Acquired Factor XI Inhibitor Presenting as Spontaneous Bilateral Subdural Hematoma in an Elderly Patient

Table 1

Laboratory data.

Variable	18 months before	Admission	Reference range
Hematocrit, %	38.1	28.2	39.0–50.0
Hemoglobin, g/dL	12.4	9.2	13.2–17.0
platelet count, ×10^9/L	435	200	150–400
PT, %	93	75	70–110
INR	1.06	1.18
aPTT, sec	25	51	22–34
Fibrinogen, mg/dL	—	710	200–420
FVIII, %	—	263	70–150
FIX, %	—	95	70–150
FXI, %	—	31	70–150
Lupus anticoagulant	—	absent	absent
Total protein, g/dL	5.1	6.3	6.1–8.1
Serum protein electrophoresis
Albumin, %	—	36.6	55.8–66.1
alpha1, %	—	6.7	2.9–4.9
alpha2, %	—	11.5	7.1–14.8
beta1, %	—	6.6	4.7–7.2
beta2, %	—	7.2	3.2–6.5
gamma, %	—	31.4	11.1–18.8