Fluid Shifts Between Compartments — MCQs
A decrease in which of the following is the most likely cause of peripheral edema in a patient with long-term alcoholism and liver disease?
The largest component of the total peripheral resistance is due to:
Hormone necessary for water and sodium balance is
Which of the following is hypertonic?
Major ions in ECF are:
Which of the following results in increased ADH activity?
Which of the following statements about normal saline is false?
What is the freezing point of normal human plasma?
Interstitial fluid volume can be measured by:
A 40-year-old woman presents with facial swelling, periorbital edema, and proteinuria. Which condition is most likely responsible for her symptoms?
Fluid Shifts Between Compartments Indian Medical PG Practice Questions and MCQs
Question 1: A decrease in which of the following is the most likely cause of peripheral edema in a patient with long-term alcoholism and liver disease?
- A. Interstitial colloid osmotic pressure
- B. Interstitial hydrostatic pressure
- C. Capillary hydrostatic pressure
- D. Plasma colloid osmotic pressure (Correct Answer)
Explanation: ***Plasma colloid osmotic pressure*** - **Liver disease** leads to decreased synthesis of **albumin**, the primary protein responsible for maintaining **plasma colloid osmotic pressure** [2]. - A reduction in this pressure allows fluid to extravasate from the capillaries into the interstitial space, causing **edema** [1], [3]. *Interstitial colloid osmotic pressure* - An increase, rather than a decrease, in interstitial colloid osmotic pressure would pull more fluid into the interstitial space, contributing to edema. - However, in liver disease with reduced albumin production, the primary issue is reduced plasma, not interstitial, colloid osmotic pressure [4]. *Interstitial hydrostatic pressure* - An increase in interstitial hydrostatic pressure would tend to drive fluid back into the capillaries, thus *reducing* edema. - A decrease would allow more fluid to accumulate in the interstitium, but this is not the primary mechanism in liver disease-related edema. *Capillary hydrostatic pressure* - An increase in **capillary hydrostatic pressure** can cause edema (e.g., in heart failure) [1]. - While liver disease can lead to conditions like **portal hypertension** (an increase in pressure within the portal venous system), this primarily causes ascites and not directly peripheral edema, which is more directly linked to decreased plasma colloid osmotic pressure [4].
Question 2: The largest component of the total peripheral resistance is due to:
- A. Venules
- B. Arterioles (Correct Answer)
- C. Capillaries
- D. Precapillary sphincters
Explanation: ***Arterioles*** - **Arterioles** are the primary site of **resistance** in the cardiovascular system due to their relatively small diameter and the significant ability of their **smooth muscle** walls to constrict or dilate. - This resistance plays a crucial role in regulating **blood flow** to various organs and contributes to **mean arterial pressure**. *Venules* - **Venules** are primarily involved in collecting blood from capillaries and have relatively low resistance compared to arteries and arterioles. - While they contribute to capacitance, their impact on **total peripheral resistance** is minimal. *Capillaries* - Although **capillaries** have very small diameters, their sheer number in parallel reduces the overall resistance of the capillary bed. - The primary function of capillaries is **exchange** of nutrients and waste, not primarily resistance. *Precapillary sphincters* - **Precapillary sphincters** control blood flow *into* capillaries from arterioles, acting as gates. - While they regulate flow to specific capillary beds, they are not the largest *component* of total systemic resistance; the **arterioles themselves** are.
Question 3: Hormone necessary for water and sodium balance is
- A. Progesterone
- B. Cortisol
- C. Estrogen
- D. Aldosterone (Correct Answer)
Explanation: ***Aldosterone*** - **Aldosterone** is a mineralocorticoid hormone that plays a crucial role in regulating **sodium and water balance** by acting on the kidneys to increase sodium reabsorption and potassium excretion. - This increased sodium reabsorption leads to increased water reabsorption, thereby maintaining **blood volume** and **blood pressure**. *Progesterone* - **Progesterone** is primarily involved in the **menstrual cycle, pregnancy, and embryonic development**. - While it can have some diuretic effects, its primary role is not in the direct daily regulation of **water and sodium balance**. *Cortisol* - **Cortisol** is a glucocorticoid hormone involved in stress response, metabolism, and immune function. - While it has some minor mineralocorticoid activity at high concentrations, it is **not the primary hormone** responsible for water and sodium balance. *Estrogen* - **Estrogen** is a sex hormone primarily involved in the development of female secondary sexual characteristics and reproductive processes. - It can cause **fluid retention** in some cases, but it does not have a direct or primary role in the regulation of **water and sodium balance** like aldosterone.
Question 4: Which of the following is hypertonic?
