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1. Royal academy of medicine in Ireland international conference on homocysteine metabolism from basic science to clinical medicine: Proceedings of meeting held at Dromoland Castle, Co. Clare on July 2nd–6th, 1995

Author

Björkegren, K., Bergmark, C., de Faire, U., Mansoor, M. Azam, Svardal, A., Bostom, A. G., Roubenoff, R., Dellaripa, P., Nadeau, M. R., Sutherland, P., Wilson, P. W. F., Jacques, P. F., Selhub, J., Rosenberg, I. H., Bostom, A. G., Brosnan, J. T., Hall, B., Nadeau, M. R., Selhub, J., Bostom, A. G., Shemin, D., Lapane, K. L., Sutherland, P., Nadeau, M. R., Wilson, P. W. F., Selhub, J., Bostom, A. G., Shemin, D., Nadeau, M. R., Selhub, J., Bostom, A. G., Selhub, J., Jacques, P. F., Nadeau, M. R., Williams, R. R., Ellison, R. C., Cuskelly, G. J., McNulty, H., Strain, J. J., McPartlin, J. M., Scott, J. M., Chadefaux-Vekemans, B., Coudé, M., Aupetit, J., Kamoun, P., Coudé, M., Aral, B., Zabot, M. T., Aupetit, J., Kamoun, P., Chadefaux-Vekemans, B., Calaf, R., Ghiringelli, O., Barlatier, A., Charpiot, P., Rolland, P. H., Garçon, D., Charpiot, P., Augier, T., Chareyre, C., Rolland, P. H., Garçon, D., Chango, A., Hodez, F., Tronel, H., Nuel, G., Michel, F., Frémont, S., Méjean, L., Nicolas, J. P., Candito, M., Chambon, P., Gibelin, P., Amsellem, J., Baudouy, M., Morand, P., Candito, M., Chambon, P., Pringuey, D., Aubin-Brunet, V., Beaulieu, F., Darcourt, G., Bedoucha, P., Alchaar, H., Chatel, M., Candito, M., de Valk, H. W., van der Griend, R., Eeden, M. K. G. van, de Groot, E., Duran, M., Smeitink, J. A. M., de Klerk, J. B. C., Wittebol-Post, D., Rolland, M. -O., Haas, F. J. L. M., Meuwissen, O. J. A. Th., Banga, J. D., Poll-The, B. T., de Vries, J. I. P., Dekker, G. A., van Geijn, H. P., Huigens, P. C., Jakobs, C., von Blomberg, B. M. E., Deulofeu, R., Giralt, M., Aibar, C., Bauchet, C., Ballesta, A. M., Varela, G., Vila, N., Chamorro, A., Casals, F. J., Cremades, J. Diaz, Daly, L., Meleady, R., Graham, I., den Heijer, M., Brouwer, I. A., Gerrits, W. B. J., Bos, G. M. J., Blom, H. J., den Heijer, M., Bos, G. M. J., Koster, T., Vandenbroucke, J. P., Blom, H. J., Briët, E., Rosendaal, F. R., Fischer, G., Behrend, C., Bartholmes, P., Fermo, I., Paroni, R., Vigano, S., D’Angelo, A., Fermo, I., Paroni, R., Vigano, S., D’Angelo, A., Franken, D. G., Boers, G. H. J., Blom, H. J., Hamel, B. C. J., Franken, D. G., Boers, G. H. J., Blom, H. J., Ruijs, J. H. J., Franken, D. G., Blom, H. J., Boers, G. H. J., Tangerman, A., Guttormsen, A. B., Ueland, P. M., Refsum, H., Svarstad, E., Gao, W., Goldman, E., Jakubowski, H., Sebastio, G., Sperandeo, M. P., de Franchis, R., Andria, G., Garrow, T. A., Hladovec, J., Sommerova, Z., Písariková, A., Halsted, C. H., Villanueva, J., Chandler, C. J., Stabler, S. P., Allen, R. H., Muskhelishvili, L., James, S. J., Poirer, L., Jacobsen, D. W., Savon, S. R., DiCorleto, P. E., Jourdheuil-Rahmani, D., Rolland, P. H., Garçon, D., Joosten, E., Riezler, R., Allen, R., Joosten, E., Riezler, R., Allen, R., Marquardt, T., Ullrich, K., Harms, E., Koch, H. G., Koch, H. G., Evers, S., Grotemeyer, K. H., Vogelpohl, L., von Eckardstein, A., Ullrich, K., Deufel, T., Kraus, J., Harms, E., Kozich, V., Janosik, M., Sokolová, J., Bukovská, G., Kraus, J. P., Kluitmans, L. A. J., van den Heuvel, L. P., Stevens, E., Trubels, J. M. F., Blom, H. J., Boers, G. H. J., van Oost, B. A., Kraus, J. P., Kittner, S., Macko, R., Hebel, J. R., Rohr, J., Malinow, M. R., Upson, B., Buchholz, D., Earley, C., Johnson, C., Price, T. R., Rosario, J., Sloan, M., Stern, B., Wityk, R., Wozniak, M., Sherwin, R., Stolley, P., Kluijtmans, L., Heuvel, L. van den, Stevens, E., Trijbels, F., Blom, H., Boers, G., van Oost, B., den Heijer, M., Rozen, R., Löhrer, F., Angst, C., Fowler, B., Zaugg, M., Brunner, F., Haefeli, W. E., Nedrebø, B., Ericsson, U. -B., Ueland, P. M., Refsum, H., Lien, E. A., London, J., Paly, E., Paul, V., Paris, D., Kamoun, P., Chassé, J. F., Møller, J., Rasmussen, K., Meleady, R., Graham, I., Daly, L., Verhoef, P., Meleady, R., Graham, I., Daly, L., McMartin, K. E., Phifer, T. J., Alexander, J. S., Middlebrooks, M., Childress, L. E., Nicolas, J. P., Tronel, H., Chango, A., Fremont, S., Felden, F., Guerci, B., Creton, C., Drouin, P., Oakley, G. P., Elias, P. R. P., Hann, A. C., Curtis, C. G., Rose, F. A., Tudball, N., Parrot-Roulaud, F., Cochet, C., Catargi, B., Leprat, F., Latapie, J. -L., Perna, A. F., De