27 Comparative study of suggested reference values and observed distributions in daily routine of a medical laboratory – lessons learned and open questions

Introduction The Consensus Guidelines of the TDM-AGNP working group contain a comprehensive list of suggested reference ranges based on the current literature [1]. The aim of the present study is to compare routinely observed drug concentration values in plasma with proposed reference ranges. Although no indication, dose information, comedication or adverse effects are known, the existing data holds a wealth of interesting information to be explored.

Methods Anonymized data was extracted from the routine archive and plotted as histograms. The observed frequency distribution is compared with the published reference ranges.

Results and Conclusion All analyzed drugs share the common observation of a significant number of concentrations in plasma below the limit of detection (LOD). Thus, TDM acts as a toll for compliance testing. Additional reasons of drug concentrations being below the LOD are a non-optimal pre-analytical phase or particular pharmacokinetics (agomelatine, methylphenidate).

Drugs with a clear indication of regular TDM due to its high toxicity and high prescription rates such as lithium exhibit a dense distribution. In very sparse data sets, this approach can only indicate an observed range of concentrations to be compared with the reference range.

 

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• References

• 1 Hiemke et al. Pharmacopsychiatry 2018; 51: 9-62 .

Publikationsverlauf

Artikel online veröffentlicht:
30. April 2020