Plasma antithrombin III activity: an aid in the diagnosis of preeclampsia-eclampsia

Plasma Antithrombin Activity during Long-Term Magnesium Sulfate Administration for Preeclampsia without Severe Hypertension

In preeclampsia, plasma antithrombin activity is decreased, which leads to exacerbation of the disorder. We previously showed that long-term magnesium sulfate (MgSO₄) administration prolonged the pregnancy period and may be able to improve pregnancy outcomes for patients with severe preeclampsia. The present study aimed to investigate the changes in plasma antithrombin activity during long-term MgSO₄ administration for patients without severe hypertension. This multicenter retrospective study included patients with preeclampsia and superimposed preeclampsia without severe hypertension at diagnosis. The participants were divided into two groups: MgSO₄ nontreatment group (three institutions) and MgSO₄ treatment group (one institution). Antithrombin activity from time of diagnosis to delivery were compared between the two groups. In the MgSO₄ nontreatment group (n = 16), antithrombin activity prior to delivery was significantly lower than at time of diagnosis (p = 0.015). In three cases, antithrombin activity was less than 60%. On the other hand, in the MgSO₄ treatment group (n = 34), antithrombin activity did not change until just before delivery (p = 0.74). There were no cases in which antithrombin activity was decreased below 60%. Long-term MgSO₄ administration for preeclampsia without severe hypertension may prevent a decrease in antithrombin activity and improve the disease state of preeclampsia.

Pravastatin, proton-pump inhibitors, metformin, micronutrients, and biologics: new horizons for the prevention or treatment of preeclampsia

There has been increasing research momentum to identify new therapeutic agents for the prevention or treatment of preeclampsia, drugs that can affect the underlying disease pathophysiology. Molecular targets of candidate treatments include oxidative stress, antiangiogenic factors, and the angiotensin, nitric oxide, and proinflammatory pathways. The proposed treatments undergoing preclinical and clinical trial evaluation are thought to act on placental or endothelial disease or both. Most have adopted the pragmatic strategy of repurposing drugs. Of all the therapeutic agents proposed, pravastatin has received the most interest. There are preclinical studies showing that it has pleiotropic actions that favorably impact on multiple molecular targets and can resolve a preeclampsia phenotype in many animal models. An early phase clinical trial suggests that it may have therapeutic activity. Several large prevention trials are planned or ongoing and, when completed, could definitively address whether pravastatin can prevent preeclampsia. Proton-pump inhibitors, metformin, and sulfasalazine are other drugs with preclinical evidence of multiple molecular actions that could resolve the pathophysiology of preeclampsia. These agents are also currently being evaluated in clinical trials. There have been many recent preclinical studies identifying the potential of numerous natural compounds to treat preeclampsia, such as plant extracts and micronutrients that have potent anti-inflammatory or antioxidant activity. Recent preclinical studies have also proposed novel molecular-targeted strategies, such as monoclonal antibodies targeting tumor necrosis factor alpha, placental growth factor, and short interfering RNA technology, to silence the gene expression of soluble fms-like tyrosine kinase-1 or angiotensinogen. Other treatment approaches that have transitioned to human trials (ranging from single-arm to phase III trials that have been completed or are ongoing) include folic acid, nitric oxide donors (such as L-arginine), recombinant antithrombin III, digoxin immune antigen-binding fragment, and melatonin. There have been case series showing the removal of circulating soluble fms-like tyrosine kinase-1 may help stabilize the disease and prolong pregnancy. Interestingly, there are case reports suggesting that monoclonal antibody eculizumab (complement inhibitor) may have therapeutic potential. If new agents are discovered that are proven to be effective in preventing or treating preeclampsia, the potential to improve global maternal and perinatal health will be significant.

Endothelial Cell Activation and Thrombin Generation Assessment for the Risk of Severe Early Onset Preeclampsia. the ROADMAP-EOP Study

Background

The ROADMAP-EOP study aimed to identify clinically relevant biomarkers of hypercoagulability for the identification of pregnant women at risk of early onset preeclampsia worsening.

Methods

The ROADMAP-EOP observational single center retrospective case–control study was conducted in Greece (Centre for Human Reproduction, Genesis Athens Clinic, Athens, Greece) from July 2020 to July and enrolled pregnant women diagnosed with EOP stratified in mild EOP group (n = 34) and severe EOP group (n = 15) as well as women with uncomplicated pregnancy (control group; n = 35). All women were assessed with thromboelastometry (ROTEM®), Calibrated Automated Thrombogram®, tissue factor activity (TFa), procoagulant phospholipid dependentclotting time (Procoag-PPL®), Proteins S (PS), TFPI, D-dimer, antithrombin (AT), thrombomodulin (TM), fibrinogen, prothrombin time (PT) and activated partial thromboplastin time (aPTT). The primary study end-point was severe earlyonset preeclampsia. Principal component analysis (PCA) was performed.

Results

The PCA analysis showed that a score composed of the lag-time, ttPeak and Procoag-PPL accurately predicted severe EOP (sensitivity 71.4%, specificity 61.8%, and AUC of the ROC analysis 0.953).

Conclusion

The pilot ROADMAP-EOP shows that activation of endothelial cells and blood hypercoagulability are driven events in the worsening of EOP. Among a large panel of biomarkers and coagulation assays, thrombingeneration test and procoagulant phospholipid dependent clotting time emerged as clinically relevant for the evaluation of the risk of severe EOP. This methodology for the development of a new clinic-biological risk assessment model for prompt identification of pregnant women at risk of severe EOP must be validated in a large multi-centerprospective study.

