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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
Where is AVP released?
posterior pituitary
26
What stimulates AVP release?
``` N/V Medications Pain Volume depletion Inc EC fluid osmolarity ``` (MV PAIN)
27
Which AQP is AVP-dependent?
2
28
In hyponatremia, what is too high?
total body water, causing plasma sodium below 135
29
What is wrong in hypovolemic hyponatremia?
Total body sodium decreased even more than total body water
30
How do you assess hypovolemic hyponatremia?
Measure urinary sodium concentration
31
What is wrong in euvolemic hyponatremia?
Total body water is up with no change in TBNa No edema
32
What is wrong in hypervolemic hyponatremia?
Total body water is up relative to TBNa
33
What are some causes of renal sodium loss that can lead to hypovolemic hyponatremia?
Renal parenchymal disease Mineralocorticoid deficiency Glucosuria Diuretics
34
What are some extrarenal causes of sodium loss that lead to hypovolemic hyponatremia?
Vomiting Diarrhea Burns Hemorrhage
35
What are S/S of sodium depletion?
``` 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
What happens to serum sodium levels in sodium depletion?
Normal, low, or high
37
Euvolemic hyponatremia is similar to this disorder
SIADH
38
What is the problen in euvolemic hyponatremia?
Total body water increased due to inappropriately high levels of SIADH
39
What are some causes of SIADH?
``` CANCER Pulmonary disorders CNS disorders Pain Nausea Drug-induced water retention Glucocorticoid therapy Hypothyroidism ```
40
Explain SIADH in terms of ADH, RAAS, and Urinary sodium
Dysregulation of ADH increases urine osmolality by decreasing water excretion. Hypervolemic circulation inhibits RAAS... and leads to even higher urine sodium?
41
Give the diagnostic criteria for SIADH
Serum Osm 100 Euvolemia Elevated urine Na Absence of diuretic use and of endocrine insufficiency
42
What is the problem in hypervolemic hyponatremia?
Total body water elevated relative to high TB Na
43
What are clinical signs of sodium excess?
Edema JVD Crackles
44
What are some common causes of hypervolemic hyponatremia?
CHF Cirrhosis Nephrotic syndrome Renal diseases
45
What are the symptoms of acute hyponatremia?
Nausea and malaise (120-125) Headache, fatigue, confusion(115-120) Seizures and coma (<115)
46
What are the symptoms of chronic hyponatremia?
Usually asymptomatic
47
How does the brain adapt to hyponatremia?
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
What is cerebral demyelination syndrome?
Excessive rate of serum Na correction that causes rapid re-swelling of brain cells
49
Cerebral demyelination syndrome
Children, women, malnourished
50
Cerebral demyelination syndrome S/S
Dysphagia, quadriparesis, locked-in syndrome
51
What is the treatment for acute hyponatremia?
Hypertonic saline (3%) and furosemide co-administration when presenting with seizure/coma
52
What is the proper rate of correction for acute and chronic hyponatremia?
1-2 meq/L/hr acute; .5 meq/L/hr chronic/asymptomatic
53
What is the maximum daily amount of hyponatremia correction?
10-12 meq/L/day
54
What is wrong in hypovolemic hypernatremia?
TBW low relative to low TBNa
55
What is wrong in euvolemic hypernatremia?
TBW low with now change in Na
56
What is wrong in hypervolemic hypernatremia?
TBNa high relative to high TBW
57
What is the definition of diabetes insipidus?
Hypernatrmia of Uosm <300mOsm/Kg; ADH absent or resistant
58
What are some causes of U ism > 500 mOsm/kg?
Extrarenal water loss, excess Na ingestion/infusion, or low osmotic diuresis; ADH present but extrarenal issues
59
What is the important test to do in hypernatremia to distinguish the possible causes?
ADH functionality - look at U osm
60
What are the symptoms of hypernatremia?
Weakness, irritability, seizure, coma...death
61
What is the therapy for euvolemic hypernatremia?
Replace water deficit, by half in the first 24 hours
62
What is the therapy for hypovolemic hypernatremia?
Volume correction more important than water correction; give NS until hypovolemia resolved
63
What is the therapy for hypervolemic hypernatremia?
Na removal! Discontinue hypertonic-inducing agents Give furosemide and HD? if renal failure

OS Renal (25 decks)

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