Creatinine clearance as a measure of GFR in screenees for the African-American Study of Kidney Disease and Hypertension pilot study

Serum creatinine and endogenous creatinine clearance (CrCl) are widely used measures of renal function. This study compares the precision, bias, and sources of error in using different CrCl measures to estimate the glomerular filtration rate (GFR) in 118 men and women screened for the African-American Study of Kidney Disease and Hypertension (AASK) pilot study. We measured serum creatinine, 24-hour CrCl, and CrCl during timed clearance periods conducted simultaneously with an 125I-iothalamate GFR study. Serum creatinine was measured using two different kinetic rate Jaffe methods (CX3 and Hitachi). After standardization for body surface area, the different measures of renal function available for each individual were compared with the 125I-iothalamate GFR simultaneous to the CrCl. In a subset of 50 participants, the CrCl measures were compared with a follow-up GFR (fGFR). The mean 125I-iothalamate GFR was 65.2 (SD, 26.4), with a range of 11 to 122 mL/min/1.73 m2. The mean +/- SD percentage differences from the GFR were -9%+/-22% for the Cockcroft-Gault estimated CrCl, 1%+/-29% for the 24-hour CrCl, and 8%+/-16% for the CX3 simultaneous CrCl. The Hitachi method overestimated serum creatinine and underestimated GFR. Compared with an fGFR, the mean +/- SD differences were 2%+/-19% for the first GFR, -6%+/-20% for the Cockcroft-Gault estimated CrCl, 10%+/-28% for the 24-hour CrCl, and 14%+/-29% for the CX3 simultaneous CrCl. Thus, the increased precision with which the timed CrCl predicted its simultaneous GFR did not extend to improved ability to predict a future GFR. The fractional excretion of creatinine, measured as the ratio of the CX3 simultaneous CrCl to 125I-iothalamate clearance, increased with decreasing GFR but was lower than expected (mean +/- SD of 1.21+/-0.16 for GFRs between 20 and 40 mL/min/1.73 m2). The lower fractional excretion explains why the 24-hour and Cockcroft-Gault CrCls did not overestimate GFR, but the reasons for this lower excretion are uncertain. Creatinine assay specificity and calibration are important sources of variability that must be examined in any CrCl measure of GFR. We conclude that despite requiring substantially more time and effort, neither the outpatient 24-hour urine nor the timed CrCl offered increased precision over a calculation based on serum creatinine, sex, age, and weight in predicting GFR.     

Professional and Consumer Publications, Programs, Audiovisuals, and Software

Books, curricula, audiovisuals, and other resources that nutrition professionals may use for reference, continuing education, or in a formal or informal education setting are designated “professional.” Books, handouts, diet plans, and other resources specified by authors as being written for general audiences are categorized as “consumer.” Inclusion of any material in this section does not imply endorsement by the Society for Nutrition Education. Evaluative comments contained in the reviews reflect the views of the authors. Prices quoted are those provided by the publishers at the time materials were submitted. They may no longer be current when the review is published.     

Individual and Neighborhood Differences in Diet Among Low-Income Foreign and U.S.-Born Women

BACKGROUND: Research on the "immigrant" or "Latino health paradox" has demonstrated that Latinos exhibit better health than U.S.-born whites, for multiple health outcomes, despite adjusting for socioeconomic status. However, little empirical research has focused on women and even less has focused on how the neighborhood residential environment is associated with these health differences, particularly in the area of diet. METHODS: We analyzed baseline data from 641 low-income women, nested within 184 census tracts, enrolled in a nutrition intervention trial for postpartum women. Individual-level variables, including race/ethnicity, nativity, duration of time in the United States, language acculturation, emotional and instrumental support, and socioeconomic position, were merged with tract-level variables from U.S. Census data (2000) based on residential address. We assessed daily fruit and vegetable servings through a semiquantitative food frequency questionnaire. Using MLWin 2.0 software, we employed a 2-level linear regression model to ascertain associations of neighborhood immigrant, racial, and socioeconomic composition with individual diet, adjusting for individual-level sociodemographic characteristics. RESULTS: In our fully adjusted model, we observed a statistically significant increase of 1/3 of fruit and vegetable daily servings for each 10-percentage point increase in the tract foreign-born population. Each 10-percentage point increase in the tract Black population was associated with a significant 1/5 serving decrease in individual daily fruit and vegetable intake. CONCLUSIONS: Among this population of U.S. and foreign-born women, neighborhood composition was associated with individual diet, above and beyond individual-level characteristics, illuminating neighborhood context, immigrant health, and diet.     

Urachal carcinoma: clinicopathologic features and long-term outcomes of an aggressive malignancy

BACKGROUND: Urachal carcinoma (UrC) is a rare malignancy, and patients with this disease have a poor prognosis. In this article, the authors report 50 years of experience with this tumor at the Mayo Clinic. METHODS: A urachal mass was described in 130 patients, and 66 of those masses were malignant. The authors identified multivariate predictors of malignancy in clinically diagnosed urachal masses and predictors of UrC-specific survival. This report presents a novel 4-category staging system for UrC along with the treatment history of this tumor and the results of salvage therapy. RESULTS: Twenty women and 46 men were identified with UrC. The strongest predictors of malignancy in a urachal mass were hematuria and age older than 55 years. The 5-year cancer-specific survival rate was 49%. The new Mayo staging system was less complicated than the Sheldon system, although both systems predicted cancer-specific mortality equally well. Positive surgical margins (hazard ratio [HR], 4.7), high tumor grade (HR, 3.6), positive local lymph nodes (HR, 5.1), metastases at diagnosis (HR, 3.3), advanced tumor stage (HR, 4.8), failure to perform umbilectomy (HR, 3.0), and primary radiation therapy (HR, 2.9) were all univariately associated with death (P <.05). Only grade and margins were significant in the multivariate analysis. No survival benefit was noted for lymphadenectomy or adjuvant therapy. Salvage surgery resulted in a long-term cure for 50% of patients who had local recurrences. No effective treatment was identified for patients with metastatic UrC. CONCLUSIONS: Early and complete extended partial cystectomy, including umbilectomy, is critical to the survival of patients with UrC. The authors recommend using the Mayo staging system in future studies because of its simplicity. The current results indicated that the most important predictors of prognosis were tumor grade and surgical margin status.