Renal Tubular Acidosis (RTA)

Proximal RTA (Type 2 RTA): 

• ·         Generalized Proximal Tubular dysfunction.
• ·         Manifested by glycosuria, generalized aminoaciduria, and phosphaturia  (Fanconi syndrome).
• ·         Therapy with NaHCO₃ causes hypokalemia.
• ·         Drug induced: Acetazolamide, topiramate

Treatment:

1. ·         Sodium and Potassium citrate syrup (citric acid 334mg, sodium citrate 500mg, potassium citrate 550mg per 5ml)
2. ·         Syrup preparation is not recommended for chronic administration.

 

Classic Distal RTA (Type 1 RTA):

• ·         Hypokalemia, a non-AG metabolic acidosis, low urinary NH₄⁺ excretion, inappropriately high urine pH (pH > 5.5).
• ·         Hypocitraturia, hypercalciuria, so nephrolithiasis, neprocalcinosis and bone disease are common.
• ·         Drug induced: Amphotericin B, ifofamide

Treatment:

1. ·         Acutely acidotic patient with Hypokalemia: administer potassium.
2. ·         Chronic therapy: Sodium citrate (Shohl’s solution) Or NaHCO₃ tablets ( 650mg tablets contain 7.8 meq).

 

Generalized distal RTA (Type 4 RTA):

·         Hyperkalemia is disproportionate to reduction in GFR, because of co-existing Potassium and acid secretion dysfunction.

·         Urine ammonium excretion depressed, kidney function compromised.

·         Due to diabetic nephropathy, obstructive uropathy or chronic tubulointerstitial disease.

·         Mineralocorticoid deficiency.

·         Mineralocorticoid resistance(PHA 1, autosomal dominant).

·         Voltage defect(PHA 1, autosomal recessive, and PHA 2)

Treatment

·         Chronic therapy: Sodium citrate (Shohl’s solution) OR NaHCO₃ tablets (650mg tablets contain 7.8meq).

·         Potassium Correction:

(i)      Oral sodium polystyrene solfonate (15g of powder prepared as an oral solution and without sorbitol, once daily 2-3 times per week).

(ii)    Loop diuretics

(iii)   Patiromer

·         Adrenal insufficiency: Fludocortisone (should be avoided in Hyporeninemic-hypoaldosteronism).