Potassium Disorders

-Exam 1, Dr. Wai

3.5-5

• ECF potassium concentration goal range ___ mEq/L

potassium

• most prevalent ICF cation

• ICF concentration 140 mEq/L

• ECF concentrations are not reflective of total body stores

• regulates many biochemical processes in the body

• required cell metabolism, protein, and glycogen synthesis

• key cation for electrical action potentials across cellular membrane -cardiac conduction

potassium homeostasis

• K concentrations are determined by the relationship between the following:

• K intake

• GI absorption and urinary excretion → malabsorption/chron’s, kidney disease

• hormones

• acid base balance

• body fluid tonicity

insulin

• increase cellular K uptake by stimulating cell membrane Na/K/ATPase

catecholamines

• increase cellular K uptake by stimulating cell memnbrane Na/K/ATPase

aldosterone

• promotes K+ excretion in collecting duct

angiotensin II

• stimulates aldosterone secretion

relationship between serum and total body potassium

• changes in serum K+ are directly proportional to changes in total body potassium (TBK)

• relationship is not linear

• helpful to determine magnitude of clinical problems

• serum K levels drop approximately 0.3 mEq/L for every 100 mEq reduction in total body potassium

• distributed ICF »»»» ECF

insulin, catecholamines, aldosterone, angiotensin II

• which hormones DECREASE serum potassium concentrations?

hypokalemia

• plasma K+ concentration < 3.5 mEq/L

• common clinical problem → 21% of hospitalized patients

• easily reversible → may be life threatening if severe

• midl to moderate → increased morbidity and mortality in patients with cardiovascular disease

major causes of hypokalemia

• decreased K+ intake

  • eating disorders

  • total parenteral nutrition

  • starvation

• increased GI losses

  • vomiting

  • diarrhea

  • tube drainage (nasogatric tube output)

  • laxative abuse

• increased entry into cells

  • elevated ECF pH (alkalosis)

  • increase availability of insulin *****

  • elevated B adrenergic activity

  • hypokalemic periodic paralysis

  • etc

• increased urinary losses

  • diuretics (loop)

  • amphotericin B

• others

  • increased sweat losses

  • dialysis

  • plasmapheresis

diuretics (loop)

major cause of renal losses with hypokalemia

increased availability of insulin

• main cause of hypokalemia due to increased entry into cells

drug induced hypokalemia

• loop and thiazide diuretics most common

• transcellular potassium shift

• increased renal potassium loss/excretion

• increased GI loss

transcellular potassium shift

• catecholamine B2-adrenergic agonist (epinephrine, norepinephrine)

• decongestants

• bronchodilators (albuterol)

• theophylline and caffeine

• verapamil intoxication

• insulin (high dose) ****

• chloroquinolone intoxication

increased renal potassium loss/excretion

• diuretics (loop, acetazolamide, thiazides)

• mineralocorticoids

• antibiotics (penicillins, high doses)

• drugs associated with Mg depletion

increased GI loss

• sodium polysystrene sulfonate

hypomagnesemia

• seen concomitantly in 40% of patients

• other cause of hypokalemia

• low mg decreases intracellular K+

• impairs the function of Na/K/ATPase

• promotes renal K wasting

hypokalemia clinical manifestations

• majority of healthy patients with mild hypokalemia are asymptomatic

• symptoms related to the degree and rate of development

• mild to moderate symptoms: cramping, weakness, malaise, myalgia

• symptom manifestation: cardiovascular, muscular activity

hypokalemia cardiac manifestations

• arrhythmias

• ECG changes

arrhthymias

• increased risk in elderly patients or patients with underlying heart disease

• can include:

• bradycardia, heart block

• atrial flutter, paroxysmal atrial tachycardia

• ventricular fibrillation

• increased digoxin toxicity

ECG changes

• ST- segment depression or flattening

• T wave inversion

• U wave elevation

hypokalemia neuromuscular manifestations

• results from hyperpolarization of skeletal muscle

• may include:

• muscle weakness

• cramping

• easy fatigability

• myalgias

hypokalemia general recommendations

• maintenance: potassium dosage of 20 mEq/day is usually sufficient to prevent hypokalemia from occuring

• treatment: doses of 40-1000 mEq are usually sufficient to treat hypokalemia

• approximately 10 mEq KCl will raise serum by 0.1 mEq/L (when serum K < 3, will require more