Magnesium sulphate can prolong pregnancy in patients with severe early-onset preeclampsia

OBJECTIVE

To assess whether long-term use of magnesium sulphate prolongs pregnancy in patients with severe early-onset preeclampsia.

METHODS

Retrospective cohort study included all singleton pregnancies with severe early-onset preeclampsia, expectantly managed in our institution between 2005 and 2013. Obstetric and perinatal outcomes were compared between patients managed using a current protocol that tolerates long-term (over 48 h) use of magnesium sulphate (long-term group, n = 26) and a historical control group (control group, n = 15) that underwent conventional treatment (up to 48 h use of magnesium sulphate).

RESULTS

Long-term group showed significant prolongation of pregnancy compared with the control group (9.2 ± 7.9 versus 16.6 ± 9.3 d, log-rank test, p = 0.021), which was also observed in patients with severe preeclampsia occurring before 28 weeks' gestation (n = 11, 4.5 ± 5.2 versus 13.2 ± 6.8 d, log-rank test, p = 0.035). In contrast to a progressive decrease of platelet count in patients managed without magnesium sulphate, administration of magnesium sulphate for 7 d prevented the decrease of platelet count (p = 0.001). Thirty two percent of patients (13/41) experienced a major complication irrespective of duration of magnesium sulphate use.

CONCLUSIONS

Long-term use of magnesium sulphate prolonged pregnancy in patients with severe early-onset preeclampsia and can help alleviate progression of preeclampsia.

Clinical syndromes associated with acquired antithrombin deficiency via microvascular leakage and the related risk of thrombosis

Antithrombin (AT) is a 65kDa glycoprotein belonging to a group of inhibitory factors known as serpins (serine protease inhibitors). It plays a critical role in the inhibition of coagulation and inflammation processes within the environment of the vascular endothelium. Inadequate levels of functional AT in plasma results in an increased risk of thrombotic events, both venous and arterial. AT deficiency can be inherited or acquired. Congenital AT deficiency is the most severe inherited thrombophilic condition with an odds ratio of 20 for the increased risk of venous thrombosis. Acquired AT deficiency occurs in a variety of physiologic and pathologic medical conditions with similar risks of increased thrombosis. In this article, we review clinical settings characterized by an acquired AT deficiency largely or partly subsequent to protein microvascular leakage. Other different mechanisms of AT depletion are implied in some clinical conditions together with endothelial loss, and, therefore, outlined. In addition, we provide a description of the current knowledge on the specific mechanisms underlying endothelial AT leakage and on the consequences of this protein decrease, specifically looking at thrombosis. We identify potential directions of research that might prove useful in patients with acquired AT deficiency.

Differentiation of acute fatty liver of pregnancy from syndrome of hemolysis, elevated liver enzymes and low platelet counts

As proposed criteria (Swansea criteria) for the diagnosis of acute fatty liver of pregnancy (AFLP) do not include antithrombin (AT) activity, diagnosis of AFLP may be delayed. The aim of this review is to underscore problems in the differential diagnosis of AFLP and the syndrome of hemolysis, elevated liver enzymes and low platelet counts (HELLP syndrome) and to facilitate prompt diagnosis of AFLP. Published works dealing with liver dysfunction in pregnancy, HELLP syndrome and AFLP were reviewed. AFLP and HELLP syndrome shared common clinical, laboratory, histological and genetic features, and differential diagnosis between them was often difficult. However, HELLP syndrome was likely to occur in patients with hypertension, but AFLP occurred often in the absence of hypertension. In addition, AFLP was exclusively associated with pregnancy-induced antithrombin deficiency (PIATD). Approximately 50% of patients with AFLP did not have thrombocytopenia at presentation. As the Swansea criteria for AFLP did not include PIATD, diagnosis of AFLP was delayed until manifestation of life-threatening complications; 60% of women were admitted to intensive care and 15% to a specialist liver unit. In conclusion, incorporation of AT activity of less than 65% into the diagnostic criteria for AFLP may facilitate suspicion and prompt diagnosis of AFLP, decrease uncertainty regarding the diagnosis of AFLP, and contribute to better investigation and understanding of the process leading to the development of liver dysfunction.

Association of microparticles and preeclampsia

Preeclampsia (PE) is a syndrome characterized by poor placentation and endothelial dysfunction. The diagnosis for this syndrome is based in hypertension and proteinuria presented after the 20th week of pregnancy. Despite intensive research, PE is still one of the leading causes of maternal mortality, although reliable screening tests or effective treatments of this disease have yet to be proposed. Microparticles (MPs) are small vesicles released after cell activation or apoptosis, which contain membrane proteins that are characteristic of the original parent cell. MPs have been proven to play key role in thrombosis, inflammation, and angiogenesis, as well as to mediate cell-cell communication by transferring mRNAs and microRNA from the cell of origin to target cells. Placenta-derived syncytiotrophoblast MPs are one of the most increased MPs during PE and may play an important role in the pathogenesis of this syndrome. Therefore, a better overall understanding of the role of MPs in PE may be useful for new clinical diagnoses and therapeutic approaches.

Association of antithrombin activity with plasma aldosterone concentration and plasma renin activity in pregnant women

OBJECTIVE

To test the hypothesis that the blood antithrombin (AT) activity is correlated with the plasma aldosterone concentration (PAC), the plasma renin activity (PRA), and/or the PAC-to-PRA ratio during the late stage of pregnancy.

METHODS

The AT activity, PAC, and PRA were determined within 7 days prior to delivery in 47 women, consisting of 30 normotensive and 6 hypertensive women with singleton pregnancies and 11 normotensive women with twin pregnancies.

