (300 mOsm/kg):** Excessive water loss in urine leads to hemoconcentration. Normal serum osmolality is 275–295 mOsm/kg; in DI, it typically exceeds 295–300 mOsm/kg [1], [2]. **3. Analysis of Incorrect Options** * **Option B & D:** These show high urinary osmolality (500 mOsm/kg). This indicates concentrated urine, which rules out DI [3]. * **Option C:** Shows low urinary osmolality (correct for DI) but low serum osmolality (260 mOsm/kg). Low serum osmolality is characteristic of **SIADH** or **Primary Polydipsia**, not DI [2]. **4. NEET-PG High-Yield Pearls** * **Gold Standard Diagnosis:** Water Deprivation Test [2]. * **Differentiation:** After administering Desmopressin (ADH analogue), Central DI shows a **>50% increase** in urine osmolality, whereas Nephrogenic DI shows little to no response [2]. * **Drug of Choice:** Desmopressin (DDAVP) for Central DI; Thiazides/Amiloride for Nephrogenic DI [2]. * **MRI Finding:** Loss of the

Question 272: A 52-year-old man complains of impotence. On physical examination, he has an elevated jugular venous pressure, an S3 gallop, and hepatomegaly. He also appears tanned with pigmentation along the skin folds. He has joint pain and bony overgrowth primarily affecting the second and third metacarpophalangeal joints bilaterally. The plasma glucose is 250 mg/dL, and liver enzymes are elevated. Which of the following studies will help establish the diagnosis?

A. Detection of nocturnal penile tumescence
B. Determination of iron saturation (Correct Answer)
C. Determination of serum copper
D. Detection of hepatitis B surface antigen

Explanation: The clinical presentation describes a classic case of **Hereditary Hemochromatosis (HH)**, often referred to as "Bronze Diabetes." ### **Why Option B is Correct** The patient exhibits the classic pentad of Hemochromatosis: 1. **Skin Pigmentation:** "Tanned" appearance due to melanin deposition and iron. 2. **Diabetes Mellitus:** Plasma glucose of 250 mg/dL (iron deposition in the pancreas). 3. **Hepatomegaly/Cirrhosis:** Elevated liver enzymes and hepatomegaly. 4. **Restrictive Cardiomyopathy:** Elevated JVP and S3 gallop indicate heart failure. 5. **Arthropathy:** Specifically involving the **2nd and 3rd metacarpophalangeal (MCP) joints** with "hook-like" osteophytes (pathognomonic). 6. **Hypogonadism:** Impotence due to iron deposition in the pituitary gland. The initial screening test of choice for HH is **Transferrin Saturation (Iron Saturation)**. A value >45% is highly suggestive. This is followed by serum ferritin levels and HFE gene analysis (C282Y mutation). ### **Why Other Options are Incorrect** * **Option A:** Nocturnal penile tumescence helps differentiate organic from psychogenic impotence. While this patient has impotence, it is secondary to a systemic disease (HH), so this test does not diagnose the underlying cause. * **Option C:** Serum copper is used to diagnose **Wilson’s Disease**. While Wilson’s causes cirrhosis, it typically presents in younger patients and does not cause the specific MCP arthropathy or "bronze" skin seen here. * **Option D:** HBsAg screens for Hepatitis B. While it causes liver disease, it does not explain the multi-organ involvement (heart failure, diabetes, and joint pain). ### **NEET-PG High-Yield Pearls** * **Most common mutation:** C282Y mutation in the HFE gene (Chromosome 6). * **Arthropathy:** Characterized by "squaring" of bone ends and hook-shaped osteophytes on X-ray. * **Cardiac involvement:** Initially presents as restrictive cardiomyopathy, but can progress to dilated cardiomyopathy. * **Gold Standard Diagnosis:** Liver biopsy with **Perls’ Prussian Blue stain** (to quantify the Hepatic Iron Index), though genetic testing has largely replaced it. * **Treatment:** Repeated phlebotomy is the mainstay of management.

Question 273: Hyperaldosteronism is characterized by which acid-base disturbance?

