Electrolytes Flashcards
Electrolytes
substances whose molecules dissociate into ions when placed in water
Cations
Positively charged ions
Anions
Negatively charged ions
Milliequivalents
unit of chemical activity
Faraday’s Law of Electrical Neutrality
154 mEq/l of cations = 154 mEq/l of anions if a (+) is lost, a (+) must be reabsorbed or a (-) must be lost
nutritional recovery syndrome
when there is not enough minerals to keep up with the body’s demand to make new cells
Anion Gap
Difference between the sum of cations (Na+ and K+) and the sum of anions (Cl- and HCO3-)
reflects unmeasured ions in the plasma
Used to determine the cause of metabolic acidosis
Normal Anion Gap Levels
8-16 mEq/l if K+ is used
8-12 mEq/l if K+ not used
Increase in Anion Gap
metabolic acidosis due to lactic acidosis
Normal Anion Gap
metabolic acidosis due to decrease K+ (renal tubular acidosis) or increased loss of anions (diarrhea) or diabetic ketoacidosis (most common)
Decrease in Anion Gap
metabolic acidosis due to hypoalbuminemia
What is main extracellular cation
Sodium (Na+)
functions of Na+
regulate ADH secretion
fluid control
conduction of neurological impulses
If you have an Na+ imbalance you likely have…
K+ imbalance
Normal Na+ level
135-145 mEq
Hyponatremia
< 135 mEq of Na+
Causes of hyponatremia
loss of Na+ dilution of serum Na+ salt restricted diet low aldosterone increase in ADH diuretics burns Water enemas
signs and symptoms of hyponatremia
muscle weakness anorexia nausea, vomiting, diarrhea fatigue apathy headache vertigo
if hypovolemic–poor skin turgor, low blood pressure, increased heart rate
if euvolemia/hypervolemic–increased heart rate, normal/increased blood pressure
treatment for hyponatremia
replace Na+ IV of normal saline (0.9%) if level < 120 in peds or < 115 in adults give 3% to 5% Na via IV piggyback for mild cases uses diet therapy diuretics PRN
Hypernatremia
> 145 mEq of Na+
Causes of Hypernatremia
lose more water that Na+ renal failure heart failure increased aldosterone decrease in PO fluids increase in Na+ PO or IV
signs and symptoms of Hypernatremia
if hypovolemic–dry sticky mucous membranes, nausea, thirst, rubbery tissue turgor, flushed skin, increase in temperature, decreased blood pressure, decreased urine output, increased heart rate, rough and dry tongue
if euvolemic/hypervolemic–normal or increased blood pressure, peripheral and pulmonary edema, weight gain, restlessness, agitation intense thirst
treatment of Hypernatremia
treat underlying cause
restrict Na+ intake
diuretics PRN
Normal K+ levels
3.5-5.5 mEq
principle intracellular cations
K+
functions of K+
neuromuscular activity
acid/base regulation
transport glucose into cell
hypokalemia
< 3.5 mEq of K+
causes of hypokalemia
GI loss diuretics increased aldosterone exogenous steroids inadequate intake stress polyuria alkalosis
signs and symptoms of hypokalemia
anorexia nausea and vomiting decreased bowel sounds distended abdomen paralytic ileus muscle weakness malaise polyuria shallow, increased respirations weak thready pulse dysrhythmias flat/inverted T wave
treatment for hypokalemia
IV or PO K+
(oral K+ is irritating to GI–give with food)
never give > 10-20 mEq/hr/IV without cardiac monitoring–watch urine output (do not give if < 400 cc/24 hours)–never give IV push, always IV piggyback
hyperkalemia
> 5.5 mEq of K+
causes of hyperkalemia
shock burns trauma (anything that causes cell death) renal failure adrenal insuffiency stored blood acidosis salt substitutes K+ sparing diuretics venipuncture (pseudohyperkalemia)
signs and symptoms of hyperkalemia
diarrhea and abdominal cramps nausea arrhythmias (bradycardia) oliguria general muscle weakness and cramps paresthesia of extremities peaked T wave and prolonged QRS
treatment of hyperkalemia
kayexalate PO or rectal enema hypertonic glucose IV with insulin IV sodium bicarb inhaled beta-2 agonists (albuterol) dialysis 10% Calcium Gluconate IV
normal calcium levels
4.5-5.8 mEq or 9-11mg/dL
3 forms of Ca++ in body
ionized
bound to albumin
bones/teeth
functions of Ca++ in body
needed for clotting
What is needed for Ca++ absorption?
Vitamin D and PTH hormone
What does Ca++ have an inverse relationship with?
phosphorus
hypocalcemia
< 9 mg
causes of hypocalcemia
decreased intake decrease in Vitamin D decreased PTH chronic pancreatitis small bowel disease excess renal loss
signs and symptoms of hypocalcemia
tetany--painful, muscle spasms Trousseau's Sign (carpal spasm) Chvostek's Sign (facial nerve) increased deep tendon reflexes hyperactive abdomen altered mentation increased bleeding and bruising dry, brittle hair and nails fractures (if deficit persists)
Why should Ca++ levels be monitored closely after thyroid surgery?
parathyroid glad may have been damaged or removed accidently
treatment of hypocalcemia
mild–increase Ca++ in diet, vitamin D and Ca++ supplements
severe–seizure precautions, Ca++ gluconate IV, thiazide diuretics (decreases urinary loss)
hypercalcemia
> 11 mg
causes of hypercalcemia
excess Ca++ intake increases Vitamin D intake increase in PTH renal disease prolonged bed rest bone cancer steroid intake thiazide diuretics
signs and symptoms of hypercalcemia
decreased neuromuscular activity decreased deep tendon reflexes nausea & vomiting (due to decreased GI motility) muscle fatigue constipation thirst polyuria deep bone pain if bone resorption is a problem fractures
treatment for hypercalcemia
IV saline (promotes Ca++ excretion) loop diuretics IV or PO phosphorus calcitonin (drive Ca++ into bone) force fluids (3-4 L/day) low Ca++ diet weight bearing activities prednisone (decrease Ca++ absorption in GI) parathyroidectomy
normal magnesium levels
1.5-2.0 mEq or 1.7-2.6 mg
where is Mg++ in the body?
