Serum albumin-fatty acid saturation test

Abstract

Circulating non-esterified fatty acids (NEFA) are toxic to mammalian cells. They increase in diseases such as diabetes and sepsis. Herein we propose a serum albumin-fatty acid saturation test. •We based our test on three methodologies: isoelectric focusing (IF) of human plasma albumin, staining proteins after isoelectric focusing in gels with Coomassie Brilliant Blue, and serum albumin measurement with bromocresol green.•The test consists in the determination of albumin IF and staining with bromocresol green. If albumin is saturated with NEFA, it focuses on lower pH, meaning it is the threshold to bind to them. Excessive NEFA is free and toxic. Many other tests are available for NEFA quantification as NEFA kit assay. All colorimetric assays are used for quantification of NEFA and other tests need expensive equipment to read out the results, and they do not measure albumin levels.•Our method focused on albumin-NEFA saturation instead of just NEFA quantification. Critically ill patients have an alteration in both albumin and NEFA. Therefore, our test undergoes less daytime variation compared to assays that measure absolute NEFA values, allowing a more reliable use as an indicator of albumin-fatty acid saturation and NEFA toxicity.

Keywords: Albumin; Lipotoxicity; Non-esterified fatty acids; Serum albumin-fatty acid saturation test.

Graphical abstract

Fig. 1

Experimental schematic drawing. The first step is gel polymerization with the first electrophoresis (1 and 2). Next step is sample application and second electrophoresis (3 and 4). Cut the gel in two pieces, one with two lanes without samples and cut it in pieces and place them in distilled water (5a) and stain the samples in the second gel piece (5b). After measuring pH (6) compare the stained sample’s position with pH at the same position (7).

Fig. 2

Isoelectric focalization images. Isoelectric focalization of albumin from five controls (A). The samples were processed according to MM. Albumin from all samples focalized at pH 5.11. Assessment of pH in each 0.5 cm gel piece. The bars represent the pH gradient at the end of isoelectric focusing of 7 independent runs. The data is represented as median ± standard error.