L3: Acid-Base Disorders

Question 1

What is the normal pH of the body? What is the [H+] at this pH?

Answer 1

pH = 7.4
[H+] = 40 nmol/L

Question 2

In the body, for every 0.3 pH change, how much does the [H+] change by?

Answer 2

a factor of 2

Question 3

If there is increased acid production which exceeds the normal carbonic anhydrase buffering system, buffering can be done by: [3]

Answer 3

1. bone
2. haemoglobin
3. plasma proteins

Question 4

What are the 3 important values when examining acid:base disorders?

Answer 4

1. HCO3-
2. CO2
3. pH

Question 5

If HCO3-, CO2 and pH all move in the SAME direction, what type of acid base disorder is this?

Answer 5

Metabolic (primary problem usually HCO3-)

Question 6

If HCO3-, CO2 and pH move in DISCORDANT directions, what type of acid base disorder is this?

Answer 6

Respiratory (primary problem usually CO2)

Question 7

What is the normal value of pCO2 in the body?

Answer 7

5.3

Question 8

What is the normal value of HCO3- in the body?

Answer 8

24

Question 9

What is the significance of Winter’s formula? What is Winter’s formula?

Answer 9

• to examine respiratory compensation in metabolic acidosis
• gives an expected value for the patients’ PCO2

pCO2 = (HCO3/5) + 1

Question 10

What is the normal anion gap range?

Answer 10

8-12

Question 11

What is the formula for anion gap?

Answer 11

Anion Gap = Na+ - (Cl + HCO3)

Question 12

What does it mean if there is a high anion gap?

Answer 12

it indicates the presence of more anions than cations - suggesting acidosis

Question 13

What is the general principle behind Normal Anion Gap Metabolic Acidosis?

Answer 13

• HCO3 decreases
• Cl- increases
  (anions unchanged)

Question 14

What is the general principle behind Increased Anion Gap Metabolic Acidosis?

Answer 14

• HCO3 decreases
• anions increase
  (Cl- unchanged)

Question 15

What are the 3 main causes of normal anion gap metabolic acidosis (NAGMA)?

Answer 15

1. Chloride Intoxication
2. GI Loss of HCO3- (diarrhea)
3. Renal Loss of HCO3- (renal tubular acidosis)

Question 16

What is renal tubular acidosis?

Answer 16

acidosis occurs due to reabsorption of HCO3- being impaired

Question 17

List the 4 differential diagnoses/possible causes of increased anion gap metabolic acidosis

Answer 17

1. Lactic Acidosis
2. Renal Failure
3. Ketoacidosis
4. Poisonings

Question 18

What is Type A and Type B lactic acidosis?

Answer 18

Type A = Tissue Hypoxia

Type B = Mitochondria Failure

Question 19

How does renal failure lead to increased anion gap metabolic acidosis?

Answer 19

Renal Failure - fail to excrete daily acid intake

• lowering of HCO3 set point to 18 mmol/L [DECREASE IN HCO3]
• inability to secrete anions from kidney [INCREASE OF ANIONS]

Question 20

What is the treatment of alcoholic ketoacidosis? What should the patient NOT be treated with?

Answer 20

1. Glucose
2. B Vitamins

SHOULD NOT BE GIVEN INSULIN

Question 21

What does Fomepizole injections used for?

Answer 21

• alcohol poisoning
• blocks alcohol dehydrogenase
• used if there is a high osmolar gap

Question 22

What is the possible treatment for methanol poisoning?

Answer 22

1. Fomepizole Injection

2. Folate (B9)

Question 23

In general, what are the possible treatment options for poisonings? [4]

Answer 23

• isotonic sodium bicarbonate
• fomepizole (if osmolar gap)
• dialysis if elevated toxic alcohol
• B vitamins

Question 24

What is another name for vitamin B1?

Answer 24

Thiamine

Question 25

What is another name for vitamin B6?

Answer 25

Pyridoxine

Question 26

What is another name for vitamin B9?

Answer 26

Folate/Folic Acid

Question 27

How can aspirin cause a metabolic acidosis?

Answer 27

can cause lactic acidosis (therefore can cause an increase AG metabolic acidosis)

Question 28

What is another name for aspirin? (formal name)

Answer 28

acetylsalicylic acid or salicylic acid / salicylate