Regulation and Disorders of Salt and Water

Question 1

Amount of blood which is involved in the perfusion of body tissues

Answer 1

Effective Arterial Blood Volume

Question 2

Total Body Water

Answer 2

• Males: 0.6 x body weight

- Females: 0.5 x body weight

Question 3

Percent of the body water contained within the ECF

Answer 3

2/3

Question 4

Percent of the body water contained within the ICF

Answer 4

1/3

Question 5

Surrogate marker for serum osmolality

Answer 5

Serum Na

Question 6

Osmotically active solute in the ECF

Answer 6

Na

Question 7

Osmotically active solute in the ICF

Answer 7

K

Question 8

Equation, Plasma osmolality (Posm)

Answer 8

2(Na) + Glucose/18 + BUN/2.8

Question 9

Equation, Na Concentration

Answer 9

Total Body Na (TBNa)/ Total body Water

Question 10

Type of cells which secrete Renin in response to reduced arterial blood pressure or reduced volume

Answer 10

Juxtaglomerular Cells

Question 11

2 Net effects of Angiotensin II

Answer 11

• reabsorption of Na by the proximal tubule

- Vasoconstriction

Question 12

Aldosterone promotes Na reabsorption at the…

Answer 12

Distal Tubule

Question 13

2 Net Effects of Aldosterone

Answer 13

• reabsorption of Na by the distal tubule

- secretion of K

Question 14

Mechanism of ANP (Atrial-Natriuretic Peptide)

Answer 14

-myocardial tension triggers the release of ANP, which causes afferent arteriolar vasodilation and increased excretion of Na

Question 15

Hypothalamic Nuclei from which Vasopressin (ADH) are released

Answer 15

-Supraoptic and Paraventricular Nuclei (released from the Posterior Pituitary)

Question 16

Stimuli for Vasopressin release

Answer 16

• Increased ECF Osmolality
• Decreased Effective Arterial Blood Volume (EABV)
• Vomiting/Nausea
• Angiotensin II

Question 17

Diagnostic Criteria for SIADH

Answer 17

• Decreased Serum Osmolality (<270)
• Inappropriately concentrated urine (elevated Urine Na)
• Euvolemic Hyponatremia
• Adrenal and renal insufficiencies, hypothyroidism, and diuretic use have been ruled out

Question 18

Mechanism of Cerebral Demyelination Syndrome

Answer 18

• A sudden increase in ECF (usually by overcorrection of chronic hyponatremia) causes water to leave the intracellular compartment of brain cells; this results in shrinkage of the brain cells
• Dysphagia, quadriparesis, locked-in syndrome
• can be permanent or fatal

Question 19

Tx of Hypovolemic Hyponatremia

Answer 19

-Isotonic (0.9%) Normal Saline

Question 20

Tx of Hypervolemic Hyponatremia

Answer 20

• Treat the primary disorder (heart failure, e.g.)
• Loop Diuretics (Furosemide)
• Na Restrictive Diet
• Hemodialysis if renal failure is present

Question 21

Equation, Water Excess

Answer 21

(0.6 x body weight) x (1-(Serum Na)/140))

Question 22

Tx of Euvolemic Hyponatremia

Answer 22

• Calculate Water Excess
• Loop Diuretics + NaCl
• Water Restriction
• 3% Normal Saline

Question 23

Tx of Severe Hyponatremia

Answer 23

-3% Normal Saline infusion (for acute severe hyponatremia if <24 hours OR symptomatic hyponatremia with a coma)

Question 24

Symptoms of Hypernatremia

Answer 24

• Lethargy
• Weakness
• Irritability
• Seizures, Comas

Question 25

Tx of Euvolemia Hypernatremia

Answer 25

-Restoration of Water deficit and/or 5% dextrose infusion (replace 50% over a 24 hour period)

Question 26

Tx of Hypovolemic Hypernatremia

Answer 26

• Volume correction is more important than correction of water deficit!
• Isotonic saline infusion, to restore hypovolemia

Question 27

Tx of Hypervolemic Hypernatremia

Answer 27

• Na removal is key!!
• Loop Diuretic (Furosemide) + discontinuation of any hypertonic agents/drugs
• Hemodialysis if renal failure is present