Friends, social networks, and progressive chronic kidney disease.

A report by Dunkler et al. reminds us that social factors are relevant for today's clinical scientist and practitioner. They report that an increasing number of friends reduces the incidence and progression of chronic kidney disease in type 2 diabetes. The observation that 'friends don't let friends' develop kidney disease suggests that social factors, as well as biomarkers, may be relevant in developing 'personalized renal medicine' and may identify areas for future nephrology research and education.

Management of hyperkalemia in hospitalized patients.

PURPOSE: The aim of this study was to determine the incidence of treatment of hyperkalemia in hospitalized patients. METHODS: This is a prospective chart review of adults in a tertiary care hospital with hyperkalemia (serum potassium [K] ≥5.1 mEq/L) over a 6-month period. The treatments and their effectiveness, causative factors and associated electrocardiographic (ECG) changes were examined. RESULTS: There were 154 hyperkalemic episodes, 32 with K ≥6.5 mEq/L and 122 with K<6.5 mEq/L. Overall, 97% received treatment for an average K of 5.9 mEq/L. Sodium polystyrene sulfonate (SPS) was included in 95% of the regimens. Incremental doses of SPS monotherapy yielded potassium reductions between 0.7 and 1.1 mEq/L, and inadequate responses (K <0.5 mEq/L) were less frequent with higher doses. There were no differences in the effectiveness of SPS among dialysis-dependent, chronic kidney disease, or nonchronic kidney disease patients. Greater reductions in potassium were observed using a combination of treatments. ECGs were performed in 44% of patients, and 50% showed no ECG changes despite K being ≥6.5 mEq/L. The most common abnormality, peaked T waves, was associated with a higher frequency of calcium administration but not with the number of K+-lowering therapies. CONCLUSIONS: Almost all the patients were treated for hyperkalemia. Oral SPS monotherapy was the predominant treatment with the best response at the highest dose. Some combination therapies had greater K reductions but were used infrequently. An ECG was obtained in about 50% of the cases, but two thirds showed no K-related changes. Reduced kidney function was associated with 70% of hyperkalemic episodes. Angiotensin-converting enzyme inhibitors and trimethoprim were the most commonly implicated medications.

Once-weekly vancomycin for patients receiving high-flux hemodialysis.

PURPOSE: The effectiveness of a once-weekly vancomycin dosing protocol for patients receiving long-term high-flux hemodialysis (HFHD) in the outpatient setting was studied. METHODS: Eligible patients were at least 18 years old, required hemodialysis for at least two months before study enrollment, and were not known to have any active infection. All patients received outpatient dialysis at a 1000-bed urban teaching hospital three times per week through a high-flux synthetic dialyzer. All patients received vancomycin 35 mg/kg, rounded to the nearest 250 mg, administered during hemodialysis at a rate of 1 g/hr via an infusion pump and scheduled to end when the hemodialysis session was over. Vancomycin was infused either predialyzer or postdialyzer, and infusion pumps were used in patients who received vancomycin through the postdialyzer access port. Serum vancomycin levels were measured before the third hemodialysis session (study day 8) to evaluate the percentage of patients who maintained therapeutic vancomycin concentrations of >or=10 microg/mL. RESULTS: No patients achieved a vancomycin concentration of >or=10 microg/mL on study day 8 (mean serum concentration, 5.1 microg/mL). When patients were separated into two groups based on administration technique, six patients (83%) who received vancomycin predialyzer had undetectable vancomycin levels (<3.5 microg/mL) by study day 8 (n = 6). Patients who received vancomycin postdialyzer maintained a mean serum concentration of 6.4 microg/mL at day 8 (n = 3). CONCLUSION: A single dose of vancomycin 35 mg/kg administered during HFHD in oliguric patients with end-stage renal disease did not achieve the therapeutic serum concentration necessary for once-weekly dosing.

Tissue distribution of UT-A and UT-B mRNA and protein in rat.

Mammalian urea transporters are facilitated membrane transport proteins belonging to two families, UT-A and UT-B. They are best known for their role of maintaining the renal inner medullary urinary concentrating gradient. Urea transporters have also been identified in tissues not typically associated with urea metabolism. The purpose of this study was to survey the major organs in rat to determine the distribution of UT-A and UT-B mRNA transcripts and protein forms and determine their cellular localization. Five kidney subregions and 17 extrarenal tissues were screened by Northern blot analysis using two UT-A and three UT-B probes and by Western blot analysis using polyclonal COOH-terminal UT-A and UT-B antibodies. Immunohistochemistry was performed on 16 extrarenal tissues using the same antibodies. In kidney, we detected mRNA transcripts and protein bands consistent with previously-identified UT-A and UT-B isoforms, as well as novel forms. We found that UT-A mRNA and protein are widely expressed in extrarenal tissues in various forms that are different from the known isoforms. We determined the cellular localization of UT-A and UT-B in these tissues. We found that both UT-A and UT-B are ubiquitously expressed as numerous tissue-specific mRNA transcripts and protein forms that are localized to cell membranes, cytoplasm, or nuclei.