Davis Stroop

Thrombophilia and hypofibrinolysis : pathophysiologies of osteonecrosis

In 31 patients with osteonecrosis (primarily of the hip), 74% had 1 or more primary coagulation disorders. In 18 patients, 15 (83%) who had coagulation disorders, the osteonecrosis was initially identified as idiopathic and was not associated with known underlying drugs (glucocorticoids) or diseases (alcoholism, sickle cell disease, Gauchers disease). In 13 patients, 8 (62 %) who had coagulation disorders, the osteonecrosis was initially identified as secondary, and was associated with glucocorticoids in 12 patients, and with alcoholism in 1. The coagulation disorders included thrombhophilia (increased tendency to intravascular thrombosis) and hypofibrinolysis (reduced ability to lyse thrombi). Of the 18 patients initially thought to have idiopathic osteonecrosis, thrombophilia alone was found in 12% (resistance to activated protein C in 6%, low protein C in 6%), hypofibrinolysis alone was found in 50% (high lipoprotein(a) in 44%, low stimulated tissue plasminogen activator activity was found in 6%), and mixed thrombophilia hypofibrinolysis was found in 22%. Resistance to activated protein C was more common in these 18 patients than in healthy controls (11% versus 0%), as was high lipoprotein(a) (67% versus 20%). Of the 13 patients with secondary osteonecrosis, thrombophilia alone was found in 8% (low protein C), hypofibrinolysis alone was found in 30% (high Lp(a) in 15%, low tissue plasminogen activator activity in 15%), and mixed thrombophilia hypofibrinolysis was found in 23%. Low tissue plasminogen activator activity was more common in the 13 patients with secondary osteonecrosis than in controls (27% versus 7%), as was low protein C (23% versus 0%). In aggregate, these findings lead us to the speculation that primary, heritable thrombophilia or hypofibrinolysis causes thrombotic venous occlusion in the head of the femur, leading to venous hypertension and hypoxic death of bone (osteonecrosis).

The plasminogen activator inhibitor-1 gene, hypofibrinolysis, and osteonecrosis.

In 59 patients with osteonecrosis of the hip, four genes associated with thrombophilia or hypofibrinolysis along with coagulation tests were studied to determine the pathoetiologic associations of heritable coagulation disorders with osteonecrosis. Patients did not differ from healthy control subjects for the thrombophilic Factor V Leiden, prothrombin, or methylenetetrahydrofolate reductase mutations. The plasminogen activator inhibitor-1 gene was shifted toward homozygosity for the 4G polymorphism; 41% of patients with osteonecrosis were homozygous for the 4G/4G polymorphism versus 20% of 40 healthy control subjects. The gene product of the 4G polymorphism, hypofibrinolytic plasminogen activator inhibitor activity, was higher in patients than in control subjects (median 19.2 versus 6.3 U/mL); 61% of patients had high plasminogen activator inhibitor activity (> or = 16.4 U/mL) versus 5% of control subjects. Stimulated tissue plasminogen activator activity (inhibited by plasminogen activator inhibitor activity) was lower in patients than in control subjects (3.10 versus 5.98 IU/mL); 31% of patients had low stimulated tissue plasminogen activator activity (< 2.28 IU/mL) versus 3% of control subjects. Heritable hypofibrinolysis conferred by the 4G/4G mutation of the plasminogen activator inhibitor-1 gene seems to be a major pathoetiology of primary osteonecrosis.

Association of Antithrombotic Factor Deficiencies and Hypofibrinolysis with Legg-Perthes Disease*

