Na and K Disorder

Question 1

What devastating side effect occurs with acute hyponatremia?

Answer 1

cerebral edema

Question 2

What devastating side effect occurs with chronic hyponatremia?

Answer 2

osmotic demyelination

Question 3

ADH is not measured routinely clinically. What is a good surrogate marker for the renal actions of ADH?

Answer 3

urine osmolality

urine osmo > serum osmo indicated increased ADH

Question 4

Where is ADH synthetized?

Answer 4

hypothalamus

Question 5

What will trigger a release of ADH?

Answer 5

increased serum osmolality, hypotension

Question 6

What hormone negatively regulates ADH release?

Answer 6

adrenal cortisol

Question 7

What hormone is primarily responsible for sodium conservation?

Answer 7

aldosterone

Question 8

Where is aldosterone synthesized?

Answer 8

adrenal gland

Question 9

What will aldosterone do to sodium and potassium levels in the urine?

Answer 9

it increases Na resorption, so it leads to decreased Na and increased K in the urine

Question 10

What are some causes of high urine osmo with high urine sodium?

Answer 10

Diuretic use (make you lose Na)

Primary or secondary adrenal insufficiency

cerebral salt wasting

salt-wasting nephropathy

SIADH (diagnosis of exclusion)

Question 11

What is the treatment for SIADH?

Answer 11

IV hydrocortisone until the sodium concentration is in the reference interval and then switch to oral hydrocortisone and L-thyroxine

Question 12

To avoid osmotic demyelination, the correction of hyponatremia should be limited to what rate?

Answer 12

8 mmol/L/day

Question 13

How will primary adrenal insufficiency present?

Answer 13

Usually with pigmentation
orthostatic hypotension
hyperkalemia
hypoglycemia
hypercalcemia
hyponatremia

but not necessarily with all of them…

Question 14

How do you test for primary adrenal insufficiency?

Answer 14

can be confirmed by low random cortisol concentrations, but normal concentrations still require an ACTH stimulation test for exclusion

Question 15

Why does cortisol deficiency cause hyponatremia?

Answer 15

because it increases Cortisol Releasing Hormone, which stimulates vasopressin release which makes you retain water

Question 16

Why does aldosterone deficiency cause hyponatremia?

Answer 16

increased renal sodium loss

Question 17

How does the electrolyte exclusion effect work?

Answer 17

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

Question 18

What K level will require emergent treatment?

Answer 18

over 6.5

or at any level of hyperK with EKG changes

Question 19

What med do you give first for hyperkalemia?

Answer 19

calcium gluconate

Question 20

What do you give next to shift the K into cells?

Answer 20

Bicarb or insulin with glucose

Question 21

What do you give next to remove K from the bdy?

Answer 21

kayexalate and/or furosemide with hydrogen

or just dialyze

Question 22

What are some causes of pseudohyperkalemia?

Answer 22

1. hemolysis (release K into serum)
2. delayed separation
3. EDTA contamination (check Ca concentration)
4. Fist/pumping relaxing during the draw (causes hemolysis)
5. Thrombocytosis (bc platelets release K during clotting!)
6. Lymphocytosis (release of K due to WBC consumption of glucose)