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Biomedical subjects

H Bokelund

Publications and source records attributed to H Bokelund.

17 recordsLinked to original sources
PubMed1976

Variation of serum iron concentration in young healthy men: Within-day and day-to-day changes.

1. Serum iron concentration values were determined on a group of 11 healthy young men on blood specimens which were drawn at various hours of the day: 800 h, 1100 h, and 1400 h; on each of four separate days. 2. using a three-way ANOVA (analysis of variance) model, we determined the diurnal variation both for the group as a whole (main hour effect) and for the individual subjects (subject-hour and subject-day-hour interactions). 3. the total combined within-day variation as expressed in coefficients of variation was 12.9% with the peak value seen at 1400 h. 4. on a separate study, blood specimens were obtained at 1100 h on five separate days during a two week period on the same volunteers. 5. using a two-way ANOVA model (subject and day) the day-to-day coefficient of variation was found to be 26.6% for the group. In both cases (within-day and day-to-day) the biological variation was considerably greater than the analytic variation.

Adult↗
PubMed1976

Analysis of variation in automated determination of sodium, potassium and calcium ions in human serum.

The concentration of sodium ion (Na+), potassium ion (K+) and calcium ion (Ca2+) in patient sera were assayed simultaneously on two separate flame photometers and then evaluated by analysis of variance (ANOVA). Two different experimental designs were devised in order to separate the error components assignable to pipetting, dilution, and instrumental measurement. Within-series variability was compared with the between-series variability. Similar statistical treatment of results from quality control samples gave estimates of variances between days, between dilutions, between instruments, and between channels, as well as the interaction terms and instrumental measurement errors. The total (overall) coefficients of variation (CV) were 1.15, 1.60, and 1.38% for Na+, K+, and Ca2+, respectively. The adequacy of the quality-control system to predict expected variation in patient specimens was verified by comparing errors from patient-sample duplicates and from control samples.

Analysis of Variance↗
PubMed1975

Empirical relations as interference correctives in multichannel analyzers.

Interference from turbidity and bilirubin on 20 serum constituents have been examined on the AutoChemist multichannel analytical system. Empirical relations are presented which correct for these effects on tests such as acid phosphatase, alkaline phosphatase, bilirubin, chloride, cholesterol, creatinine, iron, lactate dehydrogenase, phosphate and uric acid. The interference correctives are routinely applied to patient specimens by aid of the computer attached to the system.

Acid Phosphatase↗
PubMed1975

The effects of time of venipuncture on variation of serum constituents. Consideration of within-day and day-to-day changes in a group of healthy young men.

Within-day and the day-to-day variations of serum constituents were evaluated in 11 healthy young men. Eighteen constituents, including electrolytes, metabolites, proteins, and enzymes, were assayed using the AutoChemist MultiChannel Analytic System. Venipunctures were performed at three hours of the day, 8 A.M., 11 A.M., and 2 P.M., on five separate experimental days. A three-factor analysis of variance model was employed to separate analytic variation from biological sources of variation. Statistically significant (p less than .05) group diurnal patterns (main effect of hour) during the six-hour period were found for serum lipids, iron, urea, albumin, total protein, and chloride. A unique individual diurnal pattern (subject-hour interaction) was statistically significant for serum potassium. Statistically significant main effect of month (main effect of day) for the group of subjects was seen for total lipids and potassium; however, the subject-day interaction term, which is an index of the day-to-day variation for the subjects, was significant (p less than .05) for all of the constituents except for sodium ion. The comparison of the variation expected within-day versus the variation seen day-to-day over four months was made by pooling the sources of within-day variation (main effect of hour + subject-hour interaction + subject-day-hour interaction) and by pooling the day-to-day variation terms (main effect of day + subject-month interaction). For serum cholesterol, potassium, acid phosphatase, and phosphate ion, the within-day variation was greater than the day-to-day variation occurring over four months, while the other constituents showed day-to-day variations of a greater magnitude than that experienced during the six-hour period.

Acid Phosphatase↗
PubMed1975

Correlation of selected serum constituents: 1. Inter-individual variation and analytical error.

The intra-subject correlations of three clinically meaningful combinations of serum constituents--(a) potassium, calcium, and albumin; (b) urea, creatinine, and uric acid; and (c) aspartate aminotransferase, lactate dehydrogenase, and alkaline phosphatase--were studied in 11 healthy men. Duplicate serum samples were obtained at 800 h, 1100 h, and 1400 h on five different days. All assays were performed on the AutoChemist Multichannel Analyzer. Correlation coefficients differed significantly among the subjects for the following six pairs of serum constituents: urea and creatinine, urea and uric acid, creatinine and uric acid, aspartate aminotransferase and lactate dehydrogenase, aspartate aminotransferase and alkaline phosphatase, and lactate dehydrogenase and alkaline phosphatase. Nonbiological positive correlation between analytical errors (i.e., errors of two different assays performed on the same specimen) was demonstrated for two of the pairs: potassium and calcium, and aspartate aminotransferase and lactate dehydrogenase. The error correlations of these two pairs of constituents comprised a significant component of the observed intra-subject correlations. Probable reasons for these analytical error correlations are discussed.

Adult↗