A. Metabolic acidosis
B. Metabolic alkalosis (Correct Answer)
C. Respiratory acidosis
D. Respiratory alkalosis

Explanation: In hyperaldosteronism (e.g., Conn’s Syndrome), the excess mineralocorticoid acts on the **Principal cells** and **Alpha-intercalated cells** of the distal convoluted tubule and collecting duct [1]. **Why Metabolic Alkalosis is Correct:** Aldosterone increases the reabsorption of Sodium ($Na^+$) in exchange for Potassium ($K^+$) and Hydrogen ions ($H^+$) [2]. This occurs via two primary mechanisms: 1. **Direct $H^+$ secretion:** Aldosterone stimulates the $H^+$-ATPase pump in the alpha-intercalated cells, directly secreting protons into the urine [2]. 2. **Indirect effect:** The reabsorption of $Na^+$ creates a negative luminal potential, which "pulls" $K^+$ and $H^+$ out of the cells into the tubular lumen. The loss of $H^+$ ions leads to an increase in serum bicarbonate levels, resulting in **Metabolic Alkalosis** [1]. This is typically associated with **Hypokalemia** (due to $K^+$ wasting) [2]. **Why Incorrect Options are Wrong:** * **Metabolic Acidosis:** This occurs in conditions of aldosterone deficiency (e.g., Addison’s disease or Type 4 RTA), where $H^+$ cannot be excreted. * **Respiratory Acidosis/Alkalosis:** These are primary disturbances of $CO_2$ regulation by the lungs. Hyperaldosteronism is a primary metabolic/renal pathology. **High-Yield Clinical Pearls for NEET-PG:** * **The Triad:** Hypertension + Hypokalemia + Metabolic Alkalosis = Primary Hyperaldosteronism [1]. * **Aldosterone Escape:** Despite high sodium reabsorption, patients with primary hyperaldosteronism do not usually have clinical edema due to "ANP-mediated escape" [3]. * **Screening:** The best initial test is the **Plasma Aldosterone to Plasma Renin Activity (ARR) ratio**. A ratio >20-30 is suggestive.

Question 274: Which of the following plays an important role in the treatment of Diabetic Ketoacidosis?

A. Normal saline
B. Bicarbonate
C. Potassium
D. Insulin (Correct Answer)

Explanation: **Explanation:** The primary pathophysiology of **Diabetic Ketoacidosis (DKA)** is an absolute or relative deficiency of **Insulin** combined with an excess of counter-regulatory hormones (glucagon, cortisol, catecholamines). This leads to the "triad" of hyperglycemia, ketonemia, and metabolic acidosis. **Why Insulin is the Correct Answer:** Insulin is the definitive treatment because it halts the underlying process of **ketogenesis**. It suppresses lipolysis (breaking down fats into free fatty acids) and inhibits glucagon release, thereby stopping the production of ketone bodies [2]. While other fluids are vital, insulin is the specific agent that reverses the acidotic state. **Analysis of Other Options:** * **Normal Saline (A):** Fluid resuscitation is the *first* step in DKA management to restore circulatory volume and improve renal perfusion [1]. However, while essential, it does not correct the underlying metabolic cause (ketosis). * **Bicarbonate (B):** Its use is controversial and generally reserved only for severe acidosis (**pH < 6.9**) because rapid administration can lead to cerebral edema and hypokalemia. * **Potassium (C):** Patients with DKA have a total body potassium deficit [2]. While potassium replacement is crucial to prevent life-threatening arrhythmias during insulin therapy, it is a supportive measure rather than the primary treatment for the ketoacidosis itself [4]. **High-Yield Clinical Pearls for NEET-PG:** * **The "Rule of 0.1":** Standard protocol involves an IV insulin infusion at **0.1 U/kg/hr**. * **The Goal:** The primary goal of insulin therapy is to close the **Anion Gap**, not just to normalize blood glucose. * **Potassium Caveat:** Never start insulin if serum $K^+$ is **< 3.3 mEq/L**; correct potassium first to avoid fatal hypokalemia [4]. * **Cerebral Edema:** The most serious complication of DKA treatment in children, often due to over-aggressive fluid resuscitation [3].

