Simultaneously obtained skin-puncture serum, skin-puncture plasma, and venous serum compared, and effects of warming the skin before puncture.

Specimens of skin-puncture serum and plasma and venous serum were simultaneously obtained from healthy adults and in each specimen the concentrations of 12 chemical constituents were measured. No clinically important difference was found in the concentrations of the constituents measured in skin-puncture serum and plasma with or without warming the skin before puncture. When the concentration of each of the measured constituents was compared in skin-puncture specimens and venous serum there were important differences in the concentrations of glucose, potassium, total protein, and calcium. Except for glucose, the concentrations of these were higher in venous serum. The degree of hemolysis was the same in skin-puncture serum and plasma, but less in venous serum. The greater hemolysis in skin-puncture specimens was not reflected in a clinically important increase in the values of lactate dehydrogenase and potassium. We conclude that there is a difference in the concentration of some chemical constituents in skin-puncture specimens and venous serum and that these differences should be considered when results for these types of specimens are compared.