ic19 fluid and electrolyte disorders

Question 1

What is the distribution of intracellular fluid vs extracellular fluid in the body?

Answer 1

2/3 intracellular (ICF)
- rich in K+, Mg2+, PO4 2- (phosphate), proteins

1/3 extracellular (ECF)
- ECF = blood + interstitial, consists of intravascular (in the blood) and interstitial (between cells)
- rich in Na+, Cl-, HCO3- (bicarbonate)

Question 2

Definition of Hypovolemia VS Hypervolemia

Answer 2

Hypovolemia: decrease in ECF volume

Hypervolemia: increase in ECF volume

Question 3

Difference between dehydration and hypovolemia

Their causes

Answer 3

Dehydration
- loss of total body water (ECF + ICF)
- Cause: diabetes insipidus, excessive diuresis, low oral intake of water

Hypovolemia
- loss of ECF only
- Cause: burns, bleeding, third spacing of fluids eg. septic shock, anaphylactic shock, abdominal ascites)

Question 4

2 types of fluids for patients who are dehydrated or hypovolemic

Answer 4

1) Crystalloids
- water + electrolytes
- eg. normal saline NACL 0.9%, Dextrose 5%, Hartmann’s solution, plasmalyte

2) Colloids
- water + protein eg. Albumin
- role: to increase intravascular / plasma volume, or supplement albumin
- how? Colloids enter blood stream, proteins draw water to themselves as proteins increase oncotic pressure, shifting fluids from interstitial compartment to intravascular compartment

Question 5

What is the role of Na+?

Answer 5

Maintains ECF volume, Na+ is the predominant cation in the ECF

Changes in [Na+] can cause changes in TBW and water shifting between ICF and ECF

Question 6

What is hyponatremia vs hypernatremia

Answer 6

Serum conc of Na+ below 135mmol/L

[Na+] above 145mmol/L