Contributions to nephrology
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Stroke is a leading cause of mortality and morbidity worldwide. Traditional cardiovascular risk factors - hypertension, diabetes and dyslipidemia - are related to the incidence of stroke. Chronic kidney disease has also been recognized to be a major public health problem as a cardiovascular risk factor. ⋯ Chronic kidney disease may also be associated with an increase in nontraditional risk factors such as hyperhomocysteinemia, inflammation, asymmetric dimethylarginine, oxidative stress, and anemia, and thrombogenic factors such as left ventricular hypertrophy, endothelial dysfunction, and arterial stiffness. Herein, we review the results of meta-analyses of published cohort studies for a better understanding of the precise nature of the relationship between chronic kidney disease and stroke, important to both the clinical and public health fields. Further studies are warranted to determine whether interventions to prevent the progression of kidney impairment are effective at reducing the risk of stroke.
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Acute kidney injury (AKI) is a common but complex clinical syndrome with multiple etiologies. These etiologies target different sites and pathways within the kidney. Novel biomarkers of 'kidney damage' (which can be tubular or glomerular) can be used to diagnose AKI, even in the absence of an increase in serum creatinine or oliguria. ⋯ The presence of underlying CKD or of sepsis poses additional challenges in differential diagnosis, since these conditions alter both baseline biomarker excretion and biomarker performance. We recommend that biomarkers be validated within the clinical context in which they are to be used. Within that context, combinations of biomarkers may, in the future, allow differentiation of the site, mechanism and phase of injury.
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The parathyroid gland plays a central role in the regulation of mineral metabolism. In patients with chronic kidney disease (CKD), circulating levels of parathyroid hormone (PTH) are progressively increased as kidney function declines, as a result of phosphate retention, hypocalcemia, decreased production of 1,25-dihydroxyvitamin D [1,25(OH)2D], endogenous changes within the parathyroid gland, and skeletal resistance to the actions of PTH. In addition, the identification of fibroblast growth factor 23 (FGF23) and its cofactor Klotho offers important implications for the deeper understanding of disordered mineral metabolism in CKD. ⋯ FGF23 also acts directly on the parathyroid to decrease PTH synthesis and secretion, but this effect is blunted in advanced stages of CKD, due to decreased expression of the Klotho-FGF receptor 1 complex and increased concentrations of C-terminal FGF23 that competes with full-length FGF23 for binding to the receptor complex. Recent clinical studies also reported that high levels of FGF23 are associated with morbidity and mortality as well as treatment resistance to active vitamin D, suggesting the potential of FGF23 as a novel biomarker to guide treatment of disordered phosphate metabolism in CKD. This review will discuss the pathogenesis of secondary hyperparathyroidism, particularly focusing on the emerging role of the FGF23-Klotho axis in patients with CKD.
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Chronic kidney disease and atrial fibrillation (AF) commonly coexist, and data suggest that renal patients have AF rates in excess of double that encountered in the general population. These patients are at increased risk of stroke, regardless of the presence or absence of AF. Furthermore, a lower GFR causes increased thromboembolic risk in patients with AF - independent of other risk factors. ⋯ The new oral anticoagulants have relatively little data in patients with severe renal impairment, and all have an element of renal excretion. There is a need for large randomised control trials in patients with renal insufficiency and on haemodialysis to provide a bank of high-quality scientific data on which clinicians can base their management decisions. Until then, we must adopt a pragmatic approach which involves careful consideration of the relative risk of stroke and bleeding in each individual patient.
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Acute kidney injury (AKI) commonly occurs in hospitalized patients and is independently and strongly associates with morbidity and mortality. The clinical benefits of a timely and definitive diagnosis of AKI have not been fully realized due to limitations imposed by the use of serum creatinine and urine output to fulfill diagnostic criteria. These restrictions often lead to diagnostic delays, potential misclassification of actual injury status, and provide little information regarding underlying cause. ⋯ Promising diagnostic injury markers include neutrophil gelatinase-associated lipocalin (NGAL), kidney injury molecule 1 (KIM-1), interleukin 18 (IL-18) and liver-type fatty acid binding protein (L-FABP). However, there are currently insufficient data on damage biomarkers to support their use for AKI staging. Rigorous validation studies measuring the association between the novel damage biomarker(s) and clinically relevant outcomes are needed.