Abstract 13: Isolated bicarbonaturia: A rare case of proximal renal tubular acidosis

Case Report: A 9 years old girl presented to us with progressive bowing of legs since 2 years of age and failure to gain height since 5 years of age. She had previously received calcium and Vitamin D supplements multiple times since the age of 2 years. Her parents noticed knock knees since 5 years of age. She had undergone corrective surgery for deformity before admission. On examination, Bone age <Height age< Chronological age. Height was less than 3(rd) percentile and weight was 50(th) percentile. On evaluation, she had hyperchloremic normal anion gap metabolic acidosis and positive urinary anion gap, no evidence of nephrocalcinosis. She was having bicarbonaturia but no glucosuria, aminoaciduria, phosphaturia. So possibly a case of isolated bicarbonaturia. For this, a more common candidate gene SLC4A4 mutation was tested but was negative. Since there can be many other candidate genes involved, testing each and every potential gene couldn’t be done. Meanwhile patient was started on sodium bicarbonate, calcitriol, calcium and vitamin D supplementation. Conclusion: As an isolated defect for bicarbonate transport, proximal RTA is rare and is more often associated with Fanconi syndrome. Many candidate genes could be involved in the etiology yet to be discovered.