Acid Base Flashcards
causes of hyperchloremic (normal AG) acidosis
GI loss: diarrhea
Renal: RTA
causes of AG acidosis
MUDPILES
causes of metabolic alkalosis
- loss of H+
- GI loss: vomiting, NG suction
- Renal: Hyperaldosteronism - alkali ingestion: milk alkali syndrome
delta-delta
for every 1 increase in AG, HCO3- should fall by 1
what is the expected metabolic compensation for respiratory acidosis?
Acute: for every 10mmHg increase in PCO2, 1mEq/L rise in bicarb
Chronic: for every 10mmHg increase in PCO2, 3-4mEg/L rise in bicarb
what is the expected respiratory compensation for metabolic acidosis?
Winter’s formula: expected pCO2=1.5*[HCO3-] +8 +/- 2
Or cover the 7
what is the expected metabolic compensation for respiratory alkalosis?
Acute: for every 10mmHg decrease in PCO2, 2mEq/L decrease in bicarb
Chronic: for every 10mmHg decrease in PCO2, 4mEq/L decrease in bicarb
what is the expected respiratory compensation for metabolic alkalosis?
0.7mmHg rise in pCO2 for every 1mEq/L rise in HCO3
distal/Type 1 RTA
impaired H+ secretion in distal tubule
labs in distal/ type 1 RTA
low serum [HCO3-] 5.5
Urine AG +
hypokalemia
tx distal / type 1 RTA
potassium bicarbonate
negative UAG in presence of metabolic acidosis
means there is an extra-renal problem (kidneys are acting appropriately and eliminating lots of Cl- as NH4Cl)
positive UAG in presence of metabolic acidosis
renal problem (RTA) b/c low NH4Cl excretion
proximal / type 2 RTA
proximal tubule can’t resorb enough bicarb –> bicarbonaturia
labs in proximal / type 2 RTA
low serum [HCO3-] 12-16mEq/L
urine pH5.5 if serum bicarb exceeds tubular bicarb threshold
UAG neg
hypokalemia - worse w/ alkali therapy
tx for proximal / type 2 RTA
potassium bicarb
fanconi syndrome
generalized proximal tubular dysfunction –> type 2 RTA, glycosuria, aminoaciduria, phosphaturia, bicarbonaturia, etc…)
type 4 RTA
lack of aldosterone effects in principal cells of distal tubules –> inhibits K+ and H+ secretion
labs in type 4 RTA
low serum bicarb (mild - 16-20mEq/L)
variable urine pH
hyperkalemia
type 4 RTA tx
tx underlying etiology (mineralocorticoid deficiency for ex., hypoadrenalism)
loop diuretics
fludrocortisone
aspirin toxicity
results in:
- hyperventilation –> respiratory alkalosis
- AG metabolic acidosis (salicylate)
metabolic alkalosis - urine chloride measurement
Urine Cl- < 25 mEq/L = kidneys are working
- possible causes: vomiting, CF, low Cl- intake
Urine Cl- > 40 mEq/L = kidney defect
- possible causes: aldosterone excess, genetic (Liddle’s, Bartter’s, Gitelman’s), alkali load, diuretic
