Is It Possible to Avoid Standards in Studies With Blood Samples?

Abstract

Objective: The long-term mutual stability of a tandem radionuclide calibrator-well detector was measured to enable us to omit reference standards in the estimation of blood volume and GFR/ERPF and thus simplify the procedures, and potentially make the results more precise.

Methods: During two months 200 measurements of reference standard aliquots were taken to estimate the stability of a factor of mutual relation (FMR), which provides a conversion constant between a radionuclide calibrator reading and count rate of a diluted aliquot measured in a well detector.

Results: All measurements demonstrated the satisfactory mutual stability of the detectors.

Conclusion: An FMR can be used instead of making up standard aliquots. The activity in the syringe is measured directly in a radionuclide calibrator before injection. The value is then multiplied by the FMR and the result is used in the equation for blood volume or GFR calculation.