Santo, N. G., Ingrosso, D., Galletti, P., Zappia, V., Parrot-Roulaud, F., Sassoust, G., Boissieras, P., Blom, H. J., Majors, A. K., Ehrhart, L. A., Pezacka, E. H., Perry, I. J., Morris, R. W., Ebrahim, S. B., Shaper, A. G., Refsum, H., Ueland, P. M., Pietrzik, K., Dierkes, J., Kroesen, M., Bung, P., Rasmussen, K., Moller, J., Rasmussen, K., Remacha, A., Garcia-Die, F., Cadafalch, J., Barceló, H. J., Parellada, H., Regland, B., Gottfries, C. -G., Andersson, M., Bagby, J., Dyrehag, L. -E., Abrahamsson, L., Ronge, E., Kjellman, B., Frosst, P., Christensen, B., Goyette, P., Rosenblatt, D. S., Genest, J., Rozen, R., Riedel, B., Ueland, P. M., Svardal, A. M., Silberberg, J., Crooks, R., Fryer, J., Ray, C., Guo, X. W., Xie, L., Dudman, N., Silberberg, J., Crooks, R., Fryer, J., Ray, C., Guo, X. W., Xie, L., Dudman, N., Silberberg, J., Crooks, R., Fryer, J., Ray, C., Guo, X., Xie, L., Dudman, N., Smith, B., Kohlman-Trigoboff, D., Simsir, S., Stabler, S. P., Allen, R. H., Strydom, A. J. C., Schlüssel, E., Preibisch, G., Elstner, E. F. E., Pütter, S., Spuijbroek, M. D. E. H., Goddijn-Wessel, T. A. W., Wouters, M. G. A. J., Molen, E. F. v. d., Blom, H. J., Boers, G. H. J., Steegers-Theunissen, R. P. M., Trijbels, J. M. F., Thomas, C. M. G., Eskes, T. K. A. B., Tsai, M. Y., Hanson, N., Key, N., Schwichtenberg, K., Garg, U., Todesco, L., Fowler, B., Pollaert, N., Haefeli, W. E., Thorand, B., Hages, M., Pietrzik, K., Bung, P., Holzgreve, W., Vila, N., Chamorro, A., Deulofeu, R., Aibar, C., Giralt, M., Ballesta, A. M., van der Mooren, M. J., Wouters, M. G. A. J., Schellekens, L. A., Eskes, T. K. A. B., Rolland, R., Blom, H. J., Put, N. v. d., Trijbels, F., Heuvel, L. v. d., Blom, H., Eskes, T., Steegers-Theunissen, R., Mariman, E., Heyer, M. d., Rozen, R., Daher, R., Van Lente, F., Vilkovsky, A. B., Maev, I. V., Richter, E. L., Kirnus, M. D., Varela-Moreiras, G., Alonso-Aperte, E., Rubio, M., Gassó, M., Deulofeu, R., Alvarez, L., Caballeria, J., Rodés, J., Mato, J. M., van Aerts, L. A. G. J. M., Peereboom-Stegeman, J. H. J. Copius, Noordhoek, J., Eskes, T. K. A. B., Molen, E. F. v. d., Spuijbroek, M. D. E. H., Eskes, T. K. A. B., Heuvel, L. P. v. d., Monnens, L. A. H., Blom, H. J., van Guidener, C., Janssen, M. J. F. M., Surachno, J., Stehouwer, C. D. A., van den Berg, M., Bierdrager, E., Rauwerda, J. A., Wilcken, B., Hammond, J., Wouters, M. G. A. J., Hamilton, C. J. C. M., Blom, H. J., Boers, G. H. J., Thomas, C. M. G., Borm, G. F., Eskes, T. K. A. B., Wang, H., Tsai, J. -C., Perrella, M. A., Yoshizumi, M., Sibinga, N. E. S., Haber, E., Chang, T. H. -T., Schlegel, R., Lee, M. -E., Woodside, J., McMaster, D., Yarnell, J., Young, I., Mercer, C., Byrne, K., Evans, A., Gey, F., Gao, X. M., Dougan, G., Wordsworth, P., McMichael, A., Young, P. B., Kennedy, D. G., Molloy, A. M., Scott, J. M., Ward, P., Naughten, E., Cahalane, S., Murphy, D., Mayne, P., Chauveau, P., Chadefaux-Vekemans, B., Coudé, M., Aupetit, J., Kamoun, P., Jungers, P., van Asselt, D. Z. B., Blom, H. J., de Wild, G. M., van Staveren, W. A., Hoefnagels, W. H. L., Naruszewicz, M., Staniewicz, A., Dziewanowski, K., Evrovski, J., Cole, D. E. C., Callaghan, Michael, Lindgren, A., Brattström, L., Hultberg, B., Verhoef, P., Hennekens, C. H., Allen, R. H., Stabler, S. P., Willett, W. C., Stampfer, M. J., Frantzen, F., Sundrehagen, E., Verhoef, P., Kok, F. J., Stampfer, M. J., Willett, W. C., Gaziano, J. M., Hennekens, C. H., Allen, R. H., Stabler, S. P., Reynolds, R. D., Hsu, R. -J., Shane, B., Robinson, K., Kottke-Marchant, K., Green, R., Gupta, A., Jacobsen, D., Robinson, K., Mayer, E., Gupta, A., Miller, D., Marchant, K., Green, R., Jacobsen, D., Greene, R., Chong, Y. -Y., Jacobsen, D., Robinson, K., Gupta, M., Sheppard, C. A., Matthews, R. G., Goyette, P., Frosst, P., Rozen, R., Verhoef, P., Kok, F. J., Kruyssen, H. A. C. M., Witteman, J. C. M., Ueland, P. M., Boushey, C., Beresford, S., Omenn, G., Motulsky, A. G., Nygard, O., Vollset, S. E., Kvale, G., Stensvold, I., Ueland, P. M., Refsum, H., Fiskerstrand, T., Ueland, P. M., Refsum, H., Bugge, K. H., Oshaug, A., Bjønnes, C. H., Refsum, H., Wu, J. T., Wu, L. L., and Wilson, L. W.

