The haematology of homozygous sickle cell disease after the age of 40 years.

Haematological indices have been studied in 181 patients with homozygous sickle cell (SS) disease aged 40-73 years. Cross-sectional analyses in 5-year age bands indicated age-related decreases in HbF (males only), total haemoglobin and platelet counts. Longitudinal studies within individuals confirmed the downward age-related trend in haemoglobin and platelets and also revealed a falling reticulocyte count, most significant when expressed as absolute values. Total nucleated cells also fell although the decline was significant only in females. These observations are consistent with a progressive bone marrow failure which is not explained by the commonly occurring renal impairment in older SS patients since the changes persisted in analyses confined to patients with normal creatinine levels. The mechanism of this bone marrow failure is currently unknown.