RESULTS

The median values of the 47 women were 86% of the normal activity level for the AT activity, 442 pg/mL for the PAC, 3.7 ng/mL/h for the PRA, and 108 pg/mL per ng/mL/h for the PAC-to-PRA ratio. Women with an AT activity ≤86% had a significantly lower PRA and a higher PAC-to-PRA ratio than women with an AT activity >86% (3.5 ± 3.0 vs. 6.6 ± 4.7 ng/mL/h for PRA, p = 0.008; 156 ± 109 vs. 97 ± 46 pg/mL per ng/h for PAC-to-PRA ratio, p = 0.021). The AT activity was significantly correlated positively with the PRA and negatively with the PAC-to-PRA ratio.

CONCLUSIONS

The existence of a common pathophysiological background between a reduced AT activity and a reduced PRA during the late stage of pregnancy was suggested.

Candidates for the determination of antithrombin activity in pregnant women

BACKGROUND

Some women exhibit a gradual decrease in antithrombin activity until the time of delivery, with antithrombin activity reaching <65% of the normal level (pregnancy-induced antithrombin deficiency, PIATD). However, the clinical features of such women are not well understood and are unfamiliar to many obstetricians.

FINDINGS

PIATD is more likely to occur as the number of fetuses increases (approx. 1.0%, 10%, and 40% for singleton, twin, and triplet pregnancies, respectively) and in women with hypertension, isolated proteinuria and/or edema. However, normotensive women account for 60% of women with PIATD. Antithrombin can escape from the blood into the interstitial space. Women with PIATD suffer from a decreased plasma volume and are more likely to develop liver dysfunction, irrespective of the presence or absence of hypertension. Because antithrombin activity continues to decrease until the time of delivery in women with PIATD, women with unrecognized PIATD may be identified as patients with so-called "acute fatty liver of pregnancy" if delivery is delayed.

CONCLUSION

Knowledge of AT activity in obstetrical practice may improve management of pregnant women. The determination of AT activity should be considered in women with multifetal pregnancies, hypertension, isolated proteinuria and/or edema.

Natural coagulation inhibitors and active protein c resistance in preeclampsia

INTRODUCTION

The etiology of preeclampsia is not fully established. A few studies have shown a relationship between natural coagulation inhibitors and preeclampsia.

OBJECTIVES

The purpose of this study was to investigate the status of natural coagulation inhibitors and active protein C resistance (APC-R) in preeclampsia.

PATIENTS AND METHODS

We studied 70 women with preeclampsia recruited consecutively and 70 healthy pregnant and 70 nonpregnant women as controls. Plasma protein C (PC), free protein S (fPS), antithrombin III (ATIII) and APC-R were evaluated.

RESULTS

ATIII values were found to be significantly lower in preeclamptic patients than in the control groups (p< 0.001). Nevertheless, there was no significant difference between the healthy pregnant and nonpregnant women groups (p=0.141). The fPS values of the preeclamptic and healthy pregnant groups were lower than that of the nonpregnant group (p< 0.001), and the fPS value of the preeclamptic pregnant women was lower than that of healthy pregnant women (p<0.001). The PC value of the preeclamptic pregnant women was lower than that of the control groups (p< 0.001). The PC value of the healthy pregnant women was lower than that of the nonpregnant women (p< 0.001). The mean APC activity values were lower in the preeclamptic patients than that of the control groups (p< 0.001, p< 0.001). The APC-R positivity rates of the preeclamptic groups were higher than that of the control groups (p<0.001).

CONCLUSIONS

This study demonstrated that ATIII, fPS, PC values and APC resistance were lower and APC-R positivity was higher in preeclamptic women than in normal pregnant and nonpregnant women.

Antithrombin III activity and platelet count are more likely to decrease in twin pregnancies than in singleton pregnancies

BACKGROUND

It is not known whether antithrombin III activity and platelet count are more likely to decrease in women with twin pregnancies than singleton pregnancies.

METHODS

We enrolled 56 consecutive women with twin pregnancies and 692 consecutive women with singleton pregnancies. Antithrombin III activity and platelet count were determined at 26-31 weeks and again at 32-40 weeks of gestation. Thrombin-antithrombin complex, and plasmin-alpha2 plasmin inhibitor complex were measured simultaneously in some women.

RESULTS

In twin pregnancies, both antithrombin III activity (111 +/- 8.2%) and platelet count (244 +/- 60 x 109/l) at 28.6 +/- 1.0 weeks decreased over time to 91 +/- 12% and 205 +/- 59 x 109/l, respectively, at 35.2 +/- 1.2 weeks; these decreases were significantly greater than in singleton pregnancies. However, a small number of women with singleton pregnancies had a significant decrease in antithrombin III activity in the absence of preeclampsia. The serum thrombin-antithrombin complex was significantly higher in twin pregnancies than in singleton pregnancies (9.7 +/- 4.2 ng/ml vs. 6.7 +/- 4.4 ng/ml, respectively, p < 0.01), and this increase correlated significantly with the decrease in antithrombin III activity in twin pregnancies (r = -0.459, p < 0.001).

CONCLUSIONS

Antithrombin III activity and platelet count show a greater decrease in twin than in singleton pregnancies, perhaps due to a greater increase in thrombin generation.

