Autosomal-dominant medullary cystic kidney disease type 1: clinical and molecular findings in six large Cypriot families.
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BACKGROUND: Autosomal-dominant medullary cystic kidney disease (ADMCKD), a hereditary chronic interstitial nephropathy, recently attracted attention because of the cloning or mapping of certain gene loci, namely NPHP1, NPHP2 and NPHP3 for familial juvenile nephronophthisis (NPH) and MCKD1 and MCKD2 for the adult form of medullary cystic kidney disease. Our aim was to present and discuss the clinical, biochemical, sonographic and histopathological findings in six large Cypriot families in whom molecular analysis has confirmed linkage to the MCKD1 locus on chromosome 1q21. METHODS: The clinical, biochemical, sonographic and histopathological findings in 186 members of six large Cypriot families with ADMCKD-1 are presented. Creatinine clearance was calculated according to the Cockroft-Gault formula and was corrected to a body surface area (BSA) of 1.73 m2. DNA linkage analysis was performed with previously identified flanking polymorphic markers. RESULTS: This disease is characterized by the absence of urinary findings in the vast majority of patients, leading to end-stage renal failure (ESRF) at a mean age of 53.7 years. Hypertension and hyperuricemia are common, especially in males, the former encountered more frequently in advanced chronic renal failure (CRF). Gout has been noted in a small percentage of male patients. Loss of urinary concentrating ability was not a prominent early feature of the disease, while severe natriuresis was observed in a few males toward ESRF. Renal cysts are mainly corticomedullary or medullary, and they are present in about 40.3% of patients and appear more frequently near ESRF. CONCLUSION: ADMCKD type 1 is a common cause of ESRF among our dialysis population. The disease is difficult to diagnose clinically, particularly in the early stage when renal cysts are not usually present, making them a weak diagnostic finding. A dominant pattern of inheritance and DNA linkage analysis are helpful in the diagnosis of this disease. (+info)
Elevated serum leptin concentrations in women with hyperuricemia.
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The serum uric acid level has been said to be an independent predictor of cardiovascular disease death, mainly for women, and to be linked with the metabolic Syndrome X of insulin resistance, obesity, hypertension, and dyslipidemia. Recently, it has been suggested that the elevation of serum leptin, the ob gene product, may have a role in metabolic Syndrome X. Therefore, we studied the relationship of uric acid to leptin in 822 Japanese women in a cross-sectional manner. To estimate the effect of uric acid on the variables of metabolic Syndrome X, we calculated mean values of various components of the syndrome according to tertiles of uric acid (UA < 4.0 mg/dl, 4.0 < or = UA < 5.5, 5.5 < or = UA). Age, systolic and diastolic blood pressure (BP), body mass index (BMI), percent body fat mass (BFM), serum total cholesterol, triglyceride, atherogenic index, leptin, fasting immunoreactive insulin and homeostasis model assessment-ratio (HOMA-R: calculated insulin resistance) were significantly different across the uric acid tertiles with higher levels in the highest tertile in comparison to the first (ANOVA, p < 0.001, 0.001, 0.002, 0.001, 0.001, 0.025, 0.001, 0.001, 0.001, 0.001, 0.001, respectively), while high density lipoprotein cholesterol showed lower levels (p < 0.001). Serum leptin concentrations were also elevated in hyperuricemic women after adjusting for BMI or BFM (both p < 0.001), and were weakly correlated with serum uric acid concentrations (r = 0.22, p < 0.0001). BMI, HOMA-R, serum triglyceride, diastolic BP and age-adjusted serum leptin concentrations were calculated for each tertile of serum uric acid. Compared with the lowest tertile of uric acid level, BMI, HOMA-R, serum triglyceride, diastolic BP and age-adjusted leptin concentrations were higher in the highest tertile. In the stepwise regression analysis, serum leptin was the significant independent variable for uric acid values. These results indicate an independent relationship between leptin and uric acid, further supporting the involvement of leptin in metabolic Syndrome X. (+info)
Acute myeloid leukemia complicated with staghorn calculus.
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An 11-year-old girl who presented with hyperleukocytosis accompanied by significant increases in serum uric acid and lactate dehydrogenase levels was discovered to be suffering from acute myeloid leukemia (AML). Subsequently a staghorn calculus was identified 22 months after the start of chemotherapy. The diagnosis of staghorn calculi was suggested by plain abdominal X-ray and ultrasonography. This paper describes the course of an adolescent patient with AML and focuses specifically upon her urological complications. To the best of our knowledge, this is the first reported pediatric case of AML complicated with staghorn calculi, which developed following repeated episodes of septicemia. (+info)
A role for uric acid in the progression of renal disease.