Thirty-three (75 per cent) of forty-four unselected children who had Legg-Perthes disease were found to have coagulation abnormalities. Twenty-three children had thrombophilia (a deficiency in antithrombotic factor C or S, with an increased tendency toward thrombosis); nineteen of the twenty-three children had protein-C deficiency and four had protein-S deficiency. Seven children had a high level (0.25 gram per liter or more) of lipoprotein(a), a thrombogenic, atherogenic lipoprotein associated with osteonecrosis in adults. Three children had hypofibrinolysis (a reduced ability to lyse clots). The mean age of the children when the Legg-Perthes disease was first diagnosed was 5.8 ± 2.7 years, and the mean age at the time of the present study was 10.1 ± 4.4 years. At least one of the first-degree relatives of eleven of the nineteen probands who had a low protein-C level had a low protein-C level as well; all of these low levels represented previously undiagnosed familial protein-C deficiency. The eleven probands who had familial protein-C deficiency were more likely to have early onset of Legg-Perthes disease (at or before the age of five years) than the eleven children who had normal levels of protein C, protein S, and lipoprotein(a) as well as normal fibrinolytic activity (chi-square = 6.6; p = 0.01). At least one first-degree relative of one of the four probands who had a low protein-S level had a low protein-S level and previously undiagnosed familial protein-S deficiency. At least one first-degree relative of six of the seven probands who had a high level of lipoprotein(a) had a familial high level of lipoprotein(a). Six of the seven children who had a high level of lipoprotein(a) also had a low level of stimulated tissue-plasminogen activator activity, the major initiator of fibrinolysis. At least one first-degree relative of one of the three probands who had normal levels of protein C, protein S, and lipoprotein(a) but low stimulated tissue-plasminogen activator activity also had low stimulated tissue-plasminogen activator activity (familial hypofibrinolysis). Legg-Perthes disease, thrombophlebitis, premature myocardial infarction, and stroke, which are ramifications of the familial thrombophilic-hypofibrinolytic disorders, were common in the first and second-degree relatives of the thirty-three children with Legg-Perthes disease who also had thrombophilic-hypofibrinolytic disorders. CLINICAL RELEVANCE: Protein-C or S deficiency, hypofibrinolysis, or a high level of lipoprotein(a) may result in thrombotic venous occlusion of the femur, which leads to the venous hypertension and osteonecrosis of the femoral head characteristic of Legg-Perthes disease. When Legg-Perthes disease develops in a child, the levels of proteins C and S, lipoprotein(a), and stimulated fibrinolysis should be measured. Early diagnosis of protein-C or S deficiency, hypofibrinolysis, or a high level of lipoprotein(a) in such children may open avenues for pharmacological preventive therapy to reduce thrombophilia, stimulate fibrinolysis, or lower the level of lipoprotein(a), potentially ameliorating the Legg-Perthes disease process.

Relationships between lipoprotein(a), lipids, apolipoproteins, basal and stimulated fibrinolytic regulators, and d-dimer

In 191 newly referred hyperlipidemic patients, our specific aim was to assess relationships between levels of lipoprotein(a) [Lp(a)], lipids, apolipoproteins, regulators of basal and stimulated fibrinolytic activity, and D-dimer, a measure of in vivo fibrinolysis. Lp(a) levels correlated with none of the measures of basal fibrinolytic regulators or D-dimer. In 25 patients, levels of stimulated regulators of fibrinolytic activity and D-dimer were measured after 10-minute cuff venous occlusion. Lp(a) levels again correlated with none of the stimulated regulators of fibrinolytic activity or D-dimer. However, both basal and stimulated levels of fibrinolytic regulators and D-dimer were closely related to other major risk factors for coronary heart disease (CHD) including triglyceride, apolipoprotein (apo) A1, apo B, Quetelet index (QI), and sex. By stepwise regression in 191 patients, the following standardized partial regression coefficients were significant (P < or = .05), and model R2 and P values were as follows: basal tissue plasminogen activator (tPA) with apo B-.18, with time .17, with QI -.28, R2 = 17%, P < or = .0001; basal plasminogen activator inhibitor (PAI) with apo B..25, with time -.15, with QI .17, R2 = 14%, P < or = .0001; basal alpha 2-antiplasmin with apo A1.14, with apo B.24, with QI.17, with sex .30, R2 = 25%, P < .0001; basal plasminogen with A1.15, with apo B.21, with QI.17, with sex.17, R2 = 15%, P < or = .0001; basal fibrinogen with Lp(a).17, with QI.21, with sex.26, R2 = 14%, P < or = .0001; D-dimer with sex.15, R2 = 21%, P < or = .048. Given the absence of any relationship between Lp(a) levels and inhibition or stimulation of fibrinolysis regulators or D-dimer either in the basal or stimulated state, we postulate that Lp(a)s major atherogenic effects are mediated by mechanisms other than reduction of fibrinolysis stimulation or in vivo fibrinolysis.

Resistance to activated protein C and Legg-Perthes disease.

Thrombophilia may cause thrombotic venous occlusion in the femoral head, with venous hypertension and hypoxic bone death, leading to Legg-Perthes disease. Resistance to activated protein C, the most common thrombophilic trait, was measured in 64 children with Legg-Perthes disease. Genomic deoxyribonucleic acid was studied to delineate the CGA-->CAA substitution at position 1691 of the Factor V Leiden gene responsible for resistance to activated protein C. The activated protein C ratio was calculated by dividing clotting time obtained with activated protein C-calcium chloride by clotting time obtained with calcium chloride alone. Resistance to activated protein C, with a low activated protein C ratio (less than 2.19, the 5th percentile for 160 normal pediatric controls) was the most common coagulation defect, found in 23 of 64 children with Legg-Perthes disease versus 7 of 160 pediatric controls. Eight of 64 children with Legg-Perthes disease had a low activated protein C ratio and the mutant Factor V gene (7 heterozygotes, 1 homozygote) versus 1 of 101 normal pediatric controls. Two or 3 generation vertical and horizontal transmission of heterozygosity for the mutant Factor V gene was found in 4 of the 8 kindreds. Of 64 children with Legg-Perthes disease, only 14 (22%) had entirely normal coagulation measures. Resistance to activated protein C appears to be a pathogenetic cause of Legg-Perthes disease.

