Na and K Disorder Flashcards
What devastating side effect occurs with acute hyponatremia?
cerebral edema
What devastating side effect occurs with chronic hyponatremia?
osmotic demyelination
ADH is not measured routinely clinically. What is a good surrogate marker for the renal actions of ADH?
urine osmolality
urine osmo > serum osmo indicated increased ADH
Where is ADH synthetized?
hypothalamus
What will trigger a release of ADH?
increased serum osmolality, hypotension
What hormone negatively regulates ADH release?
adrenal cortisol
What hormone is primarily responsible for sodium conservation?
aldosterone
Where is aldosterone synthesized?
adrenal gland
What will aldosterone do to sodium and potassium levels in the urine?
it increases Na resorption, so it leads to decreased Na and increased K in the urine
What are some causes of high urine osmo with high urine sodium?
Diuretic use (make you lose Na)
Primary or secondary adrenal insufficiency
cerebral salt wasting
salt-wasting nephropathy
SIADH (diagnosis of exclusion)
What is the treatment for SIADH?
IV hydrocortisone until the sodium concentration is in the reference interval and then switch to oral hydrocortisone and L-thyroxine
To avoid osmotic demyelination, the correction of hyponatremia should be limited to what rate?
8 mmol/L/day
How will primary adrenal insufficiency present?
Usually with pigmentation orthostatic hypotension hyperkalemia hypoglycemia hypercalcemia hyponatremia
but not necessarily with all of them…
How do you test for primary adrenal insufficiency?
can be confirmed by low random cortisol concentrations, but normal concentrations still require an ACTH stimulation test for exclusion
Why does cortisol deficiency cause hyponatremia?
because it increases Cortisol Releasing Hormone, which stimulates vasopressin release which makes you retain water
Why does aldosterone deficiency cause hyponatremia?
increased renal sodium loss
How does the electrolyte exclusion effect work?
If you have some other solute causing dilution of specimens, the measurement can give lower values for electrolytes if you are using indirect ISE because they are based on total sample volume, not just the water volume (so really high cholesterol can affect this)
direct ISE will not be effected because there is no dilution of specimens
What K level will require emergent treatment?
over 6.5
or at any level of hyperK with EKG changes
What med do you give first for hyperkalemia?
calcium gluconate
What do you give next to shift the K into cells?
Bicarb or insulin with glucose
What do you give next to remove K from the bdy?
kayexalate and/or furosemide with hydrogen
or just dialyze
What are some causes of pseudohyperkalemia?
- hemolysis (release K into serum)
- delayed separation
- EDTA contamination (check Ca concentration)
- Fist/pumping relaxing during the draw (causes hemolysis)
- Thrombocytosis (bc platelets release K during clotting!)
- Lymphocytosis (release of K due to WBC consumption of glucose)
