5. Changes in Na+ and Cl- balance and the anion-gap

Question 1

List the concentrations of the main cations in the blood plasma

Answer 1

• Na⁺ = 150mmol/l
• K⁺ = 5mmol/l
• Ca²⁺ = 5mmol/l
• Mg²⁺ = 3mmol/l

Question 2

List the concentrations of the main anions in the blood plasma

Answer 2

• Cl^- = 100mmol/l
• HCO₃^- = 30mmol/l
• Pr^- = 18mmol/l
• Others = 15mmol/l

Question 3

Give the main role of Na⁺

Answer 3

Maintenance of isoosmosis with Cl^-

(responsible for 90% total osmolality)

Question 4

Na⁺ is found in great amounts in…

Answer 4

Bones

But it is not mobilisable

Question 5

What reflects the plasma concentration of Na⁺?

Answer 5

The saliva Na⁺ conc.

Question 6

Which hormone has an important role in the reabsorption of Na⁺

Answer 6

Aldosterone

Question 7

List the disorders of Na⁺ balance

Answer 7

• Hyponatraemia
• Hypernatraemia

Question 8

Give the causes of hyponatraemia

Answer 8

• Diarrhoea
• ↓ Renal reabsorption (Lack of aldosterone)
• ↑ Water intake
• ↓ Na⁺ intake
• Hypoaldosteronism (Addison’s disease)

Question 9

Give the consequences of hyponatraemia

Answer 9

• Allotriophagy
• Hypotonic dehydration
• Hyperhydration

Question 10

Allotriophagy

Answer 10

The animal eats non-nutritive substances dues to mineral loss or due to nutritional deficiency

Question 11

Hypotonic dehydration as a cause of hyperntraemia

Answer 11

As a result of the loss of saline, ↓ EC volume

Question 12

Hypotonic hyperhydration as a cause of hyperntraemia

Answer 12

• Due to an increased water intake
• ↓ Na⁺ conc.

Question 13

Give the causes of hypernatraemia

Answer 13

• Water loss
• Salt poisoning (usually poultry or pigs)
• Hyperaldosteronism

Question 14

Hyperaldosteronism as a cause of hypernatraemia

Answer 14

Conn’s syndrome

• Develops in severe liver diseases, causing metabolic disturbances

Question 15

Give the consequences of hypernatraemia

Answer 15

• CNS symptoms
• Hypertonic dehydration

Question 16

Hypertonic dehydration as a consequence of hypernatraemia

Answer 16

Results from the loss of water → ↓ EC volume

Question 17

Give the main roles of Cl^-

Answer 17

• Maintenance of isoosmosis with Na⁺
• Follows Na⁺ passively during its metabolism
• Cl^- + HCO₃^- exchange through small intestinal wall

Question 18

Give the disorders of Cl^- balance

Answer 18

• Hypochloraemia
• Hyperchloraemia

Question 19

Give the causes of hypochloraemia

Answer 19

• Vomiting
• Diarrhoea
• Hyponatraemic conditions
• Abomasal displacement

Question 20

Abomasal displacement as a cause of hypochloraemia

Answer 20

Cl^- separated from Na⁺ and cannot be taken up in the intestines but is moved back to the rumen; reflux phenomenon

Question 21

Give the consequence of hypochloraemia

Answer 21

Metabolic alkalosis - Caused by ↑ HCO₃^- level

Question 22

List the causes of hyperchloraemia

Answer 22

• Salt poisoning
• Misinfusion
• Hypernatraemic conditions

Question 23

Give the consequence of hyperchloraemia

Answer 23

No consequences are currently known

• Consequences are related to Na⁺ concentration

Question 24

Anion gap

Answer 24

The difference in the measured cations and the measured anions

• Used to distinguish the forms of acidosis

Question 25

Give examples of anion gap

Answer 25

(Na⁺ + K⁺) - (HCO₃^-) = 8-18mmol/l