Hematologic effects of hydroxyurea therapy at MTD by SCD genotype
. | HbSS . | HbSC . | HbS/β0thal . | HbS/β+thal . | HbS/OArab . |
|---|---|---|---|---|---|
| No. patients | 106 | 7 | 6 | 1 | 2 |
| Age, y | 10.3 ± 4.5 | 13.5 ± 3.8 | 12.7 ± 2.9 | 15.6 | 4.7 ± 2.4 |
| MTD, mg/kg daily | 25.9 ± 5.2 | 19.6 ± 4.2 | 22.1 ± 4.7 | 15.2 | 31.7 ± 2.2 |
| Hemoglobin level, g/dL | |||||
| MTD value | 9.5 ± 1.3 | 11.6 ± 1.2 | 9.7 ± 1.0 | 10.8 | 10.1 ± 0.8 |
| Increase from baseline | 1.5 ± 1.2* | 0.7 ± 1.0 | 1.8 ± 1.3* | 0.1 | 1.6 |
| MCV, fL | |||||
| MTD value | 107 ± 13 | 101 ± 15 | 92 ± 18 | 86 | 109 ± 9 |
| Increase from baseline | 20 ± 11* | 22 ± 11* | 20 ± 12* | 17 | 16 |
| HbF level, % | |||||
| MTD value | 19.7 ± 8.2 | 8.6 ± 3.1 | 19.0 ± 9.3 | 17.1 | 23.4 ± 17.3 |
| Increase from baseline | 11.9 ± 8.0* | 6.8 ± 2.9* | 14.0 ± 8.8* | 5.6 | 16.2 ± 13.4 |
| Reticulocyte count, × 109/L | |||||
| MTD value | 193 ± 95 | 96 ± 19 | 129 ± 73 | 68 | 110 ± 53 |
| Decrease from baseline | 178 ± 157* | 30 ± 68 | 140 ± 113* | 93 | 186 |
| WBC count, × 109/L | |||||
| MTD value | 7.2 ± 2.6 | 5.1 ± 1.2 | 7.3 ± 2.5 | 3.8 | 7.3 ± 2.5 |
| Decrease from baseline | 5.4 ± 4.1* | 2.1 ± 1.7* | 5.7 ± 4.5* | 2.1 | 10.9 ± 0.2 |
| Neutrophil count, × 109/L | |||||
| MTD value | 3.6 ± 2.0 | 2.7 ± 0.9 | 3.3 ± 1.4 | 2.6 | 2.5 ± 1.3 |
| Decrease from baseline | 2.9 ± 3.2* | 0.9 ± 1.5 | 3.9 ± 2.6* | 0.9 | 1.1 ± 6.4 |
| Platelet count, × 109/L | |||||
| MTD value | 392 ± 161 | 246 ± 58 | 281 ± 98 | 128 | 555 ± 134 |
| Decrease from baseline | 108 ± 202* | 112 ± 193 | 127 ± 109 | 61 | -167 ± 241 |
| Bilirubin level, mg/dL | |||||
| MTD value | 2.1 ± 1.7 | 1.4 ± 0.9 | 1.8 ± 0.8 | 0.5 | 2.1 ± 1.2 |
| Decrease from baseline | 1.3 ± 2.2* | 0.2 ± 0.8 | 1.5 ± 1.5 | 0.2 | 0.8 ± 2.2 |
. | HbSS . | HbSC . | HbS/β0thal . | HbS/β+thal . | HbS/OArab . |
|---|---|---|---|---|---|
| No. patients | 106 | 7 | 6 | 1 | 2 |
| Age, y | 10.3 ± 4.5 | 13.5 ± 3.8 | 12.7 ± 2.9 | 15.6 | 4.7 ± 2.4 |
| MTD, mg/kg daily | 25.9 ± 5.2 | 19.6 ± 4.2 | 22.1 ± 4.7 | 15.2 | 31.7 ± 2.2 |
| Hemoglobin level, g/dL | |||||
| MTD value | 9.5 ± 1.3 | 11.6 ± 1.2 | 9.7 ± 1.0 | 10.8 | 10.1 ± 0.8 |
| Increase from baseline | 1.5 ± 1.2* | 0.7 ± 1.0 | 1.8 ± 1.3* | 0.1 | 1.6 |
| MCV, fL | |||||
| MTD value | 107 ± 13 | 101 ± 15 | 92 ± 18 | 86 | 109 ± 9 |
| Increase from baseline | 20 ± 11* | 22 ± 11* | 20 ± 12* | 17 | 16 |
| HbF level, % | |||||
| MTD value | 19.7 ± 8.2 | 8.6 ± 3.1 | 19.0 ± 9.3 | 17.1 | 23.4 ± 17.3 |
| Increase from baseline | 11.9 ± 8.0* | 6.8 ± 2.9* | 14.0 ± 8.8* | 5.6 | 16.2 ± 13.4 |
| Reticulocyte count, × 109/L | |||||
| MTD value | 193 ± 95 | 96 ± 19 | 129 ± 73 | 68 | 110 ± 53 |
| Decrease from baseline | 178 ± 157* | 30 ± 68 | 140 ± 113* | 93 | 186 |
| WBC count, × 109/L | |||||
| MTD value | 7.2 ± 2.6 | 5.1 ± 1.2 | 7.3 ± 2.5 | 3.8 | 7.3 ± 2.5 |
| Decrease from baseline | 5.4 ± 4.1* | 2.1 ± 1.7* | 5.7 ± 4.5* | 2.1 | 10.9 ± 0.2 |
| Neutrophil count, × 109/L | |||||
| MTD value | 3.6 ± 2.0 | 2.7 ± 0.9 | 3.3 ± 1.4 | 2.6 | 2.5 ± 1.3 |
| Decrease from baseline | 2.9 ± 3.2* | 0.9 ± 1.5 | 3.9 ± 2.6* | 0.9 | 1.1 ± 6.4 |
| Platelet count, × 109/L | |||||
| MTD value | 392 ± 161 | 246 ± 58 | 281 ± 98 | 128 | 555 ± 134 |
| Decrease from baseline | 108 ± 202* | 112 ± 193 | 127 ± 109 | 61 | -167 ± 241 |
| Bilirubin level, mg/dL | |||||
| MTD value | 2.1 ± 1.7 | 1.4 ± 0.9 | 1.8 ± 0.8 | 0.5 | 2.1 ± 1.2 |
| Decrease from baseline | 1.3 ± 2.2* | 0.2 ± 0.8 | 1.5 ± 1.5 | 0.2 | 0.8 ± 2.2 |
Age refers to initiation of hydroxyurea therapy. Patients with a history of previous stroke were included only if baseline values were available before the start of chronic erythrocyte transfusion therapy. Results are mean ± 1 SD.
Statistically significant change from baseline, defined by P < .05.