0.1

• approximately 10 mEq KCl will raise serum by __ mEq/L (when serum K < 3, will require more

mild to moderate hypokalemia (3-3.4 mEq/l) treatment

• oral administration of 10-20 mEq of potassium given 2-4 times per day

severe hypokalemia (<3 mEq/L) or symptomatic hypokalemia treatment

• IV or PO administration of 40 mEq, 3-4 times per day

• monitor serum K levels every 4 hours

• monitor ECG changes

potassium salts

• hypokalemia treatment

• available in different salts: chloride, phosphate, bicarbonate

potassium chloride supplement

• preferred agent for hypokalemia

• most effective for common causes

• diuretic and diarrhea induced loss of K+ and chloirde

potassium phosphate supplements

• hypokalemia treatment

• reserved for patients with loss of both K and phosphate

potassium bicarbonate supplements

• hypokalemia treatment

• for patients with hypokalemia and a metabolic acidosis

IV potassium

• hypokalemia treatment

• more dangerous than PO

• burning sensation, risk of extravasation

• limit use to: severe cases of hypokalemia (<2.5), symptomatic patients (ECG chages, muscle spasms, patients unable to tolerate PO)

• should be mixed in saline containing solutions (0.9 or 0.45% NaCl)

• SLOW infusions

IV potassium limits

• severe cases of hypokalemia (<2 mEq/L)

• symptomatic patients: ECG patients, muscle spasms, patients unable to tolerate PO

IV potassium dose

• hypokalemia treatment

• 20-60mEq IVPB or added to fluid bag

• most patients receive 10 mEq/hr

• monitor serum K levels every 2-4 hrs

2-4

when giving IV potassium monitor serum K levels every ____ hours

magnesium

always replace low __ in patients first

hypokalemia alternative therapy

• diet- spinach, figs, seaweed, beets, carrots, cauliflower, bananas, beef, pork, nuts, avocados, dried fruits

• potassium sparing diuretics- commonly given with potassium wasting diuretics, amiloride, triamtere, spironolactone

insulin, furosemide, vomiting

67 you M with CHF and DM 2 presents to ED with N/V, muscle cramps.
Home meds: Lantus 30 mg SQ QHS, lisinopril 20 mg daily, furosemide 40 mg
daily, spironolactone 25 mg daily, carvedilol 6.25 mg BID.
Lab results: Na 122, K 2.5, Cl 82, CO2 17, BUN 18, Cr 0.9, glucose 488, ketones
0.1, EKG: heart block, T-wave inversions
Which of the following are contributing to hypokalemia?

0.9% NaCl infusion with IV KCL 40mEq IV x 4 doses

67 you M with CHF and DM 2 presents to ED with N/V, muscle cramps.
Home meds: Lantus 30 mg SQ QHS, lisinopril 20 mg daily, furosemide 40 mg
daily, spironolactone 25 mg daily, carvedilol 6.25 mg BID.
Lab results: Na 122, K 2.5, Cl 82, CO2 17, BUN 18, Cr 0.9, glucose 488, ketones
0.1, EKG: heart block, T-wave inversions
What is most appropriate to administer FIRST?

magnesium

67 you M with CHF and DM 2 presents to ED with N/V, muscle cramps.
Home meds: Lantus 30 mg SQ QHS, lisinopril 20 mg daily, furosemide 40 mg
daily, spironolactone 25 mg daily, carvedilol 6.25 mg BID.
Lab results: Na 122, K 2.5, Cl 82, CO2 17, BUN 18, Cr 0.9, glucose 488, ketones
0.1, EKG: heart block, T-wave inversions
Which other electrolyte should be checked and repleted prn?

Na, K, Mg, Glucose, EKG, Every 4 hours

67 you M with CHF and DM 2 presents to ED with N/V, muscle cramps.
Home meds: Lantus 30 mg SQ QHS, lisinopril 20 mg daily, furosemide 40 mg
daily, spironolactone 25 mg daily, carvedilol 6.25 mg BID.
Lab results: Na 122, K 2.5, Cl 82, CO2 17, BUN 18, Cr 0.9, glucose 488, ketones
0.1, EKG: heart block, T-wave inversions
What should be monitored and how frequently?

hyperkalemia

• plasma K+ concentration > 5 mEq/L

• rare in patients with normal K excretion, most often seen in renal failure

mild hyperkalemia

• serum K + 5-6 mEq/L

moderate hyperkalemia

• serum K+ 6.1-6.9 mEq/L

severe hyperkalemia

• serum K+ > 7 mEq/L

hyperkalemia primary causes

• increaed K intake

• decreased K excretion

• tubular unresponsiveness to aldosterone

• redistribution of K into the ECF

potassium sparing diuretics (spironolactone, triamterene, amiloride)

• hyperkalemia caused by tubular unresponsiveness is normally due to ____

potassium sparing diuretics, NSAIDs, ACEI, ARBs

medications that cause hyperkalemia drug induced reduced potassium excretion

hyperkalemia clinical manifestations

• acute is more dangerous than chronic

• frequently asymptomatic- heart palpitations, skipped heartbeats

• severe hyperkalemia: muscle weakness, ECG changes, peaked T waves

IV calcium gluconate

• 1st line treatment for hyperkalemia with ECG changes

• antagonism of the cardiac membrane actions of k+ (stabilize the heart)

temporary hyperkalemia treatments

• drive extracellular K+ into the cell

• insulin and glucose

• sodium bicarbonate, primarily if metbaolic acidosis

• B2 adrenergic agonist (albuterol)

hyperkalemia treatment to removal K from body

• loop or thiazide diuretics (via kidneys)

