Platelet count may impact on lysosomal acid lipase activitydetermination in dried blood spot

Background: We aimed to evaluate the influence of white blood cell (WBC) and platelet (PLT) counts on dried blood spot (DBS)-determined lysosomal acid lipase (LAL) activity in a large group of healthy subjects. Methods: One-hundred-and-seventy-two healthy subjects aged ≥18 were enrolled. Complete clinical biochemistry and LAL activity in DBS were determined. In 35 subjects, WBCs and PLTs were isolated, and LAL activity was measured in both blood cell populations. Univariate and multivariate analyses to DBS-LAL activity were performed. Results: Mean age of subjects was 44.8±17.2years, 43.6% were males, and mean DBS-LAL activity was normal (1.0±0.3nmol/spot/h). LAL activity in WBCs was significantly higher than in PLTs (458.9±133.6 vs 235.0±88.3nmol/mg/h, p<0.001). However, LAL activity in DBS correlated more strongly with that in PLTs (r=0.65, p<0.001) than with that in WBCs (r=0.49, p<0.01). Consistently, in the multivariate model, DBS-LAL activity was independently associated only with PLT count (β=0.39, p<0.001). Conclusions: PLT number may impact on the result of the DBS-LAL test, and a consideration of PLT count is recommended before interpreting LAL activity in DBS.