Potassium D2 Flashcards
Study Patho
Loss of potassium in GI tract
-Diarrhea: Large amounts of potassium are in intestinal fluids so diarrhea can cause potassium depletion -Vomiting -Fistulas -NG suction
Loss of potassium through kidneys
Sometimes too much potassium is excreted in urine - usually because of drugs that cause the kidneys to excrete excess sodium, water, and potassium (diuretics - thiazide).
Magnesium depletion
Hyperaldosteronism
Loss of potassium through skin:
Diaphoresis
Shift of K into cells:
Increased insulin (eg. IV dextrose load)
Alkalosis
Tissue repair
Increase epinephrine (eg. stress)
Clinical Manifestations Hypokalemia
-Muscle weakness
-Lethargy
-Anorexia
-Dysrhythmia
-Cardiac arrest (if severe)
-Nausea
-Fatigue
-Hyperglycemia
-Weak irregular pulse
-Paresthesias (numbness & tingling)
-Decreased bowel motility
If prolonged:
Inability of kidneys to concentrate urine (causing dilute urine) - which leads to nocturia, polyuria and excessive thirst
-Potassium depletion depresses the release of insulin and results in glucose intolerance
Normal pH of blood
7.35-7.45
Acidosis: occurs when pH?
occurs when pH of plasma falls below 7.35 -
- associated w/ increased plasma K concentration (hyperkalemia)
Alkalosis: occurs when pH?
plasma pH above 7.45 -
- associated w/ reduced plasma K concentration (hypokalemia)
Potassium balance is critical for many cellular and metabolic functions including:
- Nerve conduction
- Normal cardiac electrical conduction (for heart contractions)
- Skeletal and smooth muscle contraction
- Intracellular osmolality and cellular growth
- Role in acid-base balance as often reciprocal exchange of K-H across cell membrane
Hypokalemia happens when?
K < 3.5 mmol/L
Hyperkalemia happens when?
K > 5.0 mmol/L
What supplement or diuretics causes hyperkalemia and what is the mechanism of action?
Potassium-sparing diuretics (Spironolactone) –
Blocks reabsorption of Na and reduce secretion of K (Na - K exchange) = can result in hyperkalemia
What can cause failure to eliminate K?
- ACE inhibitors
- Renal disease
- Potassium sparing diuretics
- Adrenal insufficiency
Shift of K out of cells
- Acidosis
- Tissue catabolism
- Crush injury
- Tumour lysis syndrome
Clinical Manifestations Hyperkalemia
-Ventricular dysrhythmias
-Cardiac arrest
-Skeletal muscle weakness
(Rapidly ascending muscular weakness can lead to flaccid quadriplegia)
-Muscle twitching
-Fatigue
-Paresthesias (numbness and tingling)
-Dyspnea (difficult or labored breathing.)
-Cramping
Serum Sodium and Potassium normal values
Na: 135-145 mmol/L
K: 3.5-5.0 mmol/L
Drugs that Raise Potassium
- Potassium Chloride
- IV K additives (KCL) (20-60mmol/L)
- Potassium-sparing diuretics Spironolactone
Drugs that Lower Potassium
-Insulin and Glucose (temporary effect, moves K to cell) IV insulin pushes glucose into cell and K goes along
K leaves blood and enters cells
- Polystyrene sulfonate (Kayexalate) (po, rectal) binds to K in bowel and removed in stool
**Exchanges Na ion for K ion in the intestine
**Sometimes given with a laxative the speed up evacuation of K
-Loop diuretic
-Sodium bicarbonate (reduce acidosis, K-H exchange)
**Reduces acidosis by raising the pH of the blood
**Raised pH of blood - decreased plasma K [ ] = lower K levels
Drugs that stabilize heart function with ↑K
- Calcium gluconate
- Calcium chloride
Treatments that Lower Potassium
- Peritoneal Dialysis (removes K) long-term treatment, need peritoneal tube surgically placed
- Hemo-Dialysis (removes K) can be done urgently, primarily long-term treatment, need vascular access
Can Potassium Chloride be given as an IV bolus?
IV Potassium chloride is NEVER given IV push (bolus) because it may be FATAL (cardiac arrest)
(IV Potassium has been used as part of lethal injections in executions)
