COAGULATION AND TRANSFUSION MEDICINE
Single Case Report
A Case of Acquired Factor X Deficiency
with In Vivo and In Vitro Evidence of
Inhibitor Activity Directed Against Factor X
PATRICIA E. MULHARE, M.D., 1 PAULA B. TRACY, P H . D . , 2 ELIZABETH A. GOLDEN, MT, 1
RICHARD F. BRANDA, M.D., 2 AND EDWIN G. BOVILL, M.D. 1
A 67-year-old woman had symptoms of an upper respiratory
tract infection for which she received a five-day course of erythromycin. Epistaxis and gross hematuria subsequently developed,
and the patient was found to have a selective Factor X deficiency.
She received supportive therapy and prothrombin complex concentrates (Factors II, VII, IX, and X), with subsequent resolution
of her transient Factor X deficiency. Her hospital course, however, was complicated by the development of multiple cerebral
infarctions. This is the tenth reported case of transient Factor
X deficiency not associated with amyloidosis. In seven of the
previous cases, as in this patient, the deficiency was associated
with a preceding upper respiratory infection. This is the only
case, however, with evidence of inhibitory activity in the plasma
that was directed toward Factor X. (Key words: Factor X inhibitor; Hemostasis; Hemorrhage; Prothrombin concentrate) Am J
Clin Pathol 1991;96:196-200
Although acquired Factor X deficiency has been reported
rarely in patients without amyloidosis, it is a well-described
entity in patients with amyloidosis. The deficiency in these
patients is attributed to enhanced clearance of circulating
Factor X, resulting from the affinity of Factor X for amyloid fibrils.12
In 1959, Graham and associates described a case of
transient Factor X deficiency in a patient after exposure
to the fungicide methylbromide.3 In 1966, Stefanini and
Wiggishoff reported mild transient Factor X deficiency in
a patient with renal and adrenal cortical carcinomas.4 This
mild deficiency resolved after the tumors were removed.
It is interesting that the neoplasms were found incidentally
while the patient was being evaluated for an upper respiratory tract infection. In 1969, Bayer and associates reported the case of a four-year-old boy with transient Factor
X deficiency.5 No infectious, malignant, or toxic associations were present in this case. In 1979, Peuscher and
associates described a case of acquired Factor X deficiency
in a 57-year-old patient with lobar Mycoplasma pneumonia.6 Five subsequent reports have described acquired
Factor X deficiencies in patients with preceding upper
respiratory tract infections.7"1' In two cases, erythromycin
had been administered.8"
We report the case of a patient with transient Factor
X deficiency that developed after a viral upper respiratory
illness that was treated with erythromycin. Serologic
studies for Mycoplasma pneumoniae were negative. This
case is unique in that both in vitro and in vivo coagulation
studies showed evidence of inhibitory activity in the
plasma, directed toward Factor X. The patient was treated
with prothrombin complex concentrates (PCCs), and
multiple cerebral infarctions developed subsequently. The
cause of these infarctions is unclear, but they may have
resulted from a transient hypercoagulable state induced
by factor-replacement therapy.
From the Departments of'Pathology and 2Medicine, University of
Vermont, College of Medicine, Burlington, Vermont.
Received September 11,1990; received revised manuscript and accepted for publication February 19, 1991.
Address reprint requests to Dr. Bovill: Department of Pathology, University of Vermont, College of Medicine, Burlington, Vermont 05405.
196
REPORT OF A CASE
This 67-year-old woman was admitted with epistaxis and gross hematuria. Her medical and family histories were unremarkable. Approximately one week before admission, she had fatigue, cough, fever, and
chills develop after she swam in her pond. Her local physician examined
her, and erythromycin and aspirin were prescribed empirically.
Severe epistaxis and gross hematuria developed subsequently, and she
was admitted to her local hospital, where she received vitamin K and
fresh-frozen plasma. She was transferred to the Medical Center Hospital
of Vermont two days later, with continued brisk hemorrhage. Physical
examination on admission showed stable vital signs, with a respiratory
MULHARE ET AL.
Acquired Factor X Deficiency
rate of 32 breaths/minute. She had evidence of epistaxis and buccal
mucosal bleeding. Diffuse rales and rhonchi were present throughout
both lung fields. She also had frank melena and heme-positive stool.
The remainder of the physical examination was unremarkable. Relevant
admission laboratory data included a platelet count of 224 X 109/L (normal range, 156-312 X 109/L); prothrombin time (PT), 43.3 seconds
(normal range, 11-13 seconds); activated partial thromboplastin time
(APTT), 94 seconds (normal range, 25-37 seconds); thrombin time, 14.7
seconds (normal range, 12-20 seconds); bleeding time greater than 15
minutes (normal, 3-10 minutes);fibrinogen,4.31 g/L (431 mg/dL) (normal range, 1.70-4.10 g/L [ 170-410 mg/dL]); and Factor X concentration,
4% (normal, 60-140%). The Factor II, V, and VII concentrations were
within normal limits.
