Renal tubular acidosis (RTA)

Question 1

Type 1 (distal)

Answer 1

defect in collecting duct’s ability to excrete H+;
untreated pts have urine pH >5.5.

Associated with hypokalemia
Increased risk for calcium phosphate kidney stone
as a result of increased urine pH and bone reabsorption

Question 2

Type 2 (proximal)

Answer 2

Defect in proximal tubule bicarb reabsorption;
May be seen with Fanconi’s syndrome
Untreated pts typically have urine pH <5.5

Associated with hypokalemia

Increased risk for hypophosphatemic rickets.

Question 3

Type 4 (hyperkalemic)

Answer 3

Hypoaldo or lack of collecting tubule response to aldo

The resulting hyperkalemia impairs amminogenesis in the proximal tubule, leading to decreased buffering capacity and decreased urine pH.