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Renal > Water-sodium balance tutorial > Flashcards

Water-sodium balance tutorial Flashcards

1
Q

What is osmolality?

A

The concentration of a solution expressed as the total number of solute particles per kilogram.

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2
Q

What is the formula for osmolality? what does it refer to?

A

Osmolality= 2(Na+) + Gluc/18 + BUN/2.8

Osmolality= Water in the blood ~ solute in the blood

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3
Q

What is Osmolality equal? what is hyper/hypo/iso osmotic?

A

285 = isoosmotic=isotonic

hyper> 285
hypo<285

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4
Q

What does Tonicity refer to?

A

Tonicity= Water in the cells ~ solute in the cell

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5
Q

What is the formula for tonicity?

A

Tonicity= 2(Na+) + Gluc/18

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6
Q

What is Hypovolemomic, hypervolemic and euvolemic?

A

Hypovolemic-low volume in ECM

euvolemic- normal ECF volume

Hypervolemic- high ECF volume

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7
Q

What is tonicity?

A

is the relative concentration of solutes dissolved in solution which determine the direction and extent of diffusion.

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8
Q

What is a hypertonic solution?

A

relative high solute concetration compare to a cell

water will diffuse out of cell and cell will shrink

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9
Q

What is a hypotonic soltion

A

relative low solute concetration compare to a cell

water will diffuse in of cell and cell will swell

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10
Q

What is hypotonic?

A

equal solute concentrations inside cell and in solution

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11
Q

What is hyponatremia?

A

Low concentration of sodium in ECF

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12
Q

What is the function of ADH?

A

ADH works at the collecting duct= reabsorbs free water back into blood decreases your sodium concentration

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13
Q

What is the function of aldosterone?

A

Aldosterone works at the collecting duct= reabsorbs free water and sodium back into blood

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14
Q

Why is there a big decrease in sodium concentration when just water is added?

A

Because water can freely diffuse across the membrane of cells into cells, salt does not stay in ECF. So volme is only a small increase in ECF. Salt is a large decrease

This is hyponatremia= decrease in sodium concentration

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15
Q

What is saline? What can happen when adding saline?

A

Salt and water
an isoosmotic substance that increases volume only because salt is added

ECF remains Isotonic

this will create edema

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16
Q

What happens in patients with only a ADH problem?

A

only adding water
no edema
Hyponatremia

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17
Q

In which situations will they have edema in a patient?

A

adding saline =
adding Aldosterone=
reabsorption of salt and water
both increases salt and water

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18
Q

How is Hyponatremia tested for?

A

test osmolalality

which test the overall sodium concentration in plasma

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19
Q

What is a hyponatrimia?

A

sodium concentration in plasma less than 135

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20
Q

What are the three states of hyponatremia?

A

remember osmolality=
2*(sodium concentration) +glucose/18+BUN/2.8

Isotonic(psuedohyponatremia)
Hypertonic
Hypotonic

21
Q

How does a patient have isotonic-pseudo-hyponatremia? What must be done toget an accurate reading?

A

a patient has
hyperlipidemia and/or
Hyperproteinemia
and lab test is done that measures total blood volume. this will give a false positive.

Measure of sodium in the plasma portion will give a more accurate reading

22
Q

How is Hypertonic Hyponatremia caused? What is BUN equal to?

A

remember osmolality=
2*(sodium concentration) +glucose/18+BUN/2.8

caused by increased solutes in the ECF (not sodium)

increased osmolality is caused by Hyperglycemia and/or
increased BUN

BUN= Mannitol, Ethylene glycol(antifreeze) and Toluene (paint thinner)

23
Q

What are the three states of Hypotonic Hyponatremia?

A

Hypovolemic Hypotonic Hyponatremia

Hypervolemic Hypotonic Hyponatremia

Euvolemic Hypotonic Hyponatremia

24
Q

What is Hypovolemic Hypotonic Hyponatremia?

A

decrease in sodium concentration caused by an decrease in water but a double decrease in salt

decreased concentration[Na+]= double decrease Na/decrease water

25
Q

How is Hypovolemic Hypotonic Hyponatremia caused?

A

double lost of salt and lost of water

Renal= diuretic
Non-renal = vomiting
26
Q

What is Euvolemic Hypotonic Hyponatremia

A

No lost of salt and an increase in water

decreases salt concentration

27
Q

What causes Euvolemic Hypotonic Hyponatremia?

A

Increase ADH=
Increases free
Water

28
Q

What is Hypervolemic Hypotonic Hyponatremia?

A

an increase in salt
but a double increase
in water.
causes a decrease in sodium concentration

29
Q

What causes Hypervolemic Hypotonic Hyponatremia?

