Table 4. Results of Selected Testing for Hypercoagulable States in Initial 12 Patients With Cerebral Venous Sinus Thrombosis and Thrombocytopenia Following Emergency Authorization Receipt of Ad26.COV2.S Vaccine—US, 2021^a.

Patient No.	Antiphospholipid antibody testing			Homocysteine level	Antithrombin activity
	Anticardiolipin antibody	β2 Glycoprotein 1 antibody	Lupus anticoagulant assay
1	Negative IgM, IgG		dRVVT negative	Normal
2	Negative IgM, IgG	Negative IgM, IgG	dRVVT negative	Normal	Normal
3	Negative IgM, IgG	Negative IgM, IgG	dRVVT negative
4	Weak positive IgM (17.9 mg/dL), negative IgGb	Weak positive IgM (15.3 mg/dL), negative IgGb			Normal
5	Indeterminate IgM (16.0 mg/dL), negative IgGc	Negative IgM, IgG	dRVVT negative	Normal
6	Negative IgM, IgG	Negative IgM, IgG	dRVVT negative		Normal
7	Negative IgM, IgG		dRVVT negative	Normal	Normal
8	Negative IgM, IgG	Negative IgM, IgG	dRVVT 86 (≤45 seconds)d hex confirmation pending
9	Negative IgM, IgG	Negative IgM, IgG	dRVVT negative
10
11	Negative IgM, IgG	Negative IgM, IgG	RVVT ratio negative		Normal
12	Negative IgM, IgG	Negative IgM, IgG	RVVT ratio negative		Normal

Abbreviations: dRVVT, dilute Russell viper venom time. Blank cells indicate that testing was not found in the medical records.

^aAdditional testing performed in at least 1 patient includes for protein C and protein S activity, antinuclear antibodies, flow cytometry for paroxysmal nocturnal hemoglobinuria, serum protein electrophoresis, and heparinase testing; all results were normal. Testing for selected inherited causes of hypercoagulability were negative in all patients where results were available.

^bReference range: <15.0 mg/dL = negative, 15.0-39.9 mg/dL = weak positive.

^cReference range in IgM phospholipid (MPL) units: 0-12 = negative, 13-19 = indeterminate, 20-80 = low to moderately positive, and ≥81 = high positive.

^dThe patient was receiving anticoagulation so the elevated value is not considered abnormal.