Ch. 558 - DI

Question 1

Principal regulator of plasma tonicity

Answer 1

Vasopressin

Question 2

Release of vasopressin is largely stimulated by

Answer 2

Increases in plasma tonicity

Question 3

Volume homeostasis is largely regulated by

Answer 3

RAAS

Question 4

T/F Vasopressin has both antidiuretic and pressor activity

Answer 4

T

Question 5

Vasopressin is synthesized in

Answer 5

Paraventricular and supraoptic nuclei of the hypothalamus

Question 6

T/F Osmotic threshold for thirst is higher than osmotic threshold for vasopressin release

Answer 6

T

Question 7

Osmotic threshold for thirst is higher than osmotic threshold for vasopressin release, meaning

Answer 7

Vasopressin is released before thirst is initated

Question 8

Vasopressin exerts its principal effect on the kidney via what receptors

Answer 8

V2 > increase in CAMP > insertion of aquaporin 2 into the apical/luminal membrane > water movement along its gradient > urine concentration

Question 9

Diagnosis of DI is established if serum osm is ___ and urine osm is ___

Answer 9

> 300 mOsm/kg, <300 mOsm/kg

Question 10

Test that establishes diagnosis of DI when patient has polyuria and polydipsia but serum osm <300

Answer 10

Water deprivation test

Question 11

Test that differentiates central from nephrogenic DI

Answer 11

Water deprivation test

Question 12

DI, DM, optic atrophy, deafness resulting from vasopressin DEFICIENCY

Answer 12

Wolfram syndrome

Question 13

Triphasic response following CNS surgery

Answer 13

1) Transient DI 12-48h 2) SIADH 10 days 3) DI may be permanent

Question 14

MC primary brain lesions associated with DI

Answer 14

Germinomas and pinealomas

Question 15

Common infiltrative disorders causing central DI

Answer 15

1) LCH 2) Lymphocytic hypophysitis

Question 16

Causes 50% of idiopathic central DI

Answer 16

Hypohysitis

Question 17

T/F With intact thirst mechanism and free access to oral fluids, a person with complete DI can maintain plasma osm and Na in the high normal range

Answer 17

T

Question 18

TReatment of central DI in older children is BEST accomplished with

Answer 18

DDAVP

Question 19

Central DI of acute onset following neurosurgery is best managed with

Answer 19

1) Synthetic aquesous vasopressin (pitressin) 2) Limit TFI to 1L/BSA/day during antidiuresis

Question 20

T/F Nephrogenic DI may be genetic or acquired

Answer 20

T

Question 21

Acquired NDI can result from

Answer 21

Hypercalcemia or hypokalemia, drugs (lithium, demeclocycline, foscarnet, clozapine, amphotericin, methicillin, rifampin)

Question 22

Treatment of acquired DI

Answer 22

Elimination of the underlying disorder

Question 23

Pharmacologic treatment of NDI

Answer 23

Thiazide diuretics (to DECREASE OVERALL UO by inducing a state of mild volume depletion; Na excretion at the expense of water > decrease in GFR > proximal Na and water reabsorption)

Question 24

Initial approach to patient with hyponat

Answer 24

Determination of volume status

Question 25

Syndromic causes of hyponat

Answer 25

SIADH, CSW

Question 26

Hyponat, inappropriately concentrated urine, normal-to-high urine sodium, low serum uric acid

Answer 26

SIADH

Question 27

Initial manifestation of systemic dehydration

Answer 27

Hypernatremia and hyperosmolality

Question 28

In patients with normal renal function, kidney can excrete dilute urine with an osm as low as

Answer 28

50 mOsm/kg

Question 29

Maximum amount of water a person with normal renal function can consume

Answer 29

10L/BSA

Question 30

Maximum amount of water intake to avoid water intoxication for neonates

Answer 30

4L/BSA/day

Question 31

Results from hypersecretion of ANP and seen primarily with CNS disorders

Answer 31

CSW

Question 32

Hyponatremia, elevated urinary Na excretion , excessive UO, hypovolemia, normal or high uric acid, suppresed vasopressin, elevated ANP

Answer 32

CSW

Question 33

Urinary excretion to consider CSW

Answer 33

>150meq/L

Question 34

T/F Pseudohypernatremia can result from hypertriglyceridemia and hyperglycemia

Answer 34

F, pseudoHYPOnatremia

Question 35

Serum Na decreases by ___ for every 100mg/dL increase in blood glucose >100mg/dL

Answer 35

1.6meq/L

Question 36

Acute hyponat is defined as

Answer 36

Onset <12 hrs or a serum Na concentration <120meq/L

Question 37

Emergency treatment for cerebral dysfunction resulting from acute hyponat

Answer 37

1) Water restriction 2) HTS

Question 38

Serum Na should be raised no faster than

Answer 38

0.5meq/L/hr or 12meq/L/24hr

Question 39

Chronic SIADH is best treated by

Answer 39

Oral fluid restriction

Question 40

Treatment of patients with CSW

Answer 40

Restoring intravascular volume with NaCl and water