American Journal of Hematology 40:33-37 (1992)
Concurrent Protein C Deficiency and Lupus Anticoagulants Robert L. Harrison and Jack B. Alperin Departments of Pathology and Internal Medicine, The University of Texas Medical Branch, Galveston
An inherited deficiency of protein C, a recognized hypercoagulable state, may cause a
clinically significant deep venous thrombosis. Only some persons with a deficiency of protein C experience thrombosis, and almost always the thrombotic event occurs in the venous circulation. Warfarin-induced skin necrosis, a rare event observed in some patients soon after treatment with warfarin is begun, is believed to be another manifestation of this deficiency. We describe a young woman whose basal functional and antigenic levels of protein C were about 45% and who experienced both deep venous thrombosis and warfarin-induced skin necrosis in a clinically severe course. Evidence for lupus anticoagulants was present, with prolonged activated partial thromboplastin time that was corrected when lysed platelets were added, prolonged Russell's viper venom time, anticardiolipin antibodies, and other laboratory evidence. Lupus anticoagulants are associated also with a significant incidence of thrombosis, including arterial thrombosis, and this patient developed concurrently arterial thrombosis. The combined effects of protein C deficiency and lupus anticoagulants, exacerbated by other potentially thrombogenic conditions, are believed responsible for the severe thrombotic events experienced by this 1992 Wiley-Liss, Inc. patient. Key words: thrombosis, autoantibodies, venous thrombosis
INTRODUCTION
CASE REPORT AND METHODS
Hereditary deficiency of protein C is one of the few defined causes of thrombosis. Protein C plays a significant role in regulating coagulation since it is a precursor of a serine protease (activated protein C) that is a potent physiologic inhibitor of activated factors V and VIII and potentially is an activator of fibrinolysis [I-31. A homozygous deficiency of protein C usually presents with a severe thrombotic picture leading to purpura fulniinans 12-51, At least half of individuals with a protein C concentration less than 50% of normal will experience a thrombotic event before age 30 [ 3 ] .However, a heterozygous deficiency, with concentrations of protein C ranging from 20-60% of normal, does not eventuate in thromboses in all patients (31. It has been suggested that other factors influence the thrombotic risk [3]. This report describes a patient with recurrent thromboses who has a familial deficiency of protein C, lupus anticoagulants (LA), and anticardiolipin antibodies (ACA).
A Caucasian woman was first seen in 1984 at age 19 for deep venous thrombosis. She was initially treated with intravenous heparin, which was stopped less than 24 hr later when treatment with warfarin (Coumadin"") was begun. Three days later purpura and necrosis of the skin over both breasts appeared (Fig. 1 ) . Skin grafts were needed to cover the defects over her breasts. Plasma concentrations of protein C, both antigenic and functional (generously measured by Dr. Phillip Comp, University of Oklahoma Medical Center), measured 45% of normal after warfarin had been discontinued for three weeks.
0 1992 Wiley-Liss, Inc.
Received for publication February 8 . 1991; accepted September 26, 1991. Addre\\ reprint requests tu Robert Harrison. M.D., Department of Pathology. The University of Texas Medical Branch, Galveston. TX 77550.
34
Case Report: Harrison and Alperin
Fig. 1. The right breast three days after warfarin was begun.
Fig. 2. Extensive necrosis of the tissues of both lower extremities eventuated in bilateral amputations.