A

An increase in ADH and aldosterone

CHF
Liver Disease
Nephrotic syndrome

All three increase
Adosterone because of poor flow
To kidneys
And ADH

30
Q

What is hypernatremia?

A

increase in sodium concentration above 145

31
Q

What causes hypernatremia?

A

ADH/vasopressin

32
Q

What is Hypertonic Hypernatremia?

A

double decrease in water but no decrease in salt

causes an increase in sodium concentration

33
Q

What is the MOA of water reabsorption in the principle cell of the CCD?

A

pituitary gland release AVP

AVP activates V2 on the principle cells on the basolateral membrane.

V2 activates AQP2 on the apical membrane

AQP2 allows diffusion of water across to apical membrane into the cytoplasm

Water in the cytoplasm diffuse through AQP3 across the basolateral membrane into blood

34
Q

What is the MOA of Neruogenic DI?

A

decreases AVP release from pituratray.

V2 not activated

35
Q

What is the MOA of Nephrogenic DI?

A

V2 lost sensitivity for AVP

36
Q

How does the water deprivation test work?

A

Deprive water for a certain amount of time

you will see no increase in osmolality but increase in plasma osmolality

add AVP

if Nuerogenic DI-then there willbe an increase in Urine osmolality

if nephrogenic- no increase in plasma osmolality

37
Q

What does SIADH cause?

what will it cause?

A

Syndrome of inappropriate ADH secretion.

Will cause hyponatremia because of high water retention

38
Q

What is a defense against hyponatremia?

A

increased water intake -> decrease osmolality-> activates osmoreceptors cells-> causes decreased->AVP release-> excretetion of dilute urine

39
Q

What is the algorythym for diagnosing hyponatremia?

A

check plasma osmolality
normal= hyperlipidemia and hyperproteinimia

High osmolality = mannitol(BUN) and/or Hyperglycemia

if osmolality is low check volume status

low volume 
 =Volumeloss
-GI tract
-Skin
-Renal(Diuretics)
High Volume= 
CHF
Cirrhosis
Nephrosis
Hypoalbumin

Euuvolemic = hypothyroid or hypoadrenal= SIADH

Check urine osmolality
if urine osmolality is <100, then excess water ingestion

if > serum osmolality then SIADH

40
Q

What are the majority cases of hyponatremia?

A

90% Hypotonic

41
Q

What can cause excessive adh secretion by the hypothalnmus?

A

ECFV or effective circulating volume

pain

nasuea

drugs

CNS disruption

42
Q

What are drugs associated with SIADH?

A 
SSRI
Carbamazepine
Platinum compounds
Proton Pump Inhibitors
Alkylating agents
43
Q

What are drugs that use for hyponatremia?

A

Vaptans - blocks V2

Lithium, Demeclocycline
Both block cAMP by V2

44
Q

What can insufficient sodium damage cause?

Excessive sodium correction?

A

insufficient = osmotic demyelation syndrome (cells remain small)

excessive = cerebral edema ( cells are tool large)

45
Q

What are barnes steps to Hyponatremia?

A

Identify there is a Low Serum Sodium level

Obtain Serum and Urine Osmolality

Identify the Serum Osmolality as low, as majority of the time it is low

Evaluate the patient’s volume status

Based on the patient’s volume status identify the source

Intervene on the source of the patient’s hyponatremia for correction or utilize fluid restriction, isotonic saline, or hypertonic saline as indicated.

If recurrent hyponatremia, consider the use of a “vaptan” or demeclocycline.

46
Q

What is the bodies defense against hypernatremia?

A

Decrease in Free Water Intake

Increase Posm

Osmoreceptor Cells + Stimulation of Thirst

Increase Vasopressin Release (ADH)

Excretion of Concentrated Urine

47
Q

What are causes of neurogenic DI?

A

Head Trauma

Hereditary

Pituitary Surgery

Aneurysm

CVA

Post-partum (Sheehan’s Syndrome)

48
Q

What are causes of nephrogenic DI?

A

Lithium

Demeclocycline

“Vaptans

49
Q

What are barnes steps to hypernatremia?

A

Identify there is an Elevated Serum Sodium level

Evaluate the patient’s volume status

Calculate a Free Water Deficit

Consider use of Free Water infusions or oral administration of free water

For Euvolemic (as most cases are) perform a water deprivation test to differentiate between Central DI or Nephrogenic DI

Attempt to identify the source of DI and correct

Consider DDAVP for Central DI vs. thiazides+ low Na diet or NSAIDs for Nephrogenic DI

Renal (15 decks)

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