Influence of factor IX on overall plasma coagulability and fibrinolytic potential as measured by global assay: monitoring in haemophilia B.

We sought to determine the influence of factor IX (FIX) deficiency upon overall coagulative and fibrinolytic capacities in plasma using the clot formation and lysis (CloFAL) assay, and to investigate the role of this global assay as an adjunctive monitoring tool in haemophilia B. CloFAL assay parameters were measured in vitro in platelet-poor plasma in relation to FIX activity and antigen (FIX:Ag), and were determined ex vivo among FIX-deficient patients (n = 41) in comparison to healthy individuals (n = 48). Supplementation of FIX-deficient plasma with FIX in vitro demonstrated a non-linear concentration dependence of FIX upon overall plasma coagulability. Ex vivo, coagulability was significantly decreased in FIX-deficient vs. healthy subjects among adults [median coagulation index (CI): 4% vs. 104% respectively; P < 0.001] and children (median CI: 9% vs. 63%; P < 0.001). Fibrinolytic capacity was increased in adult FIX-deficient vs. healthy subjects (median fibrinolytic index: 216% vs. 125%, respectively, P < 0.001), and was supported by a trend in shortened euglobulin lysis time (ELT). Severe haemophilia B patients showed heterogeneity in aberrant CloFAL assay waveforms, influenced partly by FIX:Ag levels. Patients with relatively preserved FIX:Ag (i.e. dysfunctional FIX) exhibited a shorter time to maximal amplitude in clot formation than those with type I deficiency. During patient treatment monitoring, markedly hypocoagulable CloFAL assay waveforms normalized following 100% correction with infused FIX. The CloFAL global assay detects FIX deficiency, demonstrates differences in coagulability between dysfunctional FIX and type I deficiency, and appears useful as an adjunctive test to routine FIX measurement in monitoring haemophilia B treatment.

Abnormal antithrombin III with defective serine protease binding (antithrombin III "Denver").

A hereditary (three family members) deficiency of antithrombin III (AT-III) in which AT-III antigen (AT-III ag) is normal in spite of low heparin cofactor and antithrombin activity is described. Plasma levels were: AT-III ag, 0.92-0.96 U/ml; AT-III heparin cofactor activity, 0.54-0.62 U/ml; progressive antithrombin activity index, 0.13-0.18; anti-Xa activity, 0.50-0.56 U/ml. Plasma crossed immunoelectrophoresis (CIE) patterns performed with and without added heparin were normal, but serum CIE revealed a decreased complex peak. Purification of the patient's plasma AT-III by heparin-sepharose affinity chromatography showed a normal protein recovery and elution profile, but the purified AT-III fraction showed only 50% of the normal progressive thrombin neutralization and anti-Xa activity. When thrombin-antithrombin (TAT) complexes were formed by incubating with excess thrombin, SDS-polyacrylamide gel electrophoresis (PAGE) analysis revealed that half the patient AT-III formed TAT complexes while the remainder migrated as free AT-III. All the control AT-III formed TAT complexes. The patient's nonreacting AT-III (AT-III "Denver"), isolated by affinity chromatography, showed CIE and SDS-PAGE migration patterns characteristic of normal AT-III but failed to bind thrombin or Xa. Calculations from turnover studies in one patient and normal subjects with autologous 131I-AT-III suggested that AT-III "Denver" is removed from the plasma slightly more rapidly than normal. These studies indicate that the patients' variant AT-III molecule was characterized by normal heparin interaction but defective binding and inhibition of thrombin and Xa. These characteristics allow isolation of the nonreactive variant molecule by heparin-sepharose affinity chromatography.

Clinical and physiologic studies of two siblings with prekallikrein (Fletcher factor) deficiency.

