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Publications (4)17.18 Total impact

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    ABSTRACT: Analytic, within-subject, and between-subject biologic variations were estimated for leukocytes, erythrocytes, hemoglobin, hematocrit, mean cell volume (MCV), mean cell hemoglobin (MCH), mean cell hemoglobin content (MCHC), platelets, and a three-component differential count (lymphocytes, monocytes, and granulocytes in terms of both concentration and percentage of leukocytes) in cohorts of 12 male and 12 female healthy elderly subjects. The assays were performed with an Ortho ELT-800 automated analyzer. The estimates of within-subject biologic variation were similar to published data on young subjects, indicating that this aspect of homeostasis is not compromised in the elderly. The data were used to derive objective analytic goals; goals were surpassed except for assays of erythrocytes, hematocrit, and the derived MCV, MCH, and MCHC. The changes required for serial results to be significantly different were determined and found to be generally valid because most quantities have no heterogeneity of within-subject variation. All quantities had significant individuality; in consequence, conventional population-based reference values are of limited utility, and screening using reference limits will not detect latent or early disease in many subjects.
    American Journal of Clinical Pathology 11/1989; 92(4):465-70. · 2.88 Impact Factor
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    ABSTRACT: Analytical, within-subject, and between-subject components of variation were estimated for 26 clinical chemistry analytes from duplicate analyses of 10 specimens collected from 27 healthy elderly subjects over a period of 20 weeks. Within-subject variations were similar to those generated previously by us in younger subjects. We conclude, therefore, that homeostasis is not compromised by age alone, and biological variability does not increase simply with age. All analytes except serum water had marked individuality, showing that conventional population-based reference values are of limited utility. The critical differences required for two results to be significantly (P less than or equal to 0.05) changed are not the same as those that prompt action by clinicians. Although heterogeneity of within-subject variation does exist, we believe that the critical differences generated will be useful in routine clinical decision making.
    Clinical Chemistry 06/1989; 35(5):783-6. · 7.15 Impact Factor
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    ABSTRACT: We describe a method for measuring plasma, erythrocyte, and leukocyte sodium (Na+), potassium (K+), and magnesium (Mg2+) concentrations in 10-mL blood specimens. After separating cells with Ficoll-Hypaque and washing with isotonic choline chloride, erythrocytes and leukocytes are counted, so that results can be expressed as amount of substance per cell and also to monitor cell integrity and possible contamination. Plasma and cell lysates were analyzed (CV less than or equal to 7.0%) with flame photometry and atomic absorption spectrometry. Reference intervals for an elderly population with values for plasma electrolytes within reference intervals are similar to those for younger healthy subjects. From data on biological variation, reference values for erythrocyte cations are not of much use, and analytical goals for precision are not met, but the results might be useful for monitoring disease progression in individual patients. In contrast, reference values for leukocyte cations are theoretically of use and goals are achieved, but large changes are required before consecutive results can confidently be said to be significantly different.
    Clinical Chemistry 09/1987; 33(8):1326-30. · 7.15 Impact Factor
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    ABSTRACT: We describe a method for measuring plasma, erythrocyte, and Ieukocyte sodium (Na), potassium(K), and magne- sium(Mg2) concentrationsin 10-mLbloodspecimens.After separatingcells with Ficoll-Hypaque and washingwith iso- toniccholinechloride,erythrocytesand leukocytesare count- ed, so that resultscan be expressedas amountof substance per cell and also to monitor cell integrity and possible contamination.Plasma and cell lysates were analyzed (CV 7.O%) with flame photometryand atomicabsorptionspec- trometry. Reference intervals for an elderly population with values for plasma electrolytes withinreferenceintervalsare similarto those for youngerhealthy subjects.From data on biologicalvariation, referencevalues for erythrocytecations are notof muchuse, and analyticalgoalsforprecisionare not met, but the results might be usefulfor monitoringdisease progression in individual patients. In contrast, reference values for leukocyte cations are theoreticallyof use and goals are achieved, but large changes are requiredbefore consecutiveresultscan confidentlybe saidto be significantly different.