Acid-Base Flashcards
In the definition of acid and base, what is the most accepted widely and most clinically relevant?
Bronsted-Lowry definition: an acid donates a proton, a base accepts a proton.
Mnemonics- “donate some ass (ass-id)”
What is the Henderson-Hasselbalch equation?
pH = 6.1 + log HCO3/ pCO2 x 0.03
Base/Acid
In terms of compensation, what is the most effective to least effective in acid-base disorder?
Most effective compensation - Respiratory alkalosis
2nd MC - Respiratory acidosis
3rd - Metabolic acidosis
Least effective - Metabolic alkalosis
What is the formula of serum anion gap?
Na - ( Cl + HCO3) or (Na + K) - (Cl + HCO3)
Positives minus Negatives
Note: normal value 8 to 16 mmol/L or about 12 mmol/L
What are the types of renal tubular acidosis? And how to differentiate them?
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
What is the most common RTA type and what is its most common cause?
RTA type 4
Most common cause is hyporeninemic hypoaldosteronism. Diabeic nephropathy is the most common cause of hyporeninemic hypoaldosteronism.
What are the two types of lactic acidosis? And what are their usual causes?
Type A - tissue hypoxia
Type B - in the absence of tissue hypoxia, two most common causes are ANTI RETROVIRAL DRUGS and METFORMIN
Which isomer of lactic acid causes severe type of acidosis, accompanied by neurologic manifestations?
D-Lactic acid
Note: treatment includes Neomycin antibiotic and measures to alter D-LDH colonic bacterial flora.
What is the most common cause of decreased serum anion gap?
Reduction in serum albumin
What is the anion gap of early uremic acidosis?
Normal anion gap
Note: Chronic uremic acidosis = increased anion gap
In metabolic alkalosis, what are the two most common causes of increased renal bicarbonate threshold?
- Volume depletion (responds to Chloride administration)
- Potassium depletion
Notes: Decrease potassium decreases pH in proximal tubules causing increase bicarbonate reabsorption. In edematous conditions, Cl may not improve metabolic alkalosis.
This hormone normally interferes with bicarbonate reabsorption?
PTH
Note: Hypoparathyroidism therefore leads to increase in bicarb = metabolic alkalosis
Renal compensation in respiratory acidosis is at maximal in how many days?
5 days
Note: 90% complete in 3 days.
What are the two most common causes of respiratory alkalosis?
Hypoxic stimulation of the peripheral respiratory center (carotid body and aortic arch chemoreceptors) and stimulation of the pulmonary receptors by various lung disorders.
What hormone is responsible for chronic respiratory alkalosis of pregnancy.
Progesterone
