Hyponatraemia Flashcards
When initial investigations should be done when hyponatraemia is found?
- Repeat U&E
- Blood glucose
- Urine and simultaneous serum osmolality
What are the main differential diagnoses of hyponatraemia?
- Hypotonic plasma
- Syndrome of inappropriate ADH secretion
Does hyponatraemia caused by hypotonic plasma occur with hypovolaemia or hypervolaemia?
Can be either, or normovolaemia
What might cause hypotonic plasma with hypovolaemia?
Excess renal or non-renal loss, e.g.
- Excessive diuretic therapy
- Renal tubular disease
- Diarrhoea
- Vomiting
- Fistula
- Burns
- Small bowel obstruction
- Blood loss
What suggests that hypotonic plasma with hypovolaemia is the cause of hyponatraemia?
- Decreased serum sodium
- Decreased osmolality
- Loss of skin tugor
- Tachycardia
- Decreased BP
- History of possible cause
How is it confirmed that hyponatraemia is caused by hypotonic plasma with hypovolaemia?
Response to removal or treating of cause
How is hyponatraemia caused by hypotonic plasma with hypovolaemia treated?
- Treat the cause
- If symptomatic, saline.
- In chronic conditions, fluid restriction.
What might cause hypotonic plasma with normovolaemia?
Severe hypothyroidism or glucocorticoid deficiency
What suggests that hypotonic plasma with normovolaemia is the cause of hyponatraemia?
- Decreased serum sodium
- Decreased osmolality
- Normal skin turgor
- Normal pulse and BP
How is it confirmed that hypotonic plasma with normovolaemia is the cause of hyponatraemia?
Response to treating cause and balancing fluid intake
How is hyponatraemia caused by hypotonic plasma with normovolaemia managed?
Treating the cause
What might cause hypotonic plasma with hypervolaemia?
- Fluid overload
- Cardiac failure
- Cirrhosis
- Renal failure
- Nephrotic syndrome
- Inappropriate ADH secretion
What suggests that hypotonic plasma with hypervolaemia is the cause of hyponatraemia?
- Decreased serum sodium
- Decreased osmolality
- Oedema
- Basal lung crackles
How is it confirmed that hypotonic plasma with hypervolaemia is the cause of hyponatraemia?
Response to treating cause and reducing fluid intake
How is hyponatraemia caused by hypotonic plasma with hypervolaemia managed?
Treat underlying cause