3 forms
50-60% in bone combined with calcium and phosphorus
30% bound to protein
function of Mg++
role in enzyme activity
role in metabolism of fats, carbohydrates and proteins
integrity of neuromuscular system
regulates HPO4- levels
hypomagnesemia
< 1.5 mEq of Mg++
causes of hypomagnesemia
poor nutrition (alcoholism) GI loss renal loss due to nephritis severe, prolonged diarrhea decrease PTH diuretics malabsorption prolonged TPN osmotic diuresis due to high glucose levels
signs and symptoms of hypomagnesemia
increase neuromuscular irritability increased deep tendon reflexes altered mentation/aggression increased blood pressure and pulse (related to decreased cardiac function) nausea, vomiting, diarrhea
treatment of hypomagnesemia
increased dietary intake
IV MGSO4
seizure precautions
safety issues
hypermagnesemia
> 2.0 mEq of Mg++
causes of hypermagnesemia
antacids & laxatives containing Mg++ with renal failure overaggressive therapy for low Mg++ epsom salt enemas diabetic ketoacidosis rhabdomyolysis lithium
signs and symptoms of hypermagnesemia
pronounced decrease in neuromuscular function hypo-reflexes or absent reflexes decreased respirations decreased blood pressure arrhythmias drowsiness lethargy flushing & sensation of warmth
treatment for hypermagnesemia
treat underlying cause withhold Mg++ promote urinary output using diuretics/fluids dialysis IV Calcium gluconate for heart
Why is hypomagnesemia often associated with hypokalemia?
magnesium is required for Na+/K+ pumps
normal phosphorus/phosphate (HPO4-) levels
2.5-4.5 mg/dL or 1.7-2.6 mEq
will be higher in children
What is principle intracellular anion?
phosphate
hypophosphatemia
< 2.5 mg of phosphate
causes of hypophosphatemia
malnutrition aluminum and/or magnesium antacids diarrhea excess laxatives chronic intestinal disease diuresis/diuretics hyperglycemia rapid TPN administration excess carbohydrate ingestion/metabolism
signs and symptoms of hypophosphatemia
decreased cardiac function slow, faint peripheral pulse skeletal muscle weakness weak respiratory effort prolonged bleeding confusion tremors seizures decreased bone density renal calculi
treatment of hypophosphatemia
stop phosphorus-binding antacids, diuretics and Ca++ supplements PO phosphate supplements foods high in phosphorus when < 1mg IV seizure precautions
hyperphosphatemia
> 4.5 mg/dL of phosphate
causes of hyperphosphatemia
renal insufficiency aggressive treatment of neoplasms (chemo) increase intake decreased PTH enemas containing phosphorus (Fleets)
signs and symptoms of hyperphosphatemia
same as hypocalcemia
deposition of Ca-phosphate precipitates
treatment of hyperphosphatemia
management of underlying hypocalcemia antacids high calcium diet decreased phosphate in diet & medications increase renal excretion
What is one thing to suspect with TPN administration?
Nutrition Recovery Syndrome
How much Ca++ is in a tablespoon of powered milk?
50 mg of Calcium
What foods tend to decrease calcium absorption?
foods high in oxalates–spinach, asparagus, rhubarb, almonds, legumes, wheat bran
Why does lack of protein decrease Ca++ utilization?
Ca++ is bound to albumin
What causes calcium loss via the kidneys?
diet with excess protein and sodium
Why can the elderly have a decrease in calcium absorption?
lower HCl acid
What foods are high in magnesium?
green, leafy vegetables, whole grains, nuts, bananas, oranges and chocolate
What foods are high in phosphorus?
meat, dairy, whole grains, legumes containing phytates (salt form of phosphorus, principle storage in plant tissue) and most carbonated beverages
How much potassium is in a teaspoon of salt substitute?
about 50 mEq
What are IV rate limits for potassium?
10 mEq/hr via peripheral IV line
20 mEq/hr via central line without monitoring the heart
40 mEq/hr via central line with monitoring heart
What are IV concentration limits for potassium?
40 mEq per 100 cc piggy-back
40 mEq per 1000 cc continuous IV bag peripheral
80 mEq per 1000 cc continuous central line
What is max amount of potassium that can be give per day via IV?
200 mEq
How can burning be eased when giving potassium via IV?
add 10 mg 1% Lidocaine to IV bag
What are IV concentration limits for potassium?
40 mEq per 100 cc piggy-back
40 mEq per 1000 cc continuous IV bag peripheral
80 mEq per 1000 cc continuous central line
What are IV concentration limits for potassium?
40 mEq per 100 cc piggy-back
40 mEq per 1000 cc continuous IV bag peripheral
80 mEq per 1000 cc continuous central line
What is max amount of potassium that can be give per day via IV?
200 mEq
What is max amount of potassium that can be give per day via IV?
200 mEq
How can burning be eased when giving potassium via IV?
add 10 mg 1% Lidocaine to IV bag
How can burning be eased when giving potassium via IV?
add 10 mg 1% Lidocaine to IV bag
