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Background Hyperuricemia contributes to decrease in kidney function and induces additional renal damage in children with acute kidney injury (AKI). Rasburicase oxidizes uric acid (UA), decreasing its serum quantities in less than 24 h. Methods This is a retrospective study involving hospitalized patients under 18 years of age with underlying pathology diagnosed with AKI and severe hyperuricemia treated with rasburicase over a 4-year period. Results We describe 15 patients from 4 days of life to 18 years (median: 4.4 years). Seventy-three percent had known underlying pathologies. All presented worsening of basal renal function or AKI data. All received the usual medical treatment for AKI without response. Twenty percent received an extrarenal depuration technique. All had hyperuricemia with a mean (± SD) of 13.1 (± 2.19) mg/dl. After rasburicase administration UA levels fell to a mean (± SD) of 0.76 (± 0.62) mg/dl (p < 0.001) in less than 24 h. In parallel, a decrease in the mean plasma creatinine was observed (2.92 mg/dl to 1.93 mg/dl (p = 0.057)) together with a significant improvement of the mean glomerular filtration rate (16.3 ml/min/1.73 m2 to 78.6 ml/min/1.73 m2) (p = 0.001)). No side effects were recorded. Kidney function normalized in all cases or returned to baseline levels. Conclusions Although the use of rasburicase is not routinely approved in pediatric patients with severe hyperuricemia and AKI, it has been used successfully without complications, and helped prevent progressive kidney damage. This study could serve as a basis for suggesting the off-label use of rasburicase for the management of complex pediatric patients in whom UA plays an important role in the development of AKI.

[ES] La acidosis tubular renal distal (ATRD) es una enfermedad rara que se debe al fallo del proceso normal de acidificación de la orina a nivel tubular distal y colector. Se caracteriza por una acidosis metabólica hiperclorémica persistente, con anión gap normal en plasma,en presencia de un pH urinario elevado y baja excreción urinaria de amonio.Se han descrito hasta el momento 5 genes cuyas mutaciones dan lugar a ATRD primaria.Las alteraciones de los genes ATP6V1B1 y ATP6V0A4 se heredan de forma recesiva y están asociadas a formas de inicio más precoces y con sordera neurosensorial en muchos casos.Las variantes patogénicas en el gen SLC4A1 se heredan habitualmente de forma dominante y dan lugar a cuadros más leves, con un diagnóstico más tardío y alteraciones electrolíticas menores. Sin embargo, la evolución a nefrocalcinosis y litiasis, y el desarrollo de enfermedadrenal crónica a medio-largo plazo se ha descrito de forma similar en estos 3 grupos. Por último, se han descrito también formas recesivas de ATRD asociadas a mutaciones en los genes FOXI1 y WDR72. El manejo clínico de la ATRD se basa en sales de bicarbonato o citrato, que no logran corre-gir en todos los casos las alteraciones metabólicas descritas y, por lo tanto, las consecuencias asociadas a ellas. Recientemente, un nuevo tratamiento basado en sales de bicarbonato y citrato de liberación prolongada ha recibido la denominación de medicamento huérfano en Europa para el tratamiento de la ATRD., [EN] Distal renal tubular acidosis (DRTA) is a rare disease resulting from a failure in the normal urine acidification process at the distal tubule and collecting duct level. It is characterised by persistent hyperchloremic metabolic acidosis, with a normal anion gap in plasma, in the presence of high urinary pH and low urinary excretion of ammonium. To date, 5 genes whose mutations give rise to primary DRTA have been described. Altera- tions in the ATP6V1B1 and ATP6V0A4 genes are inherited recessively and are associated with forms of early onset and, in many cases, with neurosensorial deafness. Pathogenic variants in the SLC4A1 gene are habitually inherited dominantly and give rise to milder symptoms, with a later diagnosis and milder electrolytic alterations. Nonetheless, evolution to neph- rocalcinosis and lithiasis, and the development of chronic kidney disease in the medium to long term has been described in a similar manner in all 3 groups. Lastly, recessive forms of DTRA associated to mutations in the FOXI1 and WDR72 genes have also been described. The clinical management of DTRA is based on bicarbonate or citrate salts, which do not succeed in correcting all cases of the metabolic alterations described and, thus, the consequences associated with them. Recently, a new treatment based on slow-release bicarbonate and citrate salts has received the designation of orphan drug in Europe for the treatment of DTRA.