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OS Renal > Regulation of Sodium Balance - Gyamlani > Flashcards

Regulation of Sodium Balance - Gyamlani Flashcards

1
Q

Compare the volume of fluid in arteries vs. veins

A

Veins have more; 2 L vs 0.5 L

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2
Q

What is water balance regulated by in general?

A

Plasma osmolality and serum sodium

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3
Q

What is sodium balance regulated by in general?

A

circulating volume

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4
Q

What is ECFV primarily dependent on?

A

Total body sodium

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5
Q

How do you calculate plasma osmolarity?

A

2[Na] + glucose/18 + BUN/2.8

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6
Q

What is a normal plasma osmolarity?

A

About 285 mOsm/kg

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7
Q

What is the range of the kidney’s urine diluting/concentrating ability?

A

50 - 1200 mOsm/kg

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8
Q

In hypovolemia, what happens to ECV, ECFV, plasma volume, and cardiac output?

A

ECF down, ECFV down, plasma volume down, cardiac output down

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9
Q

What happens to ECV, ECFV, plasma volume, and cardiac output in CHF?

A

ECV down, ECFV up, plasma vol up, cardiac output down

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10
Q

What happens to ECV, ECFV, plasma volume, and cardiac output in cirrhosis?

A

ECV down, ECFV up, plasma volume up, cardiac output up

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11
Q

What are the sensors of plasma osmolarity?

A

Hypothalamic osmoreceptors

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12
Q

What are the sensors of volume regulation?

A

Macula densa, afferent arteriole, atria, carotid sinus

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13
Q

What are the effectors of osmoregulation (solute)?

A

ADH and thirst mechanism

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14
Q

What are the effectors of volume regulation?

A

Renin-Angiotensin, ANP, Norepinephrine, ADH

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15
Q

Does the RAAS control sodium balance or water balance?

A

Sodium balance

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16
Q

Explain RAAS

A

Kidney senses reduced arterial pressure  renin secreted by juxtaglomerular  converts Angiotensinogen to angiotensin I  ACE converts to Angiotensin II  two things, proximal reabsorption of sodium as well as vasoconstriction. Angiotensin II also stimulates aldosterone which does sodium reabsorption AT A different SITE the distal tubule.

changes in sodium!

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17
Q

Does ANP control sodium excess or volume excess? What does it do?

A

Volume - does not sense osmolarity; it responds to hypertensive stress on the heart by vasodilating the afferent arteriole and also increases Na excretion, with water following it out

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18
Q

Explain how the kidney responds in CHF

A

Low cardiac output decreases effective arterial volume, activating the RAAS system which leads to renal sodium retention.

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19
Q

Explain how the kidney responds in cirrhosis

A

Decreased protein synthesis by the liver leads to decreased plasma oncotic pressure and increased hydrostatic pressure in the portal circulation. The RAAS system is activated, causing increased sodium retention and decreased ability to excrete water. Edema occurs.

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20
Q

Does RAAS contribute to hyponatremia?

A

No

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21
Q

How does the body correct hypertonicity?

A

Hypothalamic receptor stimulatic causes thirstiness and AVP release, leading to water intake and renal water retention that restores isotonicity

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22
Q

How does the body correct hypotonicity?

A

Inhibit hypothalamus, decreasing AVP and thirst; thus more renal water excretion and less drinking

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23
Q

What stimuli can trigger the thirst mechanism?

A

Increased ECF osmolality; volume depletion; ATII

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24
Q

In which parts of the hypothalamus is AVP made?

A

Supraoptic and paraventricular

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25
Q

Where is AVP released?

A

posterior pituitary

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26
Q

What stimulates AVP release?

A 
N/V
Medications
Pain
Volume depletion
Inc EC fluid osmolarity

(MV PAIN)

27
Q

Which AQP is AVP-dependent?

A

2

28
Q

In hyponatremia, what is too high?

A

total body water, causing plasma sodium below 135

29
Q

What is wrong in hypovolemic hyponatremia?

A

Total body sodium decreased even more than total body water

30
Q

How do you assess hypovolemic hyponatremia?

A

Measure urinary sodium concentration

31
Q

What is wrong in euvolemic hyponatremia?

A

Total body water is up with no change in TBNa

No edema

32
Q

What is wrong in hypervolemic hyponatremia?

