CIS disorders of salt and water balance

Question 1

what is hyponatremia and where does water move

Answer 1

sodium is too low so water moves into cells

Question 2

what is hypernatremia and where does water move

Answer 2

sodiu is too high and fluid moves out of the cell

Question 3

What is the normal response to hyponatremia

Answer 3

inhibit release of ADH so excrete dilute urine

Question 4

What is an example of a condition where ADH release is appropriate but patient still develops hyponatremia

Answer 4

psychogenic polydipsia

Question 5

What are the two types of True hyponatremia

Answer 5

dilute urine with low ADH

concentrated urine with high ADH

Question 6

what are examples where patients have a low ADH and dilute urine yet still hyponatremic

Answer 6

psychogenic polydipsia

reset osmostat like during pregnancy

Question 7

What are examples of true hyponatremia that result in high levels of ADH

Answer 7

a decrease in effective circulating volume
SIADH
cortisol deficiency
hypothyroidism

Question 8

What can cause a decrease in effective circulating volume

Answer 8

CHF and cirrhosis

Question 9

What can result in a rapid onset of hyponatremia

Answer 9

cell swelling and neurological problems

Question 10

what is a normal osmolar gap

Answer 10

<10 mOsm/kg H2O

Question 11

how can you tell is someone is true hyponatremia

Answer 11

both plasma Na [ ] and osmolality are below normal

Question 12

what is the normal response to hyponatremia

Answer 12

dilute urine in high volumes

circulating AVP or ADH is low

Question 13

Pregnant women usually have what in regards to hyponatremia

Answer 13

reset osmostat, less osmolility triggers AVP

Question 14

A patient with low Posm and high ADH what do you suspect

Answer 14

SIADH

Uosm/Posm>1

Question 15

A patient with low Posm and low ADH what do you suspect

Answer 15

primary polydipsia with Uosm/Posm<1

Question 16

A patient with high Posm and high ADH what do you suspect

Answer 16

dehydration or nephrogenic DI

Question 17

how can you distinguis a patient from dehydration of nephrogenic DI

Answer 17

Uosm/Posm>1 in dehydration

Usom/Posm<1 in nephrogenic DI

Question 18

if a patient has high Posm and low ADH what do you suspect

Answer 18

neuro(central) DI

Question 19

If you deprive a normal patient of water what is the expected result

Answer 19

increase urine osmolarity

Question 20

In a patient with either type of DI, what would be the result of the water deprivation test

Answer 20

no change

Question 21

in a patient with nephrogenic DI what would be the measured response of ADH in water deprivation? what about after administration of desmopressin?

Answer 21

ADH elevated

no effect from desmopressin

Question 22

how can you differentiate between the types of DI

Answer 22

give ADH and if no change then nephrogenic

if gets better than central

Question 23

what are the two main causes of hypernatremia

Answer 23

extrarenal water loss and renal water loss

Question 24

how do the collecting ducts change in someone who is hydrated then dehydrated

Answer 24

increase permeability to water–> water reabsorption

Question 25

what allows for water reabsorption to take place in dehydrated individuals

Answer 25

ADH increases permeability via V2 R and insertion of AQP channels

Question 26

antidiuresis is considered high ADH or low

Answer 26

high

Question 27

water diuresis is high ADH or low

Answer 27

low

Question 28

how is the concentration of the medullary interstitium different in water diuresis

Answer 28

lower [ ] in medullary interstitium so doesn't pull water out of the tubule

Question 29

What effect can the drug lithium have on the renal system

Answer 29

limits ability of V2 R to generate cAMP resulting in diminished biologic activity of ADH leading to Nephrogenic DI

Question 30

What are common causes for nephrogenic DI

Answer 30

Lithium drug hypercalcemia hyperkalemia (acidosis)

Question 31

What can postpartum hypophysitis cause

Answer 31

Ab against ADH secreting neurons thus central DI

Question 32

common causes for central DI

Answer 32

head trauma postpoartum hypophysitis hypothalamic or pituitary tumor

Question 33

causes of SIADH

Answer 33

``` pulmonary tuberculosis oat cell carcinoma CHF CNS issues intubation with mechanical ventilation ```

Question 34

how do you treat SIADH

Answer 34

water retention | ADH antagonists like conivaptin and demclocycline

Question 35

What is the result of CHF on ANG II aldosterone, ADH and ANP

Answer 35

everything increases because low circulating volume but in the heart stretch R activate ANP

Question 36

In someone with CHF with edema and fluid overload what most likely causes hyponatremia

Answer 36

decreased free water clearance. dilution of solutes

Question 37

What causes a patient with CHF to have edema

Answer 37

increased ECF volume and imbalance of the starlings forces favoring filtration

Question 38

When BUN/Cr is above 20 what does this say

Answer 38

pre renal and BUN reabsorption is increased | hypovolemia- reduced renal perfusion

Question 39

when BUN/Cr is below 10 what does this say

Answer 39

intra renal, reduced reabsorption of BUN

Question 40

What are physical signs of hypovolemia

Answer 40

orthostatic hypotension orthostatic tachycardia loss of skin turgor dry mucous membranes