Hydroxyurea and Magnesium Pidolate to Treat People With Hemoglobin Sickle Cell Disease

SCD is an inherited blood disorder. Symptoms include anemia, infections, organ damage, and intense episodes of pain, which are called "sickle cell crises." SCD is caused by an abnormal type of hemoglobin, which is a protein inside red blood cells that carries oxygen. HbSC is a form of SCD that is characterized by the presence of dense red blood cells. People with HbSC usually develop less severe SCD symptoms than people with the more common form of the disease. There are limited treatment approaches aimed specifically at modifying the abnormal state of red blood cells. Also, few combination therapy treatments have been studied. The medication hydroxyurea is currently used to prevent sickle cell crises and to decrease the need for blood transfusions. The dietary supplement magnesium has not been widely studied as a treatment for SCD, but it may prevent dehydration, which may decrease the frequency of sickle cell crises. The purpose of this study is to evaluate the safety and effectiveness of hydroxyurea and magnesium pidolate, alone and combined, at reducing red blood cell density and the frequency of sickle cell crises in people with HbSC. This 1-year study will enroll people with HbSC. Participants will be randomly assigned to one of the following four treatment groups: * Group 1 participants will receive placebo pills and placebo liquid. * Group 2 participants will receive hydroxyurea pills and placebo liquid. * Group 3 participants will receive placebo pills and magnesium pidolate liquid. * Group 4 participants will receive hydroxyurea pills and magnesium pidolate liquid. Participants will receive the hydroxyurea or placebo pills once a day and the magnesium pidolate or placebo liquid twice a day for 11 months. Study visits will occur every 2 weeks during the first 2 months of the study, once a month for the following 9 months, and then at Year 1. At each visit, a physical exam and blood collection will occur. Selected visits will also include urine collection and a pregnancy test for female participants. Throughout the study, participants will record their study medication use in a daily diary.