556 - Pharmacotherapy Ii - Sodium & Water Balance

Front 1

What is the approximate distribution of body water, intracellular vs. extracellular, in the average person?

Back 1

2/3rds Intracellular, 1/3 Extracellular

Front 2

How would the approximate distribution of body water, intracellular vs. extracellular, be shifted as a result of obesity?

Back 2

Obesity decreases the relative amount of intracellular fluid and increases the amount found extracellularly.

Front 3

What is the approximate distribution of extracellular fluid between circulating plasma and interstitial fluid?

Back 3

25% Circulating Plasma, 75% Interstitial Fluid

Front 4

In terms of volume, which component of fluid balance is the most variable?

Back 4

The interstitial fluid varies the most. The consistency of the circulating plasma and the intracellular fluid are maintained at the expense of the interstitial fluid level.

Front 5

How is the distribution of water among compartments controlled?

Back 5

Water flows freely among compartments, but solutes do not. Therefore the distribution of water is determined by the distribution of solutes among the various compartments.

Front 6

What is the typical concentration range of sodium ion in the plasma?

Back 6

135 to 144 mEq/L

Front 7

What is the typical concentration range of potassium ion in the plasma?

Back 7

3.5 to 5.2 mEq/L

Front 8

What is the typical concentration range of chloride ion in the plasma?

Back 8

96 to 108 mEq/L

Front 9

What are the typical intracellular ion concentrations of sodium, potassium, and chloride?

Back 9

Na+ ~ 12 mmol/L, K+ ~ 140 mmol/L, & Cl- ~ 4 mmol/L

Front 10

How does the resulting distribution of fluids between the extracellular and intracellular compartments differ for a given volume supplied intravenously if the fluid is free water versus isotonic saline? Which of the two is more efficient for correcting low blood pressure?

Back 10

Free water distributes itself proportionately among the extracellular and intracellular compartments, whereas isotonic saline stays in the extracellular compartment. Therefore isotonic saline is typically three times more efficient at restoring extracellular fluid volume, and therefore the circulating plasma level.

Front 11

Which two hormones regulate the renal reabsorption of sodium ion? What is their site of action?

Back 11

Aldosterone increases the renal reabsorption of sodium ion, while atriopeptin decreases it. Both act at the collecting tubules. [Atriopeptin is also referred to as atrial natriuretic peptide (ANP), atrial natriuretic factor (ANF), & atrial natriuretic hormone (ANH).]

Front 12

What is the Institute of Medicine 2005 recommendation for intake of NaCl?

Back 12

65 to 100 mmol/day NaCl [This translates to between 1500 and 2300 mg Na+ as listed on food labels.]

Front 13

What is the minimum requirement for intake of NaCl?

Back 13

30 mmol/day NaCl is the minimum requirement. [This translates to ~700 mg Na+ as listed on food labels.]

Front 14

At which tubule segment do ACE inhibitors work to inhibit sodium reabsorption?

Back 14

Proximal Tubule

Front 15

At which tubule segment do Angiotension II inhibitors work to inhibit sodium reabsorption?

Back 15

Proximal Tubule

Front 16

At which tubule segment does a beta-1 antagonist work to inhibit sodium reabsorption?

Back 16

Proximal Tubule

Front 17

At which tubule segment does a loop diuretic work to inhibit sodium reabsorption?

Back 17

Loop of Henle

Front 18

At which tubule segment does a thiazide diuretic primarily work to inhibit sodium reabsorption?

Back 18

Distal Tubule [They also have some effect at the Proximal Tubule as well.]

Front 19

At which tubule segment does a spironolactone work to inhibit sodium reabsorption?

Back 19

Collecting Tubules

Front 20

Approximately what percentage of sodium reabsorption occurs in the proximal tubule?

Back 20

70%

Front 21

Approximately what percentage of sodium reabsorption occurs in the Loop of Henle?

Back 21

20%

Front 22

Approximately what percentage of sodium reabsorption occurs in the distal tubule?

Back 22

5%

Front 23

Approximately what percentage of sodium reabsorption occurs in the collecting tubules?

Back 23

4%

Front 24

What hormone is responsible for adjusting the water balance in the body?

Back 24

Antidiuretic Hormone (ADH)

Front 25

What is it that is counterintuitive about indicators of the respective balance of sodium and water in the body?

Back 25

Serum Na+ concentration is an indicator of free water balance, not sodium balance, and fluid volume serves as the indictor of sodium balance (with each liter of ECF representing ~ 140 mmol of Na+).

Front 26

What is the most sensitive and quantitative measure of short-term fluid imbalance?

Back 26

Weight Change (1 kg ~ 1 L)

Front 27

What are three signs of pulmonary congestion?

Back 27

Dyspnea, Orthopnea, & Crackles [Dyspnea is shortness of breath. Orthopnea is shortness of breath while lying down. Crackles are clicking, rattling, or crackling noises in the lungs that can be heard with a stethoscope.]

Front 28

Central Venous Pressure (CVP) is one of the signs used to monitor diuretic therapy in people who have heart failure. What is the CVP normally?

Back 28

CVP is normally < 5 mmHg

Front 29

What is Hepato-Jugular Reflux (HJR)?

Back 29

HJR is a distention of the jugular vein induced by applying firm pressure over the liver.

Front 30

What does a serum sodium concentration below 135 mmol/L indicate with respect to the balance of free water?

Back 30

A serum sodium concentration < 135 mmol/L indicates an excess of free water.

Front 31

What does a serum sodium concentration above 144 mmol/L indicate with respect to the balance of free water?

Back 31

A serum sodium concentration > 144 mmol/L indicates a deficiency of free water.

Front 32

For a patient having excess extracellular fluid, what rate of removal, through diuretic therapy and sodium intake reduction, is safe?

Back 32

0.5 to 1.0 kg/day is a safe range to target for body weight reduction.