The effect of magnesium on coagulation in parturients with preeclampsia

Preeclampsia is associated with complex coagulation abnormalities that include altered platelet function and consumption and activation of the fibrinolytic system. Magnesium sulfate, which is used as a therapeutic modality for the prevention of seizures in preeclamptic parturients, has anticoagulant and antiplatelet effects. We sought to determine the effects of magnesium on various components of the coagulation system in patients with preeclampsia. We assessed the coagulation status of 18 parturients with preeclampsia being treated with magnesium. The assessment was performed with the thromboelastograph test, which provides an overall assessment of blood coagulation via the coagulation index. Thromboelastography was performed before beginning magnesium therapy and 30 min and 2 h after a 6-g bolus of IV magnesium. The R value (time to first clot formation) was found to be significantly slower (P < 0.05) at 30 min after the magnesium bolus. This result suggests increased coagulant factor activity resulting from the magnesium bolus. However, there was no effect of magnesium on the overall coagulation, as evidenced by the lack of change in the coagulation index either at 30 min or at 2 h after the completion of the initial magnesium bolus. Therefore, this therapy should have no effect on the use of neuraxial techniques.

IMPLICATIONS

On the basis of the thromboelastography assessment, we found that the current practice of administering magnesium did not influence overall coagulation in preeclamptic women. Therefore, magnesium administration should not affect the use of neuraxial techniques.

Association of a decrease in antithrombin III activity with a perinatal elevation in aspartate aminotransferase in women with twin pregnancies: relevance to the HELLP syndrome

BACKGROUND/AIMS

Decreased antithrombin III (AT-III) activity and/or thrombocytopenia associated with an elevated serum level of aspartate aminotransferase in late pregnancy can threaten the lives of both the mother and the fetus. We investigated whether antenatal declines in AT-III activity and the platelet count occur in late twin pregnancy and whether reduced AT-III activity and/or thrombocytopenia precedes an increase in the serum level of aspartate aminotransferase.

METHODS

The platelet count, AT-III activity, and the serum level of aspartate aminotransferase were determined weekly or biweekly in 237 women with twin pregnancies in a longitudinal and partly prospective study.

RESULTS

Both AT-III activity and the platelet count decreased gradually in the last month of pregnancy, irrespective of the presence or absence of clinical signs of pre-eclampsia. A perinatal elevation in aspartate aminotransferase occurred in 36 (15%) of 237 women. The risk of a perinatal elevation in aspartate amino-transferase increased as the antenatal AT-III activity and/or the platelet count decreased. Pre-eclampsia developed in 60 women (25%). The relative risk of a perinatal aspartate aminotransferase elevation (95% confidence interval) for the 60 women with pre-eclampsia, the 60 women with a platelet count < or = the 25th percentile (164 x 10(9)/1), and the 60 women with AT-III activity < or = the 25th percentile (76% of normal) was 1.9 (1.0 to 3.4), 4.1 (2.3 to 7.5), and 5.9 (3.2 to 11.1), respectively, compared with the remaining 177 women.

CONCLUSIONS

AT-III activity and platelet count gradually decreased in the last month of twin pregnancies. A perinatal aspartate aminotransferase elevation was preceded by marked decreases in these parameters in women with twin pregnancies. The monitoring of AT-III activity and platelet count in women who exhibit a gradual decline in these parameters may help to avoid the development of severe HELLP syndrome.

Calciuria and preeclampsia

Urinary calcium excretion has been reported to be diminished in preeclampsia. The objective of the present study was to determine urinary calcium excretion in pregnant patients with chronic arterial hypertension (CAH) and preeclampsia (PE), and in normotensive patients (N). Forty-four pregnant patients (gestational age, 20-42 weeks; 18 CAH, 17 PE, 9 N) were evaluated for calciuria, proteinuria, plasma uric acid and blood pressure. Patients with PE (82 +/- 15.1 mg/24 h) showed significantly lower calciuria (P < 0.05) than the group with CAH (147 +/- 24.9 mg/24 h) and the N group (317 +/- 86.0 mg/24 h) (P < 0.05, Student t-test). Plasma uric acid was significantly higher in the PE group (6.1 +/- 0.38 mg/dl) than the CAH group (5.0 +/- 0.33 mg/dl; P < 0.05), which also presented higher proteinuria levels, although the difference was not statistically significant. Diastolic and systolic blood pressure did not differ between the PE (164 +/- 105 mmHg) and CAH (164 +/- 107 mmHg) groups. Calciuria was significantly lower in the group with preeclampsia than in the group with chronic arterial hypertension. We conclude that calciuria can be a further factor for identifying preeclampsia.

Pregnancy-induced hypertension: genesis of and response to endothelial injury and the role of endothelin 1

This paper discusses the spectrum of pregnancy-induced hypertension and presents a theory for its etiology. Endothelial injury is the purported precursor to pregnancy-induced hypertensive disorders, and this discussion expands on a possible mechanism by which injury could occur as a result of incomplete trophoblastic invasion. We review endothelin physiology and compare and contrast the evidence surrounding endothelin 1 as a putative mediator of PIH. An approach to treatment utilizing antagonists to the endothelin 1 receptor is introduced.

