Second Edition (NCCLS document CA2) is written for users of diagnostic laboratory tests. It offers a .. CLSI Laboratories (PA) HA3. Procedures for the Collection of Arterial Blood Specimens; Approved Standard—. CLSI CA3. November Defining, Establishing, and Verifying Reference Intervals in the Clinical Laboratory; Approved Guideline, Third. For guidance on establishing or validating reference intervals, Dr. Horowitz recommends that a laboratory obtain a copy of CA3, which was.

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Prossesing data for outliers. C28a-3 simple but effective method for the detection of outliers is visual inspection of the data. Clin Chim Acta ; For reproducibility and standardization, it is essential that the pre-analytical aspects are accurately defined and described as the preanalytical phase is known to have the highest errors in the total test process Laboratory reference intervals during pregnancy, delivery and the early postpartum period.

Transference and Validation of Reference Intervals | Clinical Chemistry

Horowitz recommends that a laboratory obtain a copy of CA3, which was developed by internationally recognized experts and scientists from regulatory bodies, diagnostic laboratories, and the in vitro diagnostic industry. Other researchers favour the indirect method as the results are clinically relevant and much simpler for an individual laboratory to implement than the time-consuming direct a priori method, which requires considerable cls and professional input 28 Recent developments to determine accurate, age-specific reference values for glucose, cllsi concentrations and white blood cell counts in CSF, amniotic fluids and aspirations in a large population of neonates and young infants will bring literature up to date at a time when molecular tools are commonly used in clinical practice 83 My laboratory uses the techniques in the document all the time.

Whether a test is cclsi or abnormal is perhaps the most important element of a laboratory test. Published online Feb However, in the report example of the CA3, in the section of the medical decision limits, the CDLs of total cholesterol and high-density lipoprotein HDL cholesterol have been given in the same column as the RIs, which is confusing on the basis of terminology Clin Biochem ; On occasion, data from multiple laboratories, following strict quality assurance guidelines, can be pooled.

Reference intervals an update. Although laboratories are well versed in method verification and validation to assess if methods are fit-for-purpose, less importance is commonly put on selecting the most appropriate reference interval to determine whether an individual is healthy. Preparation of individuals and collection of the specimens for the production of reference values.


The comprehensiveness of the population analyzed ages 3—79 years means the authors provide a considerably more meaningful account of biological changes to every analyte by age and sex, a feat rarely achieved in reference interval examination.

This approach can be a potential tool for further harmonization of RIs If three or more again fall outside these limits, the user should re-examine the analytical procedures used and consider possible differences in the biological characteristics of the two populations sampled Inherent biological variation and reference values.

Transference and Validation of Reference Intervals

However, as an alternative, indirect c28-w3 can be used for the pediatric group as recommended in the CA3 13 Biochemical marker reference values across pediatric, adult, and geriatric ages: The jacknife, the bootstrap, and other resampling plans. There are a number of laboratory tests where accuracy is more important than a traditional reference is a commonly ordered interval. If a clinical laboratory changes the method used or wishes to apply RIs established by another laboratory which has used a different method, transference of the RIs can be implemented, rather than collecting samples from reference individuals to establish a RI for the new method.

Proceed to Checkout Continue Shopping. Need for revisiting the concept of reference c8-a3. Multicenter reference interval studies The requirement that each clinical laboratory produce its own RIs is practically impossible for most clinical laboratories. This should ensure that country-specific RIs are obtained in a more reproducible manner. Although indirect methods can be used as an alternative, the problem of valid RIs for specific age groups e.

Importance of Participation According to Dr. A multicentre study of reference intervals for haemoglobin, basic blood cell counts and erythrocyte indices in the adult population of the Nordic countries.

Where a laboratory uses a method known to be biased compared with the method clzi to set the reference interval, this interval cannot be used. Written informed consent from participants is needed from each reference individual who agrees to participate in the study.

The Horn using Tukey method is a more sophisticated method, which includes Box-Cox transformation of the data to obtain Gaussian distribution followed by identification of the outliers in interquartile ranges IQR: Although some laboratories have performed local studies for their own use, there have also been multicenter studies performed with considerable numbers of subjects to establish useful RIs by laboratories in the Nordic countries 5051Spain 52Australia 5354Asia 5556 and Turkey Your Alert Profile lists the documents that will be monitored.

Reference intervals: current status, recent developments and future considerations

The case for common reference intervals. If three or four results lie outside the reference range, then another 20 samples must be collected. Therefore, it would be better to report the clei RIs only in the RI column in the laboratory results, and to cpsi CDL clearly as a comment in the laboratory report, for example at the bottom of the report when a parameter has well-defined CDLs in vlsi report.


A new protocol outlined in CA3 allows a laboratory to validate a reference interval with a smaller number of samples. The two most recent papers published by the C-RIDL include this strategy for the alignment of test results for the derivation of RIs 18 This standard is also available to be included in Standards Subscriptions. The document provides c28–a3 laboratory with guidance to define criteria for selecting a healthy reference population, determine how many subjects are needed, identify outliers, and perform the calculations necessary to generate a valid reference interval.

Reporting the correct gestational age-specific reference values can also improve the sensitivity of the RIs as mentioned before in this review by stratification of age and gender.

Any significant bias will result in misclassification of too many patients. Common reference intervals the IFCC position. I am now on a personal mission to get laboratory professionals to understand that reference interval studies are not only important, but also reasonably straightforward to do. It is known that lipids e. Selection c28-aa3 individual for the production of reference value.

Reference intervals: current status, recent developments and future considerations

The 1, individuals tested for the CK reference range study noted above were of different sexes, ages, and clai who met multiple criteria, including not exercising for three days and not taking any medications specifically, statins.

However, this method is only appropriate for analytes with a Gaussian distribution with subclasses, where the values are of similar size and standard deviation.

Overall, the procedure for standardization of test results is of the utmost importance, and all centers need to comply when dealing with standardized analytes. Contains guidelines for determining reference values and reference clsu for quantitative clinical laboratory tests.

By contrast, the hematology parameters lack certified reference materials, although several are c28-3a to reference measurement procedures, which has resulted in acceptable equivalence of measurement results between different platforms. CDLs are based on the diagnostic question and are obtained from specific clinical studies to define the probability of the presence of a certain disease or a different outcome.