| CBC with WBC differential and reticulocyte count |
| Hemoglobin F measurement |
| Renal and liver function tests |
| Pregnancy test |
| Counseling |
| Women and men taking hydroxyurea should use contraception. |
| Dosage modification is required to optimize opportunity for clinical response and avoid complications from myelotoxicity. |
| Monitoring |
| Blood counts at frequent intervals early in therapy and when dosage changes |
| Periodic renal and liver function tests |
| Hemoglobin F levels and red blood cell MCV values to detect a biologic response (i.e., an increase in these parameters) |
| Patient compliance |
| Dosage escalation end points |
| Reduction in sickle cell pain frequency and/or severity |
| A treatment period of six months may be needed to assess response in patients who continue to have symptoms. |
| If lack of clinical response: (1) myelotoxicity that defines the maximum tolerated dosage for the patientor (2) maximum dosage of 35 mg per kg per day |