Antithrombin III prevents renal dysfunction and hypertension induced by enhanced intravascular coagulation in pregnant rats: pharmacological confirmation of the benefits of treatment with antithrombin III in preeclampsia

We tested the hypothesis that enhanced intravascular coagulation in pregnancy could produce clinical symptoms similar to those of preeclampsia, such as hypertension, proteinuria, and edema. Having confirmed this, we then examined whether the pathological changes caused by intravascular coagulation could be suppressed by administration of antithrombin III (AT III), an endogenous inhibitor active to thrombin and factor X a. Intravascular coagulation was induced in Wistar rats on day 16-20 of pregnancy by 1-h arterial infusion of tissue thromboplastin (TP) through the left ventricle of the heart. One hour after the end of the infusion period, organ blood flows were measured by the radioactive ((57)Co-labeled) microsphere method, and fibrin deposition in organs was measured by radiolabeling with [(125)I] fibrinogen injected before TP infusion. Infusion of TP produced fibrin deposition in the kidney, lung, and liver, but not in the myometrium and placenta, as well as an 80% decrease in renal blood flow (RBF), with oliguria and proteinuria. TP also caused an increase in blood pressure (BP) accompanied by an increase in plasma renin activity (PRA), both of which were suppressed by bilateral nephrectomy before TP infusion. The prophylactic administration of AT III concentrates (60 or 300 U/kg intravenously (i.v.), followed by infusion of 30 or 150 U/kg/2 h, respectively) prevented all pathological changes in a dose-dependent manner. AT III increased placental blood flow regardless of the state of coagulation. These findings suggest that intravascular coagulation plays a significant part in the pathophysiology of preeclampsia and that AT III concentrates may have therapeutic potential in the treatment of this condition.

The laboratory evaluation of hypertensive gravidas

A number of laboratory tests are available for the evaluation of the hypertensive gravida. These tests can be used to either predict and/or prognosticate between preeclampsia and other hypertensive disorders of pregnancy. These laboratory tests were evaluated based on published experience with special attention to its ability to facilitate identification of the patient with preeclampsia apart from other hypertensive disorders that co-exist with and occur as a complication of pregnancy. Hypocalciuria and increased cellular plasma fibronectin seem to be good tests to differentiate preeclampsia from chronic hypertension. The management of preeclampsia with its increased risk of perinatal morbidity and mortality renders this differentiation clinically very important. Hyperuricemia, proteinuria, increased serum beta-thromboglobulin concentration, abnormal red blood cell morphology with increased hemoglobin/hematocrit, and increased serum iron individually and collectively reflect the severity of preeclampsia. Platelets and total serum lactate dehydrogenase are the best tests to reflect the severity of HELLP syndrome. Circulating hCG and serum thromboglobulin seem to be the most promising future predictors for preeclampsia.

The role of complement in pregnancy-induced hypertensive disease

Preeclampsia is a pregnancy-induced hypertensive disease with an incidence of about 5% in primigravidas and, being common, it significantly contributes to maternal and neonatal morbidity and mortality. The primary cause remains unknown but might be immunologic, since immunologic aberrations are described in preeclampsia. Activation of the complement system in pregnancy-induced hypertensive disease has been discussed during the last 60 years. It is now strongly indicated that complement activation occurs in preeclampsia. The complement system is very potent and one of the major effector pathways of the process of inflammation. The pathological manifestations, endothelial damage and microvascular injury, and thereby the clinical findings in preeclampsia, may be explained by complement activation, resulting in the direct vascular effects of biological active complement components and complement-mediated activation of leukocytes, with release of potent inflammatory mediators. This new etiological hypothesis might give other options in therapy and prevention of pregnancy-induced hypertensive disease.

Platelet activation and vascular damage in gestational hypertension

Increased plasma fibronectin levels are a highly sensitive and specific predictor of gestational hypertension. Of a total of 105 apparently healthy normotensive primigravid women seen at the outpatient clinic, 10 with increased plasma levels of fibronectin (mean +/- 2 SD), were compared with 14 controls. Parameters of early vascular damage (laminin, preprocollagen III), platelet activation (beta-thromboglobulin, platelet factor 4), and coagulation (thrombin-antithrombin III complexes, fibrinopeptide A) were measured at regular (weekly or monthly) intervals. Abnormal values of laminin (p less than 0.005) and fibronectin (p less than 0.0001) were found up to 4 weeks before the onset of clinical disease. Levels of beta-thromboglobulin (p less than 0.0001) were also elevated at least 4 weeks before the appearance of clinical symptoms. Our results show that increased levels of laminin, fibronectin, and platelet activation, as indicated by beta-thromboglobulin levels, are preclinical features of gestational hypertension and indicate that vascular damage has occurred. Fibrin formation would appear to occur later.

Prevention and treatment of pregnancy-associated hypertension: what have we learned in the last 10 years?

High blood pressure (BP) complicates approximately 10% of all pregnancies. Hypertension in pregnancy falls into four categories: (1) preeclampsia-eclampsia, (2) chronic hypertension of whatever cause, (3) preeclampsia-eclampsia superimposed to chronic hypertension or renal disease, and (4) transient or late hypertension (gestational hypertension). Preeclampsia, the association of hypertension, proteinuria, and edema, accounts for more than 50% of all the hypertensive disorders of pregnancy and is a major cause of fetal and maternal morbidity and mortality. Unfortunately, distinguishing between preeclampsia and other causes of hypertension on clinical grounds can be difficult because of the lack of specific tests for differential diagnosis. Increased vascular resistance has been claimed as the primary cause of preeclampsia; however, a variable hemodynamic profile with relatively high cardiac outputs, normal filling pressures, and inappropriately high systemic vascular resistances is now reported by most investigators. Imbalance between vasodilator and vasoconstrictor eicosanoids may account for platelet activation and increased responsiveness to pressor peptides. Altered prostacyclin (PGI2) to thromboxane A2 (TxA2) ratio in maternal uteroplacental vascular bed may favor local platelet activation and vasoconstriction contributing to placental insufficiency and fetal distress. Alternatively, recent evidence seems to suggest that fetal umbilical placental circulation may be the site of the primary vascular injury. Whether low-dose aspirin prevents preeclampsia because it inhibits the excessive maternal TxA2 or whether the partial inhibition of fetal TxA2 is also of therapeutic value remains to be established. Treatment of severe hypertension in pregnancy is probably important to prevent cardiac failure or cerebrovascular accidents in the mother. The need for pharmacological therapy of mild to moderate hypertension is still debated, since no formal studies are available to clarify whether pharmacological treatment in such instances effectively reduces maternal or fetal risk. For the treatment of preeclampsia, hydralazine and nifedipine may be used when delivery is not applicable. Labetalol and diazoxide are effective for hypertensive emergencies. Life-threatening hypertension that does not respond to more conventional therapy is an indication for the use of sodium nitroprusside. For chronic hypertension, alpha-methyldopa remains the treatment of choice; if ineffective, hydralazine or beta-blockers are suitable. Effectiveness and safety of other molecules remain elusive.

