Factor-VIII complex fetal growth retardation, and toxaemia

Reassessment of von Willebrand factor (VWF), VWF propeptide, factor VIII:C and plasminogen activator inhibitors 1 and 2 during normal pregnancy

The use of von Willebrand factor [VWF antigen (WF:Ag)] measurement as a marker of endothelial cell activation for monitoring hypertensive pregnancies is limited by the poor definition of reference values. We reassessed these reference values using different assays, and those of the propeptide (VWF:Ag II) and factor VIII coagulant activity (factor VIII:C), in a large population of normal pregnancies, at 3-week intervals of gestational age. Plasminogen activator inhibitors (PAI-1 and PAI-2) were measured in parallel. Blood was collected at single time points between 12 weeks and delivery in 306 women undergoing normal singleton pregnancy. For clinical purposes, the VWF:Ag reference values were assay independent and the influence of ABO blood group on VWF:Ag or factor VIII:c was found to be limited during the third trimester. VWF:Ag II was not influenced by the ABO blood group. The ratio, VWF:Ag/factor VIII:C was close to 1.0 throughout pregnancy. In contrast, VWF:Ag II increased more slowly than VWF:Ag and the ratio of VWF:Ag II to VWF:Ag in plasma decreased from 1.00 to 0.5 at term. PAI-1 and PAI-2 increased with gestational age, but PAI-2 decreased during the last 2 weeks, indicating physiological placental regression at the very end of pregnancy.

Evaluation of six markers of haemostatic system in normal pregnancy and pregnancy complicated by hypertension or pre-eclampsia

OBJECTIVE

To establish the plasma evolution of prothrombin fragments 1+2 (F 1+2), thrombin-antithrombin III complexes (TAT), fibrin fragment D-Dimers (DD), von Willebrand factor antigen (vWf), Type 1 plasminogen activator inhibitor antigen (PAI) and blood platelet count during normal pregnancy and to compare these values with those obtained in hypertensive or pre-eclamptic pregnancies.

DESIGN

Cross-sectional study.

SUBJECTS

Forty-seven healthy pregnant women with gestational age ranging between 5 and 40 weeks, and fourteen women with gestational age ranging between 25 and 38 weeks presenting with either gestational hypertension (n = 4) or pre-eclampsia (n = 10). Numbers of nulliparous women in the control, hypertension and pre-eclampsia groups were 13/47 (28%), 1/4 (25%) and 9/10 (90%), respectively.

RESULTS

All six markers increased with gestational age in normal pregnant women (P < 0.01). Using the upper limit of 95% prediction interval obtained from regression curves as normality threshold, TAT showed the best sensitivity (71% vs < 30% for F1+2, DD, vWf, PAI and platelet count).

CONCLUSION

TAT appears to be an interesting marker for detecting haemostatic system alterations in pregnancies complicated by hypertension or pre-eclampsia. A large prospective study to determine its clinical usefulness for such complicated pregnancies is currently in progress.

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.

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.

Factor VIII-von Willebrand factor in giant cell arteritis and polymyalgia rheumatica

Levels of three factor VIII-von Willebrand factor components (von Willebrand antigen, ristocetin cofactor, and factor VIII coagulant) were higher in specimens of plasma from 27 patients with giant cell arteritis and 18 patients with polymyalgia rheumatica than in specimens from 21 normal control subjects. Values in patients with active giant cell arteritis were higher than those in patients with either inactive giant cell arteritis or active polymyalgia rheumatica. Levels of factor VIII-von Willebrand factor components tended to decline gradually after disease activity had been suppressed by corticosteroid therapy and therefore may be indicators of vascular damage. These levels, however, did not revert to normal rapidly in response to corticosteroid therapy as did the patients' symptoms and the usual laboratory measurements indicative of inflammation; thus, measurements of these components are unlikely to be useful in day-to-day management of these diseases. Electrophoretic analysis suggested that the elevated values are due to increased amounts of normal factor VIII-von Willebrand factor rather than to the presence of an abnormal molecule.

