T3- Fluid + Electrolytes Part 2 Flashcards
Where do I generally find potassium in the body?
ICF!
Note:
Serum potassium is normally 3.5-5, which is low, so you know its all inside the cell. Another way to remember potassium is inside is that you can eat 3-5 bananas, so the range is 3.5-5 and the low number means potassium is inside the cell.
How does potassium move in/out of the cell?
Na/K/ATPase pump.
3 Na+ out
2 K+ in
1 ATP
Note: Na+ and out are 3 letters
K+ and in are 2 letters
Potassium is lowest outside the cell, so it must be going in.
What ion is the cell membrane generally impermeable to?
K
Why is K+ so important for our body?
Acid-base balance, as it is exchanged for H+! (hyperkalemia and metabolic acidosis are generally linked)
Muscle cell excitability
Nerve impulses
What kind of medications/things cause K+ to shift into a cell?
Insulin, Catecholamines, and B-agonists.
What kind of inhaled medication can help reduce serum potassium?
Nebulizing treatments.
What 4 factors promote LOWER serum potassium?
Aldosterone (Sodium retention means we get rid of potassium instead)
Insulin
B-agonists
Alkalosis (in order to get back to neutral, we need to exchange our potassium for H+)
What 4 factors promote HIGHER serum potassium?
Cell lysis (Think tourniquets)
Strenuous exercise
Alpha agonists
Acidosis (in order to get back to neutral, we need to exchange our excess H+ for more potassium)
Why are K+, H+, and Na+ all linked?
Na+ and K+ are linked via cell membrane pumps, aka they exchange for one another.
H+/K+ are exchanged with Na+ in the DCT of the nephron. If we have low H+, we need to retain and kick something else out, so we kick out Na+/K+, which is why acidosis/alkalosis can be linked often with hyper/hypokalemia.
What 3 factors are responsible for modulating our urinary excretion of potassium?
Changes in ECF concentration
Changes in pH
Aldosterone levels
What does increased ECF concentration of potassium cause in terms of potassium secretion?
Increased secretion of potassium.
What does low pH cause in terms of potassium secretion?
Lower secretion of potassium, increased secretion of H+.
Note:
every 0.1 decrease of pH in acidosis = increase of potassium by 0.7 mEq.
What does increased aldosterone cause in terms of potassium secretion?
Increased secretion of potassium as we retain sodium preferentially.
What kind of medications can block the secretion of potassium? What is the mechanism?
ACEI/ARBs/Aldosterone antagonists.
All of which block aldosterone, so we get rid of sodium instead of potassium.
Note:
This is why the side effect of all 3 is hyperkalemia and aldosterone antagonists are known as K+ sparing diuretics.
What are the 4 ways hypokalemia is caused?
Renal loss
GI loss
Poor intake
Transcompartmental shift
What ways does renal loss cause hypokalemia?
Diuretics
Renal disease
Elevated aldosterone/corticosteroids
Renal syndromes: Bartter syndrome, Liddle syndrome, Gitelman syndrome
What ways does GI loss cause hypokalemia?
Vomiting or diarrhea
What 3 things cause transcompartmental shifts of potassium into the cell?
Beta-adrenergic agonists
Insulin
Alkalosis
What are the lab abnormalities we would expect in hypokalemia?
Low serum potassium < 3.5 mEq/L
Blood pH increase (alkalosis)
Decreased urine osmolality
Decreased urine specific gravity
EKG abnormalities (QT prolongation and presence of a U wave)
Note:
A U wave appears in after a T wave and before a P wave. Normally not visible.
What happens to our urine in hypokalemia?
Polydipsia
Polyuria
AKA we can’t concentrate our urine well.
What neuro symptoms do I expect in hypokalemia?
Paresthesias
Paralysis
Irritability/Confusion
Drowsiness
What muscular symptoms do I expect in hypokalemia?
Weakness
Fatigue/Lethargy
Cramps or tenderness
What GI symptoms do I expect in hypokalemia?