Published
1995
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4. N-Terminal Prohormone Brain Natriuretic Peptide as a Predictor of Cardiovascular Disease and Mortality in Blacks With Hypertensive Kidney Disease

Author

Astor, B.C., primary, Yi, S., additional, Hiremath, L., additional, Corbin, T., additional, Pogue, V., additional, Wilkening, B., additional, Peterson, G., additional, Lewis, J., additional, Lash, J.P., additional, Van Lente, F., additional, Gassman, J., additional, Wang, X., additional, Bakris, G., additional, Appel, L.J., additional, and Contreras, G., additional

Published
2008
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28. Imprecision of urinary iothalamate clearance as a gold-standard measure of GFR decreases the diagnostic accuracy of kidney function estimating equations.

Author

Kwong YT, Stevens LA, Selvin E, Zhang YL, Greene T, Van Lente F, Levey AS, Coresh J, Kwong, Yuen-Ting Diana, Stevens, Lesley A, Selvin, Elizabeth, Zhang, Yaping Lucy, Greene, Tom, Van Lente, Frederick, Levey, Andrew S, and Coresh, Josef

Abstract

Background: Evaluating the accuracy of estimated glomerular filtration rate (eGFR) derived from serum creatinine (SCr) and serum cystatin C (SCysC) equations requires gold-standard measures of GFR. However, the influence of imprecise measured GFRs (mGFRs) on estimates of equation error is unknown.Study Design: Diagnostic test study.Setting& Participants: 1,995 participants from the Modification of Diet in Renal Disease (MDRD) Study and African American Study of Kidney Disease and Hypertension (AASK) with at least 2 baseline mGFRs from iodine 125-iothalamate urinary clearances, 1 standardized SCr value, and 1 SCysC value.Index Tests: eGFRs calculated using the 4-variable isotope-dilution mass spectrometry (IDMS)-traceable MDRD Study equation, the Chronic Kidney Disease (CKD) Epidemiology Collaboration (CKD-EPI) SCysC equation, the CKD-EPI SCr-SCysC equation, and mGFRs collected from another prerandomization visit.Reference Tests: A single reference mGFR, average of 2, and average of 3 mGFRs; additional analysis limited to consistent mGFRs (difference Results: We found that mGFRs had stable mean values, but substantial variability across visits. Of all mGFRs collected a mean of 62 days apart from the reference visit, 8.0% were outside 30% of the single reference mGFR (1 - P(30)). Estimation equations were less accurate because 12.1%, 17.1%, and 8.3% of eGFRs from the MDRD Study, CKD-EPI SCysC, and CKD-EPI SCr-SCysC equations were outside 30% of the same gold standard (1 - P(30)). However, improving the precision of the reference test from a single mGFR to the average of 3 consistent mGFRs decreased these error estimates (1 - P(30)) to 8.0%, 12.5%, and 3.9%, respectively.Limitations: Study population limited to those with CKD.Conclusions: Imprecision in gold-standard measures of GFR contribute to an appreciable proportion of the cases in which eGFR and mGFR differ by >30%. Reducing and quantifying errors in gold-standard measurements of GFR is critical to fully estimating the accuracy of GFR estimates. [ABSTRACT FROM AUTHOR]

