Is "relative" hypertension a risk factor for vaso-occlusive complications in sickle cell disease?

Supine arterial blood pressure measurements of 89 patients with homozygous sickle cell disease and normal renal function were compared with those of an age-, race-, and sex-matched normal population and with those of individuals who had similar levels of anemia due to beta thalassemia. Consistent with previous reports, sickle cell patients had significantly lower blood pressure than the normal population. However, within most age groups, sickle cell patients tended to have higher than expected blood pressure than individuals with similar or less severe degrees of anemia. Furthermore, the authors have found an association between cerebrovascular accident and elevated blood pressure in men, even in a range of systolic and diastolic pressures that would be considered normal by conventional standards. These results reiterate the intricate relationship that exists between factors governing red cell rheology and microvascular tone. They also raise the possibility that "relative" hypertension may be associated with other vaso-occlusive manifestations of the sickle cell syndromes.