Prevention of hemolytic transfusion reactions with intravenous immunoglobulin prophylaxis in U- patients with anti-U.

BACKGROUND: The U- phenotype is extremely rare and is found predominantly in black African populations at a frequency of between 0.2 and 1.7%. In European populations, U- units are therefore rare, with limited availability in the United Kingdom. Anti-U is clinically significant and is known to cause hemolytic transfusion reactions (HTRs) and hemolytic disease of the fetus and newborn. It has been suggested that intravenous immunoglobulin (IVIG) may be considered as an option among supportive therapy for urgent transfusion when clinically significant antigen-matched units are not available. We report three cases with anti-U transfused with least-incompatible RBC units, their outcomes, and their clinical management. STUDY DESIGN AND METHODS: Intravenous immunoglobulin was prescribed when least-incompatible units must be issued in patients with anti-U to ameliorate acute HTR and prevent the development of delayed HTR. We report the outcome of these cases. RESULTS: Of the case reports described, one patient with weak anti-U developed a delayed HTR after transfusion with incompatible units due to an anamnestic response. Two additional patients are described, with the use of IVIG as a precautionary measure to prevent the development of HTRs when transfused with antigen-positive incompatible units. No acute HTRs or delayed HTRs were noted upon follow-up. CONCLUSION: U- units are not always readily available and transfusion support requires close collaborative working among a multidisciplinary team. Transfusion with antigen-positive incompatible units with IVIG cover both ameliorates acute HTRs and prevents the development of delayed HTRs.

Hepatic Hemosiderosis Contributes to Abnormal Vitamin D-PTH Axis in Thalassemia Major.

OBJECTIVE: The aim of this study was to evaluate the vitamin D-PTH axis in thalassemia major (TM) in relation to hepatic siderosis liver iron content. DESIGN AND PARTICIPANTS: In this case-controlled observational study, vitamin D-PTH axis was studied in 158 TM and 84 age and ethnicity-matched healthy nonthalassemic controls attending University College Hospital, London. Patients were classified as 25-hydroxy vitamin D (25-OHD) insufficient and sufficient if the value was less than or greater than 50 nmol/L, respectively. 25-OHD data were evaluated in relation to markers of iron load in TM. RESULTS: In TM, 25-OHD insufficiency was 8-fold higher than the control group (odds ratio [OR], 8.1; 95% confidence interval [CI], 4.3-15.0; P<0.001). Similarly, serum PTH (P<0.001), calcium (P<0.001), and phosphate levels (P<0.05) were also significantly lower in TM compared with the controls. In TM, serum ferritin of >2500 µg/L (OR, 5.3; 95% CI, 2.3-12.3; P<0.01), liver iron of >7 mg/g dry weight (OR, 8.8; 95% CI, 3.5-10.3; P<0.001), and serum alanine aminotransferase of >50 IU/L (OR, 9.7; 95% CI, 4.0-23.5; P<0.001) were independent risk factors for low 25-OHD levels. CONCLUSIONS: Our results suggest that TM had a 8-fold higher risk of 25-OHD insufficiency compared with the controls. This was likely to be associated with hepatic hemosiderosis.