Sodium and Water Balance

Question 1

what is water balance controlled by?

Answer 1

ADH

Question 2

action of ADH

Answer 2

water is reabsorbed from renal tubules

Question 3

what does increased ADH do to urine?

Answer 3

small amount of concentrated urine

Question 4

what is sodium balance controlled by?

Answer 4

steroids (aldosterone and cortisol)

Question 5

what do aldosterone and cortisol do to sodium?

Answer 5

cause sodium to be reabsorbed

Question 6

what are the two fluid compartments in the body?

Answer 6

1. extracellular 33.3%

2. intracellular 66.6%

Question 7

what does the extracellular fluid compartment consist of?

Answer 7

plasma

interstitial fluid

Question 8

which fluid compartment has lower Na+?

Answer 8

intracellular

Question 9

which fluid compartments can water move through?

Answer 9

all body compartments

Question 10

what fluid compartments can sodium move through?

Answer 10

ECF only

Question 11

two causes of hyponatraemia

Answer 11

1. too little Na+

2. too much water

Question 12

what does too little Na+ cause?

Answer 12

reduces fluid in the ECF leading to dehydration

Question 13

causes of too little Na+

Answer 13

loss from the gut (vomiting, diarrhoea)
loss from adrenals/kidneys
losses from skin
rarely low intake

Question 14

management of too little Na+

Answer 14

give sodium

Question 15

what does too much water cause?

Answer 15

less of an effect as water moves through all compartments

Question 16

causes of too much water hyponatraemia

Answer 16

1. low H2O excretion (SIADH)

2. compulsive drinking

Question 17

management of too much water hyponatraemia

Answer 17

fluid restriction

Question 18

two causes of hypernatremia

Answer 18

1. too much Na+

2. too little water

Question 19

causes of too much Na+

Answer 19

increased intake

low loss

Question 20

what does too much Na+ cause?

Answer 20

fluid overload in the ECF causing oedema

Question 21

management of too much Na+ hypernatremia

Answer 21

remove sodium

Question 22

causes of too little water hypernatremia

Answer 22

DI

low intake

Question 23

what does too little water hypernatremia cause?

Answer 23

little significance

Question 24

management of too little water hypernatremia

Answer 24

dextrose

Question 25

fluid management options

Answer 25

1. plasma/blood fills plasma compartment
2. saline 0.9% fills plasma and interstitial fluid (ECF)
3. dextrose fills all