Water Balance - Ex 5

Question 1

Fluid Compartments - which do we measure?

Answer 1

ICF
Plasma - measure
ISF

Question 2

Anion gap?

Answer 2

difference between measured cations (Na and K) and the measured anions (Cl and HCO3)

Question 3

Two main solutes in Plasma

Answer 3

Na and Cl

Question 4

Two main solutes in ISF

Answer 4

Na and Cl

Question 5

Two main solutes in ICF

Answer 5

K and other anions (lots of albumin - mainly this forms anion gap)

Question 6

What regulates osmolality

Answer 6

Water is lost (urine) or gained (intake) in order to regulate:

Osmolality

Question 7

What regulates blood volume

Answer 7

Sodium is regulated in order to alter:

Blood volume

**Because water follows sodium!

Question 8

Changes in osmolality are corrected by retention or excretion of

Answer 8

water

Question 9

Changes in blood volume are corrected by retention or excretion of

Answer 9

sodium

Question 10

Small changes may not be detected in a new patient - why?

Answer 10

Normal ranges are wide

Question 11

3 reasons that cause the solute/particle content has been altered

Answer 11

• protein losing disease
• whole blood loss
• anemia for other reasons

Question 12

What could the PCV look like if animal is anemic AND dehydrated?

Answer 12

PCV can be WNL

**After animal is re-hydrated the anemia could become evident

Question 13

Caution - electrolytes

Answer 13

Electrolytes change quickly! and are not always reliable measure of water balance

Question 14

Dehydration

Answer 14

Deficit in Total Body Water

Question 15

Dehydration Status and CS

1-4%

Answer 15

Very mild

Non-detectable

Question 16

Dehydration Status and CS

5-6%

Answer 16

Mild

Skin doughy
Inelastic 
Slight loss of skin turgor 
Dry mm
Conjunctiva injected

Question 17

Dehydration Status and CS

7-9%

Answer 17

Moderate

Definite loss of skin turgor, with slow return
Enopthalmos
CRT 2-3sec

Question 18

Dehydration Status and CS

10-12%

Answer 18

Severe

Pronounced loss of skin turgor with incomplete return
Peripheral vasoconstriction
Cold extremities
CRT >3 sec

Question 19

Dehydration Status and CS

13-15%

Answer 19

Very severe

Vascular collapse
Renal shutdown
Death

Question 20

Isotonic Dehydration

Answer 20

Loss of isotonic fluids –> electrolytes are NORMAL

Question 21

Hypertonic Dehydration

Answer 21

Loss of hypotonic fluid –> electrolytes are INCREASED

Question 22

Hypotonic Dehydration

Answer 22

Loss of hypertonic fluid –> electrolytes are DECREASED

Question 23

Causes of hypertonic dehydration

Answer 23

Diabetes insipidus –> dilute urine, more water loss

Water loss from panting (dogs)

Sweat (cows)

Question 24

What kind of dehydration occurs during heat stress (horses)

Answer 24

Hypotonic! Horses sweat is hypertonic –> too much sweat = hypotonic dehydration

Question 25

Causes of hypotonic dehydration

Answer 25

Secretory diarrhea (calf scours)
Vomiting
“Third space” abnormalities (e.g. displaced abomasum)
Sweating (horses)

Question 26

What is the most common cause of dehydration??

Answer 26

Hypertonic water loss (Animal is hypotonic)

Question 27

What is osmolality influenced by?

Answer 27

Na, BUN, Glucose

Question 28

Hyperosmotic

Answer 28

osmolality exceeds normal reference interval for plasma

Question 29

Isosomotic

Answer 29

WNL

Question 30

Hypoosmotic

Answer 30

lower than normal interval