Two siblings with hereditary Fletcher factor (prekallikrein) deficiency were studied for alterations of fibrinolysis, platelet function, skin inflammatory responses, permeability factor (PF/dil) formation and leukocyte chemotaxis. In vivo stimulation of fibrinolytic activity was normal; the bleeding time and platelet functions (adhesivity, aggregation, release reaction) were also normal. Both immediate (wheal-flare reaction to histamine, bradykinin, prostaglandin E1, physical agents) and delayed sensitivity skin test reactions were within normal limits. Migration of subjects' leukocytes to attractants in skin windows and in Boyden-type chambers was the same as that of control leukocytes. Serum complement components were essentially normal. One subject's leukocytes showed normal tissue factor production on stimulation by endotoxin, although prekallikrein deficiency did impair the endotoxin-stimulated generation of serum procoagulant activity. PF/dil caused increased vessel permeability in human skin; in vitro generation of PF/dil required both the Hageman factor and prekallikrein. The Fletcher factor-deficient subjects responded in a normal manner to PF/dil. Based on the Fletcher factor-coagulation assay, the biologic half-disappearance time of prekallikrein (after the transfusion of normal plasma in one of the subjects) was estimated at 35 hours. Therefore, these studies suggest that severe prekallikrein (Fletcher factor) deficiency in man is not associated with any clinically significant impairment in hemostasis, fibrinolysis, inflammatory responses or leukocyte function.

Inherited antithrombin III deficiency and cerebral thrombosis in a child.

Identification of a family affected by antithrombin III-heparin cofactor (AT-III) deficiency was made after diagnosis of the index case, a 15-year-old boy who suffered cerebral thrombosis. The proband had a two-year history of recurrent thrombosis involving the lower extremities. His mother and sister were also affected. Studies showed a decreased biological activity (AT-IIIc) and antigen (AT-IIIag) by the Laurell technique in the proband (AT-IIIc = 0.32, AT-IIIag = 46%), his sister (AT-IIIc = 0.29, AT-IIIag = 47%), and his mother (AT-IIIc = 0.41, AT-IIIag = 56%). Crossed immunoelectrophoresis (CIE) of the affected individuals' plasma in agarose-containing heparin demonstrated a normal pattern of migration. Treatment with warfarin sodium (Coumadin) resulted in an increase in activity in two of three affected family members, and in antigen in all three. Anticoagulant therapy did not affect the pattern of AT-III on CIE. This family represents a quantitative deficiency in antithrombin III. A review of the reported cases of antithrombin III deficiency indicates that individuals with this disorder may have thromboembolic disease in childhood.

Carrier detection in classical hemophilia.

Rabbit antibody to purified human factor VIII was prepared and absorbed until it formed only one precipitin line against normal and hemophilic plasmas and no line against severe von Willebrand's disease plasma. The plasma protein which combines with this rabbit antibody to factor VIII is referred to as factor VIII antigen. The ratio of percent factor VIII activity (by coagulation assay) to percent factor VIII antigen was used for carrier detection. Thirty-seven normal women, 33 obligate carriers, 12 probable carriers, and 39 possible carriers, were studied by this technique. Using the ratio of 0.84 as the division between normals and carriers, 31 of the 33 carriers (91%) were classified carriers. Twenty of the 39 possible carriers were classified as carriers (51%) and ten of the 12 probable carriers were positively identified. The results of discriminate analysis of all three variables (VIII activity, VIII antigen, and the ratio of VIII activity to VIII antigen indicated that the discrimination power of the ratio alone could not be improved by introducing the other variables on this set of data. These findings confirm the usefulness of the VIII activity to VIII antigen ratio in the detection of carriers of classical hemophilia.

Neonatal hyperviscosity. II. Effect of partial plasma exchange transfusion.

