Clinical Queries: Nephrology最新文献

Term “ischemic nephropathy” (IN) means impairment of renal function beyond occlusive disease of the main renal arteries. Time to ESRD or death does not correlate with renovascular anatomy despite vessels showing varying presentation from non occlusion to stenosis of varying degree. The parenchymal injury is multifactorial in origin ranging from cholesterol emboli, long-standing hypertension to prolonged ischemic damage. Time to intervention in RAS is challenging as efforts must be made at a stage when these ischemic changes are reversible and much before parenchymal injury can happen. The predictors of renal improvement are also still elusive. Unexplained renal failure in the background of uncontrolled hypertension, CAD or PVD or renal function worsening following use of angiotensin-converting enzyme inhibitor (ACEI), flash pulmonary edema are clinical situations associated with IN. The main aim of treatment is to reduce cardiovascular mortality, to improve or stabilize renal function and blood pressure control. Treatment options include medication, surgical reconstruction and transluminal angioplasty with or without stenting. Revascularization should be considered in RAS with rapid worsening of renal function or resistant HTN (four or more antihypertensive agents especially in the setting of CHF or recurrent flash pulmonary edema). When the kidney size is <8.0 cm long or the RI is >0.80, there is little chance of BP improvement or recovery of GFR. Medication having proven role in preventing cardiovascular mortality including statins, renin–angiotensin antagonists, and low dose aspirin are also effective secondary prevention of IN.

Amongst patients with chronic kidney disease (CKD) and end-stage renal disease (ESRD), the leading cause of recurrent hospitalizations and death is cardiovascular diseases. Patients with CKD are more likely to die from cardiovascular causes than due to kidney related manifestations. Irrespective of the baseline renal function, even overt proteinuria and microalbuminuria are independent predictors of cardiovascular morbidity and mortality. Most current guidelines hence recommend that patients with CKD be considered to belong to the highest risk group for the development of cardiovascular diseases.

However there is a significant “therapeutic inertia” and consequent sub-optimal management of patients with ESRD and associated cardiovascular diseases, owing to the fact that many such patients are often excluded in most large trials of cardiovascular morbidity and mortality. Moreover, due to the high incidence of associated coronary artery disease in patients with ESRD, it is important to appropriately risk stratify such patients awaiting renal transplantation. Though optimal screening protocols and frequency of testing have not been well defined, this paper discusses guidelines based practical approaches to cardiovascular risk in these high-risk patients.

Dyslipidemia is a well-established metabolic disorder in patients with chronic kidney diseases (CKD), on dialysis and renal transplant recipient. The elevated serum cholesterol levels have a definite role in the development and progression of atherosclerosis and the correlation between elevated serum LDL cholesterol as a risk factor for development of CHD has been firmly established. The HMG-CoA reductase inhibitors (statins) are the current drugs of choice for the treatment of hypercholesterolemia. The treatment with statins effectively lower total and LDL-cholesterol levels, moderately decreases triglycerides (TGs) levels, and have a little effect in increasing HDL-cholesterol levels. The statins therapy reduces the morbidity and mortality associated with CHD in patients with normal renal function. However, the beneficial effect of statin therapy on CVD morbidity and mortality in patients with CKD and advanced ESRD are controversial. Statin therapy reduces CVD mortality in patient with early CKD (not yet requiring dialysis) and their use is recommended for patients with early CKD. However, the recent results from the AURORA and SHARP studies have revealed statins treatment provide no CV mortality benefit in patient with advanced CKD or on long-term dialysis. This may be because athermatous coronary artery disease account for a small proportion of the CVD observed in patients with ESRD and/or on dialysis. In addition, advanced CKD result in structural and functional abnormalities of HDL, impaired cholesterol and chylomicron metabolism which leads to accelerated atherosclerosis and CVD in such patients. Collectively, these abnormalities are largely independent of cholesterol biosynthesis, and consequently are not corrected by statin therapy. Therefore lipid lowering therapy in patient with ESRD should be individualized. Atorvastatin and Rosuvastatin are most potent agents among the available statins in cholesterol lowering but are the most expensive. Simvastatin (20 mg/day) should be considered the drug of choice for most patients with chronic kidney disease because it is less expensive. Pravastatin and fluvastatin are the most suitable agents for transplant patients to achieve target cholesterol levels because of the reduced risk of drug interactions.

