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ORIGINAL ARTICLE
Year : 2022 | Volume
: 11
| Issue : 2 | Page : 163-169
Increased thrombomodulin level in hypertensive disorders of pregnancy
Zainab Abdul Abbas Hashim1, Bassam Mohamed Hameed2
1 Department of Laboratory, Children Welfare Teaching Hospital, Baghdad, Iraq
2 Department of Pathology and Forensic Medicine, College of Medicine, Al-Nahrain University, Baghdad, Iraq
Correspondence Address:
Dr. Zainab Abdul Abbas Hashim
Department of Laboratory, Children Welfare Teaching Hospital, Baghdad
Iraq
Source of Support: None, Conflict of Interest: None
CheckDOI: 10.4103/ijh.ijh_46_22
BACKGROUND: Endothelial dysfunction is a likely pathogenic mechanism in hypertensive disorders of pregnancy leading to a hypercoagulable state.
OBJECTIVE: The present study aims to measure thrombomodulin (TM) in patients with preeclampsia (PE) and gestational hypertension (GH) and compare them with healthy pregnant control and its relation to disease severity and associated hematological parameters.
MATERIALS AND METHODS: This cross-sectional study was done for 80 participants, 30 preeclamptic, 30 GH patients, and 20 healthy age-matched pregnant from all TM assays were done in by an enzyme-linked immunosorbent assay. Other hematological parameters including complete blood count, prothrombin time, and activated partial thromboplastin time where assessed in these patients.
RESULTS: TM level was significantly higher in patients with PE when compared to both women with GH and normal pregnant women (P = 0.009) and (P < 0.001), respectively. Likewise, TM level was significantly higher in patients with GH when compared to healthy pregnant controls (P = 0.034). Plasma TM level was found to be 77% sensitive and 75% specific for the diagnosis of PE (the area under the curve was 0.835) at a 95% confidence interval.
CONCLUSION: TM is significantly elevated in pregnant women with PE and GH and is associated with the severity of the disease.
Keywords: Gestational hypertension, preeclampsia, thrombomodulin
Hypertensive disorders in pregnancy, including gestational hypertension (GH) and preeclampsia (PE), accounting for approximately 7%–10% of all pregnancies in developing countries, are the major causes for maternal and perinatal morbidity and mortality.[1] The occurrence of new arterial hypertension in pregnancy with the absence of proteinuria has been termed as GH due to the point that it occurs during gestation.[2] The etiology of PE is not fully understood though it has been linked with a widespread maternal endothelial dysfunction originating from an insufficient cytotrophoblast invasion and then hypoxic placenta.[3] Thrombomodulin (TM) is an endothelial cell surface glycoprotein that is widely distributed on vascular endothelial cells. It acts as a receptor for thrombin binding that mediates activation of protein C, thus inhibit thrombin activity.[4] It is an important regulator of thrombotic and inflammatory processes. Soluble TM fragments have been detected in the blood and urine of healthy individuals and increased particularly in endothelial injury.[5] The present study aims to evaluate the level of TM among pregnant females with GH and PE and to determine whether there is a relationship between the increased level of TM and the severity of both diseases.
Patients, Materials, and MethodsA total of 80 women were included in this case–control study that was performed at Al-Imamein Al-Kadhimein Medical City and Baghdad Teaching Hospital/Baghdad, during the period from the 1st of January till the end of June 2020. Those patients comprised 30 pregnant women with PE, who were diagnosed according to the diagnostic criteria of PE by a consultant gynecologist, 30 pregnant females with GH who were diagnosed with blood pressure ≥140/90, and 20 normotensive healthy pregnant females in their third trimester of pregnancy to be served as a control group. This study was approved by review ethical committee of Al-Nahrain university college of medicine. All patients and controlled subject were signed written informed consent prior to enrollment in the study.
Data that includes name, age, past obstetric history (gravidity, parity, previous abortion, previous history of PE, and other complications) past medical, surgical, and drug history, along with blood pressure and urine analysis were collected by direct interview or from the hospital records. Exclusion was done for: those patients who take anticoagulants, those with liver, renal, and vascular disease, patients with current thrombosis or Disseminated intravascular coagulation (DIC), within the last 3–6 months, patients with COVID-19, or any infection during the active illness of the disease.
Four ml of blood was obtained from all participants: 2 mL of blood was added to the K3-ethylenediaminetetraacetic acid tube for complete blood count (CBC) and 2 mL was added to the sodium citrate tube to obtain plasma by centrifugation for immediate assay of prothrombin time (PT) and activated partial thromboplastin time (PTT) in the hematology laboratory at Al-Imamein Al-Kadhimein Medical City, part of citrated plasma was stored (below –40°C) for TM assay. Blood samples were checked out for CBC by Sysmex XN-1000 Automated Hematology Analyzer (Sysmex Corporation, Japan). PT was performed using The STA®-NeoPTimal kit from (Diagnostica Stago, France), and activated partial thromboplastin time (aPTT) was performed using The STA®-Cephascreen® kit (Diagnostica Stago, France) according to the manufacturer instructions. Platelet-poor plasma was prepared by centrifuging of citrated blood of both the patients and control for 15 min at 2000 g. Both PT and aPTT were carried out by fully automated STA Compact Max2 (Diagnostica Stago, France).