Hypoxia developed rapidly in association with diffuse bilateral fluffy
infiltrates seen on chest roentgenogram, necessitating elective intubation.
On the second hospital day, she was given PCCs (Profilnine® [Alpha
Therapeutics; Los Angeles, CA], Hyland IX Complex® [Hyland Therapeutics; Glendale, CA]; Factor II, VII, IX, and X replacement) and
prednisone, 60 mg intravenously, twice a day. After initial in vivo recovery
studies with Factor X assays, the patient's response to therapy was monitored by APTT and her clinical bleeding status.
Over the next few days, her condition improved, with resolution of
her bleeding and gradual correction of coagulation abnormalities (Fig.
1). Serologic studies were performed, which showed no evidence of recent
adenovirus, parainfluenza, influenza A or B, Mycoplasma, respiratory
synctial virus (RSV), herpes, cytomegalovirus, or Epstein-Barr virus infections. She had negative Legionella titers and a normal serum electrophoresis. The patient was extubated on hospital day 12, at which time
her factor-replacement therapy was discontinued.
Two to three days after cessation of PCC administration, the patient
had right leg weakness, right body dyspraxia, and a deterioration in mental
status. A computed tomography (CT) scan of her head at this time was
unremarkable. The patient's neurologic status improved over the next
several days; however, she still had abnormal mentation, withflightof
speech, labile affect, and persistent right leg apraxia. A repeat CT scan
— -•II
*
&?
• • • • • • PTT
* X
—*-d/c prothrombin complex concentrates
.
^»
x
300
-60
CO
CD
O
O
40
Q_
C/l
<
200-
o
D
3
5
7
9
11 f 13
15
17
19
Time (days)
FIG. 1. Changes in hemostatic parameters over the hospital course are
shown diagramatically. Factor X (A
• ) and prothrombin ( • - - • )
levels are expressed as percent activity (1 ji/mL pooled normal plasma
= 100%) on the left X axis. The activated partial thromboplastin time
( • • • • • • ) is expressed in seconds in the right y-axis. The insetfigurein
the right upper quadrant is an expanded view of the data from the box
in the left lower quadrant demonstrating the disappearance time of Factor
X following the initial prothrombin concentrate infusion Factor X
(A
MATERIALS A N D METHODS
Factor VH-deficient substrates were purchased frozen
from the New England Regional Hemophilia Center
(Worcester, MA). Factor II and X deficient substrates were
lyophilized plasma purchased from Dade (Miami, FL).
Factor V-deficient plasma was prepared by immunodepletion as previously described.12 Lyophilized pooled
plasma for 50/50 mixing studies was purchased from Dade
(Miami, FL). Purified human Factor X was prepared by
the method of Bajaj and colleagues13 and activated to
Factor Xa with purified Factor X activator from Russell's
viper venom (RVV-X), as described previously.14 RVVX was isolated as described by Kisiel and colleagues.15
Prothrombin was purified from citrated frozen plasma as
previously described.13
Plasma Collection and Processing
Blood for PT, partial thromboplastin time (PTT), fibrinogen, thrombin time, and factor assays was collected
in 0.1 mol/L sodium citrate-citric acid at a 9:1 whole
blood-anticoagulant ratio. Plasma for platelet counts was
collected in ethylenediaminotetraacetate (7.5 mg) Vacutainer® tubes (Becton Dickinson, Rutherford, NJ). Blood
samples for fibrin degradation product analyses were collected in tubes containing thrombin (20 National Institutes of Health (NIH) units per tube) and soybean trypsin
inhibitor (approximately 3,600 NF units per tube)
(Thrombo-Wellcotest® Collection Tube; Burroughs Wellcome Company, Research Triangle Park, NC).
Factor Assays and Screening Tests
I 1 S * S • 7
Timo (hours)
O
iO
on the twentieth hospital day showed multiple cerebral infarctions; some
of which were in the "watershed" distribution. These lesions were consistent with an embolic or ischemic event. She was discharged subsequently to a rehabilitation facility and has recovered partially.
400
v
\>
197
A).