Early detection of preeclampsia

The signs and symptoms of preeclampsia are usually apparent at a relatively late stage in pregnancy (late second to early third trimester). However, the disorder results from abnormal interaction between fetal and maternal tissue much earlier in pregnancy, between 8 and 18 weeks' gestation. During the past two decades numerous clinical, biophysical, and biochemical tests have been proposed for the early detection of preeclampsia. Some of these tests are simple, whereas others are invasive; some have been studied extensively, while others are still under clinical investigation. A review of the literature indicates considerable disagreement regarding the sensitivity and predictive values of the various tests studied. The reported differences in the predictive values of these tests may be attributed to one or more of the following: populations studied, definition and prevalence of the disorder, techniques and methodology used in performing these tests, etc. As a result, there is disagreement regarding the ideal screening test to be used for identifying patients for clinical trials dealing with prevention of the disorder.

Thrombin-antithrombin III complex levels in normal pregnancy with hypertensive disorders and after delivery

The plasma concentration of the thrombin-antithrombin III-complex (TAT) was investigated during uncomplicated pregnancy in 15 women in the first, 22 in the second and 46 in the third trimester, and in 19 women with hypertensive disorders between 25 and 40 weeks gestation. Eight women at term after a normal pregnancy were studied before the onset of labour and within 60 min and 24 h after delivery. A comparison group of 16 healthy, non-pregnant women was investigated. The mean TAT concentration in normal pregnancies increased significantly in the second and third trimester compared with values in the first trimester and in non-pregnant women. In the group with hypertensive disorders during pregnancy TAT levels were significantly higher than in uncomplicated pregnancies. Within 60 min after delivery a distinct increase of TAT concentrations occurred compared to levels before the onset of labour but the levels had returned to normal by 24 h after delivery. Our findings suggest that an activation of the coagulation system occurs in normal pregnancy. A further activation takes place immediately after delivery. The significantly increased TAT levels in pregnancies with hypertensive disorders suggest a state of chronic disseminated intravascular coagulation leading to an enhanced consumption of and a decreased plasma concentration of antithrombin III.

Clinical and biochemical characterization of antithrombin III Franconville, a variant with Pro 41 Leu mutation

We describe a familial study of AT III, a type III antithrombin III variant which was identified in the propositus by gene analysis as Pro 41 Leu heterozygous mutation. None of the four members of the family who presented with defective heparin cofactor (hep-cofactor) activity, and therefore probably carried the mutation, had experienced deep venous thrombosis. The abnormal AT III was purified from the propositus' plasma, taking advantage of the difference in NaCl concentrations required to elute variant and normal AT III from heparin-Sepharose. The antithrombin and anti-Xa activities of the purified variant AT III were comparable to those observed for normal AT III, but hep-cofactor activity was strikingly reduced. The enhancement by heparin of thrombin and F Xa inhibition by normal and variant AT III was compared in the absence of NaCl and in the presence of normal NaCl concentrations. The difference between the degrees of inhibition by normal and variant AT III was maximal at physiological ionic strength (i.e. at a concentration of 0.15 M). The quantification of heparin AT III interaction with both normal and variant purified proteins in a double reciprocal plot yielded similar dissociation constants but a 9-fold decrease in the maximal pseudo-first order constant. This suggests that Pro 41 is more involved in the molecular changes induced by heparin than in the primary binding of the activator.

Elimination of antithrombin III concentrate in healthy pregnant and preeclamptic women with an acquired antithrombin III deficiency

The activity elimination half-life of heat-treated antithrombin III (AT III) concentrate was studied in 5 healthy pregnant and 5 preeclamptic women with a documented AT III deficiency. Healthy pregnant women received 1500 units over 20 minutes. Serial blood specimens were obtained over the next 12 hours. The mean (+/- SEM) activity elimination half-life of AT III was 29.4h +/- 3.4h. Preeclamptic subjects had a mean baseline AT III activity of 70.5 +/- 2% (range 61 to 75%). Their activity eliminator half-life after 3000 units of AT III concentrate was 8.5 +/- 1.2h. There was a direct relationship between the pre-concentrate AT III activity level and the AT III activity elimination half-life (r = 0.79, p = 0.01) for all subjects. Based upon parameters calculated from the first infusion, the AT III activity of preeclamptic subjects was maintained by a constant infusion at approximately 100% for 96h. At the conclusion of the infusion, the activity elimination half-life was again measured. A dramatic increase in the activity elimination half-life was demonstrated (433.6h). We conclude that the activity elimination half-life of AT III concentrate is increased during normal pregnancy and further increased in preeclamptic women with an acquired deficiency.