Thrombophilia, hypofibrinolysis, and alveolar osteonecrosis of the jaws

OBJECTIVES Our specific aim in 49 patients (42 women, 7 men) with osteonecrosis of the jaw was to determine whether thrombophilia (increased tendency to intravascular thrombosis) or hypofibrinolysis (reduced ability to lyse thrombi) were associated with this regional avascular necrosis. STUDY DESIGN Determinants of thrombosis and fibrinolysis were compared in healthy controls and in 42 women and 7 men who had biopsy-proven idiopathic osteonecrosis of the jaw with severe chronic jaw or facial pain syndromes and failure to respond to conventional medical and dental treatments. RESULTS Of the 49 patients, 35 (71%) had thrombophilia or hypofibrinolysis and only 14 were normal. Thrombophilia as a sole coagulation defect was found in 10 patients, 7 with resistance to activated protein C and 3 with low protein C (deficiency of an antithrombotic protein). Hypofibrinolysis with low stimulated tissue plasminogen activator activity and high lipoprotein (a) (an atherogenic, hypofibrinolytic lipoprotein) were found as sole coagulation defects in seven and eight patients, respectively. Ten patients had mixed defects; 7 of these 10 had thrombophilia with resistance to activated protein C. Sinusoidal dilatation was a constant feature in maxillary and mandibular bone biopsies, suggesting venous occlusion with intramedullary hypertension. Marrow fibrosis and occasional fibrin plugs were additional microscopic features believed to impair venous drainage and to contribute to ischemic necrosis of the alveolar bone. CONCLUSIONS Primary thrombophilia and hypofibrinolysis appear to be common, heritable, pathophysiologic risk factors for idiopathic osteonecrosis of the jaws. These coagulation defects may also contribute to alveolar neuralgia, atypical odontalgia and facial neuralgia, idiopathic trigeminal neuralgia, and to treatment failures so often encountered in patients with alveolar osteonecrosis and disabling chronic facial and jawbone pain syndromes.

Sex Hormone-Binding Globulin, Oligomenorrhea, Polycystic Ovary Syndrome, and Childhood Insulin at Age 14 Years Predict Metabolic Syndrome and Class III Obesity at Age 24 Years

OBJECTIVE We hypothesized that oligomenorrhea (menstrual cyclicity ≥42 days), hyperandrogenism, low levels of sex hormone-binding globulin (SHBG), childhood insulin, and metabolic syndrome (MetS) at age 14 years would predict MetS and class III obesity (body mass index ≥40 kg/m(2)) at age 24 years. STUDY DESIGN In this prospective study of schoolgirls, at age 14 years, the girls were categorized as regularly cycling (n = 375), oligomenorrheic (n = 18), or oligomenorrhea plus biochemical hyperandrogenism (polycystic ovary syndrome [PCOS]; n = 12), together designated PCOS. RESULTS Significant explanatory variables for MetS at age 24 years included childhood insulin, MetS, and PCOS category (all positive) and SHBG (negative) at age 14 years. Using categorical data, top decile of childhood insulin, MetS at age 14, bottom decile of SHBG, and PCOS category were significant positive predictors for MetS at age 24. SHBG (negative), black race (positive), and oligomenorrhea (positive) were significant explanatory variables for class III obesity at age 24. Using categorical data, black race, MetS at age 14, bottom decile of SHBG, PCOS category, and top decile of childhood insulin were positive explanatory variables for class III obesity at age 24 years. CONCLUSIONS Oligomenorrhea, PCOS (a subcohort of oligomenorrhea), hyperandrogenism, low SHBG, MetS, and childhood insulin at age 14 years may represent a critical, reversible pathway for the development of MetS and class III obesity in young adulthood.