To determine the effect of partial plasma exchange transfusion, 20 newborn infants with neonatal hyperviscosity were randomly assigned to observation or treatment with partial plasma exchange transfusion within the first eight hours after birth. They were studied for organ involvement by roentgenogram, blood count, coagulation studies, and neurologic behavior and were followed up using the Brazelton Neonatal Behavior Assessment scale at 8, 24, and 72 hours and 2 weeks of age; in addition, ten control infants without hyperviscosity of similar birth weights and gestational ages were also studied. Exchange transfusion improved blood viscosity but both hyperviscous groups showed a higher proportion of abnormal results than did the control subjects. Infants receiving exchange transfusions subsequently improved during the period from 8 hours to 2 to 3 weeks of age, until they were indistinguishable from the control subjects. Neurologic improvement in hyperviscous infants who had not received exchange transfusions were significantly slower during this period. At 8 months of age, abnormal neurologic and developmental findings were impressive in both groups; no significant differences in neurologic abnormalities were noted at that time. Developmental delays, tremors, spastic diplegia, and monoparesis were found in four of six untreated infants and five of ten infants who had received exchange transfusions. A fine tremor was present in one control child.

Role of coagulopathy in newborn intracranial hemorrhage.

Fifty newborn infants of less than 33 weeks' gestation were followed prospectively from birth with serial coagulation and real-time ultrasound studies. A significant association of hypocoagulability in the first four hours of life with subsequent onset or progression of intraventricular or other clinical hemorrhages was documented. Abnormalities included lower values for fibrinogen, platelet count, antithrombin III, and factor VIII with higher values for fibrin monomer and longer Laidlaw whole blood clotting times. These abnormalities tended to correct spontaneously in surviving infants. An association between gestational complications and incidence of hypocoagulability and intracranial hemorrhage (ICH) was noted. Babies of preeclamptic mothers had fewer abnormalities and babies born to mothers with premature rupture of membranes and suspected amnionitis manifested more hypocoagulability and more severe intracranial hemorrhages.

Timing and antecedents of intracranial hemorrhage in the newborn.

Fifty newborn infants of less than 33 weeks' gestation were followed prospectively from birth to evaluate the temporal relationships of various clinical factors to the onset and progression of intracranial hemorrhage (ICH) in an inborn population given maximal support. ICH was diagnosed and followed with bedside ultrasound every eight hours. The incidence of intraventricular hemorrhage was 30% and of any ICH was 40% with onset from less than 2 hours to 8 days of age. Grades 2, 3, and 4 ICH correlated with Apgar scores of less than 5 at five minutes, vaginal delivery, longer labors, and intrapartum hemorrhage. There was a significant correlation between ICH and both blood pressure fluctuations of greater than 100% and rapid colloid infusions. Slow transfusions of packed red cells did not appear to precipitate episodes of ICH. In a setting of optimal care, ICH appears to be more related to prenatal stresses than to specific postnatal complications.

Immunologic studies of antithrombin III heparin cofactor in the newborn.

Serial quantitative immunoelectrophoretic (IE) measurements of antithrombin III heparin cofactor (AT III) were made in groups of well and sick newborn infants classified by gestational age. Collection methods (venous vs. capillary) did not influence the results; serum IE measurements were comparable to AT III activity by a clotting method. AT III is gestational age-dependent, increasing from 28.7% of normal adult values at 28--32 weeks to 50.9% at 37--40 weeks, and shows a gradual increase to term infant levels (57.4%) by 3--4 weeks of age. Infants with the respiratory distress syndrome (RDS) show lower levels of AT III in the 33--36 week group, 22% vs. 44% and in the 37--40 week group, 33.6% vs. 50.9%, then prematures without RDS. Infants of 28--32 week gestational age had only slight differences, RDS = 24%, non-RDS = 28.7%. The lowest levels of AT III were seen in patients with RDS complicated by disseminated intravascular coagulation and those with necrotizing enterocolitis. Crossed IE on representative infants displayed a consistent pattern which was identical to adult controls except for appropriate decreases in the amplitude of the peaks. The thrombotic complications seen in the sick preterm infant may be related to the low levels of AT III.

Biochemical and functional study of antithrombin III in newborn infants.

