The use of radioisotopes in haematology.

Radioisotopes used in haematology may be divided into four groups: 1. those used for in vivo studies, involving the labelling of cells in the blood or bone marrow and the use of labelled plasma albumin; 2. investigations involving surface counting over organs such as the bone marrow, spleen, liver and heart; 3. in vitro use of radioisotopes in the haematology laboratory and 4. isotopes used as part of imaging procedures. The shorter the half life of the isotope, the more limited patient exposure to radioactivity will be, but the greater the problems of starting and completing the investigation before the isotope has decayed. Isotopes studies should not be carried out in children or pregnancy unless there are exceptional clinical indications.