Protein S antigen was normal. Antithrombin 111 (AT 111) measured 95% of normal. A thrombin clotting time was normal. During the first one and one-half months of hospitalization the patient’s hemoglobin declined progressively from 1 37 g/L to 69 g/L (normal 120- 180 g/L), and no evidence of a site of blood loss was present. Spherocytic red cells of various sizes were found on microscopic examination of a blood smear. Reticulocytes measured 25% and the red cell distribution width (RDW) was 27% (normal 11.5-14.5%). With therapy, the hemoglobin had risen again to 120 g/L by the time of discharge. The platelet count during the hospitalization declined from 187 X 10’ to 134 X 10y/L (normal 130-400 X 10’/L), and total serum bilirubin climbed to 208 pmol/L (normal range 1.7-18.8 pmol/L). with 132 pmol/L unconjugated bilirubin (normal range 1.7-15.4 kmol/L). A direct antiglobulin test was 1 +, anti-IgG antibody was 3 + , and anticomplement antibody was 2 + . Anemia was attributed to autoimmune hemolytic disease (AIHD), and treatment with prednisone was begun. Fluorescent antinuclear antibody assay, antinuclear and anti-Sm antigens, and anti-ribonucleoprotein antibody tests were negative. The patient denied the use of alcohol. She had smoked one pack of cigarettes daily for five years. There WHS a family history of diabetes mellitus. Protein C was assayed once for the patient’s mother and brother. Her mother had a protein C antigen level of 52% of normal, a protein S antigen level of I 19% of normal, and a factor X concentration of 149%. Protein C and protein S antigens were measured in the Medical Branch laboratories using kits from American Bioproducts Company. The patient’s brother’s concentration of protein C was 64% (measured by Dr. Comp). No liver disease or other predisposing factors that might contribute to diminished levels of the vitamin K dependent proteins were recognized in either the mother or the sibling. The patient was discharged
from the hospital and instructed to give herself injections of heparin subcutaneously. She also continued taking prednisone for four weeks after discharge because of continuing AIHD. The patient was readmitted in 1986 with a ten-day history of pain in the right calf, shortness of breath, and pleuritic right chest pain. Both feet were cold, and the lower extremities were discolored from the toes to approximately midway up the calves of both legs (Fig. 2). There was evidence of recurrent AIHD. Platelets measured 75 X IO’/L. A ventilation-perfusion scan was consistent with pulmonary thrombosis. An aortogram and peripheral arteriogram showed diffuse small vessel disease involving the posterior tibial, peroneal, and anterior tibial arteries. There was also a thrombus involving the left common femoral and proximal profundus arteries (Fig. 3). Streptokinase was administered without improvement. Additional treatment included azathioprine, prednisone, red blood cell infusions, fresh frozen plasma [ 5 ] ,and cryoprecipitate. Because of clinical deterioration, bilateral amputations of the lower extremities at the knees were performed. Random sampling of major vessels of the two lower extremities demonstrated thrombi in several large and small veins. One dose of 1,320 units of prothrombin complex concentrate, which has been used in cases of homozygous protein C deficiency [6,7], was administered, as Proplex Th‘ , without apparent clinical improvement. An infusion of heparin was begun following surgery and was continued for ten days. Treatment with warfarin was then started, and the heparin infusion was discontinued after a stable and appropriately prolonged prothrombin time had been attained. After discharge from the hospital the patient continued to take warfarin at a dose to maintain the prothrombin time between 1.5 and 1.9 times the control value. She has also continued to take azathioprine to control hemolysis. New thrombotic
Case Report: Protein C and Lupus Anticoagulants
35
TABLE I. ACA Assay'
Patient, 1984 Patient, 1986 Patient, 1989 Patient's mother, 1984 Patient's mother, 1989 Normal
0.82 0.22 0.84 0.102 0.061 0.0 19-0.037
0.070 0.070 0.058 0.02 1 0.014 0.006-0.014
0.098 0.0 I3 0.1 I 0.0 12 0.007 0.002-0.004
*Numbers are optical density; normal values are mean optical density f one SD. An optical density is considered positive if it is more than five SDs above the mean normal optical density 18.91.
neutralization tests probably reflect combined warfarin and LA effects. DISCUSSION
Fig. 3. Arteriogram shows a filling defect (arrow) due to thrombus in the left common femoral and proximal profundus arteries.
