Untitled Document

ORIGINAL ARTICLE

Year : 2020  |  Volume : 3 |  Issue : 2 |  Page : 1 |  DOI : https://DOI-10.46319/RJMAHS.2020.v03i02.001

 

Plateletcrit - An important indicator of hypertension induced organ damage
Swathy Shanker1, Niranjana Murthy B2
1 Postgraduate, 2 Professor & Head, Department of Pathology,
Sri Siddhartha Medical College & Research Centre, Tumakuru,
Sri Siddhartha Academy of Higher Education, Tumakuru.
DOI-10.46319/RJMAHS.2020.v03i02.001
Abstract
Background: Hypertension being a major health problem worldwide, has been found to result in end-organ damage. Hypertensive patients have deranged haematological parameters, which in turn have been studied to be the cause of this outcome. Previous studies have evaluated the increase in haematocrit and RBC count in hypertensive patients. Hypertension related organ damage has a positive correlation with platelet activation. Variation in values of platelet indices have been reported as indicators of hypertension induced organ damage. We aim to assess the haematological parameters of individuals with hypertension and to compare the results with the haematological parameters of normotensive individuals and also highlight the parameter which can give an indication of the extent of endothelial damage. Material and Methods: This retrospective study includes patients chosen from medical records who had presented to Department of General Medicine, Sri Siddhartha Medical College for a period of 2 months and met the criteria to be included in the hypertensive group. A total of 60 patients' records were collected. 60 normotensive individuals were also chosen similarly from medical records of patients admitted in department of medicine and surgery, Sri Siddhartha Medical College during the same time period. Complete blood count reports of the patients were analysed. Results: The mean values of most haematological parameters showed higher values among hypertensive subjects compared to the normotensive group, with the exception of Mean Corpuscular Volume (MCV) which showed no variation among the two groups. Conclusion: The role of plateletcrit as a significant parameter in analysis of hypertension is understood and combination of haematocrit with plateletcrit values would be a better indicator of hypertension induced organ damage.
Keywords: Plateletcrit (PCT), Hypertension (HT), Hematocrit (HCT)

Introduction
Hypertension, also known as high blood pressure, is defined as a systolic blood pressure greater than 140mmHg and a diastolic blood pressure of more than 90 mm Hg based on the average of two or more accurate blood pressure measurements taken during two or more visits.[1] According to American Heart Association Hypertension Guidelines, blood pressure is said to be elevated in patients systolic blood pressure 120-129mmHg and diastolic blood pressure more than 80mm Hg. Stage 1 of hypertension is defined as systolic blood pressure within the range of 130-139 mm Hg or diastolic blood pressure of 80-89 mmHg. Stage 2 of hypertension is defined by systolic pressure of more than or equal to 140 mmHg or diastolic pressure of more than or equal to 90 mmHg.[2]
Hypertension (HT), a major health problem affects around 25% of the adult population.[3] It is a significant risk factor for numerous cardiovascular as well as cerebrovascular events. These include including heart attack and stroke.[4] Hypertension also affects the renal system causing proteinuria, which is the earliest indicator of renal damage.[3] The effect of hypertension on platelets is said to be the causative factor for vital organ damage .The endothelial injury caused as a result of hypertension activates the coagulation system. Endothelial damage caused by hypertension is due to sheer stress. This in turn causes activation of the fibrinolytic pathway and coagulation pathway. When the coagulation cascade is activated, there is increased platelet activation to control the bleeding.
Hypertension related organ damage is caused, to a large extent, by platelet activation. During passage through an unaffected vessel, platelets retain their form and are inactive. Platelets adhere to collagen released from the sub endothelial tissue during the process of hypertension induced endothelial damage. Activated platelets with increased adherence are generally bigger in size and volume. These activated platelets are responsible for majority of the hypertension mediated organ damage. The activated platelets have dense granules which secrete eicosanoids like thromboxane A2 and B2, in turn increases the thrombotic activity.[5]
Cytokines including Interleukin-3 and Interleukin-6 play a significant role in the pathogenesis of ischemic stroke. These mediators are found to influence megakaryocyte ploidy inturn affecting the platelet size and producing more reactive platelets.[6]
Platelet indices include platelet count, mean platelet volume (MPV), plateletcrit (PCT) and platelet distribution width (PDW) which is calculated in routine blood counts. Reports of increase in MPV in patients with hypertension, diabetes mellitus, coronary artery disease and hyperlipidaemia have been published. Poorer cardiovascular outcome has been reported in patients with increased MPV. PCT was recently accepted to be an indicator of activation of platelets, and is found to increase in cardiovascular diseases.[7] PDW is also an indicator of platelet activation and is found to increase in acute coronary syndrome and rheumatological diseases.
Under physiologic conditions, to maintain a constant PCT value the rate of platelet production is continuously regulated to maintain a state of equilibrium. A decrease in platelet count results in the production of more immature platelets that are larger in size and thus an increase in MPV is noted.[8]
Although studies showing the positive correlation of hypertension with platelet indices have been published, a very little evidence of how reliable the indices can be in predicting the outcome of hypertension-induced organ damage is available. This study was taken to highlight the hematological parameter(s) that can be used as early indicators of hypertension induced organ damage.
Material and methods
This was a retrospective study conducted in Tumkur from March 2020 to April 2020. Data was collected from patient records from the medical records department. The study included records of patients who presented to department of medicine, Sri Siddhartha Medical College and hospital for a period of 2 months i.e. from March-April 2020. Patients records which met the criteria during the study period were  included in the hypertensive group. A total of 60 patients' records were collected. 60 normotensive individuals were also chosen similarly from medical records of patients admitted in  Department of medicine and surgery, Sri Siddhartha Medical College during the same time period.
Inclusion criteria- Complete medical history and drug history were taken from patients presenting with blood pressure more than 140/90 mmHg and these patients were included in the hypertensive group.
Patients with blood pressure equal to or less than 120/80mmHg and with no other comorbidities were included in the normotensive group.
Exclusion criteria-Patients with haematological malignancies, other malignancies that can lead to secondary hypertension, drug history of usage of anticoagulants, liver and renal dysfunction were excluded.
Data was entered in MS Excel 2010 and analysed using SPSS version 20, Student's t test was applied to draw a comparison between haematological indices and increase in blood pressure.
Results
60 patients with hypertension and 60 normal healthy individuals were part of this study (Table 1). The complete blood counts of all patients were evaluated. Haemoglobin values ranged from 10.5 to 13.2 g/dl with a mean of 11.9 g/dl in the hypertensive group and 11.1 g/dl in the healthy group. Total count was on the higher range for the hypertensive group ranging from 5000 to 9300cells/cumm with an average of 7690 cell/cumm. The healthy group showed an average value of 7050cells/cumm. Both groups showed a predominance of neutrophils in the differential count with an average of 62.6% for hypertensive patients and 64.3% for healthy patients.
Table 1: Number of subjects included in hypertensive and normotensive groups

