Stabilization of glomerular filtration rate in advanced chronic kidney disease: a two-year follow-up of a cohort of chronic kidney disease patients stages 4 and 5.

This study examines whether stabilization of the glomerular filtration rate (GFR) is possible in patients with advanced chronic kidney disease (CKD), managed in a CKD clinic. A cohort of 82 patients with stages 4 and 5 CKD was followed for a period of 2 years after initiation of erythropoietin for anemia to determine the GFR and the frequency of primary outcomes (dialysis, transplantation, or death). GFR, calculated by the abbreviated Modification of Diet in Renal Disease formula, was determined every 3 months. After 24 months, 35 subjects (43%) developed a primary outcome. Controlled for other risk factors, the risk of having a primary outcome increased 19.7% for every unit that the GFR decreased (95% confidence interval [CI], 11.9%-26.8%, P < .001) and decreased 21.7% for every unit that the hemoglobin increased (95% CI, 0.5%-38.4%, P < .001). Blacks had a 3.1 times higher risk (95% CI, 1.4-6.9, P = .006) of developing a primary outcome than other ethnicities. In subjects who did not develop primary outcomes (n = 47 or 57%), GFR remained unchanged (19.5 +/- 9.1 at the end of the study v 20.8 +/- 5.3 mL/min/1.73 m(2) at baseline, P = .16). The standardized mortality rate was 4.75 and 9.77 per 100 person-year for stages 4 and 5, respectively. We conclude that stabilization of GFR over a 2-year period can be achieved in many patients with advanced CKD treated with erythropoietin in a CKD clinic. Although the precise reason for the stabilization of GFR cannot be elucidated from this study, our data are "proof of concept" that CKD outcomes can be improved in a CKD clinic setting.

Distal renal tubular acidosis and the potassium enigma.

Severe hypokalemia is a central feature of the classic type of distal renal tubular acidosis (RTA), both in hereditary and acquired forms. In the past decade, many of the genetic defects associated with the hereditary types of distal RTA have been identified and have been the subject of a number of reviews. These genetic advances have expanded our understanding of the molecular mechanisms that lead to distal RTA. In this article, we review data published in the literature on plasma potassium from patients with inherited forms of distal RTA. The degree of hypokalemia varies depending on whether the disease is autosomal autosomal-recessive or dominant, but, interestingly, it occurs in defects caused by mutations in genes encoding the AE-1 exchanger, the carbonic anhydrase II gene, and genes encoding different subunits of the H+ adenosine triphosphatase. This shows that a unique defect involving the H+/K+-adenosine triphosphatase leading to renal potassium wastage cannot explain the hypokalemia seen in virtually all types of classic distal RTA.

Effect of predialysis eating on measurement of urea reduction ratio and Kt/V.

Physicians utilize the measurement of the urea reduction ratio (URR) and Kt/V as surrogates for the adequacy of hemodialysis, as well as to follow the course of patients longitudinally. These measurements are affected by the duration of a dialysis treatment, the type and size of the dialyzer membrane used during the treatment, the blood flow rate during the treatment, and the adequacy of vascular access. We, and others, have noted that eating during dialysis can be associated with decreases in URR and Kt/V. However, there have been no previous studies that have examined the effects of eating before dialysis on these variables. This study examined the effects of eating one-third of a daily diet 2 hours before dialysis as opposed to fasting for a minimum of 3 hours before dialysis on the measured URR and Kt/V as obtained routinely in our dialysis unit. Sixty seven patients gave informed consent for the study, and 42 completed the protocol. No differences were found in URR or Kt/V when dialysis was performed 2 hours after eating compared with performing dialysis after at least a 3-hour fast in the group as a whole or in subgroup analyses of men, women, patients with diabetes, patients in different age groups, or patients who dialyzed on different shifts. Unlike intradialytic food ingestion, moderate predialysis food intake does not affect the measurement of dialysis adequacy as determined by URR and Kt/V.