Published
2010
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29. Clinical chemistry

Author

Anderson, D. J., primary, Van Lente, F., additional, Apple, F. S., additional, Kazmierczak, S. C., additional, Lott, J. A., additional, Gupta, M. K., additional, McBride, N., additional, Katzin, W. E., additional, Scott, R. E., additional, and et al., ., additional

Published
1991
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30. A new equation to estimate glomerular filtration rate.

Author

Levey AS, Stevens LA, Schmid CH, Zhang YL, Castro AF 3rd, Feldman HI, Kusek JW, Eggers P, Van Lente F, Greene T, Coresh J, CKD-EPI (Chronic Kidney Disease Epidemiology Collaboration), Levey, Andrew S, Stevens, Lesley A, Schmid, Christopher H, Zhang, Yaping Lucy, Castro, Alejandro F 3rd, Feldman, Harold I, Kusek, John W, and Eggers, Paul

Abstract

Background: Equations to estimate glomerular filtration rate (GFR) are routinely used to assess kidney function. Current equations have limited precision and systematically underestimate measured GFR at higher values.Objective: To develop a new estimating equation for GFR: the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation.Design: Cross-sectional analysis with separate pooled data sets for equation development and validation and a representative sample of the U.S. population for prevalence estimates.Setting: Research studies and clinical populations ("studies") with measured GFR and NHANES (National Health and Nutrition Examination Survey), 1999 to 2006.Participants: 8254 participants in 10 studies (equation development data set) and 3896 participants in 16 studies (validation data set). Prevalence estimates were based on 16,032 participants in NHANES.Measurements: GFR, measured as the clearance of exogenous filtration markers (iothalamate in the development data set; iothalamate and other markers in the validation data set), and linear regression to estimate the logarithm of measured GFR from standardized creatinine levels, sex, race, and age.Results: In the validation data set, the CKD-EPI equation performed better than the Modification of Diet in Renal Disease Study equation, especially at higher GFR (P < 0.001 for all subsequent comparisons), with less bias (median difference between measured and estimated GFR, 2.5 vs. 5.5 mL/min per 1.73 m(2)), improved precision (interquartile range [IQR] of the differences, 16.6 vs. 18.3 mL/min per 1.73 m(2)), and greater accuracy (percentage of estimated GFR within 30% of measured GFR, 84.1% vs. 80.6%). In NHANES, the median estimated GFR was 94.5 mL/min per 1.73 m(2) (IQR, 79.7 to 108.1) vs. 85.0 (IQR, 72.9 to 98.5) mL/min per 1.73 m(2), and the prevalence of chronic kidney disease was 11.5% (95% CI, 10.6% to 12.4%) versus 13.1% (CI, 12.1% to 14.0%).Limitation: The sample contained a limited number of elderly people and racial and ethnic minorities with measured GFR.Conclusion: The CKD-EPI creatinine equation is more accurate than the Modification of Diet in Renal Disease Study equation and could replace it for routine clinical use.Primary Funding Source: National Institute of Diabetes and Digestive and Kidney Diseases. [ABSTRACT FROM AUTHOR]

Published
2009
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31. Cystatin C and creatinine in an HIV cohort: the nutrition for healthy living study.

Author

Jones CY, Jones CA, Wilson IB, Knox TA, Levey AS, Spiegelman D, Gorbach SL, Van Lente F, Stevens LA, Jones, Clara Y, Jones, Camille A, Wilson, Ira B, Knox, Tamsin A, Levey, Andrew S, Spiegelman, Donna, Gorbach, Sherwood L, Van Lente, Frederick, and Stevens, Lesley A

