Renal Tubular Acidosis

Question 1

types

Answer 1

distal renal tubular acidosis (type 1)
proximal renal tubular acidosis (type 2)
hyperkalemic tubular acidosis (type 4)

Question 2

defect in type 1 renal tubular acidosis

Answer 2

inability of α-intercalated cells to secrete H+ -> no new HCO3- is generated -> metabolic acidosis

Question 3

urine pH in type 1 RTA

Answer 3

> 5.5

Question 4

serum K in type 1 RTA

Answer 4

decrease

Question 5

causes of type 1 RTA

Answer 5

amphotericin B toxicity, analgesic nephropathy, congenital anomalies (obstruction) of urinary tract, autoimmune diseases (SLE)

Question 6

associations with type 1 RTA

Answer 6

increase risk for calcium phosphate kidney stones (due to increase urine pH and increase bone turnover)

Question 7

defect in type 2 RTA

Answer 7

defect in PCT HCO3- reabsorption -> increase excretion of HCO3- in urine -> metabolic acidosis
urine can be acidified by α-intercalated cells in collecting duct, but not enough to overcome the increased excretion of HCO3- -> metabolic acidosis

Question 8

urine pH in type 2 RTA

Answer 8

< 5.5

Question 9

serum K in type 2 RTA

Answer 9

decrease

Question 10

causes of type 2 RTA

Answer 10

fanconi syndrome, multiple myeloma, carbonic anhydrase inhibitors

Question 11

associations of type 2 RTA

Answer 11

increase risk for hypophosphatemic rickets (in Fanconi syndrome)

Question 12

defect in type 4 RTA

Answer 12

hypoaldosteronism or aldosterone resistance; hyperK -> decrease NH3 synthesis in PCT -> decrease NH4+ excretion

Question 13

urine pH in type 4 RTA

Answer 13

< 5.5 (or variable)

Question 14

serum K in type 4 RTA

Answer 14

increase

Question 15

cauess of type 4 RTA

Answer 15

decrease aldosterone production from diabetic hyporenism, ACEi, ARBs, NSAIDs, heparin, cyclosporine, adrenal insufficiency or aldosterone resistance (K+ sparing diuretics, nephropathy due to obstruction, TMP-SMX)