A systematic approach to the assessment of erythropoiesis.
The pathogenesis of anaemia may be simple or complex and the differential diagnosis can be difficult. An appreciation of the erythropoietic processes is required, together with regular review of investigations, to ensure that appropriate protocols are adopted. The application of tests, which define different facets of erythropoiesis, should be appropriate to the clinical circumstances. In some situations, such as the anaemia of chronic disorders, pregnancy and chronic renal failure, a detailed analysis of erythropoiesis is often required. Guidelines for investigating anaemia due to megaloblastosis or haemoglobinopathy are well established, whereas disturbances of iron metabolism are often difficult to classify. These require a clear distinction between storage and functional iron to differentiate whether the defect is due to readily treatable simple iron deficiency or more complex mechanisms, which do not respond to iron supplementation. Determination of red cell haemoglobin content, reticulocyte analysis and the assay of serum transferrin receptors are new generation parameters developed to address this. Practice pressures and new treatment options have contributed to investigations becoming more complex, especially those of the secondary anaemias, as new tests have become more readily available and often automated. This has resulted in reduced turnaround times and clinical demand has driven request patterns. Initiatives to develop evidence-based anaemia management protocols are welcomed but, wherever possible, should be developed through collaboration between the haematology department and the user unit, and based on available guidelines.