Acute hyponatraemia Flashcards
What is hyponatraemia?
Na < 125mmol/L plasma
What are signs and symptoms of hyponatraemia?
Anorexia, nausea, malaise
Headache, irritability, confusion, weakness, reduced GCS and seizures depending on severity.
Why do you get seizures in hyponatremia?
Neurological symptoms typically occur with very low levels of plasma sodium (usually <115 mmol/L).[10] When sodium levels in the blood become very low, water enters the brain cells and causes them to swell. This results in increased pressure in the skull and causes hyponatremic encephalopathy. As pressure increases in the skull, herniation of the brain can occur, which is a squeezing of the brain across the internal structures of the skull.
What are causes of hyponatraemia?
Hypovolaemic Diarrhoea, vomiting, sweating, diuretics Addison's disease Pancreatitis Prolonged exercise and sweating combined with drinking water without electrolytes MDMA use
Normovolaemic
SIADH
Hypothyroidism
Hypervolaemic Liver cirrhosis Congestive heart failure Nephrotic sydnrome Excessive drinking of fluids
Why might a marathon runner get acute hyponatramemia?
This disorder can develop when marathon runners or endurance event athletes drink more fluid, usually water or sports drinks, than their kidneys can excrete. This excess water can severely dilute the level of sodium in the blood needed for organs, especially the brain, to function properly.
What is immediate management for emergency acute hyponatraemia?
Fluid restriction
Hypertonic saline 1.8% saline IV infusion
100ml of 3% saline hourly
High flow O2
FurosemideAim for gradual increase in plasma sodium to 125mmol/L
What is management for mild and acute/symptomatic hyponatraemia without seziures/coma?
Mild/asymptomatic - adequate solute intake - sal t and protein and fluid restriction
Moderate/symptomaticx : raise serum sodium by 0.5 to 1 mol/L/h for 8mool/L during first day with furosemide replacing sodium nd potassium losses with 0.9% saline IV infusion.
What are potential complications of rapid correction or hyponatraemia?
Central pontine myelinolysis - severe damage of the myelin sheath of nerve cells in the pons - acute paralysis, dysphagia and dysarthria.
Heart failure
Avoid correction that leads to serum sodium rise of 12mEq/L/day
What is SIADH? How is it diagnosed?
Concentrated urine (Na>20mmol/L) and osmolality >100mosmol/kg) with hyponatremia (plasma Na < 125mmol/L) and low plasma osmolality (<260msoml/kg) in the absence of hypovolaemia, oedema or diuretics.
What are causes of SIADH?
Malignancy: lung small cell, pancreas, prostate, thymus, lymphoma CNS disorders Chest disease: TB, pneumonia, abscess Endocirin Drugs: opiates, psuycotropics, SSRIs
What is treatment for SIADH?
Treat cause and restrict fluid
Consider salt ± loop diuretic if severe
ADH antagonist use is rare (demeclocycline)
Vasopressor receptor antagonists