Question 275: All of the following are true about osteomalacia EXCEPT:

A. Vitamin D deficiency
B. Proximal myopathy
C. Raised serum calcium (Correct Answer)
D. Bone biopsy shows increased demineralized bone matrix

Explanation: **Explanation:** Osteomalacia is a metabolic bone disease characterized by **defective mineralization** of the organic bone matrix (osteoid) [1], most commonly due to Vitamin D deficiency. **Why "Raised serum calcium" is the correct answer (The Exception):** In osteomalacia, serum calcium is typically **low or low-normal**, never raised [1]. The pathophysiology involves a primary deficiency in Vitamin D, leading to decreased intestinal calcium absorption. This triggers **Secondary Hyperparathyroidism** (increased PTH), which attempts to normalize calcium levels by mobilizing it from bones and increasing renal phosphate excretion [1]. Consequently, the classic biochemical profile shows low/normal calcium, low phosphorus, and elevated Alkaline Phosphatase (ALP) [1]. **Analysis of other options:** * **A. Vitamin D deficiency:** This is the most common cause of osteomalacia in adults [1], leading to inadequate calcium and phosphate availability for bone mineralization. * **B. Proximal myopathy:** A hallmark clinical feature [1]. Patients often present with a "waddling gait" and difficulty rising from a chair or climbing stairs due to Vitamin D deficiency affecting muscle metabolism and secondary hyperparathyroidism. * **D. Bone biopsy:** Histologically, osteomalacia is defined by an **increased thickness of osteoid seams** (demineralized matrix) and an increased osteoid volume [1], as the matrix is formed but cannot be mineralized. **NEET-PG High-Yield Pearls:** * **Radiological Sign:** **Looser’s zones** (Pseudofractures/Milkman’s fractures) are pathognomonic—translucent bands perpendicular to the bone cortex [1]. * **Biochemical Triad:** ↓ Serum Calcium/Phosphate + ↑ ALP + ↑ PTH [1]. * **Gold Standard Diagnosis:** Bone biopsy with tetracycline labeling (though rarely done clinically) [1].

Question 276: According to the American Diabetes Association, which of the following criteria indicates a prediabetic condition?

A. Fasting plasma glucose between 100 to 125 mg/dL (Correct Answer)
B. 2-hour plasma glucose of 100 mg/dL
C. HbA1c greater than 6.5%
D. All of the above

Explanation: According to the **American Diabetes Association (ADA)**, prediabetes is a high-risk state where blood glucose levels are higher than normal but do not yet meet the threshold for a diagnosis of Type 2 Diabetes Mellitus [1]. ### **Explanation of Options:** * **Option A (Correct):** Fasting Plasma Glucose (FPG) between **100 mg/dL and 125 mg/dL** is defined as **Impaired Fasting Glucose (IFG)** [1]. This is a hallmark criteria for prediabetes. * **Option B (Incorrect):** A 2-hour plasma glucose (post 75g OGTT) must be between **140 mg/dL and 199 mg/dL** to be classified as **Impaired Glucose Tolerance (IGT)**. A value of 100 mg/dL is considered within the normal range (<140 mg/dL). * **Option C (Incorrect):** An **HbA1c ≥ 6.5%** is the diagnostic threshold for **Diabetes Mellitus**. For prediabetes, the HbA1c range is **5.7% to 6.4%**. * **Option D (Incorrect):** Since options B and C represent normal and diabetic ranges respectively, "All of the above" is incorrect. ### **High-Yield Clinical Pearls for NEET-PG:** | Category | Normal | Prediabetes | Diabetes | | :--- | :--- | :--- | :--- | | **Fasting (FPG)** | < 100 mg/dL | 100–125 mg/dL | ≥ 126 mg/dL | | **2-hr OGTT** | < 140 mg/dL | 140–199 mg/dL | ≥ 200 mg/dL | | **HbA1c** | < 5.7% | 5.7–6.4% | ≥ 6.5% | * **Random Plasma Glucose:** A value of **≥ 200 mg/dL** in a patient with classic symptoms of hyperglycemia (polyuria, polydipsia, weight loss) is also diagnostic of Diabetes [1]. * **Screening:** ADA recommends screening all adults starting at age 35, or earlier in asymptomatic individuals with a BMI ≥ 25 kg/m² and additional risk factors.

Question 277: What is the most common cause of chronic renal failure?

