Biomedical subjects
Publications and source records attributed to O W van Assendelft.
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In assigning values to fresh blood specimens used for calibrating automated blood cell analysers, haemoglobin concentration should be determined by the ICSH recommended hemiglobincyanide (HiCN) method. Errors in the reference method may be caused by inadequate blood collection, e.g. incorrect anticoagulation; inadequate dilution, e.g. use of inadequately calibrated pipettes; incomplete conversion of haemoglobins to HiCN, e.g. insufficient time for reactions to come to completion; during measurement, e.g. due to turbidity of the HiCN solution to be measured; or by transcription error. Readily available commercial reagent systems and secondary standards are compared with ICSH standards as to their compliance with these standards.
The "alkaline haematin D-575" method for determining haemoglobin, described by Zander et al. [1984) Clin. Chim. Acta 136, 83-93) was tested. Claims that different non-ionic detergents in the reagent result in identical values for the haemoglobin concentration being measured could not be verified. It could also not be verified that a stable end-product with unique spectral characteristics is always reached within approximately 2 min and that conversion of fetal haemoglobin is faster than that with the haemiglobin cyanide method. Because of the many questions regarding the nature and characteristics of the alkaline haematin/detergent complex or complexes, it is not yet possible to recommend this method for routine haemoglobinometry.
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American medical journals are shifting to selected SI (Système International d'Unités) units for reporting measurements. Limitation of SI units deemed suitable for use in reporting clinical laboratory results stems from recommendations put forth by the International Federation of Clinical Chemistry and the International Union of Pure and Applied Chemistry. Limitations are: 1) the liter as sole recommended unit of volume in concentration measurement; 2) substance concentration (unit mole) favored over mass concentration (submultiples of the kilogram); and 3) discouraging the use of the prefixes hecto-, deca-, deci-, and centi-. Further discussion by the American Medical Association and other organizations is required before consensus in the US medical community can be reached as to extent of and time frame for conversion to SI for reporting clinical laboratory measurements.
Since 1971, the National Health and Nutrition Examination Surveys have collected data on white blood cell counts and on white cell differential counts that are valid for the U.S. population. This article discusses the validity of the differential counts that result from the availability of a set of reference values for all cell types.
This protocol is proposed for the evaluation of automated blood cell counters to assess the performance, advantages and limitations of such instruments. It is based on the International Committee for Standardization in Haematology (ICSH) 'Protocol for type testing equipment and apparatus used for haematological analysis' (1978a) and the British Committee for Standardization in Haematology 'Guidelines for the evaluation of instruments used in haematology' (Shinton, England & Kennedy, 1982). The document has been prepared by the ICSH Panel on Cytometry after discussion with colleagues. This tentative protocol will be reviewed 1 year after publication, in accordance with the ICSH rules, before it is adopted as a definitive standard.
To determine whether transferrin is stable to repeated freezing and thawing, we used blood specimens from 100 normal adults. Their transferrin concentrations were determined by a laser kinetic nephelometric immunoassay. The sera were stored at 4 degrees C and analyzed the next day (day 1). Specimens 1-25 were stored at -20 degrees C and assayed again on days 3, 4, 8, 16, 22, and 43. Specimens 26-100 were stored at 4 degrees C and analyzed again on day 2. Transferrin proved to be stable to repeated freezing and thawing. Normal reference values with respect to sex and age are given, as determined with the Baker 420 Immunological Nephelometer.
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