Unit 2: Diabetes Insipidus vs SIADH

Question 1

Does increased ADH cause fluid retention or loss?

Answer 1

H2O retention!
So Decreased ADH = fluid loss

Question 2

Diabetes insipidus (DI) = increased or decreased ADH?

Answer 2

DECREASED ADH
(DI = Decreased)

Question 3

If DI results in water loss, what’s happening to our Na+?

Answer 3

Hypernatremia!
circulatory system is more concentrated (hemoconcentration = high serum osmo)

Question 4

DI can be neurogenic or nephrogenic, but can also be caused by what drug?

Answer 4

Lithium!
(and demeclocycline–tetracycline Abx)

Question 5

So DI causes water loss, but how much exactly?

Answer 5

4-30 L!!
RISK for HYPOVOLEMIC SHOCK

Question 6

What type of IV fluid would we want for DI?

Answer 6

1/2 NS
(already have hypernatremia, so don’t want to make it worse)

Question 7

Drug therapy for DI

Answer 7

Desmopressin (DDAVP) aka ADH/vasopressin

Question 8

SIADH = increased or decreased ADH?

Answer 8

INCREASED
“Syndrome of Increased ADH”

Question 9

So if SIADH causes water retention, what’s happening to out Na+?

Answer 9

HYPOnatremia!
(RAAS inhibited = Hemodilution = decreased serum osmo)

Question 10

So if we’re not peepin’ with SIADH, what are we at risk for? (2)

Answer 10

FVO!
Neurologic issues (seizures) = hyponatremia

Question 11

What happens to body temp r/t SIADH?

Answer 11

HYPOthermia!
(more water = more energy needed to stay warm)

Question 12

What type of IV fluid would we want for SIADH?

Answer 12

0.9% NS to replace Na+

Question 13

When would we use 3% NaCl for SIADH

Answer 13

VERY LOW Na+
(risk for HF/exacerbation though)

Question 14

What do we want to do about fluid intake r/t SIADH?

Answer 14

RESTRICT FLUID INTAKE!
500-1000 L/day

Question 15

Drug therapy for SIADH

Answer 15

Vasopressin Antagonist (“Vaptans”)

Question 16

ADRs of Vasopressin Antagonist (“Vaptans”)

Answer 16

1. Rapid Na+ increase → cerebral edema, electrolyte imbalances (K+)
2. Liver failure
3. DEATH!

Question 17

What extra precautions should we take with SIADH r/t hyponatremia?

Answer 17

Seizure precautions!
-frequent neuro assessments, reduce stimuli, dim lights, fall precautions