T2: Water and Electrolyte Balance Part 2 Flashcards
Sodium Reference Range
136-145 mEq/L
Most common cause of water intoxication
Extracellular fluid gain caused by syndrome of inappropriate ADH secretion (SIADH)
Four functions of sodium
1 maintain normal H2O distribution
2 maintain normal osmotic pressure
3 neuromuscular processes
4 acid-base balance
Sodium is a major extracellular ________
cation
Three renal processes by which normal levels of sodium are maintained in the body
1 Kidneys-filtered in glomeruli; reabsorption in the PCT, Loops of Henle, and DCT
2 Aldosterone controls Na in DCT
3 BNP gets rid of Na
Depletional hyponatremia causes ________ hyponatremia
absolute
two general causes of depletional hyponatremia
1 renal losses
2 non-renal losses
Two general causes of renal losses in depletional hyponatremia
1 diuretic use
2 hypoaldosteronism
Two general causes of non-renal losses in depletional hyponatremia
1 GI loss
2 skin loss
Dilutional hyponatremia is a _________ hyponatremia
relative
Two general causes of dilutional hyponatremia
1 SIADH
2 Hyperglycemia
Why does SIADH and hyperglycemia lead to increased water volume in dilutional hyponatremia?
1 ADH secreted all the time, which causes us to retain H2O diluting Na
2 increased glucose in urine causes it to be diluted with H2O
Two general causes of pseudohyponatremia
1 hyperlipidemia
2 hyperproteinemia
Why does hyperlipidemia and hyperproteinemia cause low sodium results in pseudohyponatremia?
Displaces some H2O, picks up more lipids or protein than plasma H2O
Three general causes of hypernatremia due to water loss
1 GI losses
2 Excessive sweating
3 Diabetes insipidus
Two general causes of hypernatremia due to sodium gain
1 ingestion or infusion of Na
2 Hyperaldosteronism
Reference Range of potassium
3.5-5.0 mEq/L
Two functions of potassium
1 regulation of many cellular processes
2 neuromuscular excitation (heart)
Why does insulin cause hypokalemia?
too much glucose and potassium
Why does alkalosis compensation cause hypokalemia?
Need more acid in bloodstream so RBCs push H ions into blood and take up more K
Four general caues of hypokalemia due to renal loss
1 hyperaldosteronism
2 diuretic theory
3 licorice ingestion
Three general causes of hypokalemia due to excessive gastrointestinal loss
1 vomiting
2 diarrhea
3 laxative abuse
Three general causes of hyperkalemia due to increased in vivo cell lysis
1 cellular trauma
2 cellular injury
3 in vivo hemolysis
Two general causes of hyperkalemia due to altered cellular uptake
1 compensation for acidosis (H taken into cell, K pushed out=electroneutrality)
2 insulin deficiency
Two general causes of hyperkalemia due to imapired renal excretion
1 renal insufficiency or failure
2 hypoaldosteronism
Reference Range of Chloride
99-109 mEq/L
Chloride is a major extracellular _____
anion
three functions of chloride
1 maintains H2O balance
2 maintains osmotic pressure
3 Acid-base balance with “chloride shift”
Three general causes of hypochloremia and associated conditions
1 GI Losses- prolonged vomiting, nasogastric suctioning
2 Burns-tissue trauma
3 renal losses-diuretic therapy, compensation for metabolic acidosis
Two general causes of hyperchloremia and associated conditions
1 dehydration
2 renal tubular acidosis-Na gain
3 compensation for metabolic alkalosis
REMEMBER: Cl levels altered in same direction as Na = ______ _____
water imbalance
REMEMBER: Cl levels not proportional to Na = _____ ______ ______
Acid-base imbalance
Clinical usefulness of sweat chloride measurements
sweat induced by pilocarpine iontophoresis; cystic fibrosis detected if >60 mEq/L and normal if <40 mEq/L
