A Case Report of Atypical Presentation of Distal Renal Tubular Acidosis in a Pediatric Patient

Primary distal renal tubular acidosis (dRTA) can have varying manifestations. The case report discussed a three-year-old girl diagnosed with dRTA who presented with symptoms including polyuria, failure to thrive, and developmental delays. Despite being treated with vitamin D and calcium for rickets for a period of three months, her condition persisted. Initial examinations revealed growth failure, rachitic features, normal calcium levels, low phosphorus, high alkaline phosphatase, and normal parathyroid hormone levels. Further tests indicated a normal anion gap hyperchloremic metabolic acidosis, alkaline urine pH, hypercalciuria, phosphaturia, and proteinuria, alongside ultrasonography showing bilateral nephrocalcinosis.

The diagnosis was complicated by both proximal and distal tubular features, and she was initiated with potassium citrate and phosphorus supplementation. A three-month follow-up showed normalization of potassium and phosphorus levels, allowing for the cessation of phosphorus replacement. Genetic testing confirmed a pathogenic variant in ATP6V1B1.  She was treated with potassium citrate supplementation alone.

The report emphasizes that dRTA can present with atypical features and can potentially delay the diagnosis. Proximal tubular abnormalities often normalize with therapy, however, some fibrosis may remain, emphasising the importance of treating hypokalaemia in these patients.

Thus, the case highlights the importance of follow-up evaluations and genetic testing for accurate diagnosis in patients with dRTA as these may present with features of both proximal and distal tubular involvement at initial presentation.

Source: Akanksha, Banerjee S, Bala A, Kushwah S, Dawman L, Yadav J. Atypical Presentation of Distal Renal Tubular Acidosis in a Child. Indian J Pediatr. 2025 Jan;92(1):97. doi: 10.1007/s12098-024-05307-7. Epub 2024 Oct 25. PMID: 39448452.