Abstract

Background: Human immunodeficiency virus (HIV)-infected persons have an increased risk of chronic kidney disease (CKD). Serum creatinine level may underestimate the prevalence of CKD in subjects with decreased lean body mass or liver disease. Level of serum cystatin C, an alternative kidney function marker, is independent of lean body mass.Study Design: Cross-sectional.Setting& Participants: 250 HIV-infected subjects on highly active antiretroviral therapy in the Nutrition for Healthy Living (NFHL) cohort; 2,628 National Health and Nutrition Examination Survey (NHANES) 2001-2002 subjects.Predictors& Outcomes: Comparison of serum creatinine levels in NFHL to those in NHANES subjects; comparison of CKD in NFHL subjects ascertained using serum creatinine versus cystatin C levels.Measurements: Standardized serum creatinine, serum cystatin C, glomerular filtration rate (GFR) estimated from serum creatinine and cystatin C levels.Results: Creatinine levels were lower in NFHL than NHANES subjects despite greater rates of hepatitis, diabetes, and drug use (mean difference, -0.18 mg/dL; P < 0.001 adjusted for age, sex, and race). Of NFHL subjects, only 2.4% had a creatinine-based estimated GFR less than 60 mL/min/1.73 m(2), but 15.2% had a cystatin-based estimated GFR less than 60 mL/min/1.73 m(2).Limitations: GFR was estimated rather than measured. Other factors in addition to GFR may affect creatinine and cystatin C levels. Measurements of proteinuria were not available.Conclusions: Serum creatinine levels may overestimate GFRs in HIV-infected subjects. Kidney disease prevalence may be greater than previously appreciated. [ABSTRACT FROM AUTHOR]

Published
2008
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32. Estimating GFR using serum cystatin C alone and in combination with serum creatinine: a pooled analysis of 3,418 individuals with CKD.

Author

Stevens LA, Coresh J, Schmid CH, Feldman HI, Froissart M, Kusek J, Rossert J, Van Lente F, Bruce RD 3rd, Zhang YL, Greene T, Levey AS, Stevens, Lesley A, Coresh, Josef, Schmid, Christopher H, Feldman, Harold I, Froissart, Marc, Kusek, John, Rossert, Jerome, and Van Lente, Frederick

Abstract

Background: Serum cystatin C was proposed as a potential replacement for serum creatinine in glomerular filtration rate (GFR) estimation. We report the development and evaluation of GFR-estimating equations using serum cystatin C alone and serum cystatin C, serum creatinine, or both with demographic variables.Study Design: Test of diagnostic accuracy.Setting& Participants: Participants screened for 3 chronic kidney disease (CKD) studies in the United States (n = 2,980) and a clinical population in Paris, France (n = 438).Reference Test: Measured GFR (mGFR).Index Test: Estimated GFR using the 4 new equations based on serum cystatin C alone, serum cystatin C, serum creatinine, or both with age, sex, and race. New equations were developed by using linear regression with log GFR as the outcome in two thirds of data from US studies. Internal validation was performed in the remaining one third of data from US CKD studies; external validation was performed in the Paris study.Measurements: GFR was measured by using urinary clearance of iodine-125-iothalamate in the US studies and chromium-51-EDTA in the Paris study. Serum cystatin C was measured by using Dade-Behring assay, standardized serum creatinine values were used.Results: Mean mGFR, serum creatinine, and serum cystatin C values were 48 mL/min/1.73 m(2) (5th to 95th percentile, 15 to 95), 2.1 mg/dL, and 1.8 mg/L, respectively. For the new equations, coefficients for age, sex, and race were significant in the equation with serum cystatin C, but 2- to 4-fold smaller than in the equation with serum creatinine. Measures of performance in new equations were consistent across the development and internal and external validation data sets. Percentages of estimated GFR within 30% of mGFR for equations based on serum cystatin C alone, serum cystatin C, serum creatinine, or both levels with age, sex, and race were 81%, 83%, 85%, and 89%, respectively. The equation using serum cystatin C level alone yields estimates with small biases in age, sex, and race subgroups, which are improved in equations including these variables.Limitations: Study population composed mainly of patients with CKD.Conclusions: Serum cystatin C level alone provides GFR estimates that are nearly as accurate as serum creatinine level adjusted for age, sex, and race, thus providing an alternative GFR estimate that is not linked to muscle mass. An equation including serum cystatin C level in combination with serum creatinine level, age, sex, and race provides the most accurate estimates. [ABSTRACT FROM AUTHOR]

Published
2008
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33. Serum cystatin C in the United States: the Third National Health and Nutrition Examination Survey (NHANES III).

Author

Köttgen A, Selvin E, Stevens LA, Levey AS, Van Lente F, Coresh J, Köttgen, Anna, Selvin, Elizabeth, Stevens, Lesley A, Levey, Andrew S, Van Lente, Frederick, and Coresh, Josef