 

Hypertensive group

Normotensive group

Number of male subjects

46(76.6%)

32(53.3%)

Number of female subjects

14(23.4%)

28(46.7%)

Total

60(100)

60(100)

The haematocrit value showed considerable variation ranging from 28.7% to 49.5%. An average value of 33.49% was observed in the hypertensive group whereas an average value of 31.60% was noted in the healthy group. There was thus a considerable increase in haematocrit value of hypertensive patients compared to normotensive patients. The RBC count was also found to show variation among the 2 groups. An average value of 4.0 million/µl was found in hypertensive patients and 3.73 million/µl in healthy group. MCV values in hypertensive patients ranged from 74.5fl to 110.1fl and showed a mean value of 83.4fl which was not of considerable difference compared to the mean value of 84.4fl in normotensive individuals.
Platelet indices showed major differences between the hypertensive group and normotensive group. Platelet count was found to be within normal limits for a majority of the hypertensive patients although a few showed thrombocytosis with a maximum platelet count of 4.1 lakhs/µl. Platelet count of normal healthy patients showed a mean of 2.1 lakhs with the platelet count of hypertensive patients at an average of 2.3 lakhs. Plateletcrit and mean platelet volume were considerably high in the hypertensive group. Plateletcrit value showed an average of 0.248% in the hypertensive patients with values ranging from 0.154% to 0.446%. This was high compared to the average value of 0.205% seen in the normal healthy patients. Mean platelet volume showed an average value 10.5fl which was higher compared to the average value of 9.43fl in the healthy individuals.
All results obtained from the study are tabulated in Table 2 and results were considered highly significant if p value was <0.01, and significant if p value was <0.05. Plateletcrit value above 0.250% could be taken as an indicator of early effects of hypertension and values above 0.300% could indicate effects of uncontrolled hypertension. The patient with the highest plateletcrit value of 0.446% showed a history of stroke 8 months back with previous history of uncontrolled hypertension. No permanent neurological damage was recorded although renal function tests showed derangement. Five hypertensive patients with plateletcrit above 0.300%, were diagnosed with mild proteinuria a month later on conducting routine blood and urine examinations, and one patient showed evidence of hypertensive retinopathy on fundoscopic examination. Four normotensive patients (one female, three male) with plateletcrit value above 0.190 presented to Medicine OPD 6 months later for routine examination and was found to have a systolic blood pressure of more than 135mmHg.
Table 2: The mean haematological values of the study


