TDMの落とし穴

〜偽陽性と偽陰性〜

抄録

Therapeutic drug monitoring (TDM) is an essential tool for the optimal use of drugs. Although rare, the drug concentration in blood determined by TDM can be higher or lower than that predicted from the dosage amount and patient information. In such cases, it is necessary to consider the occurrence of false positives and false negatives in the measurement process. Dose adjustment based on the measured blood drug concentration poses potential risks of underdosing and overdosing in patients suspected of false positive and false negative data, respectively. Therefore, pharmacists involved in TDM are required to become familiar with false positives and false negatives in TDM. In particular, the possibility of false positives in TDM of immunosuppressants by the affinity column-mediated immunoassay (ACMIA) method should be considered, while TDM of vancomycin or phenytoin requires attention to false negatives during measurement by the particle-enhanced turbidimetric inhibition immunoassay (PETINIA) method. Moreover, interference from IgM in the measurement process may be of concern in false-negative results; therefore, the measured blood drug concentration needs to be verified when the blood IgM level is high. This mini-review outlines false positives and false negatives that should be considered in TDM and presents a discussion of the relevant literature.