Abstract
BackgroundIdiopathic renal hypouricemia (iRHUC) is an autosomal recessive hereditary disorder, characterized by impaired tubular uric acid transport, re-absorption insufficiency and/or the acceleration of secretions. Some patients present with severe complications, such as exercise-induced acute kidney injury (EIAKI) and nephrolithiasis.Case presentationHerein, we report the case of a girl with severe iRHUC (serum urate 0.05 mg/dL, fractional excretion of uric acid 295.99%) associated with recurrent EIAKI, in whom the disease was caused by a homozygous mutation (g.68G > A in exon 3) in the SLC2A9 gene. Her family members (father, mother and brother) carried the same mutation but were heterozygous, without any signs of severe hypouricemia.ConclusionsOur findings indicate that iRHUC is a rare disorder but that it should also be considered in patients with EIAKI, especially in those patients who manifest with moderately elevated or normal serum concentrations of uric acid during the acute phase of AKI. Mutational screening of the SLC2A9 gene is necessary for the diagnosis of iRHUC, and homozygous mutations of the SLC2A9 alleles can cause severe hypouricemia. Careful attention should be paid to any signs of hypouricemia during the recovery phase of AKI and long-term follow-up.
Highlights
Idiopathic renal hypouricemia is an autosomal recessive hereditary disorder, characterized by impaired tubular uric acid transport, re-absorption insufficiency and/or the acceleration of secretions
Our findings indicate that Idiopathic renal hypouricemia (iRHUC) is a rare disorder but that it should be considered in patients with exercise-induced acute kidney injury (EIAKI), especially in those patients who manifest with moderately elevated or normal serum concentrations of uric acid during the acute phase of Acute kidney injury (AKI)
Mutational screening of the SLC2A9 gene is necessary for the diagnosis of iRHUC, and homozygous mutations of the SLC2A9 alleles can cause severe hypouricemia
Summary
IRHUC is a rare disorder, but it should be considered in patients with EIAKI, especially in those patients who manifest moderately elevated or normal serum concentrations of uric acid during the acute phase of AKI. To any signs of hypouricemia during the recovery phase Competing interests of AKI and during long-term follow-up. The authors declare that they have no competing interests. For classification according to the rate of decline of glomerular filtration rate, CKD is staged as blow: Stage 1: GFR ≥ 90 ml/min/1.73 m2 Stage 2: GFR 60 ~ 89 ml/min/1.73 m2 Stage 3a: GFR 45 ~ 59 ml/min/1.73 m2 Stage 3b: GFR 30 ~ 44 ml/min/1.73 m2 Stage 4: GFR 15 ~ 29 ml/min/1.73 m2 Stage 5: GFR < 15 ml/min/1.73 m2 or on dialysis. Authors’ contributions SHJ, FCY, JX & FHD carried out the molecular genetic studies, participated in the sequence alignment and drafted the manuscript. WX & LAM participated in the clinical diagnosis of the patient. SQ & DLZ participated in the sequence alignment. SHJ & MJH participated for program design, manuscript drafting.
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