Electrolyte Abnormalities

Question 1

Volume contraction

Answer 1

Decrease in total body water

Iso, hyper, hypotonic contraction

Question 2

Volume expansion

Answer 2

Increase in total body water

Iso, hyper, or hypotonic expansion

Question 3

Plasma Na+

Answer 3

135-145 mEq/L

TOtal osmolality of plasma is roughly 2X osmolality of Na+ (280-300 mOsm/kg)

Question 4

Isotonic contraction

Answer 4

Losses of Na+ and H2O are proportional.
Vomiting, diarrhea, kidney disease and diuretics may cause this
Replace with isotonic solution (NS)
Rapid replenishment may cause pulmonary edema

Question 5

Hypertonic contraction

Answer 5

Water loss > Na+ loss
Hyperosmolar state
Excessive sweating, osmotic diuresis, excessively concentrated foods to infants, burns, inability to experience or respond to thirst

Question 6

Hypertonic contraction TX

Answer 6

Hypotonic fluids (0.45% NaCl)  or solute free fluids. 
50% of estimated loss replaced in first few hours, remainder of 1-2 days

Question 7

Hypotonic contraction causes

Answer 7

Na+ loss > water loss

Diuretics, chronic renal insufficiency, lack of aldosterone (promotes sodium retention)

Question 8

Hypotonic contraction tx

Answer 8

Isotonic if its mild
3% NaCl if severe to raise serum Na+ to 130mEq/L
Monitor for signs of fluid overload
May need hormone therapy if its related to aldosterone

Question 9

Hypotonic contraction tx

Answer 9

Isotonic if its mild
3% NaCl if severe to raise serum Na+ to 130mEq/L
Monitor for signs of fluid overload
May need hormone therapy if its related to aldosterone