The Egyptian Journal of Haematology

: 2020  |  Volume : 45  |  Issue : 2  |  Page : 111--114

Hyperhomocysteinemia is associated with deep vein thrombosis in Nigerian patients

Sunday P Ogundeji, Taiwo R Kotila, Foluke A Fasola 
 Department of Haematology, University of Ibadan/Univeristy College Hospital, Ibadan, Oyo State, Nigeria

Correspondence Address:
Sunday P Ogundeji
Department of Haematology, University of Ibadan/Univeristy College Hospital, Postal Code 200 PMB 3017 G.P.O, Ibadan, Oyo State


Background Hyperhomocysteinemia is a modifiable risk factor associated with deep venous thrombosis (DVT). Low serum concentrations of vitamin B12 and folate are modifiable causes of hyperhomocysteinemia. This study was carried out to determine the prevalence of hyperhomocysteinemia in Nigerian patients with DVT and also to assess the association of homocysteine with vitamin B12 and folate. Patients and methods A case–control study was carried out in which serum homocysteine, vitamin B12, and folate levels were measured in 45 Doppler ultrasound confirmed cases of DVT and 43 controls. Hyperhomocysteinemia was defined by serum levels more than 15.0 μmol/l, low serum folate less than 3 μg/l, and low serum vitamin B12 less than 160 ng/l. Results The prevalence of hyperhomocysteinemia in DVT patients was 20 (44.4%) compared with four (9.35%) in the control (P<0.001). The mean serum folate and vitamin B12 levels of DVT patients were 8.7±4.8 and 725±475, while that of the controls were 9.3±3.8 μg/l and 821±393 ng/l (P=0.51 and 0.36), respectively. There was no correlation between hyperhomocysteinemia and low vitamin B12 and folate levels. Conclusion Hyperhomocysteinemia may be a risk factor for DVT in the Nigerian population but may not be responsible for thrombosis in all cases. There was however no significant correlation between serum level of homocysteine and serum levels of vitamin B12 and folate in DVT patients. Therefore, larger sized sample studies should be carried out to investigate the relationship between hyperhomocysteinemia and related vitamins as well as genetic causes of hyperhomocysteinemia in DVT patients in our environment.

How to cite this article:
Ogundeji SP, Kotila TR, Fasola FA. Hyperhomocysteinemia is associated with deep vein thrombosis in Nigerian patients.Egypt J Haematol 2020;45:111-114

How to cite this URL:
Ogundeji SP, Kotila TR, Fasola FA. Hyperhomocysteinemia is associated with deep vein thrombosis in Nigerian patients. Egypt J Haematol [serial online] 2020 [cited 2023 Feb 1 ];45:111-114
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Full Text


Deep vein thrombosis (DVT) which is a component of venous thromboembolism (VTE) is an important preventable cause of mortality and morbidity worldwide, being the third most common vascular disease after myocardial infarction and ischemic stroke [1]. The prevalence of DVT in the African setting is estimated to be ∼350–450 per 100 000 persons per year and this prevalence is thought to be higher than that in the Caucasians [2]. The burden in our hospital is an average of 35.6 patients per year [3].

Identification and characterization of factors that contribute to the development of VTE is necessary to reduce the incidence of DVT. Some of the modifiable risk factors present with elevated serum total homocysteine levels can be corrected by vitamin supplementation [3]. Mild to moderate hyperhomocysteinemia, vitamin B12, and folate deficiencies are associated with increased risk of VTE but the causality and independence of these associations are still controversial [4-6]. Hyperhomocysteinemia could be due to a combination of inherited enzyme deficiencies of methionine synthesis and acquired disorders of folate and vitamin B12 metabolism or deficiency. The prevalence of hyperhomocysteinemia in cases of DVT has been extensively studied in the Western population but studies of its prevalence in the Nigerian population with DVT are scarce.

Therefore, this study was aimed at bridging the gap in knowledge by determining the serum levels of homocysteine, vitamin B12, and folate in DVT patients; and also to assess the association, if any, between serum levels of homocysteine, vitamin B12, folate, and DVT.

 Patients and methods

This is a case–control study conducted at the University College Hospital, Ibadan, Nigeria. The study protocol was conducted in accordance with the Helsinki Declaration for medical research involving human participants. Forty-five consecutive patients with clinical evidence and Doppler ultrasound confirmed DVT seen between January 2014 and May 2014 in the Department of Hematology were prospectively included in the study. Forty-three apparently healthy age-matched and sex-matched adult individuals without clinical evidence of DVT who gave informed consent were recruited as control.

