11. Sodium Disorders Flashcards
What are the different ways your sodium content can be reduced?
Not having enough sodium
Having too much fluid
What is osmolality
Overall number of solute particles in the serum
How do you measure osmality? (mmol/kg)
2x serum (sodium) + (urea) + glucose (mmol/L)
What is it called when you have low sodium?
Hyponatreamia
What causes high osmalility and hyponatramia
hyperglycaemia, alcohol, mannitol
What causes a normal osmolality and hyponatreamia
pseudohyponatreamia (lipaemia/ hyperproteinemia)
What causes a low osmaliltiy and hyponatraemia?
Salt loss, water overload
What is the best way to assess whole body sodium?
Lying/standing blood pressure- bigger postural hypotension
If someone has low soidum and high ECF volume what is the cause of the hyponatreamia
congested cardiac failure
liver failure
nephrotic syndrome
If someone has low sodium and low ECF volume what is the cause of the hyponatreamia
Either caused by gut or kidneys.
urine sample, if urine sodium is low- gut problem
gut- diarrheoa and vomiting
kidneys- diuretics, adrenal insuffeciency, cerebral salt wasting syndrome (head injury), salt wasting nephropathy.
If someone has low sodium and low ECF volume what is the cause of the hyponatreamia
urine concentration high- syndrome of inappropriate antidiuretic hormone- inappropriate release of ADH due to illness
urine concentration low- drank too much water (usually caused by kidney problems)
What are the criteria for diagnosing SIADH
Hyponatraemia with hypo-osmolality (275 mmol/Kg)
Inappropriate urinary concentration (urine osmolality)
How do you treat SIADH
Fluid restrict 1L per day
treat the underlying disease
If extremely series (lehtargic,confised, seizures) use hypertonic saline with furesimide to prevent circulatory overload (get specialist)
DO NOT INCREASE BY MORE THAN 1 mmol per hour
How do you test adrenal function?
Short synacthen test-measurement of serum cortisol before and after an injection of synthetic ACTH
What is the most common cause of adrenal insufficiency?
auto-antibodies
