Repurposing dried blood spot device technology to examine bile acid profiles in human dried fecal spot samples

Abstract

Dried blood spot (DBS) analysis has existed for >50 years, but application of this technique to fecal analysis remains limited. To address whether dried fecal spots (DFS) could be used to measure fecal bile acids, we collected feces from five subjects for each of the following cohorts: i) healthy individuals, ii) individuals with diarrhea, and iii) Clostridioides difficile-infected patients. Homogenized fecal extracts were loaded onto quantitative DBS (qDBS) devices, dried overnight, and shipped to the bioanalytical lab at ambient temperature. For comparison, source fecal extracts were shipped on dry ice and stored frozen. After four months, frozen fecal extracts and ambient DFS samples were processed and subjected to targeted LC-MS/MS-based metabolomics with stable isotope-labeled standards. We observed no differences in the bile acid levels measured between the traditional extraction and the qDBS-based DFS methods. This pilot data demonstrate that DFS-based analysis is feasible and warrants further development for fecal compounds and microbiome applications.