Differences in circulating fatty acid-binding protein 4 concentration in the venous and capillary blood immediately after acute exercise

Shigeharu Numao,Ryota Uchida,Masaki Nakagaichi,Takashi Kurosaki

doi:10.1186/s40101-021-00255-z

Abstract

BackgroundCirculating fatty acid-binding protein 4 (FABP4) is a marker for various diseases. It would be highly useful to have simple and less invasive techniques for the assessment of FABP4 concentrations in the clinical research setting. The purpose of the present study was to assess the concordance of circulating FABP4 concentrations in venous and capillary blood both at rest and immediately after acute exercise in healthy young males.ResultsThirty-eight healthy young male adults aged from 19 to 25 years (mean age, 20.8 ± 1.2 years) were recruited. Paired blood samples were taken from the cubital vein (venous) and fingertip (capillary) blood at rest (resting state) and immediately after incremental exercise (exercising state). Blood samples were analyzed to determine the circulating FABP4 concentration using an enzyme-linked immunosorbent assay. Pearson’s correlation coefficients for circulating FABP4 concentrations between venous and capillary blood samples indicated a strong positive correlation in both the resting and exercising state (resting state: r = 0.982, exercising state: r = 0.989, both p < 0.001). The mean FABP4 concentration was similar between venous and capillary blood in the resting state (p = 0.178), whereas it was significantly higher in capillary blood than in venous blood in the exercising state (p < 0.001). Furthermore, Bland–Altman plots showed a non-significant bias (− 0.07 ± 0.61 ng/mL, p = 0.453) in the resting state, whereas a significant bias (− 0.45 ± 0.61 ng/mL, p < 0.001) was observed in the exercising state.ConclusionsThese results indicate that capillary blood sampling can slightly overestimate circulating FABP4 concentrations under a physiologically dynamic state. However, the association between the venous and capillary blood in terms of FABP4 concentration was very strong, suggesting that capillary blood sampling can detect changes in FABP4 concentration in both physiologically steady and dynamic states.

Highlights

Fatty acid-binding protein 4 (FABP4), known as adipocyte Fatty acid-binding proteins (FABPs) or adipose protein 2, is one of the fatty acid-binding proteins
Circulating fatty acid-binding protein 4 (FABP4) concentration is known as a biomarker for several disorders; increased circulating FABP4 concentrations are associated with the increased risk of various diseases, such as atherosclerosis [7, 8], insulin resistance [9], type 2 diabetes [10], hypertension [9, 11], dyslipidemia [9, 12], cardiovascular diseases [13, 14], and cancer [15]
The regression analysis showed that the estimated regression equation was not significant (y = 0.043x–0.356, p = 0.111, estimated standard error (SEE) = 0.594, 95%Confidence interval (CI): −0.010–0.096)

Summary

Introduction

Fatty acid-binding protein 4 (FABP4), known as adipocyte FABP or adipose protein 2, is one of the fatty acid-binding proteins. FABP4 is highly expressed in adipocytes and macrophages [2,3,4] and is primarily secreted from adipocytes into the blood [5, 6]. Circulating FABP4 concentration is increasingly useful as a biomarker of disorders. To broaden the use of circulating FABP4 as a biomarker in clinical research settings, simpler and less invasive techniques are required to determine its concentrations. It would be highly useful to have simple and less invasive techniques for the assessment of FABP4 concentrations in the clinical research setting. The purpose of the present study was to assess the concordance of circulating FABP4 concentrations in venous and capillary blood both at rest and immediately after acute exercise in healthy young males

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Conclusion