A

Total body water is up relative to TBNa

33
Q

What are some causes of renal sodium loss that can lead to hypovolemic hyponatremia?

A

Renal parenchymal disease
Mineralocorticoid deficiency
Glucosuria
Diuretics

34
Q

What are some extrarenal causes of sodium loss that lead to hypovolemic hyponatremia?

A

Vomiting
Diarrhea
Burns
Hemorrhage

35
Q

What are S/S of sodium depletion?

A 
Hypotension (but not nec hypovolemic)
Poor skin turgor
Absence of lower leg edema
BUN high relative to creatinine
Low urine Na excretion in extrarenal causes
36
Q

What happens to serum sodium levels in sodium depletion?

A

Normal, low, or high

37
Q

Euvolemic hyponatremia is similar to this disorder

A

SIADH

38
Q

What is the problen in euvolemic hyponatremia?

A

Total body water increased due to inappropriately high levels of SIADH

39
Q

What are some causes of SIADH?

A 
CANCER
Pulmonary disorders
CNS disorders
Pain
Nausea
Drug-induced water retention
Glucocorticoid therapy
Hypothyroidism
40
Q

Explain SIADH in terms of ADH, RAAS, and Urinary sodium

A

Dysregulation of ADH increases urine osmolality by decreasing water excretion. Hypervolemic circulation inhibits RAAS… and leads to even higher urine sodium?

41
Q

Give the diagnostic criteria for SIADH

A

Serum Osm 100
Euvolemia
Elevated urine Na
Absence of diuretic use and of endocrine insufficiency

42
Q

What is the problem in hypervolemic hyponatremia?

A

Total body water elevated relative to high TB Na

43
Q

What are clinical signs of sodium excess?

A

Edema
JVD
Crackles

44
Q

What are some common causes of hypervolemic hyponatremia?

A

CHF
Cirrhosis
Nephrotic syndrome
Renal diseases

45
Q

What are the symptoms of acute hyponatremia?

A

Nausea and malaise (120-125)
Headache, fatigue, confusion(115-120)
Seizures and coma (<115)

46
Q

What are the symptoms of chronic hyponatremia?

A

Usually asymptomatic

47
Q

How does the brain adapt to hyponatremia?

A

When brain swells (due to H2O moving into cells), it dumps ions out into EC fluid so that water will follow therefore decreasing the swelling

48
Q

What is cerebral demyelination syndrome?

A

Excessive rate of serum Na correction that causes rapid re-swelling of brain cells

49
Q

Cerebral demyelination syndrome

A

Children, women, malnourished

50
Q

Cerebral demyelination syndrome S/S

A

Dysphagia, quadriparesis, locked-in syndrome

51
Q

What is the treatment for acute hyponatremia?

A

Hypertonic saline (3%) and furosemide co-administration when presenting with seizure/coma

52
Q

What is the proper rate of correction for acute and chronic hyponatremia?

A

1-2 meq/L/hr acute; .5 meq/L/hr chronic/asymptomatic

53
Q

What is the maximum daily amount of hyponatremia correction?

A

10-12 meq/L/day

54
Q

What is wrong in hypovolemic hypernatremia?

A

TBW low relative to low TBNa

55
Q

What is wrong in euvolemic hypernatremia?

A

TBW low with now change in Na

56
Q

What is wrong in hypervolemic hypernatremia?

A

TBNa high relative to high TBW

57
Q

What is the definition of diabetes insipidus?

A

Hypernatrmia of Uosm <300mOsm/Kg; ADH absent or resistant

58
Q

What are some causes of U ism > 500 mOsm/kg?

A

Extrarenal water loss, excess Na ingestion/infusion, or low osmotic diuresis; ADH present but extrarenal issues

59
Q

What is the important test to do in hypernatremia to distinguish the possible causes?

A

ADH functionality - look at U osm

60
Q

What are the symptoms of hypernatremia?

A

Weakness, irritability, seizure, coma…death

61
Q

What is the therapy for euvolemic hypernatremia?

A

Replace water deficit, by half in the first 24 hours

62
Q

What is the therapy for hypovolemic hypernatremia?

A

Volume correction more important than water correction; give NS until hypovolemia resolved

63
Q

What is the therapy for hypervolemic hypernatremia?

A

Na removal!

Discontinue hypertonic-inducing agents
Give furosemide and HD? if renal failure

OS Renal (25 decks)

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