The hospital was established in 1957 and it is located in the South Western part of Nigeria and has 964 beds with a total bed occupancy rate of 53–60%. Ibadan is a large cosmopolitan city with a population of 2 550 593 people according to the 2006 census.

DVT patients with associated renal failure and established risk factors for thrombosis, for example, a deficiency of protein C, protein S, or antithrombin III, resistance to activated protein C, pregnancy or recent childbirth or use of oral contraceptive pills, patients on folic acid and vitamin B12 were excluded from the study. Medical records of the 45 patients were reviewed and a structured questionnaire was used to record data obtained from the patients, patients case notes, and controls.

Blood samples were taken from fasting patients and control individuals into EDTA-containing tubes. The blood samples were placed on ice and were centrifuged within an hour of collection. Serum samples were frozen and kept at −60°C until analyses.

The biochemical analyses for homocysteine, vitamin B12, and folate were carried out using Axis Enzyme Immunoassay by Axis-Shield Diagnostic Ltd, Dundee, Scotland.

The homocysteine reference range was taken as 5–15 µmol/l while hyperhomocysteinemia was classified as moderate (15–30 μmol/l), intermediate (31–100 μmol/l), and severe (>100 μmol/l) [7]. Normal range for vitamin B12 was set between 160 and 900 ng/l while values less than 160 ng were considered low. Normal reference range for folate was taken to be between 3.1 and 15 µg/l and values less than 3.1 µg/l were considered low [8].

IBM SPSS 23 (IBM, Chicago, Illinois, USA) was used for the statistical analysis. Statistical significance level was set at a P value of less than or equal to 0.05.

Ethical clearance for the study was obtained from the Ethics Review Committee of UI/UCH, Ibadan and individual written consent was obtained from respondents. Privacy and confidentiality of the participants were guaranteed by the coding of the data to ensure anonymity of the participants.


The mean age of patients with DVT and controls were 57±17.9 years and 54.5±15.8 (P=0.98), respectively. The sex and clinical characteristics of the participants are summarized in [Table 1]. There was no observed difference in the sex and prevalence of being overweight/obesity between patients with DVT and control. However, hypertension and diabetes were more frequent in the patient group.{Table 1}

Mean total homocysteine levels and prevalence of hyperhomocysteinemia were significantly higher in DVT patients compared with controls ([Table 2]). The prevalence of hyperhomocysteinemia was 44.4 and 9.35% in DVT patients and controls, respectively (P<0.001). Mild hyperhomocysteinemia and intermediate hyperhomocysteinemia were found in 17 (85%) and three (15%) of the patients, respectively. Hyperhomocysteinemia was significantly associated with the development of DVT [odds ratio (OR)=3; 95% confidence interval (CI)=2.7–5.3]. None of the patients and control had severe hyperhomocysteinemia.{Table 2}

There was no significant difference in the mean serum levels of vitamin B12 and folate between the DVT patients and the control group. None of the control individuals had low folate compared with six of 45 (6.8%) DVT patients (P=0.013), while low vitamin B12 was seen in seven (15.6%) of the DVT patients compared with one (2.3%) of the controls (P=0.06).

No correlation was found between age, plasma vitamin B12 and folate levels and plasma homocysteine levels, respectively(r=0.016, P=0.916; r=−0.039, P=0.799; r=−o.0735, P=0.631).

There was no significant correlation between serum homocysteine and serum folate level (r=0.02, P=0.82) and serum vitamin B12 (r=0.02, P=0.85) as well as the age of the DVT patients (r=0.01, P=0.95). Hyperhomocysteinemia was found to be significantly associated with proximal DVT (P=0.037) but not with distal DVT, recurrent DVT (P=0.16), or whether DVT was unilateral or bilateral (P=0.41).


This study supports several documented evidence that hyperhomocysteinemia is associated with increased risk of developing DVT as 44% of our patients with DVT were observed to have hyperhomocysteinemia (OR=3; 95% CI=2.7–5.3). This finding is similar to what was reported by several studies which reported a prevalence of hyperhomocysteinemia in DVT patients that ranged from 25 to 65% [7],[9],[10]. Omar et al. [11] in a case–control study in Tunisia reported hyperhomocysteinemia prevalence of 34% in their cohort of patients (OR=8.82; 95% CI=3.96–19.6). Köktürk et al. [7] in Turkey reported a prevalence of 63%. However, Ravari et al. [12] found no significant difference in homocysteine levels between DVT patients and controls. This observation along with findings of other workers suggests that high homocysteine may be a risk factor for DVT [1],[13].

