Antiphospholipid and anti-PF4 antibodies: an association affecting anti-PF4/heparin assay analysis

Inflammation and Hemostatic Activation may Contribute to Postsurgical Thrombosis in Patients With Bladder Cancer

The alterations of the inflammatory and thrombotic components in patients with cancer are not clearly understood. The purpose of this study was to profile markers of inflammation and thrombotic activation specifically in the patients with bladder cancer undergoing radical cystectomy. For this study, 134 samples were collected from patients undergoing radical cystectomy. Antiphospholipid antibodies (immunoglobulin G subtype), microparticles, and antiglycosaminoglycan antibodies were measured with a commercially available enzyme-linked immunosorbent assay kits. These biomarkers were compared in patients with bladder cancer and normal individuals (n = 20). Patients had an average value of 6.7 ± 11.9 ng/mL (median: 2.8, confidence interval: 4.69-8.75, andPvalue: .0038) of antiphospholipid antibodies versus normal individuals 1.96 ± 0.9 ng/mL (median: 1.8 and confidence interval: 1.5-2.35). Microparticles level in patients was 8.31 ± 6.14 ng/mL, (median: 6.1, confidence interval: 7.26-9.37, andPvalue: <.0001) versus normal individuals 3.57 ± 2.34 ng/mL (median: 2.85 and confidence interval: 2.476-4.664). The antiglycosaminoglycan antibodies in patients had an average value of 0.22 ± 0.1 optical density (OD; median: 0.2, confidence interval: 0.21-0.24, andPvalue: .0213) compared to normal individuals 0.25 ± 0.08 OD (median: 0.25 and confidence interval: 0.22-0.23). The correlation of antiglycosaminoglycan antibodies with antiphospholipid antibodies showed Spearmanrvalue = .2364 (95% confidence interval: 0.05-0.4 andPvalue .009). The correlation of antiglycosaminoglycan antibodies versus microparticles showed Spearmanr= -.195 (95% confidence interval: 0.37-0.01 andPvalue .0321). These data suggest that patients with bladder cancer have subclinical activation of thrombotic and inflammatory processes that may be further exacerbated by surgical procedures and lead to venous thromboembolism-related complications.

Validation of whole blood impedance aggregometry as a new diagnostic tool for HIT: results of a large Australian study

Heparin-induced thrombocytopenia (HIT) remains a challenge, with diagnosis confirmed only by functional assays. The gold standard 14C-serotonin release assay (SRA) is highly sensitive but technically challenging and unsuitable for routine use. We conducted a large study to validate whole blood impedance aggregometry (WBIA) as a suitable diagnostic tool for HIT. WBIA and SRA were used to test 181 samples positive for H-PF4 antibodies by PaGIA or ELISA. Using the same high responder donor, 77 samples were positive by WBIA (aggregation with low-dose but not high-dose heparin). Using the strict definition for SRA positivity, 72 samples were true HIT. In nine samples, serotonin release with high-dose heparin dropped by > 50% but was still >20%; these were retested after a one-half dilution and 8/9 became positive. Ten other samples were discrepant between the two assays: one strongly positive (89% release) and six weakly positive samples by SRA (average release 56%) were WBIA negative. When these samples were retested using a random donor, only two remained SRA positive. Three samples were strongly WBIA positive but SRA negative; two were retested by SRA with 0.5IU/ml heparin and one became positive. Under controlled conditions, using the same selected high-responder donor, WBIA and SRA performed similarly with slightly increased sensitivity of the WBIA when using the strict definition of SRA positivity. WBIA is easy to perform with rapid turn-around time and warrants a multi-laboratory trial to complete its validation as a confirmatory assay for platelet-activating HIT antibodies.

Venous limb gangrene and fatal hemorrhage: adverse consequences of HIT "overdiagnosis" in a patient with antiphospholipid syndrome

This unfortunate patient case highlights the problems with "overdiagnosis" of HIT. Despite "positive" tests for HIT antibodies, the low pretest probability for HIT and the known propensity of patients with APS to yield false-positive HIT antibody results suggests that the patient did not have a true diagnosis of HIT. Moreover, the early administration of warfarin and the choice of argatroban for parenteral anticoagulation when monitoring was hindered by a prolonged baseline aPTT likely play a key factor in the progression of UE DVT to VLG. Ironically, the problems of anticoagulant monitoring posed by the prolonged baseline aPTT likely contributed to the subsequent overanticoagulation and fatal pulmonary hemorrhage. With benefit of hindsight, avoiding the temptation to test for HIT in a low pretest probability situation, and treatment with either heparin using anti-factor Xa monitoring or with non-aPTT-monitored therapy such as LMWH or fondaparinux would likely have resulted in a more favorable clinical course.