Quantitative comparison of whole blood, plasma and serum metabolomes across different blood collection methods.

Objectives: This study quantitatively evaluated whether metabolite profiles differed between capillary (fingerstick vs. microblade) and venous (hypodermic needle) blood collection methods, and the corresponding WB, plasma, and serum samples.

Introduction: Blood may be collected through venipuncture, fingerstick, or microblade devices. Collected samples may remain as whole blood (WB) or be processed to serum or plasma. Differences in collection methods, blood sources (venous or capillary), body locations and processing protocols may influence metabolite composition. However, no systematic assessment has evaluated collection effects on the WB/serum/plasma metabolome.

Methods: Blood was collected from five healthy volunteers via fingerstick (finger), microblade (shoulder, using Tasso + devices), and hypodermic needle (arm) draw. WB, serum and plasma samples from each source were immediately analyzed (to eliminate storage effects) by a quantitative LC-MS assay for 142 metabolites.

Results: Fresh WB showed a distinct metabolite profile compared to fresh plasma or serum, regardless of collection method. Plasma and serum samples from all collection methods exhibited differences in only two metabolites: sarcosine and pyruvic acid. When identical biofluid types were compared, minimal metabolome differences were observed across blood collection methods, body location and peripheral blood sources.

Conclusions: For most metabolites, all three collection methods (venous, microblade, and fingerstick) produced nearly identical results when comparing identical biofluid types. We found minimal metabolic differences between serum and plasma, regardless of collection method, peripheral blood source or body location. These results prove that inexpensive blood microsampling systems (via shoulder-microblade or fingerstick) yield comparable metabolite data relative to venous collection methods.