Thrombocytopenia and platelet functional defects in pre-eclampsia: implications for regional anaesthesia

A prospective, observational study of forty pre-eclamptic patients was conducted to confirm or refute reports of a platelet functional defect superimposed on the consumptive thrombocytopenia of pre-eclampsia. Investigations included a platelet count, in vivo platelet function as assessed by a Duke bleeding time, and in vitro platelet function as assessed by thromboxane B2 and Platelet Factor 3 (PF 3). The overall incidence of thrombocytopenia was 15%. Prolonged bleeding time and slightly decreased availability of PF 3 (evidence of possible platelet dysfunction) was present in 2.5% of patients while 21% had evidence of fibrinolysis with an elevated monoclonal D-dimer. In the assessment of suitability for regional blockade, a platelet count is essential. If the platelet count is between 50 and 100 x 10(9)/l a bleeding time is indicated.

Acute coagulopathy in pregnancy

Pregnancy alters both the fibrinolytic system and coagulation cascade. In addition, pregnancy presents unique triggering mechanisms for DIC. Management of DIC in pregnancy should include removal of the triggering mechanism, blood, and factor replacement. Inherited coagulation defects, while rarely resulting in bleeding diathesis in the pregnant patient, do require monitoring of maternal factor levels. Genetic counseling should be offered to all patients with inheritable coagulation disorders.

Plasma antithrombin III levels in pre-eclampsia and chronic hypertension

Plasma levels of antithrombin III were tested during pregnancy in a control group of normal patients and in a study group that included patients with moderate and severe pre-eclampsia and chronic hypertension. The control group showed mean antithrombin III activity of 97.9 +/- 20.9%, the severe pre-eclamptic patients 22.33 +/- 18.22%, the moderate pre-eclamptic patients 56.0 +/- 7.56%, and the chronic hypertensive patients 77.5 +/- 6.69%. The difference between normal pregnancy and moderate pre-eclampsia was significant at P less than 0.002, normal pregnancy and severe pre-eclampsia P less than 0.002, moderate and severe pre-eclampsia P less than 0.002, chronic hypertension and normal pregnancy P less than 0.1, and chronic hypertension and severe pre-eclampsia P less than 0.002. All the severe pre-eclamptic patients and 2 out of 6 of the moderate pre-eclamptic women were below 55.7% (mean - 2S.D.) of normal antithrombin III activity. Patients with heavy proteinuria had depressed antithrombin III activity. However, chronic hypertensive pregnancies, although rather a small group, had almost normal values of plasma antithrombin III activity. The plasma antithrombin III value may thus help to distinguish between chronic hypertension and severe pre-eclamptic disease.

Placental-type plasminogen activator inhibitor in preeclampsia

The present cross-sectional study in patients with preeclampsia and gestational hypertension and in gestational age-matched controls was undertaken to investigate further the fibrinolytic system in these conditions. In preeclampsia we observed increased levels of total plasminogen activator inhibitor (p less than 0.001) but low levels of placental-type plasminogen activator inhibitor (p less than 0.05) compared with controls. The levels of placental-type plasminogen activator inhibitor were even more reduced (p less than 0.002) in pregnancies with a poor fetal outcome. It is concluded that placental-type plasminogen activator inhibitor does not contribute to the increased levels of total plasminogen activator inhibitor activity in preeclampsia. Placental-type plasminogen activator inhibitor levels correlated significantly with birth weight and placenta weight and may therefore reflect placental function.

Preeclampsia, delivery, and the hemostatic system

To determine the effects of preeclampsia and delivery, the hemostatic system was evaluated before and 24 to 48 hours after delivery in 59 nulliparous patients without clinical signs of disseminated intravascular coagulation. Fifteen patients with mild preeclampsia and 18 with severe preeclampsia were compared with 26 pregnant control patients. Preeclampsia was associated with high fibronectin (p less than 0.001), low antithrombin III (p less than 0.001), and low alpha 2-antiplasmin (p less than 0.005), suggesting endothelial injury, clotting, and fibrinolysis, respectively. After delivery, fibronectin decreased only in preeclamptic patients (p less than 0.005); alpha 2-antiplasmin increased in all groups (p less than 0.001). Endothelial injury in preeclampsia appeared to resolve soon after delivery, which could contribute to the rapid clinical improvement noted in the early puerperium.

Heparin cofactor activity and antithrombin III antigen levels in preeclampsia

It has been reported that patients with preeclampsia have decreased levels of antithrombin III heparin cofactor and that the degree of depression parallels the severity of disease. To determine the time course of development and resolution of this deficiency, and to gain insight into the cause of this deficiency, plasma antithrombin III antigen and heparin cofactor activity levels were measured serially in 11 women with mild preeclampsia. Although the ATIII antigen level remained stable during the antepartum period, the level of heparin cofactor was noted to fall progressively during the antepartum period. Both ATIII antigen and heparin cofactor increased promptly postpartum. The discrepancy between the levels of ATIII antigen and heparin cofactor activity suggests that in both mild and severe preeclampsia there is utilization of antithrombin III to form inactive protease inhibitor complexes.

