Renal Tubular Acidosis

Question 1

Metabolic acidosis, hyopkalemia and a urine pH >5.5

• type of tubular acidosis?
• mecahnism?
• cause?
• increased risk of…?

Answer 1

Distal (type 1) tubular acidosis

• defect in ability of alpha intercalated cells to secrete H+
• No new HCO3- is generated

causes: amphotericin B toxicity, analgesic nephropathy, congenital anomalies (obstruction) of urinary tract

increase risk for calcium phosphate kidney stones

Question 2

metabolic acidosis, Hypokalemima and a

pH less than 5.5

Answer 2

Proximal (Type 2) tubular acidosis

• defect in PCT HCO3- reabsorption
• increase excretion of HCO3- and subsequent metabolic acidosis

-Causes: Fanconi syndrome and carbonic anhydrase inhibitors

Increased risk for hypophosphatemic rickets

Question 3

Hyperkalemia and urine pH less than 5.5

Answer 3

Hypoaldoseronism

Decrease NH3 synthesis in PCT; decrease NH4+ excretion

causes: decrease in aldosterone production or aldosterone resistance