Some Haematological Parameters in Primary Hypertensive Subjects Attending a Tertiary Hospital in Nigeria ()
1. Introduction
As of 2014, approximately one billion adults or 22% of the population of the world have hypertension. It is slightly more frequent in men, in those of low socioeconomic status, and it becomes more common with age. It is common in high, medium, and low income countries [1] . In 2004, rates of high blood pressure were highest in Africa, (30% for both sexes) and lowest in the Americas (18% for both sexes). Rates also vary markedly within regions with rates as low as 3.4% (men) and 6.8% (women) in rural India and as high as 68.9% (men) and 72.5% (women) in Poland [2] Rates in Africa were about 45% in 2016 [3] .
Hypertension is a major global health problem and public health challenge, demanding a vast proportion of health care resources directly and indirectly because of its high and increasing prevalence and the concomitant risks of cardiovascular and kidney disease, disability, adjusted life years and mortality [2] . Various risk factors have been implicated in the development of hypertension, some of which include genetic, environmental, psychosocial and inflammatory factors [4] .
It has been hypothesized that increased adherence of the stimulated leukocytes to the vascular endothelium, causes capillary leukocytosis and subsequent increased vascular resistance; a raised WBC count may therefore indicate increased catecholamine levels or enhanced sympathetic nervous system activity, thus causing an increase in blood pressure and eventually resulting in sustained hypertension [5] . Recent reports suggest that people with hypertension have lower MCVs than subjects with normal blood pressure [6] . Haematocrit is a determinant of whole blood viscosity. Viscosity affects peripheral resistance to blood flow, and peripheral resistance affects blood pressure [7] . Most hypertensive patients exhibit increased blood viscosity compared with healthy controls [8] . There are indications that systolic blood pressure (SBP) and diastolic blood pressure (DBP) may increase with increasing haemoglobin (Hb) levels [9] . In previous research among haemodialysis patients, the administration of erythropoietin, an erythropoiesis-stimulating protein used for the treatment of anaemia, was related to an elevated blood pressure [10] . Formation of platelet plug (primary haemostasis) is associated with activation of the coagulation cascade with resultant fibrin deposition and linking. Normal platelets can respond to an abnormality on the vessel wall rather than to haemorrhage, resulting in inappropriate platelet adhesion/activation and thrombosis; the formation of a clot within an intact vessel which can lead to hypertension (secondary haemostasis) [11] .
The study is therefore aimed to evaluate some haematological parameters in primary hypertensive subjects attending a tertiary hospital in Nigeria.
2. Materials and Methods
2.1. Study Population
This research population were drawn from a group of subjects with primary hypertensive cases who have been on medications for 6 - 12 months period in University of Abuja Teaching Hospital, Nigeria’s Federal Capital Territory. The subjects were between 18 - 65 years of age.
2.2. Sample Size
A cross section of one hundred and thirteen (113) patients was assessed randomly for the presence of Hypertension.
The presence of Hypertension was evaluated using stethoscope and sphygmomanometer cuff.
Sample size was determined using the Leslie Kish formula (Kish, 1965).
where = n = sample size minimum
Z = 95% confidence interval = 1.96
p = proportion of the target population (8%) = 0.08
q = 1.0 − p = 0.92
d = degree of accuracy (95% interval) = 0.05%
2.3. Inclusion Criteria for Subjects
Samples were collected from Individuals with Hypertension attending Cardiology Clinic at the University of Abuja Teaching Hospital (UATH) Gwagwalada Abuja that willingly gave their consent.
The presence of the history of primary hypertension and elevated blood pressure is of ≥140/90 mmHg.
Not having any underlying causes and having no history of administration of anticoagulant therapy.
No history of chronic viral infection or liver diseases (HBV, HCV and HIV).
2.4. Exclusion Criteria for Subjects
Normotensive individuals who refused consent and also those without any Family history of Hypertension. Known cases of clotting and bleeding disorders, pregnant subjects and those suffering from hepatitis B and C, Tuberculosis, diabetes and HIV were excluded from the study.
2.5. Ethical Clearance
Ethical approval was obtained from University of Abuja Teaching Hospital (UATH) Ethical committee with approval number of UATH/HREC/PR/2019/023.
2.6. Research Protocol
Using aseptic precaution, 5 mls of blood were collected from each subject and dispensed into K3EDTA bottle for complete blood count. The samples were analyzed within six hours using MYTHIC22 five parts haematology analyzer (by PZ CORMAY).
2.7. Statistical Analysis
The data obtained were analyzed using SPSS software version 16. Comparisons of different means were done using independent students T-test and one-way analysis of variance (ANOVA).