The mechanism of how hyperhomocysteine is linked to increased risk of thrombosis has been well studied [1],[5],[14]. Homocysteine-related damage to intimal cells has been attributed to oxidative stress, production of hydrogen peroxide and superoxide, inactivation of nitric oxide and inhibition of glutathione peroxidase activity and synthesis. By stimulating the procoagulant mechanisms or by inhibiting anticoagulant mechanism, Hcy exerts its effect on thrombus formation [15],[16].

Mild to moderate forms of hyperhomocysteinemia (fasting levels of tHcy between 15 and 100 µmol/l) are encountered in phenotypically normal participants with genetic defects of homocysteine metabolism, acquired conditions, or, more frequently, a combination of both. Genetic defects associated with moderate hyperhomocysteinemia such as heterozygosity for cystathionine-beta-synthase or methylenetetrahydrofolate reductase (MTHFR) deficiency cause an ∼50% reduction in activities of the corresponding enzymes, the cumulative prevalence of which in the general population is between 0.4 and 1.5% [15]. Unfortunately, the study did not assess for MTHFR polymorphism which is a limitation to this study. Another genetic defect that is associated with a 50% reduction of the enzymatic activity is characterized by the presence of a thermolabile mutant of MTHFR which is due to the homozygous C to T substitution at nucleotide 677 of the encoding gene, converting the codon for alanine to that for valine [17].

The most frequent cause of severe hyperhomocysteinemia (characterized by fasting levels of tHcy) in the plasma higher than 100 µmol/l is the homozygous deficiency of cystathionine-beta-synthase, which has a prevalence in the general population of approximately one in 335 000, varying between one in 65 000 (Ireland) and one in 900 000 (Japan) [18]. Approximately 5–10% of cases of severe hyperhomocysteinemia are caused by inherited defects of remethylation. None of the participants in this study had severe hyperhomocysteinemia. Homozygous deficiency of MTHFR, which catalyzes the reduction of methylenetetrahydrofolate to methyltetrahydrofolate, is the most common inherited defect of the remethylation pathway [19].

In this study, we did not establish any difference in the mean plasma vitamin B12 and folate levels between patients with DVT and controls. However, the higher prevalence of low plasma levels of vitamin B12 (P=0.06) and folate (P=0.013) for DVT patients than controls may explain the significantly higher mean serum homocysteine levels in patients. Furthermore, we established that low plasma folate was independently associated with increased risk of DVT (OR=2; 95% CI=1.6–2.6)], but a similar relationship was not found with vitamin B12 (OR=0.1). This, therefore, suggests that lower levels of these homocysteine-related vitamin (folic acid) may be associated with increased risk of thrombosis and as such dietary supplementation with these vitamins has the potential of reducing the risk of DVT in those patients with high homocysteine levels [20],[21].

The mainstay of treatment for hyperhomocysteinemia is folic acid, alone or in combination with cobalamin better to say vitamin B12 and vitamin B6 [13],[22]. Although the three vitamins often were administered in combination, folic acid has been shown to be the most effective agent in that it dramatically lowered the fasting plasma homocysteine when administered alone [6],[9],[23]. The VITRO (vitamins and thrombosis) trial, a randomized, placebo-controlled, clinical trial on the effects of vitamin supplementation on the risk of recurrent VTE in patients with mild or moderate hyperhomocysteinemia, showed a statistically nonsignificant decrease of 16% in the incidence of venous thrombosis in patients treated with vitamins compared with placebo [4]. However, it is not yet established whether adding dietary supplement can lower the increased risk of thrombosis associated with hyperhomocysteinemia [1],[22].Although DVT is a multifactorial disorder, our study established an etiological role for hyperhomocysteinemia in DVT but the relationship between hyperhomocysteinemia and folate and vitamin B12 levels needs further evaluation in the African population. The supplementation of vitamins particularly folic acid would be beneficial to patients who are at risk of DVT and also patients on treatment for DVT. Folate alternative (betaine, choline, N-acetylcysteine) therapy could be considered in patients with a higher risk for cancer [5].


Sunday P. Ogundeji conceived the study and acquired the data. All authors were involved with the design of the study, analysis, and interpretation of data. They were also involved in the drafting and revision of the article and have agreed to the final approval of the version to be published.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.


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