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Hyperuricemia is associated with renal disease, but it is usually considered a marker of renal dysfunction rather than a risk factor for progression. Recent studies have reported that mild hyperuricemia in normal rats induced by the uricase inhibitor, oxonic acid (OA), results in hypertension, intrarenal vascular disease, and renal injury. This led to the hypothesis that uric acid may contribute to progressive renal disease. To examine the effect of hyperuricemia on renal disease progression, rats were fed 2% OA for 6 wk after 5/6 remnant kidney (RK) surgery with or without the xanthine oxidase inhibitor, allopurinol, or the uricosuric agent, benziodarone. Renal function and histologic studies were performed at 6 wk. Given observations that uric acid induces vascular disease, the effect of uric acid on vascular smooth muscle cells in culture was also examined. RK rats developed transient hyperuricemia (2.7 mg/dl at week 2), but then levels returned to baseline by week 6 (1.4 mg/dl). In contrast, RK+OA rats developed higher and more persistent hyperuricemia (6 wk, 3.2 mg/dl). Hyperuricemic rats demonstrated higher BP, greater proteinuria, and higher serum creatinine than RK rats. Hyperuricemic RK rats had more renal hypertrophy and greater glomerulosclerosis (24.2 +/- 2.5 versus 17.5 +/- 3.4%; P < 0.05) and interstitial fibrosis (1.89 +/- 0.45 versus 1.52 +/- 0.47; P < 0.05). Hyperuricemic rats developed vascular disease consisting of thickening of the preglomerular arteries with smooth muscle cell proliferation; these changes were significantly more severe than a historical RK group with similar BP. Allopurinol significantly reduced uric acid levels and blocked the renal functional and histologic changes. Benziodarone reduced uric acid levels less effectively and only partially improved BP and renal function, with minimal effect on the vascular changes. To better understand the mechanism for the vascular disease, the expression of COX-2 and renin were examined. Hyperuricemic rats showed increased renal renin and COX-2 expression, the latter especially in preglomerular arterial vessels. In in vitro studies, cultured vascular smooth muscle cells incubated with uric acid also generated COX-2 with time-dependent proliferation, which was prevented by either a COX-2 or TXA-2 receptor inhibitor. Hyperuricemia accelerates renal progression in the RK model via a mechanism linked to high systemic BP and COX-2-mediated, thromboxane-induced vascular disease. These studies provide direct evidence that uric acid may be a true mediator of renal disease and progression. (+info)
Mutations of the UMOD gene are responsible for medullary cystic kidney disease 2 and familial juvenile hyperuricaemic nephropathy.
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INTRODUCTION: Medullary cystic kidney disease 2 (MCKD2) and familial juvenile hyperuricaemic nephropathy (FJHN) are both autosomal dominant renal diseases characterised by juvenile onset of hyperuricaemia, gout, and progressive renal failure. Clinical features of both conditions vary in presence and severity. Often definitive diagnosis is possible only after significant pathology has occurred. Genetic linkage studies have localised genes for both conditions to overlapping regions of chromosome 16p11-p13. These clinical and genetic findings suggest that these conditions may be allelic. AIM: To identify the gene and associated mutation(s) responsible for FJHN and MCKD2. METHODS: Two large, multigenerational families segregating FJHN were studied by genetic linkage and haplotype analyses to sublocalise the chromosome 16p FJHN gene locus. To permit refinement of the candidate interval and localisation of candidate genes, an integrated physical and genetic map of the candidate region was developed. DNA sequencing of candidate genes was performed to detect mutations in subjects affected with FJHN (three unrelated families) and MCKD2 (one family). RESULTS: We identified four novel uromodulin (UMOD) gene mutations that segregate with the disease phenotype in three families with FJHN and in one family with MCKD2. CONCLUSION: These data provide the first direct evidence that MCKD2 and FJHN arise from mutation of the UMOD gene and are allelic disorders. UMOD is a GPI anchored glycoprotein and the most abundant protein in normal urine. We postulate that mutation of UMOD disrupts the tertiary structure of UMOD and is responsible for the clinical changes of interstitial renal disease, polyuria, and hyperuricaemia found in MCKD2 and FJHN. (+info)
Renal underexcretion of uric acid is present in patients with apparent high urinary uric acid output.