Factor VIII-related antigen levels in normal pregnancy and puerperium

The changes in serum Factor VIII-related antigen (Factor VIII RAg) levels in normal pregnancy and puerperium in Chinese women were studied by the Laurell 'rocket' immunoelectrophoresis. At 6 wk of gestation, the serum Factor VIII RAg levels were already higher than those of non-pregnant women and gradually increased through term pregnancy. Parturition did not have immediate effects on the circulating levels of Factor VIII RAg. The levels of Factor VIII RAg observed during labour and days 1-5 postpartum were similar to those of term pregnancy. By the 6th wk postpartum, the serum Factor VIII RAg declined to basal levels, similar to those of non-pregnant control samples.

Increased von Willebrand factor antigen in the plasma of patients with vasculitis

The plasma concentrations of von Willebrand factor antigen (vWF:Ag) were determined in 101 patients who had the following diagnoses: vasculitis 8 patients, systemic lupus erythematosus (SLE) 51, rheumatoid arthritis (RA) 28, asthma 7, hereditary angioedema 7. The greatest mean concentration of vWF:Ag, 469% (normal 100% +/- 50), was observed in patients with vasculitis, often without elevation of the erythrocyte sedimentation rate. The mean concentration of vWF:Ag was also increased in both SLE (277%) and RA (194%). Twenty-four patients (15 with SLE, 6 with vasculitis, 3 with RA) had vWF:Ag concentrations greater than 300%. Four of these patients died within 1 year of the date of the study. Of the 15 SLE patients, 9 had vasculitis and 2 had active glomerulonephritis. The 3 RA patients had severe disease associated with extraarticular manifestations. Elevated vWF:Ag may reflect vascular damage, while markedly elevated levels of vWF:Ag appear to indicate a poor prognosis.

Elevation of von Willebrand factor is independent of erythrocyte sedimentation rate and persists after glucocorticoid treatment in giant cell arteritis

Von Willebrand factor (vWF) antigen levels were measured in 39 patients with biopsy-proven giant cell arteritis (GCA), 16 patients with polymyalgia rheumatica (PMR), 12 patients with Sjögren's syndrome, and 7 with choroiditis, as well as in 20 age- and sex-matched controls. Among GCA patients, 31 (group A) had clinically inactive disease and were taking low-dose glucocorticoids for at least 1 year; their vWF levels were high even in the presence of a normalized erythrocyte sedimentation rate (ESR). When the ESR and vWF were analyzed in another 8 GCA patients (group B) before and after treatment with glucocorticoids, vWF remained elevated even though the ESR returned to normal. Among the highest levels of vWF were those of 3 GCA patients who presented with ocular symptoms and positive temporal artery biopsies, but normal ESR. The presence of elevated vWF was not specific for GCA since elevated levels were also found in patients with PMR, Sjögren's syndrome, and choroiditis. The levels of vWF in GCA were significantly higher (P less than 0.01) than in these other conditions associated with myalgias and eye symptoms. Elevation of vWF levels may help in the differential diagnosis of GCA, particularly when the ESR is normal and ocular symptoms are present.

Blood rheology in pre-eclampsia and intrauterine growth retardation: effects of blood pressure reduction with labetalol

Blood viscosity ( Contraves L S 30) and its determinants were measured in 23 patients with mild/moderate pre-eclampsia, 10 patients with intrauterine growth retardation and 22 control subjects, matched for age and gestation. Both abnormal groups had a significantly increased blood viscosity at high shear rate (94 s-1) associated with increased haematocrit. Fibrinogen levels were also increased, but there were no significant differences between groups in plasma viscosity, low shear viscosity (0.94 s-1) or red cell deformability, measured by a low-shear washed cell system of filtration through 5-micron pore diameter Nuclepore filters. In the pre-eclamptic group, measurements were repeated after 1-2 weeks in nine patients treated with labetalol (a combined alpha and beta adrenergic blocker) and in 10 patients treated with bed rest. Labetalol reduced blood pressure but no change in rheology was seen in either group. Control of blood pressure by labetalol does not adversely affect rheology, in contrast to diuretics which are known to cause haemoconcentration and increased blood viscosity.

