Red cell volume measurement - using indium as a replacement for chromium.

The withdrawal of Cr-chromate has meant that the technique commonly used for direct measurement of red cell volume has had to be replaced. Most centres moved to a Tc erythrocyte label, however, Tc is known to dissociate over time. We have investigated an alternative technique using an In-chloride and tropolone solution and tested this both in vitro and in vivo.