RTA Flashcards
define proximal RTA
type 2: tubular defect causing impaired bicarb reabsorption, hypokalemia
usually accompanies fanconi syndrome w/ lots of PCT defects- impaired AA, glucose reabsorption as well
why low urine pH w/ proximal RTA at presentation
during acute insult- increased filtered load because of less reabsorption
eventually serum bicarb low enough to reabsorb, distal acidification still intact so urine is acidic
clinical manifestations of pRTA
weakness, bone pain and fractures, impaired growth
describe distal type 1 RTA
hypokalemic- reduced net acid excretion, urine is alkaline
less H+ secretion into lumen means more negative, pulls K+ out and causes hypoK
causes of hypoK distal RTA
H+ ATPase mutations
autoimmune: sjorgen syndrome
drugs: ifosfamide, ampB, Li
hypercalciuria
clinical of distal hypoK RAT
weakness, low growth, calcium phospate kidney stones and nephrocalcinosis
high urine pH, low citrate in urine
CKD
hyperK RTA etiology
anything interfering w/ aldo secretion or activity- decreased ENaC w/ lumen +, less K+ and H+ excretion
how does hyperK contribute to met acidosis
excess serum K moves into cells, exchanges w/ H+ causing cells to perceive alkalosis- they reduce ammoniagenesis and acid excretion
urine pH in hyperK distal RTA
low because H+ are in urine w/o ammonia, distal acidification still not intact
describe voltage dependent hyperK RTA
defect in ENaC or low Na delivery to CCD as in hypovolemia- causes positive lumen (More than in type IV)
marked reduction in proton excretion, urine pH over 6
4 etiologies of voltage dependent hyperK RTA
- severe hypovolemia
- urinary tract obstruction
- sickle cell
- ENaC blockade (amiloride, triamterene, trimethoprim, pentamidine)
how to categorize the 4 RTAs
hypoK:
- acidic urine= proximal type 2
- basic urine= hypokalemic distal type 1
hyperK
- acidic urine: type 4
- basic urine: voltage dependent
describe toulene toxicity
mimics distal RTA- hippuric acid is excreted in urine and cause hypovolemia