Renal dysfunction represents a wide spectrum of conditions with various consequences on peri-operative management due to not only the underlying disease processes but also from the intervening medical and surgical therapies. Such patients need optimization prior to surgery. In this regard, this review is focused upon the surgical difficulties faced and peri-operative evaluation of patients who have renal dysfunction. Approximately 1% of patients undergoing surgery are estimated to at risk for AKI with an increased risk in certain patient population. Hospitalization rates in CKD is three times higher while that for acute kidney injury is six time higher than the patients with normal renal function. Complete evaluation is required in patients with renal disease who requires surgery. Currently no guidelines exist for the safe pre-operative potassium and hematocrit levels. To decrease peri-operative mortality and morbidity hemodialysis should be done a day before surgery.

Chronic renal failure (CRF) impairs not only appetite but also impairs immune function, resulting in increased susceptibility to infections and poor wound healing and may predispose to inflammatory diseases. Every strategy should be used to avoid complications of chronic kidney disease (CKD) manifested in uremic state including anorexia, nausea, vomiting leading to malnutrition, fluid and electrolyte imbalance leading to volume overload, hyperkalemia, metabolic acidosis, and hyperphosphatemia, as well as abnormalities related to hormonal or systemic dysfunction such as hypertension, anemia, hyperlipidemia, bone disease, pericarditis, peripheral neuropathy, and central nervous system abnormalities. With decline in GFR, nutrient requirements change. Nutritional status should be assessed periodically. Low protein diets are beneficial for CKD stages 1–5, but nutritional management should be such that the nutritional status is not compromised. In order to maintain proper nutritional status patients on maintenance dialysis require high protein diet. Timely diagnosis of protein-energy-wasting (PEW) is important for early initiation of nutritional intervention and treatment. Management of hypertension, bone mineral disease, fluid overload and gastroparesis should be given prime importance.

Customary risk factors such as hypercholesterolemia, hypertension cannot explain the high cardio vascular morbidity and mortality seen in CKD patients. This has resulted in identifying nontraditional risk factors commonly seen in uremia such as chronic inflammation and oxidative stress. Oxidative stress appears to mediate the effect of inflammation in causing endothelial injury which results in multiple pathological and clinical effects. There are multiple oxidative makers in vivo but they are difficult to assess. Many anti-oxidant therapies including dialysis membrane-coated vitamin E has been tried to reduce oxidative stress in CKD and dialysis patients.

Anemia in chronic kidney disease is a common clinical problem; it is primarily due to decreased production of erythropoietin or iron deficiency state. It is a ramification of decline in functional kidney mass. Recombinant Human Erythropoietin (rHuEPO) and it analogs are the greatest tools against the anemia in chronic kidney disease patients. Last two decades of clinical experience has greatly enhanced our understanding of the potentials as well as limitations of the current EPO based therapeutic practices.

Recent studies have brought forth new therapies like HIF stabilizers, GATA inhibitor and erythropoietin gene therapy into active research in this field. These strategies are still in proof-of-concept stage and further evaluation is ongoing.

This review also briefly touches on some other relevant issues such as pitfalls of iron therapy practices; present notions about iron mediated oxidative injury to residual renal function in PD patients and iatrogenic folic acid deficiency in HD patients.

Chronic kidney disease, although uncommon, can have a major impact on the outcome of pregnancy. Management of these women is complicated and requires close teamwork between obstetricians and nephrologists. This article reviews the available evidence for management of these women. It also includes the management of women who are on dialysis or who have had renal transplant.