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OBJECTIVE: To compare renal handling of uric acid in patients with primary gout with that of a control group. METHODS: A case-control study of 100 patients with primary gout and 72 healthy controls was undertaken. Creatinine clearance, uric acid clearance, 24-hour uric acid urinary excretion, fractional excretion of uric acid, excretion of uric acid per volume of glomerular filtration, urinary uric acid to creatinine ratio, and glomerular uric acid filtered load were calculated using 24-hour urine samples. After treatment with allopurinol to achieve similar glomerular filtered load of uric acid, patients were again compared with controls. RESULTS: Patients with gout showed lower uric acid clearance, fractional excretion of uric acid, excretion of uric acid per volume of glomerular filtration, and urinary uric acid to creatinine ratio than controls at baseline, when patients showed hyperuricemia. Although the glomerular uric acid filtered load was much higher in patients with gout than controls, 24-hour uric acid excretion was not statistically different. After treatment with allopurinol, and achieving similar uric acid filtered loads, patients still showed lower figures than controls. When patients with 24-hour urinary uric acids levels >700 mg/day were compared with controls, they had lower uric acid clearance and fractional excretion of uric acid than controls, both at baseline and after achieving similar filtered loads with allopurinol therapy. CONCLUSIONS: Renal underexcretion is the main mechanism for the development of primary hyperuricemia in gout, but even patients showing apparent high 24-hour uric acid output show lower uric acid clearance than controls, indicating that relative, low-grade underexcretion of uric acid is at work. (+info)
Long-term efficacy of hyperuricaemia treatment in renal transplant patients.
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BACKGROUND: Although hyperuricaemia and gout are frequently found in renal transplant recipients, little has been published on the efficacy of urate-lowering therapy (ULT) in this patient population. We therefore examine the effects of allopurinol and benziodarone therapy in a cohort of renal transplant patients. METHODS: We reviewed files from a cohort of 1328 patients that received renal transplantation. The selection criteria included: functioning allograft, hyperuricaemia for >12 months or gout, ULT lasting at least 1 year and at least two control measurements after the onset of ULT. Patients on azathioprine were treated with benziodarone to avoid azathioprine-allopurinol interactions. RESULTS: Two-hundred and seventy-nine patients fulfilled the criteria for review. They were treated with 289 courses of ULT: 100 with allopurinol (mean dose: 376 mg/day/dl/min of creatinine clearance) and 189 with benziodarone (mean dose: 73 mg/day). The mean follow-up was 38 months. Both drugs were effective for the control of hyperuricaemia, but benziodarone caused greater reductions in serum uric acid levels, especially when used at mean doses of >75 mg/day. Severe side effects were uncommon, in both the allopurinol and benziodarone groups. CONCLUSIONS: Both allopurinol and benziodarone were effective for the control of hyperuricaemia in renal transplantation. Benziodarone at doses >75 mg/day was more effective than allopurinol in reducing serum uric acid levels and also reduced the risk of azathioprine-allopurinol interactions. (+info)
Fenofibrate enhances urate reduction in men treated with allopurinol for hyperuricaemia and gout.
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OBJECTIVE: To assess the short-term urate-lowering effect of fenofibrate in men on long-term allopurinol therapy for hyperuricaemia and gout. METHODS: Ten male patients (38-74 yr) with a history of chronic tophaceous or recurrent acute gout with hyperuricaemia and on established allopurinol at 300-900 mg/day for > or =3 months were studied in an open-crossover study of fenofibrate therapy. Allopurinol at the established dose was continued throughout the study. Clinical and biochemical assessments (serum urate and creatinine, 24-h urinary excretion of urate and creatinine, liver function tests, creatine kinase and fasting serum lipids) were undertaken at: (i) baseline, (ii) after 3 weeks of once-daily therapy with micronized fenofibrate (Lipantil Micro) at 200 mg and (iii) 3 weeks after fenofibrate was withdrawn. RESULTS: Fenofibrate was associated with a 19% reduction in serum urate after 3 weeks of treatment (mean+/-S.E. 0.37+/-0.04 vs 0.30+/-0.02 mM/l; P=0.004). The effect was reversed after a 3-week fenofibrate withdrawal period (0.30+/-0.02 vs 0.38+/-0.03 mM/l). There was a rise in uric acid clearance with fenofibrate treatment of 36% (7.2+/-0.9 vs 11.4+/-1.6 ml/min, normal range 6-11; P=0.006) without a significant change in creatinine clearance. Both total cholesterol and serum triglycerides were also reduced. No patient developed acute gout whilst taking fenofibrate. CONCLUSIONS: Fenofibrate has a rapid and reversible urate-lowering effect in patients with hyperuricaemia and gout on established allopurinol prophylaxis. Fenofibrate may be a potential new treatment for hyperuricaemia and the prevention of gout, particularly in patients with coexisting hyperlipidaemia or those resistant to conventional therapy for hyperuricaemia. (+info)