Hyperhomocysteinemia is associated with low plasma pyridoxine levels in children with sickle cell disease

Elevated plasma homocysteine levels have been shown to be a risk factor for endothelial cell damage and thrombosis, which are implicated in sickle cell disease (SCD)-related vaso-occlusion. The aim of this study was to determine the prevalence of hyperhomocysteinemia in SCD. Fasting and postmethionine load (PML) homocysteine, red cell folate, and the MTHFR C677T mutation were determined in 77 patients with SCD and 110 African-American controls. Plasma methylmalonic acid and pyridoxine levels were determined in 54 patients and all controls. For analysis, the subjects were divided into two age groups (2–10 years and 10.1–21 years). In both age groups, median PML homocysteine levels were significantly elevated in patients with SCD compared with controls. Fasting homocysteine levels were elevated in patients with SCD versus controls only in those older than 10 years. Hyperhomocysteinemia was noted in 38% of patients versus 7% in controls. Folate levels were higher among patients than controls and showed a significant negative correlation with PML homocysteine levels in patients with SCD. Pyridoxine levels in patients with SCD were significantly lower than in controls and showed a negative correlation with PML homocysteine levels. Among patients with SCD, pyridoxine deficiency was more common (62%) among those with hyperhomocysteinemia compared with those with normal homocysteine levels (30%). Homozygosity for the MTHFR C677T mutation was rare. These data suggest that children with SCD have significant hyperhomocysteinemia, associated with pyridoxine and relative folate deficiencies.

Paradoxically high adiponectin in obese 16-year-old girls protects against appearance of the metabolic syndrome and its components seven years later.

OBJECTIVE To evaluate the relationships of adiponectin levels at age 16 years in obese schoolgirls to metabolic syndrome and its components at age 23 years. STUDY DESIGN Seven-year prospective study of 381 females. RESULTS In 144 white and 129 black non-obese 16-year old girls (body mass index < 24.6 kg/m(2)), race-specific median adiponectin levels (white 12 mg/L, black 11) was used to identify paradoxically high adiponectin levels in obese girls. Of 34 white and 74 black obese girls, 12 (35%) and 19 (26%) had paradoxically high adiponectin levels. In these 108 obese girls, adiponectin levels at age 16 years independently predicted high-density lipoprotein cholesterol (positive) and waist (negative), insulin (negative), and glucose (negative) at age 23 years; paradoxically high adiponectin levels at age 16 years was a negative independent predictor for waist, homeostatic model assessment-insulin resistance, and for the number of abnormal components of the metabolic syndrome at age 23 years. In 31 pairs of obese girls with and without paradoxically high adiponectin levels, matched by race and age 16 body mass index, adiponectin levels at age 16 years was a negative predictor for the number of abnormal metabolic syndrome components at age 23 years. CONCLUSION Paradoxically high adiponectin levels in obese 16 year old girls protects against metabolic syndrome and its components at age 23 years.

Beta Blockers, Lp(a), Hypertension, andReduced Basal Fibrinolytic Activity

To assess the hypothesis that beta blocker use and hypertension are associated with high lipoprotein(a) [Lp(a)] or with reduced basal fibrinolytic activity, the authors studied relationships of hypertension and beta blockers to Lp(a), lipids, lipoproteins, apolipoproteins, and basal fibrinolytic activity in 385 patients consecutively referred for diagnosis and therapy of hyperlipidemia. A second aim was to determine possible gender differences in fibrinolytic activity among patients with hypertension. Ninety-nine patients (58 women [88% post-menopausal] and 41 men) had drug-treated hypertension. In women, hypertension was a positive, independent predictor of the major inhibitors of fibrinolysis, plasminogen activator inhibitor antigen (p = 0.017), and plasminogen activator inhibitor activity (p = 0.004). In men and women, major risk factors for atherosclerosis were significant, independent predictors of reduced basal fibrinolysis. Median Lp(a) in the 99 patients with hypertension (16 mg/dL) did not differ from Lp(a) (18 mg/dL) in normotensive patients (p > 0.1). Of the 385 patients, the 39 beta blocker users had higher plasminogen activator inhibitor activity (p = 0.01), higher triglyceride (p = 0.02) levels, and higher Quetelet Indices (p = 0.01) than non-users (n = 346). After covariance adjusting for age, Quetelet Indices, sex, and tri-glycerides, plasminogen activator inhibitor activity was not higher in beta blocker users than in non-users (p > 0.1). Median Lp(a) did not differ in beta blocker users (16 mg/dL) and in non-users (17 mg/dL), p greater than 0.1. Hypertensive, predominantly post-menopausal women are likely to have high plasminogen activator inhibitor activity and plasminogen activator inhibitor antigen with concurrent reduced fibrinolytic activity, as well as high fibrinogen levels. These independent coronary heart disease risk factors, along with their hypertension, may put hypertensive, post-menopausal women at increased risk for coronary heart disease.