Abstract

Background: Serum cystatin C increasingly is used as a marker of glomerular filtration rate and cardiovascular risk. However, information for serum cystatin C levels in the general population, specifically across a wide age range and different ethnicities, is lacking.Objectives: To determine nationally representative serum cystatin C levels, estimate the prevalence of increased cystatin C levels in the general population, and identify factors associated with increased cystatin C levels.Study Design: Cross-sectional survey.Setting and Participants: A nationally representative subsample of 7,596 participants aged 12 years or older in the Third National Health and Nutrition Examination Survey conducted in 1988-1994.Predictors: Age, sex, race/ethnicity, risk factors for chronic kidney disease.Outcomes: Continuous serum cystatin C levels and serum cystatin C level greater than 1.12 mg/L.Measurements: Cystatin C was measured in 2006 from stored sera by using an automated particle-enhanced nephelometric assay.Results: Overall median serum cystatin C level was 0.85 mg/L. Median cystatin C levels increased steeply with age and were greater in males and non-Hispanic white persons, even in a healthy subgroup of 20- to 39-year-olds. Prevalences of increased serum cystatin C levels (>1.12 mg/L) were 1%, 41%, and greater than 50% in all persons aged younger than 20 years, 60 years or older, and 80 years or older. In persons aged 60 years and older, older age, non-Hispanic white ethnicity, hypertension, current smoking, lower levels of education and high-density lipoprotein cholesterol, and increased body mass index, C-reactive protein, and triglyceride values were associated significantly with increased serum cystatin C levels.Limitations: No measured glomerular filtration rate, single measurement of cystatin C, cross-sectional study design.Conclusions: Serum cystatin C level is related to sex and ethnicity, even in young healthy individuals. The prevalence of increased cystatin C levels increases dramatically with age, reaching greater than 50% after the age of 80 years in both sexes and all ethnic groups. [ABSTRACT FROM AUTHOR]

Published
2008
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34. A prospective crossover study comparing secretin-stimulated endoscopic and Dreiling tube pancreatic function testing in patients evaluated for chronic pancreatitis.

Author

Stevens T, Conwell DL, Zuccaro G Jr., Van Lente F, Lopez R, Purich E, and Fein S

Abstract

BACKGROUND: Direct pancreatic function tests (PFT) are conventionally performed with use of double-lumen 'Dreiling' collection tubes. We have developed an endoscopic collection method (ePFT) that eases the performance of these tests. OBJECTIVE: Our aim was to compare the bicarbonate results obtained from the secretin ePFT and Dreiling PFT methods in patients evaluated for chronic pancreatitis. DESIGN: A prospective crossover design was used to compare the PFT methods. SETTING: Tertiary care referral center. PATIENTS AND INTERVENTIONS: Twenty-four patients undergoing an evaluation for chronic pancreatitis underwent the secretin-stimulated ePFT and Dreiling PFT methods on separate days. MAIN OUTCOME MEASUREMENTS: Duodenal fluid bicarbonate concentrations and estimated bicarbonate outputs were compared. RESULTS: The mean difference in peak bicarbonate concentration (Dreiling PFT minus ePFT) was 7 mEq/L (SD 20) and not statistically significant (P = .11). A good correlation in peak bicarbonate concentrations (r = 0.74, 95% CI, 0.48-0.88) and estimated bicarbonate output (r = 0.78, 95% CI, 0.54-0.90) was observed between the two PFT methods. LIMITATION: The sensitivities and specificities of the secretin ePFT and Dreiling PFT could not be compared because of the lack of a histologic gold standard. CONCLUSION: The secretin ePFT yields results similar to those of the Dreiling PFT in patients evaluated for chronic pancreatitis. [ABSTRACT FROM AUTHOR]

Published
2008
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35. Calibration of serum creatinine in the National Health and Nutrition Examination Surveys (NHANES) 1988-1994, 1999-2004.

Author

Selvin E, Manzi J, Stevens LA, Van Lente F, Lacher DA, Levey AS, Coresh J, Selvin, Elizabeth, Manzi, Jane, Stevens, Lesley A, Van Lente, Frederick, Lacher, David A, Levey, Andrew S, and Coresh, Josef

Abstract

Background: The calibration of serum creatinine values to standardized creatinine and the commutability of serum creatinine across surveys are essential to the correct use of National Health and Nutrition Examination Survey (NHANES) data for kidney function and for generating estimates of the burden of kidney disease in the United States.Study Design: Calibration study of serum creatinine in NHANES III (1988-1994) and NHANES 1999-2000, 2001-2002, and 2003-2004 to directly compare creatinine measurements from the original surveys with standard creatinine measured using an assay traceable to known gold-standard methods. We also assessed predictors of differences between methods (potential interferences) in this general population.Setting& Participants: The NHANES are ongoing cross-sectional surveys of the civilian noninstitutionalized population of the United States. We selected random samples of approximately 200 stored specimens from persons aged 60 years or older from each survey (NHANES III, 1999-2000, 2001-2002, and 2003-2004).Measurements: Stored serum specimens from the 4 NHANES surveys were analyzed for serum creatinine by using a Roche enzymatic assay implemented at the Cleveland Clinic Research Laboratory (CCRL). The Roche assay is traceable to gold-standard reference methods. The original NHANES serum creatinine values were obtained using the Jaffé method (kinetic alkaline picrate) implemented in several different laboratories.Results: Overall agreement between the original NHANES values (Jaffé method) and CCRL measurements (Roche enzymatic) was high, but substantial biases were observed in NHANES III and 1999-2000. No bias was observed in NHANES 2001-2002 and 2003-2004. Final calibration equations to correct serum creatinine values in the relevant surveys are provided. Assay differences were independent of sex, race/ethnicity, and bilirubin and triglyceride levels, but weakly related to age and glucose concentration.Limitations: We were not able to examine drift in measurements over time within each survey or directly evaluate freeze-thaw effects.Conclusions: The magnitude of differences in serum creatinine measurements in NHANES III and 1999-2000 from standard creatinine would result in large differences in estimates of kidney function (10% to 20%). Thus, correction of original creatinine values in NHANES III and 1999-2000 is essential, but no correction is needed for NHANES 2001-2002 or 2003-2004. [ABSTRACT FROM AUTHOR]

Published
2007
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36. Impact of creatinine calibration on performance of GFR estimating equations in a pooled individual patient database.