symptoms have not arisen in the approximately five years since the 1986 hospitalization. In 1988 she presented for fallopian tuba1 ligation. In preparation for the laparoscopic surgery, treatment with warfarin was discontinued, and an infusion of heparin was begun. Heparin was discontinued 8 hr prior to and was restarted immediately after surgery. One day after surgery treatment with warfarin was reinstituted. Starting with 2.5 mg daily the dose was gradually increased. After six days the warfarin dose was 10 mg daily: heparin infusion was then discontinued. The patient was dismissed taking warfarin, 5-7.5 mg daily, regulated to a prothrombin time of 1.5-1.9 times control. The patient's plasma was serendipitously tested [8,9] and found positive for anticardiolipin antibodies (ACA) (Table I). The results of coagulation studies for the lupus anticoagulant (LA), performed as previously described 19-1 I] on plasma from the 1988 hospitalization and on plasma frozen since 1986, are shown in Table 11. Assays from both the remote and the more recent hospitalizations were consistent with LA and ACA. Because the patient was taking warfarin when the recent plasma sample was obtained, the results of the dilute Russell's viper venom time test (RVVT) as well as the mixing and platelet
For most patients with thrombophlebitis, an underlying biochemically well defined disorder cannot be identified. Hereditary deficiencies of AT 111, protein C, and protein S predispose to thrombosis. The role played by these inhibitors is defined biochemically and the underlying pathophysiology leading to thrombosis in these deficiency states is, therefore, relatively well understood. It is unclear why only some patients with deficiencies of these physiologic anticoagulants will experience a thrombotic event. It has been suggested that some patients develop thrombi because of an additional disorder or condition that predisposes to thrombosis [3,12,13]. Dysfibrinogenemia and disorders of the fibrinolytic system are likewise associated with thrombosis in some patients, but the underlying basis of a hypercoagulable state in these patients is at best only partly understood 121. The LA and ACA are markers for a propensity to thrombose [ 141 in some persons, but here the mechanism of thrombosis is not explained. About one of three people with LA or ACA will eventually experience a thrombotic event [ IS]. Although the mechanism underlying the tendency to thrombose remains undefined, several theories have been suggested [ 1 &2 I], including hypothesized effects on prostacyclin production by endothelial cells and inhibition of prekallikrein. One postulate states that LA interferes with thrombomodulin in the activation of protein C zymogen to its serine protease form [ 18-20]. It is difficult, however, to explain arterial thrombosis in the presence of LA if the mechanism of thrombosis is a consequence of defective or abnormal protein C activation. Protein C and S deficiencies manifest almost exclusively as venous thromboses [2], whereas arterial thrombosis in association with the LA is often observed. The clinical manifestations of thrombosis exhibited by this patient were judged to be unusually severe for the degree of protein C deficiency. The severity of throm-
36
Case Report: Harrison and Alperin TABLE II. In Vitro Coagulation Tests for the LA Test Patient results APTT” Platelet neutralized APTT (PNP) [ I I ’I Saline control for the PNPa RVVT [ IOJa RVVT, one part patient: one part normal plasmaa Platelet neutralized RVVTd TTI ratio ( 1 :1,000)”
RVVT~ RVVT. one part patient: one part normal plasmab Platelet neutralized RVVTh
36 sec 30.7 sec 35.6 sec 33.7 sec 3 1.4 sec
Normal values 24-36 sec Correction
Concurrent Protein C Deficiency and Lupus Anticoagulants Robert L. Harrison and Jack B. Alperin Departments of Pathology and Internal Medicine, The University of Texas Medical Branch, Galveston
An inherited deficiency of protein C, a recognized hypercoagulable state, may cause a
clinically significant deep venous thrombosis. Only some persons with a deficiency of protein C experience thrombosis, and almost always the thrombotic event occurs in the venous circulation. Warfarin-induced skin necrosis, a rare event observed in some patients soon after treatment with warfarin is begun, is believed to be another manifestation of this deficiency. We describe a young woman whose basal functional and antigenic levels of protein C were about 45% and who experienced both deep venous thrombosis and warfarin-induced skin necrosis in a clinically severe course. Evidence for lupus anticoagulants was present, with prolonged activated partial thromboplastin time that was corrected when lysed platelets were added, prolonged Russell's viper venom time, anticardiolipin antibodies, and other laboratory evidence. Lupus anticoagulants are associated also with a significant incidence of thrombosis, including arterial thrombosis, and this patient developed concurrently arterial thrombosis. The combined effects of protein C deficiency and lupus anticoagulants, exacerbated by other potentially thrombogenic conditions, are believed responsible for the severe thrombotic events experienced by this 1992 Wiley-Liss, Inc. patient. Key words: thrombosis, autoantibodies, venous thrombosis
INTRODUCTION
CASE REPORT AND METHODS
Hereditary deficiency of protein C is one of the few defined causes of thrombosis. Protein C plays a significant role in regulating coagulation since it is a precursor of a serine protease (activated protein C) that is a potent physiologic inhibitor of activated factors V and VIII and potentially is an activator of fibrinolysis [I-31. A homozygous deficiency of protein C usually presents with a severe thrombotic picture leading to purpura fulniinans 12-51, At least half of individuals with a protein C concentration less than 50% of normal will experience a thrombotic event before age 30 [ 3 ] .However, a heterozygous deficiency, with concentrations of protein C ranging from 20-60% of normal, does not eventuate in thromboses in all patients (31. It has been suggested that other factors influence the thrombotic risk [3]. This report describes a patient with recurrent thromboses who has a familial deficiency of protein C, lupus anticoagulants (LA), and anticardiolipin antibodies (ACA).
