Assorted electrolytes Flashcards
Sodium
- Mainly in ECF
- Excreted via kidneys
- Changes in concentration affect BP and intracellular fluid composition and volume
- <1% normally excreted
- Increase in blood osmolality = increase in ADH = water reabsorption and decreased urinary output
- High sodium = hypertonic hyponatraemia
- Low sodium = hypotonic hyponatraemia (caused by hypovolaemia which is when there is less water AND sodium or euvolaemia where there is more water but no change in sodium)
Hyponatraemia causes
Diuretics, diarrhoea, heart failure, liver disease, renal disease, bad ADH secretion
Hyponatraemia symptoms
Headache, lethargy, dizziness, confusion
Hypernatraemia symptoms
Fever, thirst, dry mucous membranes, restlessness
Causes of hypernatraemia
Dehydration and diuretics
Potassium
- Produced high K+ intracellularly
- Negative intracellular potential = RMP
- Kidneys maintains K+ balance
- 90% reabsorbed
- K+ exchanged for H+ in intercalated cell, stimulated by acidosis and low potassium conc
- Secretion of potassium and reabsorption of sodium in principal cells stimulated by aldosterone, increased [K+], alkalosis and increased tubular flow
- Located intracellularly
Hypokalaemia causes
Alkalosis, insulin, diarrhoea, renal loss, hyperaldosteronism
Symptoms of hypokalaemia
Skeletal muscle weakness, loss in smooth muscle tone, bradycardia
Treatment of hypokalaemia
IV K+
Causes of hyperkalaemia
Tissue damage, acidosis, aldosterone impairment (spironolactone, Addison’s)
Symptoms of hyperkalaemia
Neuromuscular irritability, restlessness, intestinal cramping, loss of muscle tone, paralysis
Causes ECG changes - sine wave and Kussmaul breathing (hyperventilation), T waves taller, P waves disappear
Treatment of hyperkalaemia
Diet and medication adjustment but if severe, administer insulin an glucose
What does calcitonin do?
Increases osteoblast activity
Causes of hypocalcaemia
Nutritional deficiency, vit D deficiency, hypoparathyroidism, kidney failure, hyperventilation
Symptoms of hypocalcaemia
Confusion, muscle spasm, paraesthesia, drowsiness, coma
Prolonged QT interval
Treatment of hypocalcaemua
Oral calcium and vit D needed, IV in severe cases
Causes of hypercalcaemia
Hyperparathyroidism, excess vit D, malignancy
Symptoms of hypercalacemia
Stones, bones, moans, groans
Short QT syndrome, depressed T waves, hypertension, kidney stones
Treatment of hypercalcaemia
Reduce calcium in diet or PTH
Causes of hypophosphataemia
Reduced intestinal absorption, primary hyperparathyroidism, osteomalacia, rickets
Symptoms of hypophosphataemia
Muscle weakness, confusion, hallucinations, convulsions
Left shift of oxy-haem dissociation curve, arrythmias, heart failure
Treatment of hypophosphataemia
Oral or IV phosphate
Causes of hyperphosphataemia
CKD
Symptoms of hyperphosphataemia
Associated with calcium depletion due to calcium phosphate formation (precipitates in lungs, kidneys, joints)
Treatment for hyperphosphataemia
Reduce dietary phosphate or start dialysis
Causes of hypomagnesaemia
Malnutrition, defective gut absorption, urinary loss, alcoholism, diuretics
Symptoms of hypomagnesaemia
Irritability, tremor, ataxia, hyperreflexia, confusion, hallucinations, convulsions
Causes QRS widening, PR interval prolongation, flat T waves
Causes of hypermagnesaemia
Kidney disease, magnesium containing laxatives or antacids
Symptoms of hypermagnesaemia
Depressed muscle contraction and nerve function, narcosis, respiratory paralysis, cardiac conduction defects
ECG changes = long QT, bradycardia and heart blocks
How is a decrease in BP corrected?
Heart decreases release of ANP
Kidney increases renin and angiotensin secretion to produce aldosterone
Pituitary increases ADH secretion
Isotonic hyponatraemia
Normal conc
Hypertonic hyponatraemia
High conc