A. Diabetes mellitus (Correct Answer)
B. Hypertension
C. Pyelonephritis
D. Cystic disease of kidneys

Explanation: **Explanation:** **Diabetes Mellitus (DM)** is the leading cause of Chronic Kidney Disease (CKD) and End-Stage Renal Disease (ESRD) worldwide, accounting for approximately 40–50% of all cases [2]. The underlying pathophysiology involves chronic hyperglycemia leading to non-enzymatic glycosylation of the glomerular basement membrane, hyperfiltration injury, and eventual Kimmelstiel-Wilson nodules (nodular glomerulosclerosis). **Analysis of Options:** * **Hypertension (Option B):** This is the **second** most common cause of CKD [2]. While it causes hypertensive nephrosclerosis, it remains statistically behind Diabetes in prevalence [1]. * **Pyelonephritis (Option C):** Chronic pyelonephritis (often due to vesicoureteral reflux) is a significant cause of tubulointerstitial disease, but it is a much less frequent cause of global renal failure compared to systemic metabolic diseases. * **Cystic disease (Option D):** Autosomal Dominant Polycystic Kidney Disease (ADPKD) is the most common **hereditary** cause of renal failure, but it accounts for only about 5% of the total ESRD population. **High-Yield Pearls for NEET-PG:** * **Most common cause of ESRD:** Diabetes Mellitus (Type 2 > Type 1 due to higher prevalence) [2]. * **Earliest clinical sign of Diabetic Nephropathy:** Microalbuminuria (30–300 mg/day). * **Earliest histological change:** Thickening of the glomerular basement membrane. * **Pathognomonic histological finding:** Kimmelstiel-Wilson (KW) nodules. * **Renal Size:** Unlike most causes of CKD where kidneys shrink, in Diabetes, the kidneys often remain **normal or enlarged** in size despite renal failure.

Question 278: All of the following are true regarding idiopathic edema in women except:

A. It is due to estrogen-mediated sodium retention. (Correct Answer)
B. It is related to the menstrual cycle.
C. There is increased water retention in the upright position.
D. ACE inhibitors can be useful in some cases.

Explanation: ### Explanation **Idiopathic Edema** is a clinical syndrome characterized by periodic swelling and weight gain, occurring almost exclusively in menstruating women. **1. Why Option A is the Correct Answer (The "Except" Statement):** While idiopathic edema occurs in women of reproductive age, it is **not** primarily due to estrogen-mediated sodium retention. The pathophysiology is complex but centers on **increased capillary permeability** and an exaggerated orthostatic response. When the patient is upright, there is excessive sequestration of fluid into the interstitial space, leading to a decrease in effective arterial blood volume. This triggers a secondary activation of the **Renin-Angiotensin-Aldosterone System (RAAS)** and ADH, causing salt and water retention. Although estrogens cause some degree of salt and water retention, they are not the primary driver of this specific clinical syndrome [1]. **2. Analysis of Other Options:** * **Option B:** Although it is distinct from Premenstrual Syndrome (PMS), idiopathic edema is **related to the menstrual cycle**, often worsening during the luteal phase due to hormonal fluctuations affecting vascular tone [1]. It is noted that normal women retain salt and water and gain weight just before menstruation [1]. * **Option C:** A hallmark of this condition is **increased water retention in the upright position** (orthostatic edema). Patients often gain >1.4 kg (3 lbs) of weight from morning to evening. * **Option D:** **ACE inhibitors** are useful because they counteract the secondary hyperaldosteronism and RAAS activation triggered by the fluid shifts. **Clinical Pearls for NEET-PG:** * **Diagnosis:** Confirmed by the "Weight-at-7 AM and 7 PM" test (diurnal weight gain >1.5 kg). * **Diuretic Abuse:** Many patients use diuretics to treat the swelling, which paradoxically worsens the condition by causing "diuretic-induced edema" (rebound sodium retention upon withdrawal). * **Management:** Treatment includes salt restriction, weight loss, wearing support stockings, and avoiding chronic diuretic use. Spironolactone or ACE inhibitors are preferred over loop diuretics.

