Nephro TBL

Question 1

what is the main determinant of plasma osmolality?

Answer 1

sodium

Question 2

what happens to cell size of there is low extracellular osmolality?

Answer 2

the cells will swell

Question 3

what happens to cells in the brain with hyponatrmia?

Answer 3

brain swelling / edema

Question 4

does there need to be brain edema for hyponatremia to affect neurological impairment?

Answer 4

no

Question 5

plasma osmolality refers to what quantity?

Answer 5

sodium

Question 6

what determines the direction and magnitude of water movement?

Answer 6

tonicity of the plasma

Question 7

when there are low sodium contents in the vasculature, what happens to the water in the blood?

Answer 7

it moves out, into the cells surrounding capillaries

Question 8

what does hypertonicity refer to?

Answer 8

high levels of sodium in the BLOOD causing cells to shrink as they give their water off into the vascularture

Question 9

what is the regulatory volume decrease mechanism?

Answer 9

the restoration of initial volume AFTER swelling due to hypotonicity

Question 10

what is involved in the RVD?

Answer 10

extrusion of intracellular osmotically active solutes in order to pump them back into the blood for liquid to follow

Question 11

where is the regulatory volume decrease mechanism found most?

Answer 11

in astrocytes of neurons

Question 12

what is the level of volume recovery accomplished by RVD within 15 minutes of swelling in the brain?

Answer 12

60-80%

Question 13

what are the aspects of variability of the RVD mechanism?

Answer 13

not all neuronal cells are alike
studies show variability
regional variability

Question 14

what are the two osmolites?

Answer 14

electrolytes and organics

Question 15

what are the mc electrolyes?

Answer 15

sodium, potassium, and chloride

Question 16

what are the most common organic osmolyets?

Answer 16

myoinosito, betaine, glutamine, taurine, and y-aminobutyric acid

Question 17

what is an osmosensor

Answer 17

a sensory element
that can detect changes in plasma osmolality

Question 18

what is the transient receptor potential vanilloid 4

Answer 18

tonicity sensor that uses calcium influx

Question 19

how do astrocytes and retinal glial cells sense calcium influx?

Answer 19

TRPV4 forms a molecular complex with AQP 4

Question 20

how does G-coupled protein receptor with protein kinase C affect eflux of electrolytes?

Answer 20

inhibition of protein kinase C can significantly reduce the eflux of potassium and taurine in
hypo-osmotically challenged glial cells
showing its role in RVD

Question 21

what are volume sensitive channels?

Answer 21

channels for RVD for electrolytes

Question 22

what are the two organic osmolyte channels talked about?

Answer 22

y-aminobutyric acid betaine transporter and the sodium myoinositol transporter

Question 23

what direction are the identified organic osmolyte channels?

Answer 23

bidirectional

Question 24

in a hyponatremic event where does hydrostatic water
movement go first in the brain?
why does this happen in adults and not babies?

Answer 24

to the CSF
because our skull is hard and would otherwise swell beyond its capacity

Question 25

in the first 6 hours of hyponatremia, what is the amount of brain swelling?

Answer 25

0.6% (40% of the predicted value)

Question 26

how long is the brain able to use the movements of intracellular electrolytes into extracellular places to compensate for hyponatremis?

Answer 26

3 hours

Question 27

what electrolytes leave the CSF and which leave the cells themselves in hyponatremia?

Answer 27

na from CSF Cl from cells both faster than intracellular potassium

Question 28

what is the max % of electrolyte loss from the brain?

Answer 28

18%

Question 29

how are intracellular fluid (ICF) and interstitial fluid (ISF) affected by hyponatremia

Answer 29

both increased in the brain

Question 30

what procedure was first noted to have death from hyponatremia complication?

Answer 30

cholecystectomy

Question 31

chronic hyponatremia can get to what level without edema why is this significant

Answer 31

100 shows us there are chronic systems

Question 32

what is the trend between loss of electrolytes in chronic hyponatremia and the amount of brain water change

Answer 32

The loss of electrolytes during chronic severe hyponatremia does not account for the magnitude of the brain water changes

Question 33

why does the brain not behave as a perfect osmometer during chronic hypo- natremia

Answer 33

organic osmolytes play a significant role in brain volume regulation

Question 34

what are the percents of affect that electrolytes vs organic osmolytes have on regulation of chronic hyponatremia?

Answer 34

70-na 30- organic

Question 35

what causes neurological abnormalities observed in patients with chronic “asymptomatic” hyponatremia

Answer 35

the loss of organic osmolytes that are otherwise used for neurotransmission and protein- folding pathways

Question 36

what takes longer to return to normal, electrolytes or organic osmolytes?

Answer 36

organic osmolytes can take more than 5 days (could play a role is osmotic demylynation)

Question 37

Hyponatremic encephalopathy (HNE) refers to what?

Answer 37

the neurological dysfunction

Question 38

if the rate of SNa decrease is <0.5 mEq/l per hour over 24 hours, then the clinical course is likely to be ____________, whereas neurological sequalae and death are more common if the rate of sodium drop is >____ mEq/l per hour

Answer 38

uncomplicated ; 1

Question 39

why is HNE is more severe in preadolescents

Answer 39

brain reaches it maximal size by 6 years of age, which is approxi- mately 10 years earlier than the skull

Question 40

what is the main concern of HNE

Answer 40

swelling that causes hypoxia through neurogenic pulmonary edema

Question 41

what symptoms are prodromal to death due to hyponatremia?

Answer 41

seizures and coma

Question 42

what neuro symptoms are seen in marathon runners due to na?

Answer 42

marathon runners with moderate hyponatremia were reported to experience nausea and vomiting, and sometimes acute confusion, which were treated effectively by correction of SNa

Question 43

who has a high risk of falls?

Answer 43

older chronic hyponatremia patients

Question 44

what is the most used organic osmolyte in hyponatremia?

Answer 44

glutamate

Question 45

what is the mainstay of treatment of HNE is the reduction of intracranial pressure

Answer 45

by decreasing brain water con- tent by rapid infusion of hypertonic saline 100 to 300 ml of 3% sodium chloride are effective until symptoms of brain edema regress

Question 46

what does urea do for HNE?

Answer 46

urea can decrease intracranial pressure by up to 8 mm Hg

Question 47

how should salt depleted patients be treated?

Answer 47

normal saliline infusion or oral salt tablets

Question 48

Patients with syndrome of inappropriate antiduiretic hormone secretion who have excessive total body water could bene t from what?

Answer 48

water restriction and aquaretics such as V2 receptors antagonist or urea

Question 49

central pontine myelinolysis (CPM) is another way of sayign what?

Answer 49

osmotic demyelination syndrome (ODS).

Question 50

what time increment of sodium replenishment is most important in avoiding osmotic demyelination

Answer 50

24 hour is more important vs by hour

Question 51

what increment of sodium addition is associated with low risk of signifiant symptoms from ODS

Answer 51

<8 to 10 mEq/l per day but less is prefered based on the chance of patients could have started to self-correct their hyponatremia before they presented to the hospital

Question 52

what is one of the first events after rapid correction of chronic hyponatremia to happen in cells

Answer 52

astrocyte damage

Question 53

what correction of hyponatremia is less prone to causing ODS?

Answer 53

Urea used for correction

Question 54

what substance assists in decreasing the unfolded protein response and endoplasmic reticulum stress in the brain after correction of hyponatremia

Answer 54

urea

Question 55

what is the point of relowering sNa?

Answer 55

to prevent ODS we try to relower na concentration to offset rapid admin