L10- consequences of electrolyte imbalance Flashcards
Substances or ions that give off an electric charge (negative or positive)
electrolytes
What would someone with electrolyte imbalance present with?
- Muscle spasms, weakness, twitching or convulsing.
- Irregular heartbeat, confusion, blood pressure changes, nervous disorders
- Respiratory imbalances
Significance of Na+ ion
– Integral to action potentials and therefore neuron
function.
– Exerts significant osmotic pressure in extracellular
fluid (ECF).
– Water follows salt – a change in plasma Na+ affects plasma volume, blood pressure,
intracellular fluid volume (ICF) and interstitial fluid
(IF) volumes.
What does hyperaldosteronism imply?
hypernatremia and
hypokalemia
Cause of Addison’s disease
Reduced aldosterone production by adrenal glands.
Low aldosterone implies implies hyponatremia and hyperkalemia
What are the 3 causes of hyponatraemia with respect to volume status?
- HYPOVOLAMIC
Both water and sodium are reduced
CAUSES: Renal losses or
excessive diuretic use
GI losses: vomiting,
diarrhea Burns
Addison’s disease - EUVOLEMIC
Water is high, but sodium is normal
CAUSES: Water intoxication
SIADH- Syndrome of Inappropriate ADH secretion - HYPERVOLEMIC:
Both water and Sodium are increased
CAUSES: Heart failure,
Liver failure, Kidney injury/failure
What are the consequences of hyponatraemia?
Na<135
- Headache
- Lethargy
- Dizziness
- Nausea & vomitting
- Abdominal cramps
- Muscle weakness
Na<120 (severe hyponatraemia)
- cerebral oedema,
- irreversible
neurological damage,
- coma,
- seizures,
- respiratory arrest,
- brainstem herniation,
- death
What causes hypernatraemia? (Na>147)
Caused by net water loss. No water to dilute sodium salt
What are the consequences of hypernatremia?
- MILD (145-150mmol/l)
Thirst
Decreased urine output
Headache
Increased body temperature - Moderate (151-154mmol/l)
decreased reflexes,
agitation, headache
3, SEVERE >155
Coma
Seizures
Why do potassium content decline with age?
Coz ~ 65 - 75% of potassium is in the muscle. And it is mainly due to a decrease in muscle
mass
What are the 3 causes of hypernatraemia with respect to volume status?
- HYPOVOLEMIC
Both water and sodium are high
CAUSES:
Excessive sweating
Burns
Diarrhea
Renal losses
2 EUVOLEMIC
Water decreased, sodium normal
CAUSES: Diabetes insipidus
Respiratory losses
- HYPERVOLEMIC:
Total body water ↑
Total body Na+ ↑ ↑
CAUSES:
Sodium gains
Primary
hyperaldosteronism
Cushing’s syndrome
Hypertonic dialysis
Hypertonic NaHCO3
NaCl tablets
Causes of hypernatremia
What are the roles of potassium?
- Regulates excitability of the nerve and muscle cells, as well as
- contractility of
cardiac, skeletal and smooth muscle tissue
What is the effect of reduced potassium in resting membrane potential?
makes the resting potential more negative
*Stimulus needed to reach thresh hold needs to be greater than normal
How the body educes excess potassium ions?
- excretion (urine, GIT, skin-sweat)
- Potassium shifts into cells from cell exterior
Name the 3 causes of potassium shift into cells
- alkalosis
- hypothermia
- Drugs (insulin, verapamil)
What is the effect of hypokalaemia on cardiac muscle?
cardiac irritability
What are the effects of having low potassium levels?
- weakness
-palpitations - changes on ECG
*Low potassium cn be asymptomatic
What are the effects of having high potassium?
cardiac arrest
What is the importance of ionized calcium?
Ionized calcium is present in ~50% ECF
- important in membrane potential
- neuronal excitability
- cardiac contractility
Why would too much calcium cause constipation?
Coz it decreases smooth muscle activity of the GIT
What is the role of calcium in neuromuscular excitability?
Is to stabilize the neuromuscular activity. But if there is less of calcium available for this action, there’s increased excitability since more sodium channels are available’
If there is too much calcium, sodium channels are blocked and there is no excitation of neurons or muscles. Hence reduced activity of stomach smooth muscle»constipation.