The factor VIII ratio in normal and pathological pregnancies

The factor VIII ratio was measured in 102 pregnant women (43 uncomplicated pregnancies, 19 with pre-eclampsia without fetal growth retardation, 8 pre-eclampsia complicated by fetal growth retardation, 12 with only fetal growth retardation and 20 with gestational diabetes). The pathological pregnancies showed a statistically significant elevation of the factor VIII ratio compared to the normal pregnancies. The group of pre-eclampsia complicated by fetal growth retardation showed the most marked increase of the factor VIII ratio. The results are discussed in relation to the hypothesis that the elevated factor VIII ratio is mainly due to the release of factor VIII antigen by various forms of vascular stress.

Haemostatic and rheological changes in normal pregnancy and pre-eclampsia

Platelet activity (microaggregate formation, ADP-aggregation and beta-thromboglobulin release), coagulation activity (fibrinogen level and factor VIII related antigen/coagulant activity), and rheological factors (plasma viscosity, whole-blood viscosity and erythrocyte deformability) were studied serially in 14 healthy pregnancies to determine the effect of gestational age. Fourteen patients with pre-eclampsia, each matched for stage of gestation with a normal pregnancy, showed normal rheology of circulating blood and normal aggregability of circulating platelets, but there was a significant increase in platelet release of beta-thromboglobulin and a shorter platelet production time, indicating a shorter life-span. The results suggest that localized platelet activation within the utero-placental microvasculature, rather than a rheological abnormality, is a likely contributory factor to the occlusive vascular lesion of pre-eclampsia and fetal growth retardation.

Summer diarrhoea in African infants and children

Of 70 black South African infants and children with acute summer diarrhoea, 30 (43%) were infected with enteropathogenic serogroups of Escherichia coli (EPEC), 13 (19%) with enterotoxigenic Gram-negative bacilli, 12 (17%) with Salmonella sp., 6 (9%) with Shigella sp., and 3 (4%) with rotaviruses. 13 (19%) patients were infected simultaneously with more than one enteropathogen, and no pathogen was detected in 22 (31%). In addition, 6 (15%) of 41 unselected patients were excreting Campylobacter fetus. Of 30 age-matched controls drawn from the same population, 5 (17%) were infected with EPEC serotypes, and 1 each with Salmonella sp. and rotavirus. This study stresses the polymicrobial nature of paediatric diarrhoea in a developing community and shows the continued importance of EPEC in this setting.

Platelet production time, uricemia, and some hemostasis tests in pre-eclampsia

In order to choose the best adapted test for pre-eclampsia monitoring, platelet production time (PPT) was measured simultaneously with uricemia, factor VIII complex, beta-thrombogobulin, and other tests of platelet activation including platelet volume, density and platelet very dense body content. In the pre-eclamptic group (11 patients). In the PPT was significantly reduced in comparison with normal pregnancies (6 patients). In the pre-eclamptic group, there was good and significant correlation between PPT and the VIIIrAg/VIIIc ration (r = 0.87) and between PPT and uricemia (r = 0.79). The correlations between PPT and the other tests are poor and non-significant. Thus, for clinical purposes, the VIIIrAg/VIIIc ratio and uricemia are convenient parameters, and give very reliable information on the severity of the consumption coagulopathy which characterizes pre-eclamptic pregnancies.

Factor VIII-related antigen and factor VIII coagulant activity in normal and pre-eclamptic pregnancy

The changes in the ratio between factor VIII-related antigen and factor VIII activity were compared in ten patients with normal pregnancies and in ten patients with severe pre-eclampsia. In the patients with pre-eclampsia, a highly significant increase in the ratio was observed during the third trimester. No difference in the ratio between the two groups was found on day 7 of the puerperium. In the pre-eclamptic patients, the highest ratios for factor VIII-related antigen to factor VIII activity were associated with either a perinatal death or with the delivery of a severely growth retarded infant. These findings are in keeping with an increased rate of thrombin production in women with pre-eclampsia, and suggest that the ratio of factor VIII-related antigen to factor VIII activity may reflect the severity of the effect of the disease process on the fetus.