TM estimation was done by enzyme-linked immunosorbent assay using commercially available Human TM/BDCA-3 Immunoassay kit, R and D Quantikine, USA.
For statistical analysis, data were made using SPSS software (version 20.0, IBM, Armonk, New York, USA). The numerical data were represented as mean ± standard deviation and nominal data were represented as numbers and percentages. Data between patients and controls were analyzed by the Student's t-test and ANOVA test. Correlations were done by Pearson's method. P <0.05 was considered statistically significant.
ResultsThe mean age of PE patients was 30.03 ± 6.92 years which did not differ significantly from that of women with GH (mean: 27.53 ± 4.72 years). In general, primigravida and nulliparous patients were more common among women with PE than those with GH; however, the differences were insignificant. The majority of patients with PE (83.33%) and those with GH (93.3%) did not experience PE before. Patients with mild PE comprised 17/30 (56.67%) of the studied PE patients, while those with severe PE comprised 13/30 (43.33%) of the total PE patients. Regarding blood pressure, preeclamptic patients showed higher systolic blood pressure (SBP) and diastolic blood pressure (DBP) (158.43 ± 18.9 mmHg and 96.17 ± 11.92 mmHg, respectively) than women with GH (139.4 ± 8.84 mmHg and 85.07 ± 3.63 mmHg, respectively) with highly significant differences (P < 0.001) as shown in [Table 1].
Table 1: Demographic and reproductive characteristics of the study populationAnemia was found in 4/30 (13.3%) of preeclamptic patients and in 8/30 (26.7%) of patients with GH. Regarding platelets count the proportion of patients with thrombocytopenia in PE was 7/30 (23.3%), while in GH, it was only 1 out of 30 (3.3%) [Table 2]. Normal ranges are shown in [Appendix 1] later on.
Table 2: Frequency of hematological parameters of the studied participants
There were no significant differences between the three groups regarding mean values of hemoglobin (Hb), white cell count (WBC), absolute neutrophil count (ANC), platelet count, PT, and PTT. Mean platelet volume (MPV) was significantly higher among PE patients but not in the GH group when compared with the control group as shown in [Table 3].
Table 3: Comparison of hematological parameters in control and two patients groupsThe mean plasma level of TM in PE patients was significantly higher than that of women with GH and healthy pregnant controls. Furthermore, the statistical analysis showed a significant difference between women with GH and healthy pregnant control as shown in [Figure 1].
Figure 1: Mean plasma level of TM in PE patients, women with GH and healthy pregnant women. TM = Thrombomodulin, PE = Preeclampsia, GH = Gestational hypertensionIn the context of discrimination between PE and controls, area under the curve (AUC) was 0.835 (95% confidence interval = 0.724–0.946), P < 0.001. The sensitivity and specificity of the test at the cutoff value of TM = 8593.9 pg/ml were 77% and 75%, respectively, as shown in [Figure 2].
Figure 2: ROC curve for TM in the context of discrimination between PE and healthy controls. ROC = Receiver operating characteristic, TM = Thrombomodulin, PE = Preeclampsia, AUC = Area under the curve, CI = Confidence intervalThere was a positive correlation between TM level and both SBP and DBP as displayed in [Table 4].
Table 4: Pearson=s correlation between thrombomodulin and other variables in preeclampsia patients and women with gestational hypertensionIn preeclamptic patients, the mean plasma level of TM was found to be higher in nulliparous women than in multiparous with a significant difference (P = 0.007). Furthermore, in preeclamptic patients, those with a history of previous abortion had higher mean plasma TM levels than those without a history of abortion with P = 0.018. Regarding severity, severe cases of PE demonstrated a higher level of mean TM than mild cases with a significant difference (P = 0.002) [Table 5].
Table 5: Association of thrombomodulin concentration with reproductive and clinical characteristics in preeclampsia patients and women with gestational hypertension (n=30) Discussion While there is evidence supporting the dysfunction of the vascular endothelium in PE, there has been little work on the role of the vascular endothelium in GH. There are many endothelial markers, but in our study, we chose to evaluate TM in both GH and PE.
