At-home blood collection for clinical chemistry analyses in a kidney transplant population: a feasibility study

OBJECTIVES: To investigate the feasibility of at-home collection of liquid capillary blood samples for clinical chemistry analyses. METHODS: Kidney transplant recipients performed a fingerprick to collect capillary blood samples. Samples were kept at room temperature for 24 h before further processing. Results were compared to results obtained from venipuncture samples using Passing-Bablok analysis and by calculating mean relative differences, which were compared to CLIA and TEa acceptance limits. In addition, transport times/temperatures and effects of postal handling were examined. RESULTS: Of 38 patients that performed a fingerprick, 29 properly filled 2 microtainers, 4 filled 1 microtainer and 5 were unable to fill any microtainer. Capillary samples were generally more hemolytic, but we found mean differences within CLIA/TEa for hemoglobin, leukocytes, hemoglobinA1c, creatinine, alanine transaminase, C-reactive protein, albumin, calcium and gamma-glutamyl transferase. For alkaline phosphatase and thrombocytes, we found a negative bias, but mean differences within CLIA/TEa. Mean differences for potassium, aspartate transaminase, hematocrit and mean corpuscular volume exceeded CLIA and/or total allowable error (TEa). For phosphate, individual samples showed large variation. Transport times did not exceed 24 h, but temperatures up to 10 °C above outside temperatures were observed. Transport of samples resulted in slight increases in H-index, lactate dehydrogenase (LDH) and aspartate transaminase (ASAT). CONCLUSIONS: At-home capillary blood collection is feasible for many patients and samples are suitable for a subset of clinical chemistry analyses. Instruction, monitoring of transport time/temperature and knowledge of the pitfalls when interpreting results are key elements upon implementation in clinical practice.