Evaluation of hemoglobin and platelet levels in mild, moderate and severe preeclampsia

Objective

The aim of this study is to find out the relationship between the hemoglobin and platelet levels and the severity of preeclampsia.

Methods

One hundred and twenty seven cases of mild preeclampsia, 96 cases of moderate preeclampsia and 71 cases of severe preeclampsia diagnosed in our clinic between the years January 2004 and August 2007 were evaluated retrospectively. One hundred and eight healthy pregnant women with similar demographic features and gestational age and without the diagnosis of preeclampsia, gestational or chronic hypertension and proteinuria were included in the study as the control group. The age, gravida, parity, gestational age, hemoglobin and platelet levels, 1st and 5th minute Apgar score of the newborn and birth weight of cases were compared. Variance analysis was used for four group comparisons.

Results

The demographic characteristics of the cases evaluated in the study were similar. There was no difference between four groups for the hemoglobin levels (control group: 11,7±1,7, mild preeclampsia: 11,9±1,5, moderate preeclampsia: 12,1±1,6, severe preeclampsia: 12,2±1,7). The mean platelet level in the severe preeclampsia group was found to be lower than the other groups (p<0.05).

Conclusion

We found a relationship between platelet levels and the severity of preeclampsia.

Keywords

Preeclampsia, pathogenesis, platelet

Introduction

Preeclampsia is a syndrome characterized by hypertension and proteinuria developing after 20 weeks of gestation. It affects approximately 6–8% of all pregnancies, most often the primigravidas (1). It is one of the most important causes of maternal and fetal morbidity and mortality.
Many theories are proposed for the pathophysiology of preeclampsia. The formation of a uteroplacental vasculature insufficient to supply adequate blood to the developing fetus results in fetoplacental hypoxia, leading to imbalances in the release and metabolism of prostaglandins, endothelin, and nitric oxide by placental and extraplacental tissues. These as well as enhanced lipid peroxidation and other undefined factors contribute to the hypertension, platelet activation and systemic endothelial dysfunction characteristics of preeclampsia (2). Activation of coagulation system in small vessels and increased platelet aggregation is present in preeclampsia. It is clear that preeclampsia is one of the cause of maternal thrombocytopenia and the platelet count increases rapidly after the delivery. There are studies suggesting the storage of platelet in the areas with endothelial damage, as the cause of thrombocytopenia (3).
The aim of this study is to evaluate the relationship between the severity of preeclampsia and hemoglobin and platelet levels.

Methods

One hundred and twenty seven cases of mild preeclampsia, 96 cases of moderate preeclampsia and 71 cases of severe preeclampsia diagnosed in Obstetrics and Gynecology Clinic of Inonu University between the years January 2004 – August 2007 were evaluated retrospectively. Hellp Syndrome was present in 15 out of 71 severe preeclampsia cases. One hundred and eight healthy pregnant women with similar demographic features and gestational age and without the diagnosis of preeclampsia, gestational or chronic hypertension and proteinuria were included in the study as the control group. The cases with systolic blood pressure greater than 140 mmHg, diastolic blood pressure greater than 90 mmHg on two measurements taken 6 hours apart, or the cases with 30 mmHg increase in systolic blood pressure, 15 mmHg increase in diastolic blood pressure compared with the pre-pregnancy values, in association with proteinuria more than 300 mg in 24 hours urine were included in the mild preeclampsia group. The cases were accepted as mild preeclampsia if the the diastolic blood pressure was less than 100 mmHg and as moderate preeclampsia if the diastolic blood pressure was 110 mmHg. The cases with the following criteria are included in the severe preeclampsia group: •Blood pressure greater than 160/ 110 mmHg •Oliguria (<400 ml in 24 hours urine) •Headache, blurred vision, right epigastric- right upper quadrant pain •Pulmonary edema and cyanosis •>5 gr proteinuria in 24 hours urine or >+++ proteinuria in spot urine sample •Thrombocytopenia (<100.000/ mm3) •Abnormal liver function tests. 
These criteria were not present in cases with moderate preeclampsia. Age, gravida and parity, gestational age, hemoglobin and platelet values at the time of diagnosis, 1st and 5th minute Apgar scores and the birth weight of the cases were compared.
Statistical analyses were carried out by employing the Statistical Package for Social Sciences soft-ware10.0 for Windows package software (SPSS, Inc., Chicago, IL, USA). For the group comparison, variance analysis was used if the data was normally distributed and Kruskal-Wallis test was used if not. If the difference between the groups was found significant, Mann-Whitney U test was used to find out the groups creating the difference after the Benferroni correction was done. For two group comparison, student t test was used if the data was normally distributed and Mann-Whitney U test was used if not. The relationship between the two data was evaluated by ki square test. The p value <0.05 was accepted as significant.