Hb, WBC, ANC, platelet count, PT, and PTT were done to all patients included in this study and their mean values showed no significant differences from the control group. Anemia in the studied cases was found to be a less frequent finding in PE (13.3%) compared to control (25%) and GH (26.7%) groups. This is most appropriate with the consensus that PE is characterized by endothelial activation and plasma leakage into interstitial tissues to result in pathological edema and hemoconcentration.[6]
Thrombocytopenia may occasionally occur before other manifestations of PE, and thus PE must be considered in the differential diagnosis of isolated thrombocytopenia developing in the third trimester.[7] In the current study, low platelet count was seen in 23.3% of the studied preeclamptic patients and in 3.3% of cases with GH. However, the mean platelet count showed no significant difference between the three groups. While the latter was insignificant in the preeclamptic group in comparison to normotensive pregnant women, other parameters, namely MPV showed a significant difference between the two groups. MPV reflects the average size of platelets in circulation. It is considered a useful surrogate marker of platelet activation or reactivity.[8] In this study, MPV showed a significant increase in PE than in normotensive pregnant women, this strengthened the hypothesis that according to the pathophysiology of PE, endothelial activation leads to increased platelet aggregation which in turn leads to a decrease in the platelet count and accelerated production of new platelets in the circulation. This was similar to those of other studies[9],[10],[11] but disagreed with AlSheeha et al.[12] and Altınbas et al.[13] who observed no significant difference. The utility of MPV in predicting PE has been shown in several studies.[14],[15],[16],[17] Thus, it was suggested that the MPV can be used as a valuable marker in the diagnosis and prediction of PE as well as in the prognosis of the disease. However, in this study, for patients with GH, MPV was not significantly increased than in normotensive pregnant women. This result was consistent with that made by Valera et al.[18] while it was demonstrated to be increased in other studies done by Baser et al.[19] and by Akhila et al.[20]
The main parameter that was aimed to be assessed in this study is TM. In the current study, the mean TM level in preeclamptic patients was far significantly higher than that of healthy pregnant females. TM is released into circulation only after damage to the endothelial cells.[21] Such damage is supposed to be involved in the development of PE and this in no doubt confirms the findings of the present study. This result was similar to Prochazka et al. and Saposnik et al. studies which showed that TM level was increased in PE than in normotensive pregnant females,[22],[23] while this was not in line with Pottecher et al.[24] and Dusse et al.[25] studies which showed no statistically significant difference between those two groups. Moreover, in the present study, TM higher plasma levels were found in GH compared to normotensive pregnant women. This might indicate that vascular endothelial abnormalities are recognized to be a dominant process in GH, as also described in Nadar et al. study.[26] On the other hand, the mean TM was significantly higher in women with PE than in women with GH. This data further supports a widespread endothelial dysfunction associated with PE. Hsu et al.[27] reported that serum TM level was significantly higher in pregnant women with PE than in those with GH or normal blood pressure, but unlike this study, it was not significantly higher in patients with GH compared to normotensive pregnant women. Concerning the severity of PE, the mean TM level was significantly higher in severe preeclamptic pregnancies than in mild preeclamptic pregnancies, which validated that the plasma TM level is associated with the progression of the disease and that it seems to be a major contributor to the development of end-organ involvement in PE. This result was comparable with that of Dusse et al.[28] study.
Regarding gravidity and parity, there were no significant differences between preeclamptic patients and the control group which was similar to studies in Japan and Nigeria.[29],[30] However, in the preeclamptic group, those with elevated TM show a significant association with nulliparas and those who had previous abortions, this could explain the epidemiological link between PE and nulliparity.[31]
In both GH and PE, plasma TM was positively correlated with both systolic and DBPs. This showed that the level of TM is linked to the degree of endothelial dysfunction in hypertensive disorders of pregnancy, which could be upstream, in the pathogenesis of endothelial dysfunction, or downstream, as a consequence of endothelial dysfunction. Turner et al.[32] observed that the placental expression of TM was lowest in those preeclamptic women with the highest DBP, and Nadar et al. revealed that plasma TM was significantly correlated only with SBP.[26] The correlations of TM with Hb, WBC, ANC, platelets count, MPV, PT, and PTT were statistically insignificant (P > 0.05). These results were comparable to that reported by Hsu et al. study.[27] The current study demonstrated that plasma TM level can distinguish women with PE from healthy pregnant ones, at the third trimester with good sensitivity (77%) and specificity (75%) and with a high AUC that was statistically highly significant (AUC = 0.835, P < 0.001).
TM level can distinguish women with PE from healthy pregnant ones, at the third trimester with good sensitivity (77%) and specificity (75%) and with a high AUC that was statistically highly significant (AUC = 0.835, P < 0.001). Swellam et al.[33] displayed that TM level had receiver operating characteristic and AUC = 0.95, P < 0.001 at which sensitivity = 81.3% and specificity = 95.2%. However, in a study conducted by Dusse et al.,[28] the AUC was equal to 0.66 which was not statistically significant (P > 0.05) to discriminate between PE and normotensive pregnant women.
ConclusionPlasma TM estimation can reflect the severity of endothelial damage in hypertensive disorders of pregnancy which can be related to blood pressure levels. This marker might be used as a valuable prognostic marker in PE and may contribute for the complications associated with it. MPV is an easy accessible marker and it can be useful in diagnosing PE even in the absence of thrombocytopenia. Besides, plasma TM levels can distinguish women with PE from healthy pregnant ones at the third trimester with good sensitivity and specificity.
Acknowledgment
The authors would like to thank Al-Nahrain University/faculty of medicine particularly Department of Pathology and Forensic Medicine for the support during the work. Deep appreciation goes to the hematology laboratory staff of both Al-Imamein Al-Kadhimein Medical City and Baghdad Teaching Hospital for all facilities they performed throughout this work.
Financial support and sponsorship
Nil.
Conflicts of interest
There are no conflicts of interest.
References
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