Author

Stevens LA, Manzi J, Levey AS, Chen J, Deysher AE, Greene T, Poggio ED, Schmid CH, Steffes MW, Zhang YL, Van Lente F, and Coresh J

Abstract

BACKGROUND: Variation in performance of glomerular filtration rate (GFR) estimating equations is related to variation in calibration of the creatinine assay across clinical laboratories. STUDY DESIGN: Cross-sectional analysis. SETTING & PARTICIPANTS: 6 research studies and 4 clinical populations including 5,504 participants who had GFR measured using urinary clearance of iothalamate. MEASUREMENTS: Standardized serum creatinine values obtained by means of calibration to the Cleveland Clinic Research Laboratory using frozen specimens, a calibration panel, and/or survey results from the College of American Pathologists. PREDICTOR: Noncalibrated serum creatinine assayed in research and clinical laboratories compared with standardized serum creatinine. OUTCOME: Difference between measured GFR versus GFR estimated from the Modification of Diet in Renal Disease (MDRD) Study and Cockcroft-Gault equations. RESULTS: For a noncalibrated serum creatinine value of 1 mg/dL (88.4 micromol/L), standardized serum creatinine value was 0.07 mg/dL (6.2 micromol/L) less than noncalibrated values. In the pooled data set, for the MDRD Study equation, calibration improved median percentage of difference between measured and estimated GFR from 9.0% (interquartile range [IQR], 28%) to 5.8% (IQR, 28%) and improved the percentage of estimates within 30% of measured GFR (P30) from 80% to 83%. The effect of calibration was greater at higher levels of GFR and varied across studies. For the Cockcroft-Gault equation, calibration worsened the median percentage of difference from -2.0% (IQR, 38%) to -11.4% (IQR, 39%), and the P30, from 74% to 69%. LIMITATIONS: College of American Pathologist samples were used for calibration of clinical populations; calibration factors do not account for drift over time in the serum creatinine assay; calibration cannot account for variation in assay performance among individuals. CONCLUSION: Calibration improves the performance of the MDRD Study equation. After calibration, larger errors remain for GFR estimates greater than 60 mL/min/1.73 m2 (>1 mL/s/1.73 m2).Copyright © 2007 by National Kidney Foundation, Inc. [ABSTRACT FROM AUTHOR]

Published
2007
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37. Using standardized serum creatinine values in the modification of diet in renal disease study equation for estimating glomerular filtration rate.

Author

Levey AS, Coresh J, Greene T, Stevens LA, Zhang Y, Hendriksen S, Kusek JW, Van Lente F, Chronic Kidney Disease Epidemiology Collaboration, Levey, Andrew S, Coresh, Josef, Greene, Tom, Stevens, Lesley A, Zhang, Yaping Lucy, Hendriksen, Stephen, Kusek, John W, and Van Lente, Frederick

Abstract

Background: Glomerular filtration rate (GFR) estimates facilitate detection of chronic kidney disease but require calibration of the serum creatinine assay to the laboratory that developed the equation. The 4-variable equation from the Modification of Diet in Renal Disease (MDRD) Study has been reexpressed for use with a standardized assay.Objective: To describe the performance of the revised 4-variable MDRD Study equation and compare it with the performance of the 6-variable MDRD Study and Cockcroft-Gault equations.Design: Comparison of estimated and measured GFR.Setting: 15 clinical centers participating in a randomized, controlled trial.Patients: 1628 patients with chronic kidney disease participating in the MDRD Study.Measurements: Serum creatinine levels were calibrated to an assay traceable to isotope-dilution mass spectrometry. Glomerular filtration rate was measured as urinary clearance of 125I-iothalamate.Results: Mean measured GFR was 39.8 mL/min per 1.73 m2 (SD, 21.2). Accuracy and precision of the revised 4-variable equation were similar to those of the original 6-variable equation and better than in the Cockcroft-Gault equation, even when the latter was corrected for bias, with 90%, 91%, 60%, and 83% of estimates within 30% of measured GFR, respectively. Differences between measured and estimated GFR were greater for all equations when the estimated GFR was 60 mL/min per 1.73 m2 or greater.Limitations: The MDRD Study included few patients with a GFR greater than 90 mL/min per 1.73 m2. Equations were not compared in a separate study sample.Conclusions: The 4-variable MDRD Study equation provides reasonably accurate GFR estimates in patients with chronic kidney disease and a measured GFR of less than 90 mL/min per 1.73 m2. By using the reexpressed MDRD Study equation with the standardized serum creatinine assay, clinical laboratories can report more accurate GFR estimates. [ABSTRACT FROM AUTHOR]

Published
2006
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43. Electrolyte composition of endoscopically collected duodenal drainage fluid after synthetic porcine secretin stimulation in healthy subjects

Author

Stevens, T., Conwell, D.L., Zuccaro, G., Van Lente, F., Khandwala, F., Purich, E., Vargo, J.J., Fein, S., Dumot, J.A., Trolli, P., and O'Laughlin, C.