PARAMETERS

NORMOTENSIVE MEAN±SD

HYPERTENSIVE MEAN±SD

T
VALUE

P VALUE

SIGNIFICANCE

HEMOGLOBIN
(g/dl)

11.1±0.81

11.9±0.79

5.64

<0.01

HS

WBC COUNT(x103/µl)

7.05±1.05

7.69±0.99

3.43

<0.01

HS

HEMATOCRIT (%)

31.6±3.56

33.49±3.54

2.92

<0.01

HS

RBC COUNT
(million/µl)

3.73±0.34

4.01±0.31

4.55

<0.01

HS

MCV(fl)

84.4±3.76

83.4±5.76

1.13

>0.5

NS

PLATELET COUNT (lakhs/µl)

2.18±0.29

2.36±0.55

2.19

<0.05

S

PLATELETCRIT (%)

0.205±0.027

0.248±0.061

5.00

<0.01

HS

MPV(fl)

9.41±0.745

10.52±0.749

8.11

<0.01

HS

Discussion
In the present study, haemoglobin value was increased in the hypertensive group compared to normotensive groups. This finding is in agreement with few other studies9,10 but is in contradiction with a study conducted in São Paulo, Brazil.[11] Previous studies have also shown a positive correlation with systolic, diastolic and mean arterial pressure. Haematocrit values showed considerable variation between the hypertensive and normotensive group with the hypertensive group having a higher mean haematocrit value which is similar to Sangareddy and Ethiopia studies.[9,12] Studies have shown a positive correlation between haematocrit and MAP blood pressure, diastolic and systolic blood pressure in hypertensive patients. The reason behind this is that HCT is the causative factor for high blood viscosity in individuals with hypertension, which in turn leads to high peripheral resistance and hypertension.
The study showed a higher mean WBC count in hypertensive patients compared to normotensive individuals. Similar to this, a study conducted in 2017 showed a significantly higher median WBC count of 6900 cells/cumm compared to the median value of 5200 cells/cumm in the normotensive individuals.[9] This finding is also in agreement with other similar studies. [10] In contradiction to this study, a study conducted in Brazil showed a lower mean value of total WBC count in individuals with hypertension, when compared to the group of apparently healthy normotensive individuals, but could not demonstrate a significant association.[11]
The RBC count of hypertensive patients in this study showed slight variation from the normotensive individuals with a mean value of 4.0 million cells in hypertensive patients and a mean value of 3.73 million cells in normotensive individuals. This was similar to other studies published. [9, 11, 12, 13]  The possible mechanism of the association between RBC and blood pressure is unknown although it can be attributed to the increased level of stem cell factor.
In the present study, MCV values in hypertensive individuals showed no significant variation when compared to normotensive individuals.This is in agreement with studies done in São Paulo, Brazil, and in Saudi Arabia, which showed MCV values to be similar in both groups.[10, 11]  But other studies in these parameters showed contradictions of results. A study conducted in 2015 showed a significant decrease in MCV values[9] similar to a study conducted in France which showed that MCV is lower by 2% in hypertensive patients[13]. Study done by Bamlaku Enawgaw et al showed increased MCV in hypertensive groups.[12]
A considerable variation in the platelet indices among hypertensive and normotensive individuals were noted. Platelet count was increased in our study in the group of hypertensive individuals. Increase in blood pressure causes damage to the endothelium. This results in an increase in platelet activation which leads to an increase in values of MPV, PDW and platelet count. A significant increase was found in MPV and PCT values in hypertensive groups compared to normotensive groups. This finding is in agreement with the findings of other studies. [9, 10, 13, 14]
Numerous studies have reported that an increase in MPV levels is linked to overall vascular mortality. Increase in MPV indicates the presence of more activated platelets in circulation. Currently, it has been proven that platelet indices (including MPV and PCT) have a positive correlation with vascular risk factors and can be used as a prognostic indicator of acute ischemic stroke. Findings of Akpinar et al. revealed that PCT is a more predictor of cardiovascular diseases compared to other platelet indices.[15]


Conclusion
Plateletcrit and mean platelet volume along with haematocrit could give a better understanding of hypertension induced organ damage while MCV showed no significant change.
Acknowledgement : Nil
Financial support and sponsorship: Nil
Conflict of interest: Nil
References
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Address for Correspondence: Dr Niranjana Murthy B, Professor and Head, Department of Pathology, Sri Siddhartha Medical College, Tumkur Karnataka, India. Email: niranjana_dr@rediffmail.com

 


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