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At least 19 recordsLinked to original sources
PubMed1999

Laboratory data in healthy volunteers: reference values, reference changes, screening and laboratory adverse event limits in Phase I clinical trials.

OBJECTIVE: Laboratory data are key evaluation procedures for Phase I clinical pharmacology for two reasons. Firstly, laboratory data are used within the screening process to exclude subjects with asymptomatic diseases, which could result in increased danger to themselves or confuse interpretation of the study results. Secondly, during study implementation, safety evaluation and in particular maximum tolerated dose determination have to be done by a case-by-case analysis, sometimes using laboratory adverse events (LAEs). Thus, relevant limits are needed to discriminate between a usual common variation and a significant abnormality, which is considered to be a LAE. This report presents laboratory data distribution, reference values and reference changes and, based on previously published new methods, suggests inclusion limits at screening and laboratory adverse event limits for analysis during study implementation. SUBJECTS AND METHODS: Nine hundred and twenty-seven young healthy male volunteers were recruited in one centre (Association de Recherche Thérapeutique). A standard screening process was carried out. Protocols were approved by the local ethics committee. Blood sampling was performed in the same conditions. Reference values (at screening and at baseline) were determined by a non-parametric procedure selecting 2.5% and 97.5% of the distribution of data. Reference changes were also defined as the 2.5-97.5% interval of distribution of the variations between the end of treatment and baseline. Inclusion limit and LAE limit methods of determination used had been specified in previous articles. RESULTS: Detailed results of laboratory data distribution, reference values at screening and at baseline, reference changes, inclusion limits and LAE limits are presented in tables with number of subjects, mean, median, standard deviation, minimal and maximal values and the 2.5-97.5% interval for each laboratory parameter. CONCLUSION: The key aims of this paper are to provide clinical pharmacologists with data, reference values or changes obtained in the real conditions of Phase I study implementation, and to propose relevant limits, either for screening as inclusion limits, or during studies as LAE limits. Thus, these data, reference values and specific limits improve the capacity to screen healthy volunteers and to analyse LAEs during Phase I studies.

Adult↗
PubMed1975

Current concepts of "normal values," "reference values," and "discrimination values," in clinical chemistry.

The term "normal values" is seriously afflicted by sylleptic ambiguities and conceptual problems, and it is gradually being discarded from the lexicon of clinical chemistry. The neutral term "reference values" preferable on semantic and scientific grounds, and its use in clinical chemistry is rapidly gaining acceptance. The term "discrimination value" has been added to the lexicon of clinical chemistry. Use of the "discrimination value" for the results of a laboratory test in a specified clinical situation provides the optimal discrimination between the "healthy" and the "diseased," or between "those who need not be investigated further" and "those who do."

Biometry↗
PubMed1980

The use of reference values.

Reference values on concentrations of chemical components in body fluids/tissues serve as indispensable guides for the interpretation of results of biochemical investigations. They provide the criteria necessary for deciding if laboratory results obtained on patients indicate the presence of pathological states or abnormal metabolism. However, in order for reference values to fulfill their expected function, their preparation must take into account the multitude of factors that are now known to have influence on their magnitude and distribution. Ignorance of the effect of such factors can lead to misuse of reference values or preparation of reference data which are of limited use and sometimes misleading. On the other hand, it must be emphasised that even when comprehensive sets of reference values are available, it is necessary to take into consideration all relevant clinical information, including treatment and other diagnostic procedures on the patient before attempting interpretation of any laboratory data. In view of the increasing number of factors that can affect laboratory results, the clinical chemist has an increasingly important role in assisting his clinical colleagues in the interpretation of results and ensuring the intelligent and proper use of reference values for patient diagnosis and management, through comprehensive reporting and education.

Chemistry, Clinical↗
PubMed1990

Recommendation for collection of venous blood from children, with special reference to production reference values.

Reference values should be produced under standardized conditions. To enable comparison it is desirable to use the same procedure also in other clinical situations. A procedure for the collection of venous blood from children with special reference to production of reference values is recommended. It deals with five items: preparation of the child before specimen collection, preparation of the blood collection site, equipment for specimen collection, the specimen collection itself, and handling and storage of the specimen. Alternative methods are described since no single method is suitable for all paediatric age groups. The problem of adhering to a proposed procedure during routine clinical work is also commented upon. The recommendation has been produced as a joint effort of the Scandinavian Committee on Reference Values and a working group set up by the National Paediatric Societies in the Nordic countries.

Adolescent↗
PubMed1987

[Amino acids in cerebrospinal fluid. Reference values].

Reference values are determined for 28 amino-acids in the cerebro spinal fluid, from literature data. The data collected in this document result from the dosage of amino-acids in the cerebro spinal fluid of 453 patients, adults and children. Two series of reference values are proposed: one for children over 2 and adults, the other for children under 2.

Adolescent↗
PubMed1997

Multicentric reference values: shared reference limits.

