HemosIL CL HIT-IgG(PF4-H)

HemosIL CL HIT-IgG(PF4-H) is a fully automated chemiluminescent immunoassay that detects IgG antibodies against Platelet Factor 4 complexed with heparin in human citrated plasma. The test is used on the ACL TOP 970 CL instrument to help diagnose heparin-induced thrombocytopenia (HIT) in adult patients suspected of the condition, though results must be interpreted alongside clinical and laboratory findings.

The new device uses the same chemiluminescent methodology, magnetic particle reagents coated with PF4/PVS complex, isoluminol-labeled anti-human IgG tracer, and fixed 1.00 U/mL clinical cut-off as the predicate. Key differences are: operation on ACL TOP 970 CL instrument versus ACL AcuStar, use of HEPES buffer instead of phosphate/Tris buffer, acceptance of only 3.2% citrated plasma versus 3.2% or 3.8% citrated plasma and serum, and slight variations in calibrator (16.50 vs 16.00 U/mL) and control (3.50 vs 3.00 U/mL high) target values.

CLSI EP05-A3 (3rd Edition) for precision; CLSI EP17-A2 (2nd Edition) for limit of detection; CLSI EP07 (3rd Edition) for interference testing; CLSI EP28-A3c (3rd Edition) for normal reference range establishment.

Substantial equivalence rests on identical analytical principles, reagent composition, antibodies, and clinical cut-off values producing comparable diagnostic performance. Method comparison with the predicate device achieved 99% total agreement (97% PPA, 100% NPA) across 341 patient samples at three sites. Analytical performance—including precision (≤10.7% CV), reproducibility across sites and operators (≤16.4% CV), and clinical validation against the Serotonin Release Assay (98.9% agreement)—demonstrates the new assay performs equivalently despite instrument platform and formulation changes that do not impact safety or effectiveness.