Prothrombin time and APTT were performed by standard automated methods using Dade Thromboplastin C®
reagent (Dade, Aguada, Puerto Rico) and General Diagnostics Auto APTT® reagent (General Diagnostics,
Morris Plains, NJ). Functionalfibrinogenlevels were assessed with a Dade Fibrinogen Kit® (Dade, Miami, FL)
on a BBL Fibrosystem® fibrometer, according to the
manufacturer's instructions. Fibrin degradation products
were measured with the use of the Thrombo-Wellcotest
(Burroughs-Wellcome, Dartford, UK). Standard Ivy
bleeding times were performed with the use of the General
Diagnostics Simplate II® device. Our normal range, based
on a sample of 100 evenly matched male and female subjects, is 3-10 minutes. Thrombin times were obtained by
adding bovine thrombin (10,000 NIH units; Parke-Davis,
Morris Plains, NJ) to citrated plasma. The thrombin had
Vol. 96 • No. 2
198
COAGULATION AND TRANSFUSION MEDICINE
Single (
been adjusted to give a clotting time of 15.5-16.5 seconds
in normal plasma. Platelet counts were performed on a
Coulter S+IV® by standard methods.
Factor II and X coagulation assays were measured by
a one-stage tilt-tube method against pooled reference
plasma, as previously described.16 Mixing studies were
performed by adding patient plasma to an equal quantity
of normal plasma and measuring the PT and APTT as
described above. Total Factor V activity was measured
by a two-stage assay as described previously.16
Two-stage Factor Xa assays were performed by activation of plasma with Russell Viper Venom (Wellcome
Reagents, Ltd, Dartford, UK) before assay. Patient
plasma, normal plasma, and an equal mix of patient and
normal plasma were assayed.
Purified prothrombin was added to normal sodium citrate-anticoagulated plasma to increase the prothrombin
concentration from 100 mg/L (100 fig/mL) to 500 mg/L
(500 /ig/mL). PTs and PTTs were performed on these
plasmas and appropriate control plasmas to evaluate the
effect of high prothrombin concentrations on the screening
assays.
RESULTS
In view of the patient's prolonged PT and PTT on admission, 50/50 mixing studies were performed, and, as
illustrated in Table 1, these showed only partial correction.
This finding suggested the presence of an inhibitor rather
than an isolated factor deficiency.
To determine the specificity of the inhibitor, extrinsic
and common pathway factor assays (Factors II, VII, V,
and X) were performed. Factors II, VII, and V were normal; Factor X was 4%.
A Factor X assay using RVV-X activator was performed on an equal mixture of patient and normal plasma
using a Russell's Viper Venom Factor X assay. A Factor
X level of 32% was observed in the equal part mixture,
in contrast to the 50% Factor X level observed in the
control plasma. This inhibitory activity was verified by
addition of purified human Factor Xa to patient plasma
and normal plasma (10 mg/L [10 jug/mL], final concentration). After a 5-minute incubation, there was significant
prolongation of the clotting time in the patient plasma
compared with the normal pooled plasma (Table 2).
Report
TABLE 2. EFFECT OF ADDITION OF PURIFIED FACTOR Xa
ON RUSSELL VIPER VENOM CLOTTING ASSAY
Incubation
Reaction Mixture
Immediate
5 Minutes
F Xa + normal plasma
F Xa + patient plasma
22.1 seconds
24.7 seconds
35 seconds
65.6 seconds
F Xa = activated Factor X.
The Factor IX concentration is identified for commercially available Factor IX concentrates, but they also contain variable amounts of prothrombin, Factor X, and
Factor VII. So that in vivo recovery studies could be performed more accurately, Factors IX and X and prothrombin were measured in several brands and lot numbers of factor concentrates used to treat this patient. The
findings are shown in Table 3.
In vivo recovery studies, performed after infusion of
PCCs early in the patient's hospital course, showed an
accelerated clearance of Factor X. An estimated half-life
of four hours was observed, which is considerably shorter
than the expected half-life of 30 hours (Fig. I). 12 In contrast, prothrombin levels increased rapidly to more than
400%. In addition, with clearance of the X inhibitor and
continued concentrate therapy, the Factor X level increased to a peak of 345% on the tenth day of factor replacement (Fig. 1). The addition of large amounts of prothrombin (similar to the levels achieved in this patient)
to normal plasma increased the PTT by 1.4 times and the
PT by 1.3 times. The initially prolonged bleeding time
was normal by the third day of concentrate therapy.
DISCUSSION
This is the tenth reported case of non-amyloidosis-associated transient Factor X deficiency (Table 4). In preTABLE 3. ASSAYED LEVELS* OF FACTORS IX, X, AND II IN
PROTHROMBIN COMPLEX CONCENTRATES
A. Alpha Therapeutics Profilnine Lot CW7007A
(vial assay value = 570 n F IX)
Factor IX = 570 U/vial
Factor X = 432 U/vial
Factor II = 576 U/vial
B. Hyland IX Complex Lot 2836011A
(vial assay value = 600 ^ F IX)
Factor IX = 648 U/vial
Factor X = 548 U/vial
Factor II = 606 U/vial
C. Hyland IX Complex Lot 2836010AA
(vial assay value = 600 /*/F IX)
Factor IX = 605 U/vial
Factor X = 436 U/vial
Factor II = 612 U/vial
TABLE 1. MIXING STUDIES
APTT (seconds)
PT (seconds)
Normal
Patient
1:1 Mix
Normal
Patient
1:1 Mix
12
43.3
14.2
31
94
37
PT = prothrombin time; APTT = activated partial thromboplastin time.