In order to obtain shared reference limits, three laboratories in the same geographical area with a homogeneous population have developed a proposal to produce multicentric reference values. The strategy simulates a virtual laboratory, actually formed by the laboratories involved; the reference limits produced in the virtual laboratory are in fact derived from the blend of reference values obtained by each laboratory. Each laboratory has chosen its own reference sample and has measured the biochemical quantities under study. Reference individuals (n = 171) and 15 biochemical quantities among the most measured in clinical laboratories were selected. The reference values obtained in each laboratory were blended when permitted by the Harris & Boyd test (Clin Chem 1990; 36:265-70). The multicentric reference limits obtained by the virtual laboratory for each quantity were estimated according to the recommendations of the International Federation of Clinical Chemistry. For each quantity, each laboratory, with the results observed in their reference sample, estimated the diagnostic specificity, using as cut-off values the corresponding multicentric reference limits. Each observed value of diagnostic specificity was compared with the theoretical diagnostic specificity value, equal to 0.975, that should be observed when a reference limit is used as cut-off value. The multicentric reference limits obtained by the virtual laboratory are valid in all cases with the exception of the upper reference limit for the concentrations of calcium(II) and urate in serum in one of the laboratories.

Adult↗
PubMed2001

Arsenic species excretion in a group of persons in northern Germany--contribution to the evaluation of reference values.

Reference values for four arsenic species (inorganic As(III); inorganic As(V); dimethylarsinic acid DMA; monomethylarsonic acid MMA) in urine were evaluated for 101 male persons in northern Germany (46.9 +/- 10.5 y) applying anion exchange chromatographic species separation with on-line hydride-technique atomic absorption spectrometry (between-days imprecision 6.8-10.1%; 11.0-50.0 micrograms/l; n = 30; detection limits d. l. 1; 10; 2; 2 micrograms/l). DMA was found in 88.1% of the persons (x +/- s = 7.21 +/- 9.64 micrograms/g creatinine; median 4.02 micrograms/g; 95% < 22.5 micrograms/g) followed by As(III) (11.3%; median < d. l.; 95% < 0.54 microgram/g) whereas no MMA and As(V) could be found. Seafood consumption within the last 2 days led to higher DMA levels compared to having seafood more than 6 days ago (n = 43 vs. n = 42; 10.04 +/- 11.58 vs. 3.47 +/- 3.55 micrograms/g; p < 0.01).

Adult↗
PubMed1988

Trace elements in human clinical specimens: evaluation of literature data to identify reference values.

Reference values are proposed for the concentrations of As, Cd, Co, Cr, Cu, Fe, Hg, Mn, Mo, Pb, Se, and Zn in whole blood, blood serum, urine, milk, liver, and hair from adult human subjects. For F, I, and Ni, it was not possible to evaluate reference intervals for all the specimens mentioned above. For several elements, including Al, B, Br, Cs, Li, Rb, U, and V, the present status of the literature does not provide an adequate basis for formulating baseline concentrations; therefore, results from selected investigations are listed for information only. For elements such as Cu, Fe, and Zn, which are known to be homeostatically controlled, the concentrations in whole blood and blood serum follow a gaussian-like frequency distribution, and we could consider both median and mean values for evaluation. On the other hand, elements whose concentrations in tissues and body fluids are influenced by dietary availability (e.g., As and Se) or environmental factors (e.g., Cd, Hg, and Pb) show wide scatter. In these cases, the median appeared to be a better indicator of the central tendency than the mean, when different populations are involved. These points are illustrated.

Body Fluids↗
PubMed1980

The current concepts of "normal values" and "clinical reference values" in the clinical laboratory (trials for determining clinical reference values of the Tokai University Hospital).

The purposes of this commentary are 1) to summarize the problems and ambiguities that cause many clinical pathologists to discard the term "normal values"; 2) to describe and define two terms, 'normal values" and "clinical reference values", which are becoming important for clinical interpretation of laboratory data; 3) to describe a new method for estimating clinical reference ranges of blood chemistry laboratory tests performed on selected Tokai University Hospital patients; and 4) to provide a bibliography of articles that have focused attention on the conceptual problems in this field.

Blood Chemical Analysis↗
PubMed1979

Canine hematology and biochemistry reference values.

Reference hematology and biochemistry values for 53 variables are presented from 51 clinically healthy dogs, 26 female and 25 male, approximately six to 24 months of age and of mixed breed. These dogs were sampled because of their good health status and the opportunity to collect the volume of blood required to complete the variable analysis of interest. Collection of blood specimens and laboratory analysis was done in a standard described manner, the latter including a continuing quality control program. For each variable the data were examined for homogeneity and when present, outliers (n = 9) were excluded. Parametric analysis was used to calculate the reference interval for those variables which had a Gaussian distribution or could be changed to a Gaussian distribution by any of four transformations. For those variables in which Gaussian distribution was not present or attained, nonparametric analysis was used. Due to the small size of the population sample, the uncertainty of breed and the exact age of each dog, breed, age and sex effects were not examined. Reference values should be used to assist interpretation of observations obtained from an animal or animals of comparable origin, i.e. similar subpopulation, and only if the same laboratory techniques are followed. Until each laboratory is able to generate reference values using adequate sample size and current methodology for the numerous subpopulations of interest, reference intervals such as these are useful to clinicians and researchers.

Animals↗