Question 279: Jod-Basedow phenomenon is seen in all of the following, EXCEPT:

A. Amiodarone
B. Iodine-containing contrast agents
C. Iodine in seafood
D. Normal thyroid gland (Correct Answer)

Explanation: The **Jod-Basedow phenomenon** refers to iodine-induced hyperthyroidism. It occurs when an excess load of iodine is administered to a patient with an underlying thyroid abnormality, leading to the unregulated overproduction of thyroid hormones. [2] ### Why "Normal Thyroid Gland" is the Correct Answer: In a **normal thyroid gland**, the body utilizes a protective mechanism called the **Wolff-Chaikoff effect**. When exposed to high iodine levels, a healthy gland temporarily shuts down iodine organification to prevent hyperthyroidism. Therefore, the Jod-Basedow phenomenon **cannot** occur in a normal gland because its autoregulatory mechanisms are intact. ### Explanation of Incorrect Options: * **Amiodarone:** This anti-arrhythmic drug contains 37% iodine by weight. It can trigger Jod-Basedow (Type 1 Amiodarone-Induced Thyrotoxicosis), especially in patients with underlying multinodular goiter or latent Graves' disease. * **Iodine-containing contrast agents:** Used in CT scans and angiography, these agents provide a massive acute load of iodine, which can trigger thyrotoxicosis in susceptible individuals. [1] * **Iodine in seafood:** While rare, excessive dietary intake of iodine (e.g., kelp or seaweed) can precipitate hyperthyroidism in patients living in iodine-deficient areas who have developed autonomous thyroid nodules. ### High-Yield Clinical Pearls for NEET-PG: * **Wolff-Chaikoff Effect:** Iodine-induced **hypo**thyroidism (The gland "shuts off"). * **Jod-Basedow Phenomenon:** Iodine-induced **hyper**thyroidism (The gland "runs wild"). * **Risk Factors:** Most commonly seen in patients with **Endemic Goiter, Multinodular Goiter (MNG), or Graves' Disease.** * **Clinical Note:** Unlike Graves' disease, Jod-Basedow typically presents with **low/absent radioactive iodine uptake (RAIU)** because the gland is already saturated with exogenous iodine. [1], [2]

Question 280: What changes are seen in the early stage of type-2 diabetes mellitus?

A. Decreased output of glucose from the liver
B. Increase in C-peptide
C. Increase in GIP (Correct Answer)
D. All of the above

Explanation: The pathophysiology of early Type 2 Diabetes Mellitus (T2DM) is characterized by insulin resistance and a compensatory response from the endocrine system [1]. **Why Option C is Correct:** The **Incretin Effect** refers to the observation that oral glucose loads elicit a much higher insulin response than intravenous glucose. This is mediated by two primary hormones: **GIP (Glucose-dependent Insulinotropic Polypeptide)** and **GLP-1 (Glucagon-like Peptide-1)**. In the early stages of T2DM, there is often a compensatory **increase in GIP levels** as the body attempts to overcome insulin resistance by stimulating more insulin secretion. However, as the disease progresses, the beta cells become resistant to GIP's action, and GLP-1 levels eventually decline. **Why Other Options are Incorrect:** * **Option A:** In T2DM, there is an **increase** in hepatic glucose output [2]. Insulin resistance in the liver leads to impaired suppression of gluconeogenesis and glycogenolysis, contributing to fasting hyperglycemia [2]. * **Option B:** While insulin (and thus C-peptide) levels may be high initially to compensate for resistance, the most specific hormonal change highlighted in recent literature regarding early incretin dynamics is the compensatory rise in GIP. Furthermore, C-peptide eventually declines as beta-cell exhaustion occurs [1]. **High-Yield Clinical Pearls for NEET-PG:** * **The Incretin Effect** is significantly blunted in established T2DM. * **GIP vs. GLP-1:** GIP is secreted by K-cells (duodenum), while GLP-1 is secreted by L-cells (ileum/colon). * **DPP-4 Inhibitors** (e.g., Sitagliptin) work by preventing the breakdown of these endogenous incretins. * **Early T2DM** is defined by the "Ominous Octet," where insulin resistance in muscles and increased hepatic glucose production are primary drivers [2].

Practice by Chapter

Diabetes Mellitus

Practice Questions

Thyroid Disorders

Practice Questions

Adrenal Gland Disorders

Practice Questions

Pituitary Disorders

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Calcium and Bone Metabolism

Practice Questions

Reproductive Endocrinology

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Lipid Disorders

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Endocrine Hypertension

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Multiple Endocrine Neoplasia

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Obesity and Metabolic Syndrome

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Neuroendocrine Tumors

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Endocrine Emergencies

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