If the tracer for an ERPF determination using the blood sampling method is administered at 0900, at what time should the blood sample be collected?

For the determination of Effective Renal Plasma Flow (ERPF) using the blood sampling method, the timing of the blood sample collection after tracer administration is critical for accurate results. Typically, the blood sample should be collected a certain duration after the tracer is administered to allow for adequate distribution and clearance in the bloodstream.

In this case, the tracer is administered at 0900. The optimal time to collect the blood sample for ERPF should occur approximately 45 minutes to 1 hour post-administration, which allows enough time for the tracer to circulate and reflect the plasma flow accurately.

Choosing 0944 gives a 44-minute interval after tracer administration, which is close to the ideal 45-minute mark. This timing allows the tracer to equilibrate and ensures that the sample reflects the ERPF accurately, making 0944 the most appropriate choice for collecting the blood sample after administrating the tracer.