- A. 5% dextrose
- B. 0.45% normal saline
- C. 0.9% normal saline (NaCl)
- D. 3% normal saline (Correct Answer)
Explanation: ***3% normal saline*** - This solution contains a significantly **higher concentration of sodium chloride** (NaCl) than the body's normal plasma osmolality (approximately 154 mEq/L for 0.9% NS). - Its high solute concentration creates an **osmotic gradient**, causing water to move out of cells and into the extracellular space, classifying it as **hypertonic**. *5% dextrose* - While initially isotonic in the bag, dextrose is rapidly metabolized by the body, leaving behind free water. - This makes it functionally a **hypotonic solution** once administered intravenously, as it dilutes plasma and can cause fluid shifts into cells. *0.45% normal saline* - This is also known as **half-normal saline**, meaning it has half the sodium chloride concentration of 0.9% normal saline. - With a lower solute concentration than plasma, it is considered a **hypotonic solution**, causing fluid to shift into cells. *0.9% normal saline (NaCl)* - This solution has an osmolality of approximately 308 mOsm/L, which is **similar to that of human plasma**. - It is therefore considered an **isotonic solution**, meaning it does not cause significant fluid shifts between the intracellular and extracellular compartments.
Question 5: Major ions in ECF are:
- A. Potassium and phosphate
- B. Sodium and phosphate
- C. Potassium and chloride
- D. Sodium and chloride (Correct Answer)
Explanation: ***Sodium and chloride*** - **Sodium (Na+)** is the primary cation, and **chloride (Cl-)** is the primary anion in the extracellular fluid (ECF). - These ions play crucial roles in maintaining **osmotic pressure**, **fluid balance**, and **nerve impulse transmission**. *Potassium and phosphate* - **Potassium (K+)** is the major intracellular cation, while **phosphate (PO43-)** is a major intracellular anion. - While present in the ECF, their concentrations are significantly lower compared to sodium and chloride. *Sodium and phosphate* - **Sodium** is a major ECF cation, but **phosphate** is predominantly an intracellular anion. - Therefore, phosphate is not considered one of the major extracellular ions. *Potassium and chloride* - **Potassium** is primarily an intracellular ion, not a major ECF cation. - While **chloride** is a major ECF anion, its pairing with potassium does not represent the two major ions in the ECF.
Question 6: Which of the following results in increased ADH activity?
- A. Hypervolemia
- B. Hypertension
- C. Decrease osmolarity
- D. Hypovolemia (Correct Answer)
Explanation: ***Hypovolemia*** - **Hypovolemia** (decreased blood volume) is a potent stimulus for antidiuretic hormone (ADH) release, as the body attempts to conserve water and increase blood volume. - Reduced **stretch receptor activity** in the atria and great vessels due to decreased blood volume signals the posterior pituitary to release ADH. *Hypervolemia* - **Hypervolemia** (increased blood volume) would lead to a *decrease* in ADH activity, as the body tries to excrete excess water to normalize blood volume. - Increased stretch receptor activity in the atria inhibits ADH release. *Hypertension* - **Hypertension** (high blood pressure) generally *reduces* ADH secretion because the increased stretch on baroreceptors signals to decrease fluid volume. - This typically promotes diuresis rather than water retention. *Decrease osmolarity* - A **decrease in plasma osmolarity** (more dilute blood) inhibits ADH release, as the body aims to excrete excess water to bring osmolarity back to normal. - **Osmoreceptors** in the hypothalamus are sensitive to changes in plasma osmolarity and are the primary regulators of ADH secretion.
Question 7: Which of the following statements about normal saline is false?
- A. fluid of choice for hypovolemic shock
- B. lead to hyperchloremic metabolic acidosis
- C. fluid of choice for head injury patient
- D. normal saline 0.9% is most suitable to treat acute severe hyponatremia (Correct Answer)
Explanation: normal saline 0.9% is most suitable to treat acute severe hyponatremia - While 0.9% normal saline can be used in some hyponatremia cases, **acute severe hyponatremia** (especially with neurological symptoms) typically requires **hypertonic saline (3%)** to rapidly increase serum sodium and prevent cerebral edema. [2] - Normal saline contains 154 mEq/L of sodium, which is often insufficient to correct severe hyponatremia quickly enough [1]. *fluid of choice for head injury patient* - **Normal saline (0.9%) is often *not* the fluid of choice for head injuries**; rather, **hypertonic saline** is often preferred as it can decrease intracranial pressure (ICP) by drawing water out of brain cells. - Isotonic fluids like normal saline can contribute to cerebral edema if given in large quantities, though it's still safer than hypotonic fluids. *fluid of choice for hypovolemic shock* - **Normal saline (0.9%) is generally considered the fluid of choice for initial resuscitation in hypovolemic shock** as it is an isotonic crystalloid that effectively expands intravascular volume [1]. - It readily distributes across the extracellular fluid compartment, restoring circulating blood volume. *lead to hyperchloremic metabolic acidosis* - **Normal saline (0.9%) contains a higher concentration of chloride (154 mEq/L) than plasma (98-106 mEq/L)**, and when infused in large volumes, it can lead to **hyperchloremia** [1]. - This excess chloride can shift the bicarbonate buffer system, resulting in a **non-anion gap (hyperchloremic) metabolic acidosis**.
