CIS #1

Question 1

hyponatremia

Answer 1

sodium < 135

induces fluid movement into cells

Question 2

hypernatremia

Answer 2

sodium > 145

induces fluid movement out of cells

Question 3

main cause of hyponatremia?

Answer 3

inability to excrete water

inability to suppress ADH

exception polydipsia
-drink a ton of water

Question 4

pseudohyponatremia

Answer 4

not caused by change in water balance

other substances in plasma that make measurement of sodium inaccurate

hyper: protein, lipid, cholesterol
or unmeasured osmol

sodium concentration not changed**
-just inaccurate

Question 5

true hyponatremia

Answer 5

dilute urine, low ADH:
reset osmostat (pregnancy)
psychogenic polydipsia

concentrated urine, high ADH:
decreased effective circulating volume
SIADH

Question 6

hyponatremia leads to ?

Answer 6

cell swelling

Question 7

hyponatremia in DM patient?

Answer 7

glucose pulls water to vascular space and dilutes plasma sodium concentration

Question 8

anion gap

Answer 8

Na - Cl + HCO3

Question 9

plasma osmolality

Answer 9

2xNa + glucose/18 + BUN/2.8

used in osmolar gap

Question 10

osmolar gap

Answer 10

difference between calculated and lab osmolality

large difference in two may suggest another substance pressure that exerts osmotic effect**

Question 11

reset osmostat

Answer 11

pregnancy
-volume expanded

-reset to new lower level

Question 12

polydipsia

Answer 12

hyponatremia

lots of dilute urine

Question 13

U-osm:P-osm

Answer 13

ratio of how concentrated urine is

Question 14

SIADH

Answer 14

lung cancer

TB

Question 15

lithium treatment

Answer 15

damages kidney and can’t concentrate urine

can lead to hypernatremia

may lead to nephrogenic diabetes insipidus

Question 16

nephrogenic DI

Answer 16

high ADH but can’t respond

also high osmolality

Question 17

neurogenic DI

Answer 17

low ADH levels

also high osmolality

Question 18

desmopresin

Answer 18

exogenous ADH
can give via inhalation
-should work unless nephrogenic DI

Question 19

extrarenal water loss?

Answer 19

sweating, fever, diarrhea, vomiting
-urine output low, circulating AVP high

hypernatremia

Question 20

renal water loss

Answer 20

central or nephrogenic DI

hypernatremia

Question 21

lithium mechanism?

Answer 21

inhibits V2 receptors
-no aquaporins in collecting duct

nephrogenic DI

Question 22

hypercalcemia and hyperkalemia

Answer 22

also associated with nephrogenic DI

Question 23

common causes of central DI?

Answer 23

head trauma
postpartum hypophysitis (can give steroids)
hypothalamus/pituitary tumor

Question 24

other causes of SIADH?

Answer 24

TB
CHF
CNS issues
intubation
drugs

Question 25

CHF?

Answer 25

initial hypovolemia

• activate RAAS and increased ADH
• ANP also high (senses high pressure)
• net effect: decreases excretion of Na and water
• RAAS and ADH overcome ANP

Question 26

two more cases

Answer 26

look at them