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Endocrinology > Sodium & Water Balance > Flashcards

Flashcards in Sodium & Water Balance Deck (30)
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1
Q

what hormone is water balance controlled by?

A

ADH

2
Q

what releases ADH?

A

posterior pituitary

3
Q

ADH makes you pee more/less

A

ADH makes you pee LESS

4
Q

ADH causes water to be ____________ from the renal tubules

A

ADH causes water to be REABSORBED from the renal tubules

5
Q

high ADH = ______ volume of _____________ urine

low ADH = ______ volume of _______ urine

A

high ADH = SMALL volume of CONCENTRATED urine

low ADH = LARGE volume of DILUTE urine

6
Q

what do we measure urine concentration/dilution as?

A

urine osmolarity

7
Q

concentrated urine = low/high osmolarity

dilute urine = low/high osmolarity

A

concentrated urine = high osmolarity

dilute urine = low osmolarity

8
Q

mineralocorticoid activity:

name the main steroid and 1 other involved

too much MA = sodium gain/loss

too little MA = sodium gain/loss

A

mineralocorticoid activity:

ALDOSTERONE (MAIN)
CORTISOL

too much MA = sodium GAIN

too little MA = sodium LOSS

9
Q

state the important equation for water balance

A

[Na+] = Na+/H2O

10
Q

what can cause low [Na+]?

A

low sodium OR high water

11
Q

what can cause high [Na+]?

A

high sodium OR low water

12
Q

intra/extracellular:

(a) high fluid and low sodium
(b) low fluid and high sodium

A

(a) high fluid and low sodium - INTRACELLULAR

(b) low fluid and high sodium - EXTRACELLULAR

13
Q

wherever sodium goes, what follows?

A

water

14
Q

what can cause too little sodium?

A

increased Na loss OR decreased Na intake

15
Q

what can cause too much water?

A

reduced water excretion OR increased intake

16
Q

what can cause too much sodium?

A

increased Na intake OR decreased Na loss

17
Q

what can cause too little water?

A

increased water loss OR decreased water intake

18
Q

what condition causes increased water loss?

A

DM

19
Q

what condition causes reduced water excretion?

A

SIADH - syndrome of inappropriate antidiuretic hormone secretion

20
Q

whats the very very common cause of reduced sodium?

A

reduced water excretion - SIADH

21
Q

whats the uncommon but fatal if you miss it cause of reduced sodium?

A

increased sodium loss

22
Q

treatment:

(a) too little sodium =
(b) too much water =
(c) too much sodium =
(d) too little water =

A

treatment:

(a) too little sodium = GIVE SODIUM
(b) too much water = FLUID RESTRICT
(c) too much sodium = REMOVE SODIUM
(d) too little water = GIVE WATER AS DEXTROSE

23
Q

why give dextrose?

A

can enter the intracellular compartment

24
Q

name some stimuli for ADH release

A

osmotic

non-osmotic in disease

hypo/hypertension
pain
nausea/vomiting

25
Q

oedema treatment?

A

loop diuretic

26
Q

patient with oedema has too much what?

A

water and sodium

27
Q

low sodium in a well patient diagnosis?

A

pseudohyponatraemia

28
Q

A 24 year-old student presents with a six month history of malaise, tiredness, poor appetite and one stone weight loss. She has developed a craving for salty foods – crisps in particular. She has had a number of dizzy spells particularly while in warm places.

She is thin. She has low BP which falls further on standing. You have the impression that she is tanned, and you find increased pigmentation in her mouth and hand creases.

Her bloods show low sodium [122 mmol/L] and high potassium [5.8 mmol/L].

diagnosis?

A

Addisons disease

too little sodium

primary adrenal insufficiency

adrenal not making aldosterone

29
Q

A 29 year-old man is admitted to ITU following a cycling accident in which he sustained a severe head injury. During his ITU stay his urine output is in excess of 12 litres daily; his IV fluid requirement is correspondingly large.

Serum sodium is 167 mmol/L on admission to ITU and slowly falls as fluid replacement ‘catches up’. He is in addition commenced on desmopressin (exogenous ADH) which produces a sharper fall in sodium.

diagnosis?

A

DM

30
Q

those with too little sodium will look what?

A

dehydrated