The authors determined mean day-to-day (daily over five days), mean week-to-week (weekly over five weeks) and mean hour-to-hour (800 h, 1100 h, 1400 h) physiologic intra-individual variation of concentration values of leukocyte cell types, platelet count, and erythrocyte values (hematocrit, hemoglobin) for a group of 20 healthy adult volunteers. Total leukocyte counts and concentration values of leukocyte cell types were determined in duplicate on the Hemalong-DTM Automated Leukocyte Differential Cell Counter to minimize analytic variation. The data sets were analyzed according to an analysis of variance model. The mean physiologic hour-to-hour and week-to-week intra-individual variations in terms of % coefficient of variation included: hemoglobin, 2.5, 2.2; hematocrit, 2.6, 2.7; platelets, 1.6, 6.6; total leukocyte count, 9.4, 15.7; neutrophils, 12.9, 26.0; lymphocytes, 10.3, 13.2; monocytes, 18.6, 19.3; eosinophils, 19.9, 26.9; basophils, 7.4, 15.0; large unstained cells, 13.7, 16.0; "high-peroxidase" cells, 32.7, 25.7. Hour-to-hour variation was partitioned into random diurnal variation, group-consistent diurnal variation, and subject-specific unique individual variation. Subject-specific diurnal variation contributed greatly and statistically significantly to total diurnal variation for many of the leukocyte cell types--especially in the case of eosinophils, where it represented more than half of total diurnal variation.

The physiologic within-day (700-2200 h) variation of leukocyte-type concentrations in blood as determined for 21 healthy young adults is reported. All blood specimens were obtained in duplicate such that the within-batch analytic variation, as well as the pertinent biologic sources of variation, was able to be determined. All specimens were analyzed on each of two automated leukocyte differential systems: Hemalog-D Differential System and the Hematrak-240 Analyzer. On the basis of a comparison of the performances of the two analyzers, it was decided to report the neutrophil and the lymphocyte values as measured on both systems, the monocyte values as measured on teh Hematrak only, and the eosinophil and basophil values as measured on the Hemalog-D only. The intrasubject within-day physiologic variations for the cell on the Hemalog-D and Hematrak, respectively, in terms of coefficient of variation wee as follows: neutrophils 19.4% and 19.6%; lymphocytes, 13.8% and 17.5%. For monocytes, as measured on the Hematrak, it was 13.4%. For eosinophils and basophils, as measured on the Hemalog-D, it was 27.2% and 8.3%, respectively. There was a consistent group-specific diurnal variance that amounted to more than 40% of the total within-day variance, both for lymphocytes and for eosinophils. The within-day physiologic variation of the cell type concentrations for eight of the volunteers was compared with that of the plasma cortisol concentrations, as determined on specimens derived from the same veni-puncture sessions. The decrease in plasma cortisol values was in most instances associated with decreases in eosinophils and increases in neutrophils. For total leukocytes and neutrophils, the mean concentration for smokers was significantly higher than that for nonsmokers.

Many sources of variation affect urinalysis testing. These are due to physiologic changes in the patient, therapeutic interventions, and collection, transportation, and storage of urine specimens. There are problems inherent to the manual performance of this high-volume test. Procedures are poorly standardized across the United States, and even within the same laboratory there can be significant technologist-to-technologist variability. The methods used can perturb the specimen so that recovery of analytes is less than 100 per cent in the aliquot examined. The absence of significant automation of the entire test, with the one exception of the Yellow IRIS, is unusual in the clinical laboratory setting, where most other hematology and chemistry testing has been fully automated. Our evaluation of the Yellow IRIS found that this system is an excellent way to improve the quality of the results and thereby physician acceptance. There is a positive impact for those centers using this instrument, both for the laboratory and for the hospital.