Constipation
Ileus
Abdominal distension
Note:
AKA abdominal weakness. Food isn’t moving well cause muscles are weak/fatigued.
What cardiac symptoms do I expect in hypokalemia?
Hypotension
Palpitations
Dysrhythmias
Weak, thready pulse
Note:
Imagine a heart that is getting weaker ):
What does potassium do to the T wave in an EKG?
Low K = low T
High K = high T
Note:
Normal would have a T wave and maybe a tiny U wave.
Hypo would have a shallow T wave with a big U wave.
What is the acronym for hypokalemia symptoms?
I am
Alkalosis
Shallow respirations
Irritability
Confusion/drowsiness
Weakness/fatigue
Arrthymias (tachy and/or brady)
Lethargy
Thready pulse
Also
Decreased intestinal motility, nausea, vomiting, and ileus.
How do I manage hypokalemia?
Treat underlying cause!!!!!!!!!
AND
check for hypomagnesemia!!
How do I treat acute hypokalemia?
Potassium replacement via oral/IV KCl at 10-20 mEq/hr.
How do I treat chronic hypokalemia?
Eat more potassium-rich foods
Check for other predisposing conditions (such as chronic metabolic acidosis)
Consider oral potassium (CONSIDER!!! not automatic)
What lab value is hyperkalemia?
> 5.0 mEq/L
What generally causes hyperkalemia?
Excess intake
Inadequate elimination
Release from ICF
What is the main cause for excess intake of potassium?
IVs
What can cause impaired/inadequate elimination of K+?
CKD, adrenal insufficiency, meds
Note:
Addison’s causes hyperkalemia by impairing aldosterone production.
What can cause K+ to be released from cells?
Cell damage, excessive/severe muscle contractions
What can cause pseudohyperkalemia?
Hemoylsis of samples, prolonged tourniquet time, traumatic stick
Note:
All of these cause cells to explode, and most of our potassium is contained in cells! If you retake the labs properly, potassium will be different by a decent amt.
What meds can cause hyperkalemia?
ACEI/ARBs/K+ sparing diuretics
NSAIDs
Trimethoprim
Heparin
What conditions can cause hypoaldosteronism?
Addison’s
Congenital adrenal hyperplasia
Hyporeninemic state
Severe dehydration
SLE (Systemic lupus erythematosus)
Type 4 renal tubular acidosis
What cause cause an extracellular shift of potassium?
Hemolysis
Tissue damage (both of these generally need renal failure to actually cause hyperkalemia)
Acute acidosis (decreased insulin or digoxin OD)
Beta-blockers
Hyperosmolar state (think diabetes)
What lab abnormalities do I expect in hyperkalemia?
Serum potassium > 5.0 mEq/L
EKG changes (wide QRS, huge, peaked T wave)
What neuro symptoms do I expect in hyperkalemia?
Paresthesia
Weakness
Dizziness/drowsiness
Note:
Weakness and dizziness are the distinct symptoms.
Paresthesia and drowsiness is found in both kalemias.
What muscle symptoms do I expect in hyperkalemia?
Weakness
Cramps
Note:
Overlaps with hypokalemia, but hypokalemia also includes fatigue.
What GI symptoms do I expect in hyperkalemia?
Diarrhea
Abdominal cramps
Nausea/vomiting
Note:
No overlap with hypokalemia!
What cardiac symptoms do I expect in hyperkalemia?
Palpitations
Dysrhythmias
Cardiac arrest
Hypotension
Note:
Only difference is cardiac arrest.
In hypokalemia, its a weak and thready pulse.
What EKG changes do I expect in hyperkalemia?
High K = high T, so I would see a tall, peaked T wave.
I would also see a wide QRS with ST depression.
What are the summarized hyperkalemia symptoms?
Muscle twitches = cramps = paresthesias
Irritability & anxiety
Low BP
EKG changes
Dysrhythmias
Abdominal cramping
Diarrhea
How do I treat hyperkalemia?
Treat UNDERLYING cause!!!!!