A.J.C.P. •
F IX = Factor IX.
• Concentration designated "U" for units with one unit being the amount of the specific coagulation factor activity present in 1 mL of pooled normal plasma.
just 1991
MULHARE ET AL.
Acquired Factor X Deficiency
199
TABLE 4. TRANSIENT FACTOR X DEFICIENCY
Investigator
Associated Disease
Transient
Inhibitor
Demonstrated
Directly
Graham 3 and associates
Stefanini and Wiggishoff4
Fungicide
Tumor: acute
pulmonary disease
Nil
Acute pulmonary disease
(mycoplasma)
Acute pulmonary disease
(viral)
Acute pulmonary disease
(viral)
Acute pulmonary disease
(viral)
Acute pulmonary disease
(viral)
Acute pulmonary disease
(viral)
Yes
Yes
No
No
_
—
Yes
Yes
No
No
Penicillin
Yes
No
—
Yes
No
Penicillin
Yes
No
Erythromycin
Yes
No
Erythromycin
Yes
No
—
Bayer and associates5
Peuscher and associates6
Edgin and associates9
Bayer and associates
7
Hosker and Jewell"
Currier and associates
8
Henson and associates10
vious case reports, inhibitory activity could not be documented in association with the factor deficiency. In this
case, the existence of an inhibitor was demonstrated
clearly by in vivo and in vitro evidence. In vitro studies
established the presence of a specific inhibitor to Factor
X and Xa. In vivo recovery studies after infusion of PCCs
showed a significantly decreased Factor X half-life.
Seven previously reported cases of transient Factor X
deficiencies also were preceded by upper respiratory tract
infections.4'6"" It is hypothesized that antibodies to the
microorganisms cross-reacted with the patient's Factor
X. However, attempts to isolate specific immunoglobulins
directed against Factor X in our patient were unsuccessful.
Three patients, including this one, received erythromycin
for their infections. It is not known whether this antibiotic
played a role in the development of the factor deficiencies.8-"
The patient's clinical bleeding complications and laboratory hemostatic abnormalities improved dramatically
after her factor concentrate replacement. It was believed
that her acute respiratory failure resulted from intrapulmonary hemorrhage, which also responded to the replacement therapy. The initially prolonged bleeding time
with a normal platelet count may have been related to
her aspirin therapy. In addition, an abnormal bleeding
time has been reported previously in a patient with acquired Factor X deficiency and associated defects in
platelet aggregation.9
Another interesting feature in this case is the patient's
subsequent development of multiple cerebral infarctions.
The patient first manifested neurologic symptoms two to
three days after factor replacement therapy was discontinued. There were no preceding hypotensive or ischemic
events. On CT scan, these lesions were compatible with
Antibiotics
—
either embolic or ischemic infarctions with multiple, discrete, nonhemorrhagic lesions. The relationship of factor
replacement therapy to the cerebrovascular events in this
patient is unclear. It is conceivable that this treatment,
which resulted in significant increases in the prothrombin
and Factor X levels, predisposed her to the development
of multiple thrombotic emboli. Thrombotic complications
have been described in patients treated with PCCs.17"19
The most serious of these include myocardial infarctions
and disseminated intravascular coagulation. In a previously reported case, a large myocardial infarct developed
in a 15-year-old hemophiliac, for which the patient subsequently received a cardiac transplant.18 It is interesting
that the Factor X level was 400% at the time of infarction.
Factor X replacement with PCCs appears to have been
effective treatment for the acute bleeding episode. The
patient's PT and PTT improved dramatically after replacement therapy was started but did not become completely normal until three days after PCC treatment was
stopped. However, her bleeding clinical diathesis improved promptly, coincident with replacement therapy.
Consequently, after the initial Factor X recovery studies,
the patient's response to replacement therapy was monitored by the PT and APTT. Assays for Factors II and X
that were performed subsequently demonstrated extremely high levels of prothrombin. The high levels of
prothrombin appear to have affected the PT and PTT and
may have played a role in the thromboembolic complication. The cause of the prolonged PT and PTT associated
with high levels of prothrombin is not clear, but may have
resulted from increased "self-association"20 at these high
concentrations. Such polymerization might hinder normal
prothrombinase function. We conclude that PCCs constitute effective treatment for transient Factor X inhibitors.
Vol. 96 • No. 2
200
COAGULATION AND TRANSFUSION MEDICINE
Single Case Report
However, Factor X levels should be measured to monitor
therapy, to avoid unnecessarily high levels of vitamin Independent procoagulant proteins.
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A.J.C.P. • August 1991