A Caucasian woman was first seen in 1984 at age 19 for deep venous thrombosis. She was initially treated with intravenous heparin, which was stopped less than 24 hr later when treatment with warfarin (Coumadin"") was begun. Three days later purpura and necrosis of the skin over both breasts appeared (Fig. 1 ) . Skin grafts were needed to cover the defects over her breasts. Plasma concentrations of protein C, both antigenic and functional (generously measured by Dr. Phillip Comp, University of Oklahoma Medical Center), measured 45% of normal after warfarin had been discontinued for three weeks.
0 1992 Wiley-Liss, Inc.
Received for publication February 8 . 1991; accepted September 26, 1991. Addre\\ reprint requests tu Robert Harrison. M.D., Department of Pathology. The University of Texas Medical Branch, Galveston. TX 77550.
34
Case Report: Harrison and Alperin
Fig. 1. The right breast three days after warfarin was begun.
Fig. 2. Extensive necrosis of the tissues of both lower extremities eventuated in bilateral amputations.
Protein S antigen was normal. Antithrombin 111 (AT 111) measured 95% of normal. A thrombin clotting time was normal. During the first one and one-half months of hospitalization the patient’s hemoglobin declined progressively from 1 37 g/L to 69 g/L (normal 120- 180 g/L), and no evidence of a site of blood loss was present. Spherocytic red cells of various sizes were found on microscopic examination of a blood smear. Reticulocytes measured 25% and the red cell distribution width (RDW) was 27% (normal 11.5-14.5%). With therapy, the hemoglobin had risen again to 120 g/L by the time of discharge. The platelet count during the hospitalization declined from 187 X 10’ to 134 X 10y/L (normal 130-400 X 10’/L), and total serum bilirubin climbed to 208 pmol/L (normal range 1.7-18.8 pmol/L). with 132 pmol/L unconjugated bilirubin (normal range 1.7-15.4 kmol/L). A direct antiglobulin test was 1 +, anti-IgG antibody was 3 + , and anticomplement antibody was 2 + . Anemia was attributed to autoimmune hemolytic disease (AIHD), and treatment with prednisone was begun. Fluorescent antinuclear antibody assay, antinuclear and anti-Sm antigens, and anti-ribonucleoprotein antibody tests were negative. The patient denied the use of alcohol. She had smoked one pack of cigarettes daily for five years. There WHS a family history of diabetes mellitus. Protein C was assayed once for the patient’s mother and brother. Her mother had a protein C antigen level of 52% of normal, a protein S antigen level of I 19% of normal, and a factor X concentration of 149%. Protein C and protein S antigens were measured in the Medical Branch laboratories using kits from American Bioproducts Company. The patient’s brother’s concentration of protein C was 64% (measured by Dr. Comp). No liver disease or other predisposing factors that might contribute to diminished levels of the vitamin K dependent proteins were recognized in either the mother or the sibling. The patient was discharged
from the hospital and instructed to give herself injections of heparin subcutaneously. She also continued taking prednisone for four weeks after discharge because of continuing AIHD. The patient was readmitted in 1986 with a ten-day history of pain in the right calf, shortness of breath, and pleuritic right chest pain. Both feet were cold, and the lower extremities were discolored from the toes to approximately midway up the calves of both legs (Fig. 2). There was evidence of recurrent AIHD. Platelets measured 75 X IO’/L. A ventilation-perfusion scan was consistent with pulmonary thrombosis. An aortogram and peripheral arteriogram showed diffuse small vessel disease involving the posterior tibial, peroneal, and anterior tibial arteries. There was also a thrombus involving the left common femoral and proximal profundus arteries (Fig. 3). Streptokinase was administered without improvement. Additional treatment included azathioprine, prednisone, red blood cell infusions, fresh frozen plasma [ 5 ] ,and cryoprecipitate. Because of clinical deterioration, bilateral amputations of the lower extremities at the knees were performed. Random sampling of major vessels of the two lower extremities demonstrated thrombi in several large and small veins. One dose of 1,320 units of prothrombin complex concentrate, which has been used in cases of homozygous protein C deficiency [6,7], was administered, as Proplex Th‘ , without apparent clinical improvement. An infusion of heparin was begun following surgery and was continued for ten days. Treatment with warfarin was then started, and the heparin infusion was discontinued after a stable and appropriately prolonged prothrombin time had been attained. After discharge from the hospital the patient continued to take warfarin at a dose to maintain the prothrombin time between 1.5 and 1.9 times the control value. She has also continued to take azathioprine to control hemolysis. New thrombotic
Case Report: Protein C and Lupus Anticoagulants
35
TABLE I. ACA Assay'
Patient, 1984 Patient, 1986 Patient, 1989 Patient's mother, 1984 Patient's mother, 1989 Normal
0.82 0.22 0.84 0.102 0.061 0.0 19-0.037
0.070 0.070 0.058 0.02 1 0.014 0.006-0.014
0.098 0.0 I3 0.1 I 0.0 12 0.007 0.002-0.004
*Numbers are optical density; normal values are mean optical density f one SD. An optical density is considered positive if it is more than five SDs above the mean normal optical density 18.91.
