tokens: Patients were screened for SCD - related organ damage and complications ( microalbuminuria , renal failure , elevated tricuspid regurgitation flow velocity ( TRV ) ( ≥2.5 m / seconds ) , retinopathy , iron overload , cholelithiasis , avascular osteonecrosis , leg ulcers , acute chest syndrome ( ACS ) , stroke , priapism and admissions for vaso - occlusive crises ( VOC ) biannually .