Haemorheological parameters in hypertensive Nigerians with and without sickle-cell trait

Haemorheological parameters including whole blood (WBF) and erythrocyte filterability (EF), haematocrit (H'ct), haemoglobin levels (Hb) and plasma fibrinogen concentration (PFC) were measured in 61 adult Nigerians with uncomplicated essential hypertension during the course of their routine anti-hypertensive treatment. Results from these patients were compared to those of 39 age and sex-matched normotensive controls. Sixteen (26.2%) of the hypertensive patients and 6 (15.4%) of the controls had the sickle-cell trait (HbAS); the rest were normal homozygotes (HbAA). Although there were no significant difference between WBF in the HbAA-hypertensive and control groups, the former had a significantly lower EF than the latter (p less than 0.025). Both WBF and EF were highly significantly decreased in the HbAS-hypertensives (p less than 0.001). Significant differences in H'ct and Hb levels between HbAA-hypertensives and controls were attributed to sex rather than to hypertension per se. Plasma fibrinogen concentration values were consistently and significantly elevated in all hypertensives irrespective of sex or haemoglobin genotype. In contrast to the HbAA-hypertensives, all 16 HbAS-hypertensives had a persistently raised diastolic blood pressure above 90 mm Hg, suggesting that these patients are either resistant or are less responsive to conventional anti-hypertensive therapy. A more extensive follow-up study is in progress to assess the possible relationship of these parameters and blood pressure, particularly in hypertensive individuals with sickle-cell trait (HbAS).