neutralization tests probably reflect combined warfarin and LA effects. DISCUSSION
Fig. 3. Arteriogram shows a filling defect (arrow) due to thrombus in the left common femoral and proximal profundus arteries.
symptoms have not arisen in the approximately five years since the 1986 hospitalization. In 1988 she presented for fallopian tuba1 ligation. In preparation for the laparoscopic surgery, treatment with warfarin was discontinued, and an infusion of heparin was begun. Heparin was discontinued 8 hr prior to and was restarted immediately after surgery. One day after surgery treatment with warfarin was reinstituted. Starting with 2.5 mg daily the dose was gradually increased. After six days the warfarin dose was 10 mg daily: heparin infusion was then discontinued. The patient was dismissed taking warfarin, 5-7.5 mg daily, regulated to a prothrombin time of 1.5-1.9 times control. The patient's plasma was serendipitously tested [8,9] and found positive for anticardiolipin antibodies (ACA) (Table I). The results of coagulation studies for the lupus anticoagulant (LA), performed as previously described 19-1 I] on plasma from the 1988 hospitalization and on plasma frozen since 1986, are shown in Table 11. Assays from both the remote and the more recent hospitalizations were consistent with LA and ACA. Because the patient was taking warfarin when the recent plasma sample was obtained, the results of the dilute Russell's viper venom time test (RVVT) as well as the mixing and platelet
For most patients with thrombophlebitis, an underlying biochemically well defined disorder cannot be identified. Hereditary deficiencies of AT 111, protein C, and protein S predispose to thrombosis. The role played by these inhibitors is defined biochemically and the underlying pathophysiology leading to thrombosis in these deficiency states is, therefore, relatively well understood. It is unclear why only some patients with deficiencies of these physiologic anticoagulants will experience a thrombotic event. It has been suggested that some patients develop thrombi because of an additional disorder or condition that predisposes to thrombosis [3,12,13]. Dysfibrinogenemia and disorders of the fibrinolytic system are likewise associated with thrombosis in some patients, but the underlying basis of a hypercoagulable state in these patients is at best only partly understood 121. The LA and ACA are markers for a propensity to thrombose [ 141 in some persons, but here the mechanism of thrombosis is not explained. About one of three people with LA or ACA will eventually experience a thrombotic event [ IS]. Although the mechanism underlying the tendency to thrombose remains undefined, several theories have been suggested [ 1 &2 I], including hypothesized effects on prostacyclin production by endothelial cells and inhibition of prekallikrein. One postulate states that LA interferes with thrombomodulin in the activation of protein C zymogen to its serine protease form [ 18-20]. It is difficult, however, to explain arterial thrombosis in the presence of LA if the mechanism of thrombosis is a consequence of defective or abnormal protein C activation. Protein C and S deficiencies manifest almost exclusively as venous thromboses [2], whereas arterial thrombosis in association with the LA is often observed. The clinical manifestations of thrombosis exhibited by this patient were judged to be unusually severe for the degree of protein C deficiency. The severity of throm-
36
Case Report: Harrison and Alperin TABLE II. In Vitro Coagulation Tests for the LA Test Patient results APTT” Platelet neutralized APTT (PNP) [ I I ’I Saline control for the PNPa RVVT [ IOJa RVVT, one part patient: one part normal plasmaa Platelet neutralized RVVTd TTI ratio ( 1 :1,000)”
RVVT~ RVVT. one part patient: one part normal plasmab Platelet neutralized RVVTh
36 sec 30.7 sec 35.6 sec 33.7 sec 3 1.4 sec
Normal values 24-36 sec Correction