Antithrombin III (AT-III) was isolated by heparin affinity chromatography from adult venous and newborn term and preterm umbilical cord blood. The purified proteins were compared by SDS-PAGE, rocket immuno-electrophoresis, protein concentration by microbiuret relative to optical density at 280 nm, heparin cofactor specific activity, progressive neutralization of thrombin and factor Xa at 37 degree C and pH related antithrombin kinetics. The structural evaluations revealed a fetal AT-III of molecular weight, charge and electrophoretic migration indistinguishable from adult AT-III. The functional studies showed that, on an equimolar basis, the rates of thrombin and Xa interactions with fetal AT-III were as rapid as those with adult AT-III. The catalytic rates of various concentrations of heparin were also equal. The newborn infant, therefore, displays a quantitative but not quantitative deficiency of AT-III.

Bleeding diathesis in Noonan syndrome: a common association.

The Noonan syndrome (NS) is a multiple congenital anomalies (MCA) syndrome with well-known manifestations. Excessive bleeding has been described occasionally. We report on 19 patients with NS and a bleeding diathesis. Several different defects are identified in the coagulation and platelet systems occurring singly or in combination. Clinical expression is variable. It is concluded that bleeding diatheses occur in NS at a much higher frequency than previously suspected. Consideration is given to possible relationship to underlying metabolic defects which could explain the diverse nature of the bleeding diatheses and also play a role in the pathogenesis of NS. The variety of bleeding diatheses may also reflect heterogeneity within NS. NS patients frequently undergo surgery with increased risk of bleeding. Appropriate evaluation and management is discussed. Evaluation of all NS patients and their families for bleeding disorders should provide important information about the frequency and type of bleeding diatheses which occur and perhaps help to clarify the etiology and pathogenesis of NS.

Activated partial thromboplastin time and minor coagulopathies.

Five commercially available activated partial thromboplastin time (APTT) test systems were compared with the kaolin partial thromboplastin time (KPTT) method to determine sensitivity in detecting minor coagulation defects. All reagent systems detected severe factor VIII-, IX-, and XI-deficient hemophilia. Homozygous states of factor XII deficiency, Fletcher factor deficiency, and high-molecular-weight kininogen deficiency (Fitzgerald trait) also showed abnormally long APTTs by all systems. Of 19 samples from patients with deficiencies of factors XII, VIII, IX, XI, and II ranging from 2.5 to 52%, eight had deficiencies that were not detected by reagent A (ellagic acid); two, by reagent B (ellagic acid); two, by reagent C (kaolin); one, by reagent D (silica); one, by the KPTT method. All deficiencies were detected by reagent E (celite). Heparin effect on plasma was less well detected by reagent A (ellagic acid) than with the other test systems. APTT test systems can vary greatly in their abilities to detect minor coagulation abnormalities.

Collagen-binding of von Willebrand's factor antigen in the classification of von Willebrand's disease.

Analysis of the multimeric structure of von Willebrand's factor (vWf) was compared with vWf-binding to collagen in subjects' plasma. The percentage binding of vWf to collagen was determined by both an enzyme-linked immunosorbent assay (ELISA) method and quantitative immunoelectrophoresis. Normal subjects, type I von Willebrand's disease (vWd), and type II vWd were studied. The authors have found by correlating collagen-binding results with multimeric analysis that normal controls exhibit 85.4 +/- 5.1% collagen absorption of their vWf, patients with type I vWd 80.8 +/- 5.3%, whereas patients exhibiting a deficiency of high molecular weight vWf have 32.3 +/- 16.6% collagen absorption of vWf. The results suggest that this functional assay of vWf can be used in the classification of vWd and in the detection of new dysfunctional forms of vWf.

New insights on vitamin K.

Vitamin K catalyzes the post-translational carboxylation of coagulation proteins C, S, and factors II, VII, XI, and X. Detection of the noncarboxylated forms allows an indirect and specific measure of the vitamin K deficiency found in early, classic, and late hemorrhagic disease of the newborn (HDN), malabsorption syndromes, and drug related (warfarin, anticonvulsants, and antibiotics) states. Idiopathic late HDN (CNS bleeding) occurs in exclusively breast-fed infants and is prevented by appropriate parenteral and oral vitamin K prophylaxis given at birth. All newborn infants and older infants with malabsorption syndromes should receive prophylactic vitamin K.

Immunoelectrophoretic studies of prekallikrein in human plasma.

