Acid-Base

Question 1

In the definition of acid and base, what is the most accepted widely and most clinically relevant?

Answer 1

Bronsted-Lowry definition: an acid donates a proton, a base accepts a proton.
Mnemonics- “donate some ass (ass-id)”

Question 2

What is the Henderson-Hasselbalch equation?

Answer 2

pH = 6.1 + log HCO3/ pCO2 x 0.03

Base/Acid

Question 3

In terms of compensation, what is the most effective to least effective in acid-base disorder?

Answer 3

Most effective compensation - Respiratory alkalosis
2nd MC - Respiratory acidosis
3rd - Metabolic acidosis
Least effective - Metabolic alkalosis

Question 4

What is the formula of serum anion gap?

Answer 4

Na - ( Cl + HCO3) or (Na + K) - (Cl + HCO3)
Positives minus Negatives
Note: normal value 8 to 16 mmol/L or about 12 mmol/L

Question 5

What are the types of renal tubular acidosis? And how to differentiate them?

Answer 5

RTA type 1 and 2 - hypokalemia
RTA type 4 - hyperkalemia
Urine pH > 5.5 - type 1 (Classic or distal RTA)
Urine pH < 5.5 - type 2 (Proximal) (suggest Fanconi syndrome- best evidence is renal glycosuria)
Type 4 - aldosterone deficiency or aldosterone unresponsiveness

Question 6

What is the most common RTA type and what is its most common cause?

Answer 6

RTA type 4
Most common cause is hyporeninemic hypoaldosteronism. Diabeic nephropathy is the most common cause of hyporeninemic hypoaldosteronism.

Question 7

What are the two types of lactic acidosis? And what are their usual causes?

Answer 7

Type A - tissue hypoxia

Type B - in the absence of tissue hypoxia, two most common causes are ANTI RETROVIRAL DRUGS and METFORMIN

Question 8

Which isomer of lactic acid causes severe type of acidosis, accompanied by neurologic manifestations?

Answer 8

D-Lactic acid

Note: treatment includes Neomycin antibiotic and measures to alter D-LDH colonic bacterial flora.

Question 9

What is the most common cause of decreased serum anion gap?

Answer 9

Reduction in serum albumin

Question 10

What is the anion gap of early uremic acidosis?

Answer 10

Normal anion gap

Note: Chronic uremic acidosis = increased anion gap

Question 11

In metabolic alkalosis, what are the two most common causes of increased renal bicarbonate threshold?

Answer 11

1. Volume depletion (responds to Chloride administration)
2. Potassium depletion
   Notes: Decrease potassium decreases pH in proximal tubules causing increase bicarbonate reabsorption. In edematous conditions, Cl may not improve metabolic alkalosis.

Question 12

This hormone normally interferes with bicarbonate reabsorption?

Answer 12

PTH

Note: Hypoparathyroidism therefore leads to increase in bicarb = metabolic alkalosis

Question 13

Renal compensation in respiratory acidosis is at maximal in how many days?

Answer 13

5 days

Note: 90% complete in 3 days.

Question 14

What are the two most common causes of respiratory alkalosis?

Answer 14

Hypoxic stimulation of the peripheral respiratory center (carotid body and aortic arch chemoreceptors) and stimulation of the pulmonary receptors by various lung disorders.

Question 15

What hormone is responsible for chronic respiratory alkalosis of pregnancy.

Answer 15

Progesterone

Question 16

Respiratory alkalosis renal compensation is completed in how many days?

Answer 16

2 to 3 days

Note: Compensation is most effective in respiratory alkalosis