Use of filter paper stored dried blood for measurement of triglycerides

Abstract

Adaptation of assays on dried blood has advantages of ease of collection, transportation, minimal invasiveness and requirement of small volume. A method for extraction and estimation of triglyceride from blood spots dried on filter paper (Whatman no. 3) has been developed. A single dried blood spot containing 10 muL blood was used. Triglyceride was efficiently extracted in methanol from blood dried on filter paper by incubation at 37 degrees C for two hours with gentle shaking. For the estimation, a commercially available enzymatic method was used. Blood spot assays showed mean intra and inter assay coefficient of variance of 6.0% and 7.4% respectively. A comparison of paired whole blood spots and plasma samples (n = 75, day 0) gave an intraclass correlation of 0.96. The recovery was 99.6%. The dried blood triglyceride concentrations were stable for one month when the filter discs were stored at room temperature (16-28 degrees C). Storage of filters at 4 degrees C extended the stability and triglycerides could be quantitatively recovered after 3 months of storage.

Figure 1

Relationship between dried blood and plasma triglyceride concentrations in 75 paired samples. Regression curve for triglyceride measurement in fresh plasma and blood dried on filter paper. Triglyceride values (n = 75) obtained in dried blood were correlated with values obtained in fresh plasma. Equation for the line is y = 0.88x + 0.13 (r = 0.97, P < 0.001). The intraclass correlation of the paired samples (ICC) is 0.96. Values represent the mean of duplicate measurement.