Using a rabbit anti-human prekallikrein antibody crossed immunoelectrophoresis (CIE) and Laurell rocket antigen determinations were done in plasma of subjects with Fletcher (prekallikrein, PKA), Fitzgerald (high molecular weight kininogen), Hageman (XII), and PTA (XI) deficiencies as well as in patients with activation of coagulation (intravascular coagulation syndromes). Abnormal CIE patterns were seen in the Fletcher and Fitzgerald deficient plasmas and also in some of the patients with intravascular coagulation. In vitro studies of plasma treated with thrombin, plasmin, and contact activating agents indicated that abnormal CIE patterns and increased PKA antigen levels were indicative of activation of the Hageman factor dependent pathway and not the result of plasma clotting by thrombin. In vivo activation of the Hageman factor dependent pathway frequently results in an abnormal CIE and a low PKA antigen level.

Acute bleeding emergencies.

The successful management of acute bleeding depends on the ability to make a rapid diagnosis so that specific hemostatic therapy can be used whenever possible. Three kinds of manifestations--acute hemorrhage in a child with a known or suspected hereditary bleeding disorder; the bleeding tendency that occurs secondary to a specific disease process; and an unexpected and isolated episode in an otherwise well child--are discussed.

Hypercoagulability in childhood cancer.

Thirty-two children with solid tumors (lymphangioma, fibrosarcoma, hepatocarcinoma, osteogenic sarcoma, rhabdomyosarcoma, lymphosarcoma, mesenchymoma, hepatoma, Ewing's sarcoma, reticulum cell sarcoma, neuroblastoma, Hodgkin's disease, and brain tumors) were studied for alterations in coagulation by means of platelet counts, platelet aggregation, thrombelastogram, procoagulant and antigenic factor VIII, fibrin split products, and antithrombin III level. Results indicated hypercoagulability as shown by abnormally short thrombelastograms and elevated factor VIII levels and platelet counts in approximately one-half of the group. With the exception of increased fibrin split products in a third of the patients, little laboratory or clinical evidence for disseminated intravascular coagulation was seen. Hypercoagulability, as noted in adult carcinoma patients, can also occur in childhood sarcoma patients.

Vitamin K deficiency.

Vitamin K (phylloquinone, K1; menaquinone, K2) functions as an essential cofactor for the synthesis of the coagulation protein factors II, VII, IX, X and protein C and S by promoting a unique post-translational modification of specific glutamic acid residues to gamma-carboxylglutamic acid, thus mediating calcium binding to phospholipid surfaces. Vitamin K deficiency results in a depletion of liver stores of phylloquinone, decreased plasma levels of vitamin K1, increased levels of K1 epoxide, appearance of noncarboxylated protein (PIVKA), decreased levels of functioning vitamin K-dependent clotting factors and prolongation of the APTT, PT and thrombotest. When the progression of deficiency leads to abnormal clotting tests a generalized bleeding tendency occurs. Noncarboxylated prothrombin (PIVKA-II) determinations are a sensitive indicator of vitamin K deficiency. Although Vitamin K deficiency can occur at any age (warfarin, fasting, antibiotic therapy, malabsorption syndromes) the major public health problem is related to prevention of early, classic and late hemorrhagic disease of the newborn (HDN). A single dose of oral or parenteral vitamin K prevents classic HDN but the most effective way to prevent early HDN is by giving large doses to the mother prior to delivery (2 weeks). Late HDN in breastfed infant occurs with a prevalence of about 20 per 100,000 live births when no neonatal prophylaxis is given. Parenteral (1 mg) K1 prevents late HDN and single or repeated doses of oral vitamin K reduces the incidence but does not eliminate all late HDN. The optimal (cost, feasibility, effective) mode of neonatal prophylaxis remains to be determined.

Easy bruising in children.

It is necessary to determine whether easy bruising in children is caused by a hemorrhagic disorder. A careful history for the patient and family should be obtained and a physical examination should be done. Any positive indications of hemorrhagic diathesis call for basic coagulation screening tests.