Color doppler ultrasonography of renal vascular resistance in sickle cell disease: Clinical implications

Abstract

The major complications in sickle cell disease (SCD) are microcirculation lesions and impairment of renal function. The aim of this study was to evaluate renal vascular resistance by means of color and duplex ultrasonography (CDU) and its relationships with hematological and clinical features in patients with SCD. Forty patients with SCD (mean age 22.4 ± 7.0) and 14 age- and sex-matched healthy subjects (mean age 25.7 ± 9.5) were included in the study. CDU of the main renal, segmental, and interlobar arteries was performed in both kidneys in all patients and controls. Peak systolic, end diastolic, and mean velocities through the entire cardiac cycle were obtained with further calculation of resistive (RI) and pulsatile (PI) indices. All the patients were investigated in stable state condition and had not been transfused within a month before investigation. Patients had a 6-month follow-up. Patients with SCD had higher RI and PI values than control subjects (p < 0.0001, p < 0.0001, respectively). Patients with high RI values (RI > 0.70) had more pronounced disturbances of blood parameters (all p < 0.05) than patients with normal RI values (<0.70). The significant positive correlation between RI and ISC number, MCHC level (r=0.52, p < 0.001 and r=0.42, p < 0.01), as well as RBC and Hgb level, correlated inversely with RIs (r=−0.39, p < 0.01 and r=−0.42, p < 0.01). During the follow-up, in nine patients (33.3%) with high RIs and one (5.5%) with normal RIs developed painful crises. In conclusion, renal vascular resistance, assessed by CDU is raised in SCD patients as compared with age-matched, apparently healthy persons. These changes are more pronounced in those with more severe manifestations of disease and correlated with hematological and clinical features of sickle cell disease.