Question 8: What is the freezing point of normal human plasma?
- A. 0° C
- B. –0.54° C (Correct Answer)
- C. –1.54° C
- D. 4° C
Explanation: ***–0.54° C*** - The **freezing point depression** of normal human plasma is approximately **–0.54° C**, which is a key physical property used to assess plasma osmolality. - This specific value reflects the **total concentration of solutes** (like electrolytes, glucose, and urea) in the plasma. *0° C* - This is the freezing point of **pure water**, which does not account for the dissolved solutes in human plasma. - Due to the presence of solutes, the freezing point of plasma is **depressed below 0° C**. *–1.54° C* - This value represents a significantly **lower freezing point depression**, suggesting a much higher concentration of solutes than found in normal human plasma. - Such a low freezing point would indicate a state of **severe hyperosmolality**. *4° C* - This temperature is above the freezing point of water and human plasma, typically used for **refrigeration** rather than indicating freezing point. - Plasma would be in a **liquid state** at this temperature.
Question 9: Interstitial fluid volume can be measured by:
- A. Tritium oxide - Sodium thiosulfate
- B. Inulin - Serum albumin labelled with radioactive Iodine (Correct Answer)
- C. Inulin - Radioactive sodium
- D. Aminopyrine - Sucrose
Explanation: ***Inulin - Serum albumin labelled with radioactive Iodine*** - The **interstitial fluid volume** is calculated by subtracting the plasma volume from the extracellular fluid volume. - **Inulin** is used to measure **extracellular fluid volume** because it freely distributes throughout the extracellular space but does not enter cells. - **Serum albumin labeled with radioactive iodine** measures **plasma volume** as it stays primarily within the bloodstream due to its large size. *Tritium oxide - Sodium thiosulfate* - **Tritium oxide** (or D2O) is used to measure **total body water (TBW)**, as it distributes throughout all fluid compartments. - **Sodium thiosulfate** is used to measure **extracellular fluid volume**, similar to inulin. *Inulin - Radioactive sodium* - While **inulin** measures **extracellular fluid volume**, **radioactive sodium** (typically 24Na) also measures extracellular fluid volume but can slightly overestimate it due to slow intracellular penetration. - This combination doesn't directly provide a method for exclusively calculating interstitial fluid by subtraction from plasma volume. *Aminopyrine - Sucrose* - **Aminopyrine** is primarily used to measure the **volume of distribution of specific drugs** or gastric acid secretion, not fluid compartments. - **Sucrose** can be used to measure **extracellular fluid volume** as it does not readily cross cell membranes, similar to inulin, but it's not the primary combination for measuring interstitial fluid from the given options.
Question 10: A 40-year-old woman presents with facial swelling, periorbital edema, and proteinuria. Which condition is most likely responsible for her symptoms?
- A. Congestive heart failure
- B. Liver cirrhosis
- C. Hypothyroidism
- D. Nephrotic syndrome (Correct Answer)
Explanation: ***Nephrotic syndrome*** - The combination of **facial swelling**, **periorbital edema**, and **proteinuria** is the classic triad of symptoms defining nephrotic syndrome [1]. - This syndrome is characterized by **massive proteinuria** (>3.5g/day), leading to **hypoalbuminemia**, which in turn causes reduced plasma oncotic pressure and fluid extravasation into interstitial spaces [1]. *Congestive heart failure* - While it can cause **edema**, it typically presents with **dependent edema** (e.g., in legs), **dyspnea**, and signs of fluid overload, not prominent facial or periorbital edema as a primary symptom with proteinuria. - **Proteinuria** can occur in chronic heart failure due to reduced renal perfusion, but it is usually not the massive proteinuria characteristic of nephrotic syndrome. *Liver cirrhosis* - Can cause **peripheral edema** and **ascites** due to portal hypertension and hypoalbuminemia, but **facial and periorbital edema** are less common as primary presenting symptoms. - While some **proteinuria** can be seen in chronic liver disease, it's typically milder and not the massive proteinuria seen in nephrotic syndrome. *Hypothyroidism* - Can cause **non-pitting edema** (myxedema), often described as puffy facial features and periorbital swelling, due to the accumulation of **hyaluronic acid** in the interstitial space. - However, **significant proteinuria** is not a characteristic feature of hypothyroidism; hence, it's less likely to explain the full constellation of symptoms.
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