Comparison of plasma fatty acid binding protein 4 concentration in venous and capillary blood.

Circulating fatty acid binding protein 4 (FABP4) is associated with various diseases and simple and less invasive techniques for assessment of FABP4 concentration are required in clinical research setting. The purpose of the present study was to assess the correlation of plasma FABP4 concentration between venous and capillary blood in healthy young adults. Twenty-eight healthy young adults aged from 20 to 26 years (mean age, 22.2 ± 1.4 years, 14 males and 14 females) were included. Paired resting blood samples were taken from the cubital vein (venous) and fingertip (capillary) blood. Plasma FABP4 concentration in both blood was analyzed by enzyme-linked Immunosorbent assay. Plasma FABP4 concentration did not differ significantly between venous and capillary blood (-0.11± 0.75 ng/mL, p = 0.447, 95%CI: -0.402-0.182). Pearson's correlation coefficient for plasma FABP4 concentration between venous and capillary blood samples suggests strong correlation (r = 0.961, p < 0.001). The Bland & Altman plot showed a non-significant bias (-0.11 ± 0.75 ng/mL, p = 0.684) and the 95% limits of agreement ranged from -1.59 to 1.37 ng/mL. FABP4 concentration in both venous and capillary blood was significantly higher in females than in males (venous blood: p = 0.041; capillary blood: p = 0.049). These results suggest that capillary blood sampling can detect gender difference and is useful for the assessment of FABP4 concentration.