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Renal Phenotype in Lowe Syndrome: A Selective Proximal Tubular Dysfunction
Background and objectives: Lowe syndrome is defined by congenital cataracts, mental retardation, and proximal tubulopathy and is due to mutations in OCRL. Recently, mutations in OCRL were found to underlie some patients with Dent disease, characterized by low molecular weight proteinuria, hypercalciuria, and nephrocalcinosis. This phenotypic heterogeneity is poorly understood.
Design, setting, participants, & measurements: The renal phenotype of 16 patients with Lowe syndrome (10.9 ± 7.0 yr) under care of the authors was characterized to define overlap of symptoms with Dent disease and infer clues about OCRL function. Medical charts of patients were reviewed for data regarding glomerular filtration rate and markers of proximal tubular function.
Results: All patients had low molecular weight proteinuria and albuminuria. Lysosomal enzymuria was elevated in all 11 patients assessed. Fifteen patients had hypercalciuria, and 14 aminoaciduria. Seven patients required bicarbonate and three required phosphate replacement; all others maintained normal serum values without supplementation. None of the patients had detectable glycosuria, and none had clinically overt rickets. GFR was mildly to moderately impaired and highly variable, with a trend of deterioration with age.
Conclusions: Patients with Lowe syndrome do not have renal Fanconi syndrome but a selective proximal tubulopathy, variable in extent and dominated by low molecular weight proteinuria and hypercalciuria, the classical features of Dent disease. These findings suggest that OCRL and ClC-5, the chloride channel mutated in Dent disease, are involved in similar reabsorption pathways in the proximal tubule.
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Age-related Blood Pressure Patterns and Blood Pressure Variability among Hemodialysis Patients
Background and objectives: Despite the high prevalence of cardiovascular disease among hemodialysis patients, the relationship between age and blood pressure (BP) is not well understood. It was postulated that the relationship of BP to age differs among hemodialysis patients versus the general population and that there is significant variability in dialysis unit BP measurements.
Design, setting, participants, & measurements: To explore this hypothesis, the patterns of systolic, diastolic, mean arterial, and pulse pressures in the general population using data from National Health and Nutrition Examination Survey participants (n = 9242) were compared with those in a cohort of hemodialysis patients (n = 9849).
Results: In contrast to the increase in systolic BP with age in the general population, systolic BP was elevated in young hemodialysis patients and declined slightly among the elderly. The inverted "U"-shape relationship between age and diastolic BP in the general population was absent in hemodialysis patients. Diastolic BP was elevated among hemodialysis patients <50 yr of age and declined with advancing age. Mean arterial and pulse pressures were elevated among young hemodialysis patients and exhibited less age dependency than in the general population. Variability in BP within patients was similar to that between patients.
Conclusions: The relationship of BP to age differed from that in the general population. The variability in dialysis unit BP measurements may limit their use in managing hypertension and predicting outcomes. Nevertheless, dialysis unit BP measurements are necessary to minimize acute complications during the dialysis procedure.
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Chronic Kidney Disease Heightens Medical-Error Risk - MedPage Today
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Hepcidin: A New Tool in the Management of Anaemia in Patients with Chronic Kidney Disease?
Hepcidin is a newly discovered protein that plays an important role in iron metabolism. Learn more about its potential uses for anemia management in chronic kidney disease.
Nephrology Dialysis Transplantation
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Reasons for, and the need to address, low fistula use in US hemodialysis patients
Reasons for, and the need to address, low fistula use in US hemodialysis patients
Nature Clinical Practice Nephrology 4, 468 (2008). doi:10.1038/ncpneph0873
