electrolyte 2 and CMP Flashcards
range Na
135-145 mEq/L
range K
3.5-5 mEq/L
range Cl
98-106 mEq/L
range bicarb
22-32 mEq/L
electrolyte panel CPT code
80051
EKG hypokalemia
prominent U wave
EKG hyperkalemia
tall peaked T wave
what is K
K: major intracellular CATion, renal excretion, regulated in distal nephron
RAS system aldosterone actions
increase renal Na reabsorption and increase renal K excretion
hyperkalemia dx and etiology
Hyperkalemia: K>5.0 (>6-6.5 = serious problem)
May be caused by:
- false elevation
- pseudohyperkalemia
- inadequate excretion
- redistribution from ICF to ECF
- excess administration
clinical features of hyperkalemia
Neuro: weakness, numbness, tingling, paralysis, hypoactive DTR
EKG changes, arrythmia, cardiac arrest: early EKG tall peaked T wave, end event: sine wave pattern with arrest
Causes of pseudohyperkalemia
- hemolysis due to poor venipuncture technique *most common
- Thrombocytosis, leukocytosis
* *repeat K determination to check for artifactual elevation
Inadequate excretion of K etiology cause of hyeperkalemia
- Renal failure: assess BUN/Cr
- Meds blocking K excretion: spironolactone, triamterene, amiloride
- Hypoaldosteronism (adrenal insufficiency ie Addisons disease, ACE inhibitors-common, NSAIDS -uncommon, Renal tubular disease)
Etiology redistribution of K cause of hyperkalemia
K moves from ICF to ECF:
- tissue damage ie rhabdomyolysis
- acidosis (a 0.1 decrease in pH raises serum K+ about 0.5-1.0 mEq/L due to ECF shift)
- decreased insulin
Etiology of excess K+ admin
K supplement (oral, IV) K based salt sub
Tx hyperkalemia, rapid
r/o pseudohyperkalemia via repeat K+
If K+ is >6.5 send to ER or ICU
*rapid correction: CaCl IV to protect heart; maneuvers to shift K from ECF to ICF (sodium bicarb IV to increase pH, D50W plus insulin IV)
*give dextrose with insulin to prevent hypoglycemia
tx hyperkalemia, slow
Slow correction:
- diuretics (furosemide)
- kayexalate + sorbitol (po or rectal) - cation exchange resin (Na for K in gut)
- dialysis
Correct underlying cause:
- stop K sparing diuretic
- stop ACE inhibitor, K supp etc
- mineralcorticoid replacement if Addisons
dx and etiology hypokalemia
Hypokalemia: K< 3.0 is potentially dangerous; 2.0 = ~ 200 mEq deficit in adult Cause: 1. inadequate intake 2. GI tract loss 3. Renal loss 4. Redistribution ECF to ICF
Clinical features/sx hypokalemia
sx:
neuromuscular: malaise, weakness, cramps, constipation, paralysis
polyuria, polydipsia with hyperglycemia
signs:
cardiac: arrythmia, hypotension (EKG - flattened T wave, ST depression , U WAVES, ventricular ectopy)
low potassium is more dangerous when taking what?
digoxin
etiology GI loss cause of hypokalemia
vomiting, diarrhea (laxative abuse, IBD), fistula, villous adenoma (rectosigmoid tumor)
Upper GI loss (vomiting, NG suction) –> metab alkalosis which promotes renal K loss (*Cl losing diarrhea can cause metab alkalosis as well) however note that lower GI loss ie diarrhea or fistula usually causes metab ACIDosis
Etiology renal loss cause of hypokalemia
diruetic*, osmotic diuresis (hyperglycemia or EtOH), renal tubular acidosis (RTA), Bartter’s syndrome (elevated renin and aldosterone)
Causes of K redistribution from ECF to ICF (hypokalemia)
- Metab alkalosis (each 0.1 increase in pH lowers serum K+ by 0.5-1 mEq/L)
- insulin administration
- mineralocorticoid excess ie hyperaldosteronism, cushings, steroid
- hypokalemic periodic paralysis
- B agonist induce cellular uptake of K and promote insulin secretion by pancreas (Albuterol)
Prompt tx of hypokalemia is critical if taking what?
Digitalis