Nucl Med Mol Imaging.  2016 Dec;50(4):337-343. 10.1007/s13139-016-0436-7.

Random Assay in Radioimmunoassay: Feasibility and Application Compared with Batch Assay

• Lee JM
• Lee HH
• Park S
• Kim TS
• Kim SK

• KMID: 2386157
• DOI: http://doi.org/10.1007/s13139-016-0436-7

Abstract

PURPOSE
The batch assay has been conventionally used for radioimmunoassay (RIA) because of its technical robustness and practical convenience. However, it has limitations in terms of the relative lag of report time due to the necessity of multiple assays in a small number of samples compared with the random assay technique. In this study, we aimed to verify whether the random assay technique can be applied in RIA and is feasible in daily practice.
METHODS
The coefficients of variation (CVs) of eight standard curves within a single kit were calculated in a CA-125 immunoradiometric assay (IRMA) for the reference of the practically ideal CV of the CA-125 kit. Ten standard curves of 10 kits from 2 prospectively collected lots (pLot) and 85 standard curves of 85 kits from 3 retrospectively collected lots (Lot) were obtained. Additionally, the raw measurement data of both 170 control references and 1123 patients' sera were collected retrospectively between December 2015 and January 2016. A standard curve of the first kit of each lot was used as a master standard curve for a random assay. The CVs of interkits were analyzed in each lot, respectively. All raw measurements were normalized by decay and radioactivity. The CA-125 values from control samples and patients' sera were compared using the original batch assay and random assay.
RESULTS
In standard curve analysis, the CVs of inter-kits in pLots and Lots were comparable to those within a single kit. The CVs from the random assay with normalization were similar to those from the batch assay in the control samples (CVs%of low/high concentration; Lot1 2.71/1.91, Lot2 2.35/1.83, Lot3 2.83/2.08 vs. Lot1 2.05/1.21, Lot2 1.66/1.48, Lot3 2.41/2.14). The ICCs between the batch assay and random assay using patients' sera were satisfactory (Lot1 1.00, Lot2 0.999, Lot3 1.00).
CONCLUSION
The random assay technique could be successfully applied to the conventional CA-125 IRMA kits. The random assay showed strong agreement with the batch assay. The random assay procedure could increase the flexibility and decrease the turnaround time of the radioimmunoassay technique.

Keyword

Radioimmunoassay; Immunoradiometric assay; Batch assay; Random assay; Standard curve; CA-125

MeSH Terms

Immunoradiometric Assay
Pliability
Prospective Studies
Radioactivity
Radioimmunoassay*
Retrospective Studies