Metabolic Acidosis Flashcards
GI causes of normal gap metabolic acidosis
(loss of bicarb)
- Diarrhea
- Drainage of panc/biliary sec
- Small bowel fistula
- Utero-enterostomy or obstruction of ileal conduit
Renal causes of normal gap metabolic acidosis
- RTA
- Carbonic anhydrase inhibition
- Kidney failure
- Mineralocorticoid def/resistance
- Drugs
Causes of high anion gap metabolic acidosis?
- Diabetic, fasting, or alcoholic ketoacidosis
- Lactic acidosis
- Toxic ingestions: methanol, ethylene glycol, diethylene glycol
- Pyroglutamic acidosis
- Toluene intox
- Advanced kidney failure (reduced GFR)
What are the causes of acidosis with reduced GFR?
Decreased nephron function (causes the reduced GFR) causes a dec in the filtration of many acids, an increase in K+ reabs, and a decrease in sensitivity to aldosterone
- K+ effects: hyperkalemia leads to a alkalemia of the intracellular space (switches with H+) which impairs NH4 generation
- ECF volume expansion: due to kidney failure causes an inhibition fo aldosterone which reduces distal acidification
- Can be normal or high gap
SUMMARY:
- Can’t filter your acids
- Hyperkalemia (NH4)
- Aldosterone effects
Fanconi Syndrome
Looks like proximal RTA with glucosuria, aminoaciduria, phosphousturia, urocosuria (hypouricemia and hypophos)
Causes of type I distal RTA
Alpha interacalated cell:
- H-ATPase or H-K ATPase defect
- Cl-HCO3 co transporter mutation
- CA-II def
Amphotericin (med) causing H+ backleak into apical membrane of alpha intercalated cell
Type I and II RTA effects on calicum
HYPOkalemia
Which causes worse acidemia, dRTA or pRTA?
dRTA
Causes of type IV (hyperkalemia distal) RTA
Aldo def
Resistance
DT dysfxn
Drugs that cause aldo def?
Heparin, ACE inhib, ARB
Ethylene glycol and methanol
- Metabolized into acids by ADH (alcohol has a higher affinity) so it takes a while for the high gap acidosis to occur.
- At first, before there is a big acidosis, see a high serum osmolal gap so you know they ingested something (measured=lab - expected =sodium, glucose, urea)
- Ethylene glycol see calcium oxalate in the urine
Clinical manifestations of metabolic acidosis
- Hyperkalemia (concomitant kidney failure, cell lysis, tissue injury)
- Hemodynamic compromise
- Chronic musculoskeletal manifestations
- Hyperventilation (kaussmaul)
Order of compensation for metab acidosis
- ECF buffering
- ICF buffering
- Resp compensation
- Renal acid excretion (mostly inc ammonium)
Winter’s formula
1.5(bicarb)+8 +/- 2
ONLY used for metab acidosis, tells you if pCO2/resp is compensating correctly. If not, there is another acid/base disturbance
Delta/delta
- Amt anion gap inc from normal=amt bicarb falls (because it is buffering the additional acid)
- Mismatch means that there is more than one acid/base disturbance
