- Tubular but not glomerular damage
- Primary or Acquired (sickle cell disease, Sjögren’s syndrome, SLE, lithium).
- Type 1 distal RTA - defect in excretion H+
- Type 2 proximal RTA - poor bicarbonate re-absorption
- Type 4 aldosterone deficiency (apparent or real)
↑Cl-, metab acidosis, normal AG, Urinary pH >5.5 (± K+ loss)
Check urinary AG. Metabolic acidosis normally triggers an excretion of ammonia into urine. In RTA kidneys unable to acidify the urine to balance the ammonia being excreted. So in RTA Urinary AG is raised.
Distal (type 1) RTA causes nephrolithiasis, nephrocalcinosis, osteodystrophy, and poor growth in children.
- Oral potassium and bicarbonate replacement
- Refer to nephrologist to investigate