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2 ENDOCRINE > Sodium and water balance > Flashcards

Sodium and water balance Flashcards

1
Q

what hormones control water and sodium balance

A

ADH
(anti-diuretic hormone)

aldosterone and steroids (mineralocorticoid)

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2
Q

what does ADH do

A

makes you pee less

causes water to be reabsorbed by the renal tubules

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3
Q

what happens to urine when there’s an increase in ADH

A

Small volume of concentrated urine

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4
Q

what happens to urine when theres a low secretion of ADH

A

large volume of dilute urine

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5
Q

how do you measure urine concentration/dilution

A

urine osmolarity
(concentrated urine - high osmolarity)
(dilute urine - low osmolarity)

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6
Q

where is ADH released from

A

posterior pituitary

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7
Q

how does ADH cause water reabsorption in the kidneys

A

watch video linked in slide

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8
Q

what controls sodium balance

A

steroid hormones from the adrenals

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9
Q

what is the effect of steroids on Na+ balance called

A

mineralocorticoid activity

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10
Q

how do steroids affect Na+ balance

A

cause Na+ reabsorption in renal tubules in exchange for K+/H+

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11
Q

what is the main steroid with mineralocorticoid activity

A

aldosterone

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12
Q

what happens if theres too much mineralcoritcoid activity

A

sodium gain

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13
Q

too little mineralcorticoid activity

A

sodium loss

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14
Q

how much sodium is there inside cells

A

4mmol/L

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15
Q

how much sodium is in extracellular fluid

A

140 mol/L

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16
Q

where do you loose water from

A

the WHOLE BODY

water can move between all the body compartments

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17
Q

what body compartment is sodium confined to

A

extracellular fluid

sodium potassium pump makes sure the concentrations of sodium and potassium in and out the cells is kept

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18
Q

what does water follow by osmosis

A

solute

therefore water follows sodium

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19
Q

what happens to water if you loose sodium

A

you loose water too

water follows sodium

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20
Q

low sodium concentration with a unremarkable volume status

A

too much water?

21
Q

high sodium with unremarkable volume status

A

too little water??

22
Q

what happens clinically if theres not enough sodium

A

clinical dehydration

dry mucus membranes

23
Q

clinical picture of too much sodium

A 
water overload 
raised JVP
oedema 
plural effusion 
swelling
24
Q

what are the scenarios where you would loose sodium

A

diarrhoea and vomiting
fistulae - loos gut fluid from body
from skin -burns
if adrenals aren’t working - steroid hormones aren’t causing sodium uptake

rare but can be fatal

25
what scenarios would you have too much water
decreased H2O secretion (common) increased H2O intake (compulsive water drinking)- rare
26
what are the scenarios when theres too much sodium
increased sodium intake - Some IV meds - Near-drowning - Malicious (child being given salt maliciously) decreased sodium loss rare but fatal
27
what scenarios is there too much sodium due to water
increased water loss (not very common) decreased water intake (v common)
28
how do you treat too much sodium
loop diuretic causes loss of sodium and water just replace the water
29
how do you treat patient with not enough water
give water as dextrose (glucose as a concentration similar to that of blood)
30
how do you treat too little sodium
give sodium
31
how do you treat too much water
fluid restriction
32
if you give dextrose what body compartment will it go into
all of them (its water)
33
if you give saline what body compartment will it go into
plasma and interstitial fluid
34
if you give plasma/blood what body compartment does it go into
plasma
35
when is sodium concentration normal
135-145
36
when is a low sodium v serious
<120
37
when is a high sodium v serious
>160
38
what are the symptoms of life threatening hypo/hypernatraemia
``` altered consciousness confusion nausea vomiting fitting ```
39
what are the two stimuli for ADH release
osmotic (high Na so osmolarity is high which stimulates more ADH to reabsorb more water and dilute the blood) Non-osmotic (in disease, eg. hypovolaemia, hypotension, pain, nausea and vomiting)
40
what does oedema signify
excess fluid in interstitial space so circulating vascular volume is depletes
41
what does an oedemas patient have
too much water and sodium treat with loop diuretics
42
why is oedema a vicious circle
because the vascular volume is depleted this causes ADH and aldosterone secretion these cause water and sodium retention this causes hyponatramiea
43
what is pseudohyponatraemia
check with serum osmolarity whether theres low sodium or normal sodium just in less?? idk
44
what does Addisons disease cause
adrenal indeficiency so steroid hormones aren't being made so theres no mineralocorticoid activity so patient can't hold onto sodium and therefore cant hold on to water decreasing the ECF and giving rise to clinical dehydration
45
symptoms of Addisons disease
dizziness reflects hypotension from decreased ECF | excess pigmentation reflects excess ACTH from anterior pituitary
46
why does excess ACTH cause tanned skin
ACTH is broken down by proteases releasing MSH from within it which causes excess pigmentation in skin
47
what is the typical presentation of someone who has too much water
patient often in hospital with other illness routine biochem shoes decreased Na volume status unremarkable (do to loss of water being distributed everywhere) Addisons disease tests negative most patients have inappropriate ADH secretion often no symptoms
48
cause of too much water in someone who is already ill
ADH secreted in response to a non-osmotic stimulus causes water retention distributed all over body compartments so patients volume status seems unremarkable first noticed when U&Es done often diagnosis of exclusion
49
how does diabetes insidious cause too little water
patient cant secrete ADH from the posterior pituitary due to disruption of pituitary stalk No ADH to act on kidneys to cause water reabsorption so LOTS of pure water lost in urine Patients Na is high reflecting water deficit treat with exogenous ADH

2 ENDOCRINE (32 decks)

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