Clinical chemical analyses of serum obtained from capillary versus venous blood, using Microtainers and Vacutainers.

The concentrations of sixteen chemical constituents determined in specimens from skin puncture serum (capillary serum) collected in Microtainer were compared to the concentrations in venous serum collected in Vacutainer from adult individuals. Compared to venous serum, the concentrations in skin puncture serum were higher for potassium (2.9%), chloride (2.3%) and thyroid stimulating hormone (TSH) (86.7%) and lower for sodium (1.6%), calcium (3.2%), phosphorus (5.0%), creatinine (6.6%) and total protein (4.7%), whereas no differences were observed for urea, bilirubin, ASAT, ALAT, LD, insulin and thyroxin. The differences for sodium, calcium and TSH are explained by interference form the sampling device (Microtainer). Except for TSH, the differences are small and probably of minor clinical importance.