Abstract

BackgroundTraditional pancreatic function tests are sensitive for the diagnosis of pancreatic exocrine insufficiency but are cumbersome and difficult to perform. A sedationless endoscopic pancreatic function test that has the potential for wide clinical application was developed by us, but data on the results of this method in healthy subjects are lacking. This study analyzed endoscopically collected duodenal fluid from healthy subjects after synthetic porcine secretin stimulation.MethodsHealthy subjects underwent the sedationless endoscopic pancreatic function test. After secretin stimulation, duodenal aspirates were obtained every 5 minutes for 1 hour. The collected fluid was analyzed for electrolyte concentrations.ResultsSixteen healthy subjects (8 women, 8 men; median age 34.5 years) underwent the endoscopic pancreatic function test. The concentrations of the sodium ([Na^+]) and potassium ([K^+]) cations remained constant, similar to normal concentrations in plasma (median [Na^+], 155 mEq/L; median [K^+], 4.3 mEq/L). The concentrations of the bicarbonate ([HCO"3^-]) and chloride anions increased and decreased, respectively, in an inverse and reciprocal manner, similar to the previously characterized ''secretory curve.'' The median peak [HCO"3^-] was 108 mEq/L IQR: 99-110). By the 20-minute collection, the [HCO"3^-] was greater than 80 mEq/L for 94% (15/16) of subjects, the historic cut point for [HCO"3^-] in studies based on traditional methods of pancreatic function testing.ConclusionsEndoscopic collection of pancreatic fluid reproduces the anion-cation secretory curve described by prior studies of pancreatic secretory physiology based on traditional collection methods.

Published
2004
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44. An endoscopic pancreatic function test with cholecystokinin-octapeptide for the diagnosis of chronic pancreatitis

Author

Conwell, D.L., Zuccaro, G., Vargo, J.J., Morrow, J., Obuchowski, N., Dumot, J.A., Trolli, P.A., Burton, A., O'Laughlin, C., and Van Lente, F.

Abstract

Background & Aims: Current pancreatic function tests are cumbersome and unavailable to the clinical gastroenterologist. We have developed a function test that can be modified to a purely endoscopic collection method (ePFT). The aim of this study was to compare the endoscopic and traditional Dreiling tube collection methods. Methods: Two separate groups of healthy subjects and patients with chronic pancreatitis underwent pancreatic function testing. One group underwent the endoscopic collection method (ePFT). Intravenous cholecystokinin (CCK 40 ng . kg^-^1 . h^-^1) was started in preprocedure area. Duodenal fluid was collected with upper endoscope during endoscopy at 30, 40, 50, and 60 minutes during infusion. Another group underwent the traditional Dreiling collection method. Intravenous CCK was started in postprocedure area after endoscopic tube placement. Duodenal fluid was collected at 0, 20, 40, 60, and 80 minutes during infusion. Lipase concentration was determined (IU/L) on laboratory autoanalyzer. Results: Seventy-three patients were studied. Thirty-four underwent endoscopic collection and 39 underwent Dreiling collection. The mean peak lipase concentrations (+/- standard deviation) for healthy subjects and patients with chronic pancreatitis in the endoscopic collection method group were 1,612,500 +/- 556,152 IU/L and 369,594 +/- 281,624 IU/L, respectively (P < 0.001). The mean peak lipase concentrations (+/- standard deviation) for healthy subjects and patients with chronic pancreatitis in the Dreiling tube collection method group were 1,670,324 +/- 786,731 IU/L and 478,956 +/- 406,061 IU/L, respectively (P < 0.001). There was no statistical difference between collection methods at distinguishing healthy subjects and patients with chronic pancreatitis. Receiver operating characteristic curves (ROC) for the endoscopic and Dreiling collection methods were 0.993 (standard error of mean, 0.009) and 0.921 (standard error of mean, 0.041). A lipase concentration cut point of 810,600 IU/L distinguishes healthy subjects from patients with chronic pancreatitis with a sensitivity and specificity of 92% and 95%, respectively. The ePFT was safe, short in duration, minimized costs ($1890 vs. $2659), required small amounts of fluid for analysis (1-3 mL), and eliminated radiation exposure. Conclusions: Analysis of timed endoscopic aspirations of pancreatic juice after hormonal stimulation can distinguish healthy subjects from patients with chronic pancreatitis. This new endoscopic collection method (ePFT) is less cumbersome and more time efficient, when compared to traditional collection methods. The ePFT broadens the availability of function testing to the practicing clinical gastroenterologist.

Published
2003
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