4.2 - Electrolyte Imbalances Flashcards
4 Types of Electrolyte Imbalances
1) Hyperkalemia
- too much K in intravascular space
2) Hypokalemia
- too little K in intravascular space
3) Hypernatremia
- too much Na in intravascular space
4) Hyponatremia
- too little Na intravascular space
Function of Potassium
- range: 3.5-5
- maintains heart and muscle contraction
- excreted by kidneys
Cause of Hyperkalemia
1) Excessive intake
2) Decreased excretion
3) Intracellular to Extracellular movement
- K moves from cells into blood
Pathogenesis of Hyperkalemia
- in early stages, there is an increased excitability of cells; bc the resting membrane potential is less negative and thus easier to fire an AP
- in late stages, there is decreased excitability; bc persistent depolarization can deactivate Na channels that are needed to generate an AP
Clinical Significance of Hyperkalemia
1) Cardiac contractility
- in early stages, bc there is potential for increased excitability, it can also cause tachycardia and palpitations
- in later stages, bc deactivated Na channels = bradycardia
2) Musculoskeletal Impairment
- EALRY: twitches and tingling (paraesthesia), ↑ reflexes
- LATE: numbness, ↓ reflexes
3) Organ Function
- EARLY: hyperactive bowel sounds (diarrhea)
Cause of Hypokalemia
1) Increased K excretion
2) Inadequate K intake
3) Extracellular to intracellular movement
- K is shifted out of bloodstream and into cells
Pathogenesis
Early: decreased excitability of cells
- resting potential is more negative (hyperpolarized)
- cell is further from threshold to generate AP
Clinical Significance of Hypokalemia
1) Cardiac contractility
- palpitations and dizziness
- fucks with hearts coordinated contractions
2) Musculoskeletal Impairment
EARLY: tingling (paraesthsia), muscle weakness
LATE: numbness, flaccid paralysis (loss of muscle tone)
3) Organ Function
- EARLY: hypoactive bowel sounds
- bowel obstruction
- paralytic ileus: loss of normal peristalsis
Function Of Na
- range: 135-145mol/L
- dominant in extracellular fluid
- controls fluid distribution
Cause of Hypernatremia (too much Na)
1) Decrease excretion of Na (kidney dysfunction, meds)
2) Excessive Intake
3) Dehydration
- not enough water, means too much Na
4) Hyperaldosteronism
- excessive aldosterone = fluid retention
Pathogenesis of Hypernatremia
- too much Na means not enough water
- cell shrinks
- ↓ blood volume
Structural Alterations
- Shrinkage of organs; bc a lot of Na means not enough water
Clinical Significance of Hypernatremia
EARLY: polydipsia (excessive thirst), muscle weakness
LATE: ↓ LOC, seizures, coma
- dry mucous membranes, ↓ skin turgor
Causes of Hyponatremia
1) Increased Na excretion
2) Decreased Na intake
3) Excessive water intake or retention
4) SIADH secretion
- body produces excesses ADH which promotes water retention
Pathogenesis of Hyponatramia
- too little Na means too much water
- too much water = cell swelling
- ↑ blood volume
Structural Alterations
- organs swelling
- can cause ↑ intracranial pressure
Clinical Significance of Hyponatremia
Early: headache, nausea, confusion
Late: LOC, seizures, coma
- polydipsia (excessive thrist)
Function of Chloride
- involved in blood pressure/volume
- maintains pH
Function of Magnesium
- involved in neuromuscular contractility
Hypermagnesemia
Symptoms
- bradycardia
- ↓ BP
- weakness
- lethargy, coma
Hypomagnesemia
Symptoms
- tachycardia
- ↑ BP
- twitching, paraesthesia
- irritbaility and confusion
Function of Ca
- stored in bone
- also involved in neuromuscular contractility
- closely linked to magnesium (if magnesium is low, Ca is low)
- Ca absorption is dependent on vitamin D
Causes of Hypercalcemia
> 2.6
1) Increased absorption
2) Decreased excretion
3) increased bone resorption/break down
- Ca is released from bone into blood
Pathogenesis of Hyper calcemia
- bone break down releases Ca into blood
Structural Changes of Hypercalcemia
** not enough Ca in bones**
- osteoporosis
- fractures
- kidney stones (nephrolithiasis); more Ca is filtered in kidneys and crystallized
Clinical Significance of Hypercalcemia
-polyuria
- polydipsia (polyuria leads to this)
- anorexia
- constipation; Ca slows GI motility
- fatigue
- hypoactive bowel sounds (constipation)
Severe: confusion, delirium, coma
Causes of Hypocalcemia
1) Low magnesium
- low mg = low Ca
2) Excess Ca excretion
3) Inadequate Ca intake
Structural Changes of Hypocalcemia
1) Impaired teeth mineralization
- ↓ Ca = weaker teeth
2) Osteomalacia - weakened, soft bone tissue
3)Neuromuscular excitability
- less Ca means more Na into cells which makes cell hyperactive and more likely to fire AP’s
Clinical Significance of Hypocalcemia
- paraesthesia
- muscle cramps
- tetany; involuntary muscle contractions
- positive chvostek: contarction of facial muscle in response to tapping
- trousseau: carpal spasm from inflating BP cuff
Function of Phosphate
- stored in bone and some soft tissue
- P and Ca have an inverse relationship
- bone and teeth health, RBC function
