Dried blood spot sampling for monitoring children with immune-mediated glomerulopathies and after kidney transplantation

IntroductionMonitoring 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.MethodsIn 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.ResultsNo significant differences in parameter values between DBS and standard methods were observed (creatinine, −1.7 ± 14.5 μmol/l; EVR, 0.1 ± 1.2 μg/l; TAC, 0.3 ± 1.1 μg/l; CsA, 2.8 ± 9.8 μg/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.ConclusionCapillary 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.