Correlation between venous and capillary blood samples for cyclosporine monitoring in pediatric liver transplant patients.

Venipuncture has traditionally been required to monitor serum cyclosporine levels. This is a difficult if not impossible task in pediatric patients. Capillary blood sampling has eliminated the need for venous access in the majority pediatric laboratory investigations. Although the practice of capillary sampling for cyclosporine monitoring is discouraged, there has never been any investigation into the reliability of this method. Thus, we compared 18 capillary cyclosporine levels from 4 pediatric liver transplant patients to simultaneous venipuncture serum levels. The correlation coefficient of the paired samples (range 32-1005 ng/ml) was 0.914. This excellent correlation between the two sampling methods suggests that capillary cyclosporine levels may be adequate to monitor the immunosuppression of pediatric liver transplant patients.