Renal tubular acidosis (RTA) can be classified into 3 types: proximal, distal, and hyperkalemic (hypoaldosteronism). Distal (type 1) RTA leads to a non-anion gap metabolic acidosis due to impaired distal acidification of urine. Causes of distal RTA can be divided into primary lesions (hereditary gene mutations) or secondary (eg, autoimmune, nephrotoxins, medications).

• In adults, the most common cause is autoimmune disease, eg, Sjögren syndrome or rheumatoid arthritis, or hypercalciuria. In otherwise healthy adults with unexplained distal RTA, diagnosis of Sjögren syndrome should be considered.
• In children, hereditary causes of distal RTA are most common and are due to genetic mutations in the basolateral chloride-bicarbonate exchanger and in the apical hydrogen-ATPase. The autosomal recessive form presents in infancy, whereas the autosomal dominant form typically presents in adolescence or adulthood.
• Both ifosfamide and toluene ingestion can cause distal RTA in children and adults.

Hereditary distal RTA will manifest in children while secondary forms of distal RTA most often manifest in adults.