A syndrome of liver damage and intravascular coagulation in the last trimester of normotensive pregnancy. A clinical and histopathological study

Six women without hypertension or proteinuria, admitted for severe upper abdominal pain in the third trimester of pregnancy had elevated serum liver enzymes (SGOT, SGPT), markedly increased serum LDH levels, thrombocytopenia and abnormal blood coagulation tests, in particular low antithrombin III levels, indicating disseminated intravascular coagulation (DIC). Liver biopsies showed periportal and/or focal parenchymal lesions with large fibrin deposits, comparable to the liver lesions in eclampsia. Immunofluorescence (IF) showed microthrombi and large fibrin deposits. Three of the six women recovered spontaneously before delivery; in the remaining three all signs and symptoms rapidly disappeared after delivery. Perinatal outcome was poor. Seven women with pregnancy-induced hypertension and elevated serum liver enzymes constituted a reference series. Histopathological examination of liver biopsies in the reference group revealed periportal and/or focal parenchymal lesions in three whereas IF showed fibrin deposition in all seven, but less extensive than in the study group. The present findings indicate that upper abdominal pain in the last trimester of pregnancy can be caused by a syndrome of (pre)-eclamptic liver damage and DIC, even when hypertension and proteinuria are lacking.

Low antithrombin III and high plasma fibronectin in pre-eclampsia

Antithrombin III activity and plasma fibronectin levels were determined in patients with preeclampsia. In several cases low antithrombin III and high plasma fibronectin concentrations could be related to proteinuria. Altered plasma fibronectin and antithrombin III concentrations might contribute to a hypercoaguable state in patients with preeclampsia.

Preeclampsia

The case of a 32-year-old primigravida, 32 weeks gestation, with nausea, vomiting, thrombocytopenia, and abnormal liver function tests is presented. A diagnosis of severe preeclampsia was made and the patient underwent emergency cesarean section. Improvement of clinical symptoms and laboratory studies followed over the succeeding days. These less common manifestations of preeclampsia indicate severe disease necessitating aggressive management, even in the setting of a normal blood pressure. Thrombocytopenia, microangiopathic hemolytic anemia, or abnormal liver functions in a patient presenting in the latter half of pregnancy may be manifestations of severe preeclampsia.

Antithrombin III levels in preeclampsia correlate with maternal and fetal morbidity

In 57 patients with pregnancy-induced or aggravated hypertension, antithrombin III levels correlated inversely with maternal morbidity. Morbidity was determined by the maximal diastolic blood pressure, disturbance of renal and liver function, and thrombocytopenia. Antithrombin III levels and platelet counts correlated inversely with the degree of placental infarction. Proteinuria (grams per 24 hours) was most predictive of fetal outcome, which was considered to be either favorable if a healthy baby could be discharged with its mother or unfavorable in case of perinatal death or a prolonged stay in the neonatal intensive care unit. Plasma antithrombin III and serum glutamic oxaloacetic transaminase levels, in that order, augmented the number of correct predictions. Antithrombin III inhibits blood coagulation by forming irreversible complexes with activated clotting enzymes, notably with factor Xa and thrombin. Evidence is presented which suggests that antithrombin III levels in preeclampsia are depressed as a result of increased consumption in the maternal vascular tree, rather than decreased synthesis or increased urinary loss.

Clinical applications of the altered iron kinetics of toxemia of pregnancy

The previously reported elevation of serum iron in association with toxemia of pregnancy was evaluated to determine if this chemical test could be clinically useful. When patients with toxemia and pregnant women with chronic hypertension were compared, a serum iron value greater than 100 micrograms/dl or an increase greater than 70% above baseline was a sensitive and specific indicator of toxemia. The predictive value is high and exceeds that of other commonly available tests. The clinical value of this model is discussed.

Vasoactivity generated from platelets by immune complexes in pre-eclampsia

Circulating immune complexes in excess of the equivalent of 20 micrograms/ml heat-aggregated IgG were found in fourteen out of twenty patients diagnosed as having preeclampsia. Only six of the nineteen controls tested had similar levels of immune complexes. Recent studies have established that concentrations of heat aggregated IgG in excess of 20 micrograms/ml activate human platelets to release sufficient concentrations of vasoactive agents to constrict a human blood vessel in vitro. It is therefore suggested that in vivo platelet activation by circulating immune complexes may release sufficient concentrations of vasoactive agents to contribute to the hypertension in pre-eclampsia.

Plasma antithrombin III levels in pre-eclampsia

In a prospective study plasma AT III was determined in 2423 samples obtained from 653 women during pregnancy and post partum. The women were allocated to groups, according to the highest diastolic blood pressure, in the third trimester. AT III levels were normal throughout pregnancy, during labour and after vaginal delivery, except in 57 women with pregnancy induced or aggravated hypertension. We present evidence that AT III depression in pre-eclampsia is caused by increased consumption. AT III levels correlate with maternal morbidity as revealed by hepatorenal damage. A weak but significant correlation of AT III and platelets with placental infarction was demonstrated. Proteinuria was the best predictor of fetal outcome. AT III plasma levels increased the number of correct predictions. Following vaginal delivery AT III plasma levels rapidly returned to normal values.

Immune complexes and vasoactivity generated from platelets in pre-eclampsia

In vivo platelet activation by circulating immune complexes has been suggested as one of the underlying mechanisms in preeclampsia. Using a modification of the polyethylene glycol protein-A immune complex assay, immune complexes were found in excess of the equivalent of 20 micrograms/ml heat aggregated IgG in fourteen out of twenty patients diagnosed as having pre-eclampsia. Only six out of nineteen normal controls were found to have similar levels of immune complexes. Furthermore, using a small volume bio-assay method, concentrations of heat aggregated IgG in excess of 20 micrograms/ml were found to activate platelets to release sufficient concentrations of vasoactive agents to constrict a human blood vessel in vitro. These results support the hypothesis that in vivo platelet activation by immune complexes can release sufficient concentrations of vasoactive agents to contribute to the hypertension characteristic of pre-eclampsia.