Hematologic responses to hydroxyurea treatment in patients with SCA
| Year . | No. of patients . | Average age, y . | MTD . | Average dose, mg/kg/d . | Treatment duration, y . | Hemoglobin, g/dL . | MCV, fL . | HbF, % . | WBC, ×109/L . | ANC, ×109/L . | Reference . |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 1992 | 32 | 27.6 | Yes | 21.3 | 0.8 | 9.7 | 117 | 15 | 8.4 | 4.6 | 15 |
| 1999 | 71 | 9.8 | Yes | 25.6 | 1.5 | 9.1 | 102 | 16.3 | 9.1 | 4.4 | 21 |
| 2004 | 106 | 10.3 | Yes | 25.9 | 3.8 | 9.5 | 107 | 19.7 | 7.2 | 3.6 | 26 |
| 2005 | 11 | 3.4 | Yes | 30.0 | 6 | 9.0 | 96 | 23.3 | 8.9 | NA | 28 |
| 2007 | 37 | 6.8 | Yes | 27.9 | 0.8 | 9.4 | 104 | 22.7 | NA | NA | 56 |
| 2009 | 14 | 3.9 | Yes | 28 | 2.1 | 9.5 | 99 | 25.9 | NA | 3.0 | 53 |
| 2009 | 111 | 7.6 | Yes | 26.7 | 3.2 | 9.7 | 107 | 23.2 | 7.5 | 3.8 | Unpublished |
| 1996 | 22 | 8 | No | ∼ 20 | 0.5 | 8.5 | 96 | 15.3 | 8.9 | NA | 18 |
| 2001 | 21 | 1.3 | No | ∼ 20 | 2.0 | 8.8 | 90 | 20.3 | NA | 4.2 | 22 |
| 2001 | 22 | 7 | No | ∼ 20 | 5 | 8.7 | 97 | 12.9 | NA | 4.0 | 25 |
| 2005 | 32 | 6 | No | ∼ 20 | 6 | 8.8 | 92 | 12.5 | NA | 4.6 | 57 |
| Year . | No. of patients . | Average age, y . | MTD . | Average dose, mg/kg/d . | Treatment duration, y . | Hemoglobin, g/dL . | MCV, fL . | HbF, % . | WBC, ×109/L . | ANC, ×109/L . | Reference . |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 1992 | 32 | 27.6 | Yes | 21.3 | 0.8 | 9.7 | 117 | 15 | 8.4 | 4.6 | 15 |
| 1999 | 71 | 9.8 | Yes | 25.6 | 1.5 | 9.1 | 102 | 16.3 | 9.1 | 4.4 | 21 |
| 2004 | 106 | 10.3 | Yes | 25.9 | 3.8 | 9.5 | 107 | 19.7 | 7.2 | 3.6 | 26 |
| 2005 | 11 | 3.4 | Yes | 30.0 | 6 | 9.0 | 96 | 23.3 | 8.9 | NA | 28 |
| 2007 | 37 | 6.8 | Yes | 27.9 | 0.8 | 9.4 | 104 | 22.7 | NA | NA | 56 |
| 2009 | 14 | 3.9 | Yes | 28 | 2.1 | 9.5 | 99 | 25.9 | NA | 3.0 | 53 |
| 2009 | 111 | 7.6 | Yes | 26.7 | 3.2 | 9.7 | 107 | 23.2 | 7.5 | 3.8 | Unpublished |
| 1996 | 22 | 8 | No | ∼ 20 | 0.5 | 8.5 | 96 | 15.3 | 8.9 | NA | 18 |
| 2001 | 21 | 1.3 | No | ∼ 20 | 2.0 | 8.8 | 90 | 20.3 | NA | 4.2 | 22 |
| 2001 | 22 | 7 | No | ∼ 20 | 5 | 8.7 | 97 | 12.9 | NA | 4.0 | 25 |
| 2005 | 32 | 6 | No | ∼ 20 | 6 | 8.8 | 92 | 12.5 | NA | 4.6 | 57 |
Studies in which hydroxyurea was escalated to maximum tolerated dose (MTD) usually averaged > 25 mg/kg per day and achieved laboratory thresholds of hemoglobin > 9 g/dL, mean corpuscular volume (MCV) > 100 fL, and fetal hemoglobin (HbF) ∼ 20%. In contrast, studies in which hydroxyurea was not escalated to MTD usually averaged 20 mg/kg per day and achieved hemoglobin < 9 g/dL, MCV < 100 fL, and HbF ∼ 15%.
SCA indicates sickle cell anemia; WBC, white blood cell; ANC, absolute neutrophil count; and NA, not available.