3. Results
Table 1 was the comparison of some haematological parameters between hypertensive and normotensive subjects. Mean Cell Volume, Mean Cell Haemoglobin, Mean Cell Haemoglobin Concentration (Red cells indices) were significantly higher in hypertensive compared to normotensive (P < 0.05). Total White Blood Cell count was also higher in hypertensive than normotensive but not statistically significant (P > 0.05). However, Platelet counts, Red Blood Cell, Packed Cell Volume and Haemoglobin concentrationwere significantly lower in hypertensive subjects when compared with normotensive subjects (P < 0.05).
Table 2 was the Comparison of some haematological parameters in hypertensive and normotensive subjects in different gender. The platelets count, total white cell count, mean cell volume, mean cell haemoglobin concentration were significantly lower among male hypertensive subjects when compared with the females, while the mean cell haemoglobin, red blood cell count, packed cell volume and haemoglobin concentration were significantly higher (P < 0.001).
Table 3 was the comparison of some haematological parameters in hypertensive subjects in different age groups. When the haematological parameters were compared among the different age groups, they showed no significant difference (P > 0.05).
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Table 1. Comparison of some haematological parameters between hypertensive and normotensive subjects.
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Table 2. Comparison of some haematological parameters between hypertensive and normotensive subjects in different gender.
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Table 3. Comparison of some haematological parameters in hypertensive subjects in different age groups.
4. Discussion
Platelets and WBCs are essential parameters used in assessing thrombosis. The haematological indices reflect oxidative stress and inflammatory state that postulate as major mechanisms of hypertension and its vascular complication. In this study, the Mean Cell Volume, Mean Cell Haemoglobin, Mean Cell Haemoglobin Concentration (Red cells indices) were significantly higher in hypertensive compared to normotensive, total white blood cell count was also higher in hypertensive than normotensive but not statistically significant. However, Platelet counts, Red Blood Cell, Packed Cell Volume and Haemoglobin were significantly lower in hypertensive compared to normotensive. The same pattern was observed in comparison of haematological parameters in hypertensive and normotensive subjects in different gender however, there was no significant difference among different age groups.
The elevated total White Blood Cell count in hypertensive patient may be as a result of abnormal function of vascular system in those patients that may cause activation of cytokine system to renew the endothelial injury; involve in differentiation and proliferation of hematopoietic cell [12] . An increase in blood pressure occurs when activated and differentiated total white blood cell counts release additional cytokines thereby raising attachment of the stimulated leukocytes to the vascular endothelium; resulting to capillary leukocytosis and subsequent elevated vascular resistance [13] .
In this study the mean value for haemoglobin concentrations, Red Blood Cell and Packed Cell Volume were shown to be lower among hypertensive compared to normotensive subjects (P > 0.05). This could be attributed to the release of haemolysis, haemoglobin and arginase enzyme to circulation from erythrocytes. This free haemoglobin is a remover of nitric oxide that is produced in the endothelial cell that lines the blood vessels, which is important for relaxation of blood vessels while arginase enzyme reduces the substrate used for nitric oxide synthesis by conversion of arginine to ornithine, thereby reducing nitric oxide production [14] .
This is in agreement with previous studies where hypertension is a complication of haemolysis and associated with haemolytic anaemia [15] .
Our finding is also consistent with a previous report which indicated that haematological disorder was reported which may be a powerful signal of hypertensive end-organ damage, particularly kidney failure [16] [17] [18] . Precisely, low Haemoglobin levels causes anaemia and heart failure [19] .
In this study, Platelet counts were significantly lower in hypertensive compared to normotensive. This could be as result of endothelial dysfunction that leads to platelet activation and clot formation. This is in agreement with previous work where during hypertension, there is endothelial dysfunction which leads to platelet activation and clot formation causing platelets to be consumed, thereby reducing the platelet count [20] .
Furthermore, this study showed that Mean Cell Volume, Mean Cell Haemoglobin, Mean Cell Haemoglobin Concentration (Red cells indices) were significantly higher in hypertensive compared to normotensive subjects. The trend is comparable to the findings of Bamlaku et al. (2017) on a comparative cross- sectional study of some haematological parameters of hypertensive and normotensive individuals at the university of Gondar hospital, Northwest Ethiopia [21] .
5. Conclusion
Our findings show that hypertension may be associated with haematological derangement if not properly managed. Therefore, haematological parameters can be used to monitor the prognosis of the disease and manage hypertensive related complications. It is important to assess haematological parameters for hypertensive individuals which may help to prevent complications associated with haematological disorders. Anaemia is associated with higher cardiovascular risk, higher blood pressure values, and lower dipping status in hypertensive patients, and haemoglobin concentration should be monitored in hypertensive patients
Recommendations
Based on these findings, it is recommended that a drastic awareness/education on the dangers and need to check blood pressure more frequently be made. Also, red cell indices such as PCV, HB, MCV, MCH and MCHC are made routine tests during evaluation of hypertensive subjects.
Contribution to Knowledge
This research contributes to knowledge by exposing the frontiers of researchers to the knowledge that some haematological parameters (red cell indices) such as MCV, MCH and MCHC play significant roles in hypertension management.