Seminars in nephrology
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It has been known for decades that urinary potassium excretion varies with a circadian pattern. In this review, we consider the historical evidence for this phenomenon and present an overview of recent developments in the field. ⋯ We propose the circadian clock mechanism as a key regulator of renal potassium transporters, and consequently renal potassium excretion. Further investigation into the regulation mechanism of renal potassium transport by the circadian clock is warranted to increase our understanding of the clinical relevance of circadian rhythms to potassium homeostasis.
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During the past century, investigators have increased our understanding of renal potassium excretion significantly using many techniques. Notable among these were renal clearance experiments, renal micropuncture, isolated tubule microperfusion, and electrophysiological and patch clamp analysis. These experiments have been made possible by technical advances that have allowed the measurement of potassium in progressively smaller quantities. ⋯ Additional micropuncture and microperfusion studies showed that a component of potassium secreted by the distal cortical nephron and cortical collecting duct is reabsorbed in the medullary collecting duct, which results in renal medullary potassium recycling. Studies have defined the cellular and molecular mechanisms responsible for potassium secretion and potassium reabsorption in the collecting duct. Further understanding of renal potassium handling will require integrated investigation of the renal and extrarenal signaling systems that control these transport mechanisms.
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Seminars in nephrology · Nov 2012
ReviewHigh-output heart failure: how to define it, when to treat it, and how to treat it.
Although hemodialysis patients who initiate and maintain a permanent form of dialysis vascular access have improved all-cause and cardiovascular survival compared with those who use catheters, the presence of an arteriovenous fistula has been shown to have a short-term, adverse effect on cardiac function. Through its effect as a left-to-right extracardiac shunt, the arteriovenous fistula can increase cardiac workload substantially, and, in certain patients, result in a high-output state and resultant heart failure over time. Here we review the mechanisms by which dialysis arteriovenous access may promote the development of high-output cardiac failure in end-stage renal disease patients, describe risk factors for and the diagnosis of high-output heart failure, and suggest management strategies for patients who develop high-output heart failure.
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Seminars in nephrology · Jan 2012
Diagnosis and management of fluid overload in heart failure and cardio-renal syndrome: the "5B" approach.
Cardio-Renal syndrome may occur as a result of either primarily renal or cardiac dysfunction. This complex interaction requires a tailored approach to manage the underlying pathophysiology while optimizing the patient's symptoms and thus providing the best outcomes. Patients often are admitted to the hospital for signs and symptoms of congestion and fluid overload is the most frequent cause of subsequent re-admission. ⋯ This stands for balance of fluids (reflected by body weight), blood pressure, biomarkers, bioimpedance vector analysis, and blood volume. Addressing these parameters ensures that the most important issues affecting symptoms and outcomes are addressed. Furthermore, the patient is receiving the best possible care while avoiding unwanted side effects of the treatment.
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Seminars in nephrology · Jan 2012
Neutrophil gelatinase-associated lipocalin curve and neutrophil gelatinase-associated lipocalin extended-range assay: a new biomarker approach in the early diagnosis of acute kidney injury and cardio-renal syndrome.
Cardio-Renal syndrome (CRS) is a common and complex clinical condition in which multiple causative factors are involved. The time window between renal insult and development of acute kidney injury (AKI) in acute heart failure (AHF) can be varied in different patients and AKI often is diagnosed too late, only when the effects of the insult become evident with a loss or decline of renal function. For this reason, pharmaceutical interventions for AKI that have been shown to be renoprotective or beneficial when tested in experimental conditions do not display similar results in the clinical setting. ⋯ We propose that NGAL may increase its usefulness in the diagnosis and prevention of CRS if a curve of plasma values rather than a single plasma measurement is determined. To apply the concept of measuring an NGAL curve in AHF patients, however, assay performance in the lower-range values becomes a critical factor. For this reason, we propose the use of the new extended-range plasma NGAL assay that may contribute to remarkably improve the sensitivity of AKI diagnosis in AHF and lead to more effective intervention strategies.