metabolic acidosis Flashcards
how and why is the anion gap calculated ?
needs to be calculated to identify the cause of metabolic acidosis
anion gap = Na - (Cl + HCO3)
what is the normal value for the anion gap ?
8 to 12
what is the other term used referring to non anion gap metabolic acidosis ?
also called hyperchloremic metabolic acidosis
what are the causes of non anion gap metabolic acidosis ?
usuallly due to diarrhea
saline infusion ( chloride toxicity )
renal tubular acidosis
parenteral nutrition
acetazolamide
addisons disease. or the use of spironolactone
what are the causes of anion gap metabolic acidosis ?
MUD PILES
methanol
uremia
diabetic ketoacidosis
propylene glycol
iron tablets or INH
lactic acidosis
ethylene glycol
salicylates
what is methanol metabolized to in the body ?
formic acid
what is the classic scenario with a patient with methanol poisoning ?
alcoholics , suicide attempts
confusion
visual symptoms
high anion gap metabolic acidosis
what is the treatment for methanol poisoning ?
inhibit alcohol dehydrogenase
use fomepizole ( antizol)
ethanol
where is ethylene glycol found and what is it metabolized into ?
found in antifreeze and some cleaners it is metabolized into oxalate and glycolate
what is the problem with glycolate and oxalate ?
oxalate causes kidney stones
glycolate is nephrotoxic
what is the presentation of ethylene glycol poisoning ?
similiar in mechanism to methanol but instead present with flank pain and oliguria
hig metabolic acidosis
what is the treatment for ethylene glycol ?
inhibits alcohol dehydrogenase
use fomepizole
use ethanol
where is propylene glycol found ?
found in anti freeze , used s a solvent for IV benzodiazepene
what is the main symptom associated with propylene glycol ?
CNS depression , anion gap MA , no nephrotoxicity no visual problems
industrial solvent consumption but no high anion gap MA ?
usually referring to isopropyl alcohol
what is the classic trigger of DKA ?
infection
when does lactic acidosis ?
this happens when there is a switch from anaerobic respiration to anaerobic due to ow tissue oxygen delivery
here pyruvate is converted to lactate
what are the clinical scenarios associated with lactic acidosis ?
metformin therapy
shock
ischemic bowel
seizures
what are the phases of iron poisoning ?
initial gastrointestinal phase ( 0 to 6 hours)
abdominal pain
later : can present with shock and coagulopathy
abdominal pain that became shock , coagulopathy and heart failure
weeks later presents with bowel obstruction
TB patient with AG metabolic acidosis ?
usually due to isoniazid
what are the two phases associated with aspirin overdose ?
initially respiratory alkalosis
later on develops into AG metabolic acidosis
what are the lab features associated with aspirin overdose ?
1- pH will be variable due to mixed disorders
2- pCo2 will below due to hyperventilation
3- HCO3 low due to acidosis
4- winters formula will predict CO2 higher than actual
what is the compensation for metabolic acidosis ?
respiratory hyperventilation
what is the delta ratio ?
similar to winters formula
where you calculate the difference in anion gap divided by the difference in the bicarb levels
only used in high anion gap metabolic acidosis