• cation exchange resin (via GI)

• dialysis, preferably hemodialysis if severe

calcium

• used in treatment of hyperkalemia

• antagonism of membrane actions of K+

• antagonizes cardiac membrane effects of hyperkalemia

• reverses ECG changes within mins

• indicated in patients with significant ECG changes

• gluconate preferred over chloride → because chloride associated with tissue necrosis if extravasation occurs

• duration of action 30-60 min

• no effect on potassium levles ******

IV calcium gluconate dose

• 1g (one 10ml ampule) IV bolus over 5-10 minutes

insulin and glucose

• hyperkalemia treatment

• drives extracellular K into the cells (transient effect)

• increase activity of Na/K/ATPase pump to drive K intracellular

• effect seen in 15 minutes

• peaks at 60 min, duration several hours

• temporary lowering of plasma K+*******

insulin and glucose dose for hyperkalemia

• 5-10 units of insulin IV

• Dextrose: 50ml ampule of 50%

sodium bicarbonate

• treatment for hyperkalemia

• drives extracellular K into the cells (transient effect)

• preferred treatment in hyperkalemic patients with a metabolic acidosis (low pH, low bicarbonate)

• dose: 50-100 mEq infused over 2-5 min

• effect begins within 30-60 min

• temporary lowering of plasma K

beta 2 adrenergic agonist (albuterol)

• hyperkalemia treatment

• drives extracellular K into cells (transient effect)

• MOA- stimulates Na/K/ATPase pump, stimualtes pacnreatic B receptors to increase insulin release

• adjunctive therapy for patients already receiving insulin and dextrose ***

• temporary lowering of plasma K+

albuterol dosing for hyperkalemia

• 10-20 mg in 4 ml of saline by inhalation over 10 minutes

sodium zirconium cyclosilicate (Lokelma)

• hyperkalemia treatment

• removal of K from the body

• no sorbitol content

• onset of action: 1 hr

• drug interactions: separate adminsitration of other medication by at least 2 hours

sodium polysteren sulfonate (Kayexalate)

• hyperkalemia treatment

• removal of K from the bdoy

• onset 1 hour

• separation administration of other medication by at least 6 hours

Patiromer calciium sorbitex (Veltessa)

• hyperkalemia treatment

• removal of K from the body

• onset of action: hours to days

• not recommended acute treatment of hyperkalemia

loop diuretics

• hyperkalemia treatment

• removal of K from the body

• promote urinary excretion of K+

• dose: Furosemide 20-40 mg IV or PO, titrate to response

losartan, triamterene, CKD stage IV, bactrim

58 yo F with HTN, CKD stage IV presents with weakness, palpitations. She recently
started Bactrim DS for a UTI.
Home meds: Bactrim DS daily, losartan 50 mg, triamterene 50 mg BID.
Labs: Na 135, K 6.2, Cl 108, CO2 20, BUN 52, Cr 3.2, glucose 106. Ca 9.5.
EKG: peaked T waves
What is contributing to her electrolyte disorder?

calcium gluconate

58 yo F with HTN, CKD stage IV presents with weakness, palpitations. She recently
started Bactrim DS for a UTI.
Home meds: Bactrim DS daily, losartan 50 mg, triamterene 50 mg BID.
Labs: Na 135, K 6.2, Cl 92, CO2 20, BUN 52, Cr 3.2, glucose 106. Ca 9.5.
EKG: peaked T waves
After holding home meds, what should be administered FIRST?

insulin and dextrose

58 yo F with HTN, CKD stage IV presents with weakness, palpitations. She recently
started Bactrim DS for a UTI.
Home meds: Bactrim DS daily, losartan 50 mg, triamterene 50 mg BID.
Labs: Na 135, K 6.2, Cl 92, CO2 20, BUN 52, Cr 3.2, glucose 106. Ca 9.5.
EKG: peaked T waves
Which option does NOT remove potassium from the body?

separate form other medications by at least 2 hours

58 yo F with HTN, CKD stage IV presents with weakness, palpitations. She recently
started Bactrim DS for a UTI.
Home meds: Bactrim DS daily, losartan 50 mg, triamterene 50 mg BID.
Labs: Na 135, K 6.2, Cl 92, CO2 20, BUN 52, Cr 3.2, glucose 106. Ca 9.5.
EKG: peaked T waves
Which is an important counseling point about cation exchange resins, like Lokelma?