Dried Blood Spot Sampling for Monitoring Children With Immune-Mediated Glomerulopathies and After Kidney Transplantation

Introduction: Monitoring kidney function and immunosuppressant levels in children post-kidney transplantation or those with glomerulopathies is challenging due to frequent venipunctures and clinic visits. Capillary dried blood spot sampling (DBS) offers a potential alternative. Methods: In this prospective single-center study, 89 children (38% female and 62% male) requiring therapeutic drug monitoring (TDM) and kidney function assessment were enrolled. Of the patients, 79% were kidney transplant recipients, and 21% had immune-mediated glomerulopathies. The mean age was 13.4 (range, 5.7-18.0) years. DBS and standard venous serum samples were collected simultaneously for tacrolimus (TAC), cyclosporine A (CsA), everolimus (EVR), and creatinine levels. Furthermore, patient feedback on pain perception and feasibility was collected via questionnaire. Results: No significant differences in parameter values between DBS and standard methods were observed (creatinine,-1.7 f 14.5 mu mol/l; EVR, 0.1 f 1.2 mu g/l; TAC, 0.3 f 1.1 mu g/l; CsA, 2.8 f 9.8 mu g/l). DBS demonstrated sufficient accuracy compared with standard methods. Patients favored DBS and telehealth consultations, especially due to less travel and school absences. Patients preferred finger pricking over ear pricking. Conclusion: Capillary DBS proves reliable for TDM and kidney function assessment in pediatric kidney disease. It reduces patient and family burden compared with venous blood collection and enables telehealth consultations.