Results

Demographic characteristics of the cases were similar. There were no difference between the four groups in respect to age, gravida and parity. The gestational age was significantly greater in mild preeclampsia cases (Table 1) (Table 2). While the mild preeclampsia cases were delivered mostly vaginally, the cesarean section rates increased with increasing severity of preeclampsia (p<0.05). The birth weight and the first and fifth minute Apgar scores were significantly lower in severe preeclampsia cases (p<0.05) (Table 2) (Table 3). There was no difference between the four groups in respect to hemoglobin values. The mean platelet values were lower in severe preeclampsia cases (p<0.05) (Table 1) (Table 2) (Figure 1).

Discussion

A transient mild thrombocytopenia is seen due to increased consumption during pregnancy. In a study aiming to find the reference values of hematological parameters in pregnancy, healthy pregnant women were compared with non pregnant women, and the hemoglobin values were found to be decreased through out the pregnancy, while the platelet values decreased in the third trimester (4). In another study comparing the platelet count and volume in 23 weeks healthy pregnant women and nonpregnant women, the platelet count and volume were found to be similar (5).
Thrombocytopenia is found in approximately 6, 6 to11, 6 % of pregnancies (6). The most common cause is gestational thrombocytopenia (7) and the second common cause is preeclampsia and eclampsia (8). It’s found that thrombocytopenia increases the severity of the primary disease it’s associated with and increases the risk of perinatal complications as placental abruption, preterm delivery, low Apgar score and stillbirth (7).
The pathogenesis of thrombocytopenia in preeclampsia is not clear, but it’s suggested that thrombocytopenia is due to endothelial damage and the peripheral consumption (9). It’s also found that in pregnancies complicated with preeclampsia, the life span of platelet is reduced to 3 to 5 days and the altered platelet membrane accelerates its aggregation and destruction (10).
Jaremo et al (11) found in a study that, platelet count decreases significantly in preeclampsia and the mean platelet volume increses in severe preeclampsia.
In a retrospective study conducted to determine whether changes in platelet counts precede the onset of preeclampsia, platelet counts were compared in preeclamptic and healthy pregnancies. Platelet counts during the first half of pregnancy, 3–6 weeks before delivery, and at the time of delivery were compared. In pregnant women who developed preeclampsia, mean platelet counts at 3–6 weeks before delivery was significantly lower, but within lower limit of normal range. Mean platelet counts at time of delivery were significantly lower in preeclamptic cases. According to this study, mild thrombocytopenia or subclinical thrombocytopenia (platelet counts at lower limit of normal range) during the second half of pregnancy precedes preeclampsia, so serial platelet counts in high-risk pregnant women is necessary to predict the development of preeclampsia (12). In another study, also subclinical thrombocytopenia is detected in preeclamptic cases with platelet count within normal range (13). Howarth et al (14) in a study conducted with 349 cases with normal pregnancy and 30 cases with preeclampsia, evaluated the platelet count and mean platelet volume and found the sensitivity as 90% and specificity as 83,3% for the prediction of preeclampsia development. Ahmet et al (15) also proposed that serial detection of platelet volume can be helpful in determining the cases with preeclampsia risk.
Studies evaluating the correlation between the severity of preeclampsia and the degree of thrombocytopenia, couldn’t find any relationship. Neiger et al (13) evaluated the platelet count in preeclamptic pregnancies and couldn’t find significant difference between the mild and severe preeclampsia. In 2005 Ceyhan et al (16) evaluated the hematological parameters in 56 preeclamptic and 43 healthy pregnancies, and again couldn’t find significant difference between mild and severe preeclampsia in respect to hemoglobin and platelet values.
In our study, the preeclamptic cases were evaluated under three groups as mild, moderate and severe preeclampsia. We evaluated the relationship between the hemoglobin and platelet values and the severity of preeclampsia. The hemoglobin values were not significantly different between the groups. It is known that, iron preparations are widely used during pregnancy and this can influence the hemoglobin values. The preeclampsia cases included in our study didn’t have regular prenatal visits so we have no idea about the iron usage during the pregnancy.
We found the platelet count significantly low in severe preeclampsia group. This result proposes a possible relationship between the platelet count and the severity of preeclampsia. We also found the birth weight and 1st and 5th minute Apgar scores lower in severe preeclampsia group. Early identification of the cases with preeclampsia risk is important for the management of both mother and the new born. Randomized controlled studies with more extensive series of samples are required.

Conclusion

We found a relationship between the platelet count and the severity of preeclampsia. Randomized controlled studies with more extensive series of samples are required to detect the relationship between the platelet count and the severity of preeclampsia.
 

References

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	File/Dsecription
	Figure 1 Platelet value of groups.
	Table 1. Demographic characteristics.
	Table 2. P values of the two group comparisons.
	Table 3. Neonatal results.