A Case Report of Familial Renal Hypouricemia Confirmed by Genotyping of SLC22A12, and a Literature Review

A 24-year-old male visited our hospital because of pain in both flanks. His biochemistry profile showed an elevated serum creatinine level and low serum uric acid level. History taking revealed that he had undertaken exercise prior to the acute kidney injury (AKI) event, and he stated that family members had a history of urolithiasis. His renal profile improved after hydration and supportive care during hospitalization. Although the patient was subsequently admitted again due to AKI, his status recovered with similar treatment. Since the diagnosis of the patient was familial renal hypouricemia with exercise-induced AKI, we performed genotyping of SLC22A12, which encodes human urate transporter 1. The diagnosis was confirmed by the detection of a homozygous mutation of W258X. We herein, report a case of familial renal hypouricemia confirmed by genotyping of SLC22A12, and review the relevant literature.

Clinical characteristics of acute renal failure with severe loin pain and patchy renal vasoconstriction

BACKGROUND: Acute renal failure (ARF) with severe loin pain and patchy renal vasoconstriction (PRV) is a syndrome presenting with sudden loin pain after anaerobic exercise. We aimed to investigate the clinical characteristics and the efficacy of diagnostic imaging studies of patients with this syndrome. METHODS: We retrospectively selected 17 patients with ARF accompanied by loin or abdominal pain who showed multiple patchy wedge-shaped delayed contrast enhancements on a computerized tomography scan. Information about the clinical characteristics, including the nature of pain and combined symptoms, suspected causes, such as exercise, drug or alcohol intake, and renal hypouricemia, and the results of laboratory and imaging tests were gathered. RESULTS: The mean age of patients with episodes of ARF accompanied by loin pain was 23.0+/-6.5 (range 16-35) years old. Pain was mainly located in the loin (70.6%) or abdominal area (76.5%) and continued for approximately 3.5+/-4.0 days. Exercise was suspected as a primary cause of disease in 12 (70.6%) patients. Maximal serum creatinine was 5.42+/-3.16 (1.4-12.1) mg/dL 3.1+/-1.8 (1-7) days after the onset of pain. The peak level of serum uric acid was 9.41+/-2.91 (6.0-15.8) mg/dL. All of the patients recovered to near-normal renal function, and one patient showed hypouricemia after recovery. CONCLUSION: ARF with severe loin pain and PRV can present with loin or abdominal pain, even without a history of anaerobic exercise. Careful history taking and appropriate imaging studies are critical in the diagnosis and management of this syndrome.

A Case of Recurrent Exercise-Induced Acute Renal Failure and Renal Hypouricemia with R90H Mutation in a SCL22A12 Gene / 영남의대학술지

Acute renal failure with severe loin pain and patch renal ischemia after anaerobic exercise (ALPE) is a rare cause of exercise-induced acute kidney injury. Some ALPE patients also have renal hypouricemia. Mutations in the SCL22A12 gene are among the major factors of hypouricemia. Education for the prevention of relapse and genetic counseling should be recommended to ALPE patients with renal hypouricemia. This paper reports a 25-year-old man who showed recurrent exercise-induced ARF and renal hypouricemia with R90H mutation in his SCL22A12 gene.

A Case of Exercise-induced Acute Renal Failure with G774A Mutation in SCL22A12 Causing Renal Hypouricemia

Acute renal failure with severe loin pain which develops after anaerobic exercise is rare. One of predisposing factors of exercise-induced acute renal failure is renal hypouricemia. Idiopathic renal hypouricemia is a genetic disorder characterized by hypouricemia with abnormally high renal tubular uric acid excretion. The mutation in SCL22A12 gene which encodes renal uric acid transporter, URAT1, is the known major cause of this disorder. We here described a 25-yr-old man showing idiopathic renal hypouricemia with G774A mutation in SCL22A12 who presented exercise-induced acute renal failure. There have been a few reports of mutational analysis in Korean idiopathic renal hypouricemia without acute renal failure. This is the first report of genetically diagnosed idiopathic renal hypouricemia with exercise-induced acute renal failure in Korea.

A case of idiopathic renal hypouricemia / 소아과

Idiopathic renal hypouricemia is a disorder characterized by impaired urate handling in the renal tubules. This disease usually produces no symptoms, but hematuria, uric acid nephrolithiasis or acute renal failure may develop. A defect in the SLC22A12 gene, which encodes the human urate transporter, is the known major cause of this disorder. We describe a 10-month-old boy with idiopathic renal hypouricemia. He was diagnosed with transient pseudohypoaldosteronism at admission, but hypouricemia was accidentally found through follow-up study. By gene analysis, his diagnosis was confirmed to idiopathic renal hypouricemia. In addition, we report a mutation in the human urate transporter 1 (hURAT1) gene identified in his family.

Exercise-induced Acute Renal Failure in a Patient with Renal Hypouricemia / 대한신장학회잡지

We report a case of exercise-induced acute renal failure associated with renal hypouricemia in a 35- year-old man who complained of oliguria and back pain after swimming. Laboratory tests revealed that serum blood urea nitrogen and creatinine level were elevated, the serum uric acid concentration was subnormal(2.1 mg/dL). After conservative treatment, renal function was recovered. But, uric acid level decreased to 0.4 mg/dL. In addition, there was no supression of urate clearance to creatinine clearnace ratio(CUA/CCr) following the administration of pyrazinamide, and no increase of CUA/CCr after benzbromarone. Therefore, we think the cause of renal hypouricemia in this patient may be the subtotal defect in the urate transport.

Recurrent Hematuria due to Renal Hypouricemia

A marked low concentration of serum uric acid(0.7-1.2mg/dl) was detected in a 14-year-old boy with recurrent episodes of gross hematuria. The hypouricemia accompanied with a markedly increased urinary clearance of uric acid (32.6-56.0ml/min), which was only minimally changed after both the administration of pyrazinamide, and inhibitor of the renal tubular secretion of uric acid, and the administration of probenecid, and inhibitor of the renal tubular reabsorption of uric acid. Other renal tubular functions were normal. There were no other family members with hypouricemia. Thies is the first case report of isolated renal hypouricemia due to presecretory reabsorption defect of uric acid in the renal proximal tubule in Korea. And renal hypouricemia should be included in the diagnosis of hematuria.