When a new steady state is reached (new Tmax) all the filtered
HCO 3 will be reabsorped. The condition is characterized by metabolic
acidosis, low plasma HCO 3 , hyperchloraemia, normal acidic urine (less
than 5.2), no bicarbonaturia and normal excretion of ammonium ions and
titratable acids.
Etiology:
PRTA is more rare than distal RTA. The list of causes of PRTA
includes:
- Primary single tubular defect
- Genetic (very rare) • Idiopathic
- Transient in infants
- Autoimmune disease
- Sjogren's Syndrome
- Tubulo-interstitial disease
- Medullary cystic disease • Renal transplant rejection
- Drug and Toxins
- Outdated tetracyclines • Streptozotocin
- Lead, mercury, sulfonamide
- Dysproteinaemia
- Multiple myeloma
- Other renal diseases
- Amyloidosis • Nephrotic Syndrome
Clinical features and diagnosis:
- Usually metabolic acidosis with manifestations of other proximal
tubular defects e.g. Fanconi Syndrome. - Hypokalemia