(P-TS-31) Changes to Laboratory Variables in Response to Chronic Red Blood Cell Exchanges in Sickle Cell Disease

Background/Case Studies: Patients with sickle cell disease (SCD) require red blood cell (RBC) transfusions to lower hemoglobin S levels and minimize symptomatology associated with crises. A proportion of patients undergo red blood cell exchanges (RCE) chronically to lower hemoglobin S (hgb S) concentration more efficiently and to hopefully maintain iron concentration neutral. Thus, the goal of this study was to determine changes to laboratory values and how procedures affect systemically SCD patients during a twelve-month period of scheduled RCEs.

Study

Design/Methods: Records from our blood bank and our apheresis center for patients in our chronic RCE program were reviewed during a twelve-month period. Variables such as ferritin, hematocrit, hgb S concentration, number of RBC units, renal studies, liver studies, and cardiac reports were analyzed and contrasted between the start of the observation period to those obtained a year later in a group of SCD patients.

Results/Findings: Ten patients did not miss appointments and of these 6 were male and 4 were female. The mean age of the group was 36. All patients received chronic RCE in 5–6-week intervals. The mean pre-transfusion ferritin concentration at start of the twelve-month observation was 2600 µg/L (range 61-6180), while the post-transfusion ferritin at the end of twelve months was a mean of 2488 µg/L (range 58-5700). Six out of 10 patients received iron chelation therapy while the remaining 4 could not tolerate chelation and did not receive it. In one patient post-transfusion ferritin concentration increased from 3348 µg/L to 4325 µg/L despite chelation. Pre-RCE Hgb S concentration decreased from a mean of 50% to 21.8%. Hematocrit increased from a mean of 24% to 27% post-RCE. Five patients experienced minimally increased post-RCE BUN from 8 to10 mg/dL and similarly increased creatinine from 0.67 to 0.75 mg/dL. Six patients developed higher post-RCE alkaline phosphatase levels from 81.5 to104.5 U/L, aspartate aminotransferase from 27 to 36.5 U/L, and increased alanine transaminase from 18 to 24 U/L. Additionally, 4 patients had increases in bilirubin levels from 2 to 3.1 mg/dL at the end of twelve months. Finally, 6 patients who had normal echocardiography or had cardiac disease including cardiomyopathy and decreased left ventricular ejection fraction showed mild to moderate changes from their baseline.

Conclusions: Chronic RCE does not appear to increase ferritin despite restoring patients to a higher hemoglobin/hematocrit at the end of each RCE secondary to RBC senescence. Similarly, both renal and liver functions remained stable with the use of RCE. Randomized clinical trials are needed to determine the definitive role that chronic RCE plays in disease markers for patients receiving procedures.