Hydroxyurea is an antimetabolite which increases the production of HbF and  decreases HbS synthesis leads to a decrease in HbS polymerization. One of the major concerns in using this medication is myelotoxicity and the development of tolerance over time. No significant effect on GFR but has potential benefit on proteinuria, specifically in the pediatric population. The use of hydroxyurea has been shown to decrease lactic hydrogenase and reticulocytes which is typically used as a predictor for CKD progression since it increases during hemolysis. Since a decrease in hemolysis is correlated with positive SCN outcomes, hydroxyurea may be beneficial in decreasing the risk of SCN complications.Erythropoietin stimulating agents (ESAs): During normal kidney function in those with SCD, in response to anemia and hypoxia, erythropoietin synthesis is induced, causing increased erythropoietin compared to baseline. Once GFR falls below 60 mL/min, erythropoietin production also declines and it is recommended to add on an ESA to the current therapy; usually at higher doses. The target hemoglobin level should be lower than a normal patient with CKD because of the risk of vaso-occlusive events. Even in ESRD when those with SCD become transfusion dependent, ESAs can still be used to increase the interval between infusions. If using ESAs, it is important to maintain iron levels to maintain the ability to produce red blood cells especially in those with CKD since sub-clinical bleeding is common, and there is decreased iron absorption.
Sickle cell nephropathy is a type of nephropathy associated with sickle cell disease which causes kidney complications as a result of sickling of red blood cells in the small blood vessels. The hypertonic and relatively hypoxic environment of the renal medulla, coupled with the slow blood flow in the vasa recta, favors sickling of red blood cells, with resultant local infarction (papillary necrosis). Functional tubule defects in patients with sickle cell disease are likely the result of partial ischemic injury to the renal tubules. Also the sickle cell disease in young patients is characterized by renal hyperperfusion, glomerular hypertrophy, and glomerular hyperfiltration. Many of these individuals eventually develop a glomerulopathy leading to glomerular proteinuria (present in as many as 30%) and, in some, the nephrotic syndrome. Co-inheritance of microdeletions in the -globin gene (thalassemia) appear to protect against the development of nephropathy and are associated with lower mean arterial pressure and less protein in the urine. Mild increases in the blood levels of nitrogen and uric acid can also develop. Advanced kidney failure and high blood urea levels occur in 10% of cases. Pathologic examination reveals the typical lesion of "hyperfiltration nephropathy" namely, focal segmental glomerular sclerosis. This finding has led to the suggestion that anemia-induced hyperfiltration in childhood is the principal cause of the adult glomerulopathy. Nephron loss secondary to ischemic injury also contributes to the development of azotemia in these patients

Pathophysiology
The development of sickle cell nephropathy (SCN) typically occurs in childhood as seen in the appearance of hyperfiltration and proteinuria.