A rapid whole blood ATP secretion test can be used to exclude platelet dense granule deficiency

Delta storage pool disease (δ-SPD) is a rare platelet function disorder (PFD) characterized by deficiency of dense granules or defective granule secretion, leading to bleeding diathesis. Diagnostics of δ-SPD are difficult and lack standardization, leading to underestimation of its prevalence. Current diagnostic methods are based on granule content assays or lumi-aggregometry, which have limited availability. Therefore, there is an unmet need for a rapid, accessible test for δ-SPD. To evaluate the diagnostic value of a rapid whole blood ATP secretion test for δ-SPD. ATP secretion after PAR-1 Activating Peptide (PAR-1 AP; TRAP-6) stimulation was assessed in whole blood using luminescence in 50 healthy controls, 22 patients with a suspected PFD other than SPD (non-SPD) and 25 δ-SPD patients and corrected for platelet count. Diagnostic value of the test was determined with C-statistics, sensitivity, specificity, likelihood ratios (LLR) and predictive values (PV). PAR-1 AP mediated ATP secretion in the rapid test was lower in δ-SPD compared with healthy controls and non-SPD patients (P