Homocysteine and risk of developing hypertension in men

Homocysteine levels, H-Hypertension, and the MTHFR C677T genotypes: A complex interaction

Background and objectives

High homocysteine levels are associated with increased risk of hypertension and stroke. Homocysteine is metabolized by the methylenetetrahydrofolate reductase (MTHFR). We aimed to investigate the levels of homocysteine and their association with hypertension, stroke, and antihypertensive medication usage in patients with different MTHFR C677T genotypes.

Methods and results

Genotype frequency of MTHFR polymorphism was performed, and plasma homocysteine levels were measured in 2,640 adult Lebanese patients. Hypertension, history of stroke, and list of medications were documented, among other clinical and demographic parameters. The TT mutant genotype and the T mutant allele of MTHFR were more prevalent in hyperhomocysteinemia (HHcy) and H-hypertensive (H-HTN, defined as hypertension with hyperhomocysteinemia) patients when compared to non-HHcy subjects and non H-HTN patients respectively. Homocysteine levels were significantly higher in hypertensive patients specifically among those on diuretics. A higher level of homocysteine was found in hypertensive patients with the MTHFR T allele compared to patients carrying the C allele. Among the T allele carriers, the average plasma homocysteine level was 13.3 ± 0.193 μmol/L for hypertensive subjects compared to 11.9 ± 0.173 μmol/L (non-hypertensives). Furthermore, homocysteine levels significantly correlated with stroke risk in patients with the T alleles.

Conclusions

We found an association of homocysteine with hypertension, hypertensive medication, and stroke risk among patients with the MTHFR T allele and the TT genotype. The association of diuretics therapy with higher homocysteine levels calls for routine measurements and therapeutic control of homocysteine in patients on diuretic, to improve health-related outcomes.

The Relationship between Elevated Homocysteine and Metabolic Syndrome in a Community-Dwelling Middle-Aged and Elderly Population in Taiwan

(1) Background: Metabolic syndrome has become a serious health problem in society. Homocysteine is a biomarker for cardiovascular disease. We investigated the relationship between homocysteine levels and metabolic syndrome. (2) Methods: A total of 398 middle-aged and elderly individuals were included in our study. First, we divided the participants into two groups: the metabolic syndrome group and the nonmetabolic syndrome group. Second, according to tertiles of homocysteine levels from low to high, the participants were divided into first, second, and third groups. Pearson's correlation was then calculated for homocysteine levels and metabolic factors. Scatterplots are presented. Finally, the risk of metabolic syndrome in the second and third groups compared with the first group was assessed by multivariate logistic regression. (3) Results: In our study, the metabolic syndrome group had higher homocysteine levels, and the participants in the third group were more likely to have metabolic syndrome. Multivariate logistic regression revealed that the third group, which had the highest homocysteine level, was associated with metabolic syndrome with an odds ratio of 2.32 compared with the first group after adjusting for risk factors. (4) Conclusions: We concluded that high plasma homocysteine levels were independently associated with MetS in our study population.

Association of hypertension with infection and inflammation in a setting of disadvantage in rural India

We assessed the association of hypertension with markers of inflammation and infection in a rural and disadvantaged Indian population. In a case-control study, we age- and gender-matched 300 cases with hypertension to 300 controls without hypertension. Blood pressure was measured according to a strict protocol. We measured markers of inflammation and infection including serum high-sensitivity C-reactive protein (hs-CRP), blood lymphocyte count, serum homocysteine, tooth loss, overcrowding and exposure to fecal contamination. Multivariable conditional logistic regression was used to determine their association with hypertension. Median serum hs-CRP was 42% greater in cases than controls, while median serum homocysteine was 10% greater. In multivariable conditional logistic regression, elevated homocysteine (OR 1.75, 95% CI 1.09-2.82), greater lymphocyte count (OR 1.49, 95% CI 1.01-2.01) and exposure to fecal contamination, defined as a distance from the field used for toilet purposes to the household of ≤50 m (OR 2.38, 95% CI 1.07-5.29), were independently associated with hypertension in this rural population. In separate analyses for each gender, elevated hs-CRP (OR 2.62, 95% CI 1.04-6.58) was associated with hypertension in men, whereas edentulism (OR 4.75, 95% CI 1.62-13.96) was associated with greater odds of hypertension in women. Our findings demonstrate specific associations between hypertension and markers of inflammation and infection including hs-CRP, homocysteine, lymphocyte count, edentulism and exposure to fecal contamination. Thus, strategies aimed at reducing inflammation and infection may reduce the burden of hypertension in such settings of disadvantage in rural India.

Association between plasma levels of homocysteine, folate, and vitamin B12, and dietary folate intake and hypertension in a cross-sectional study

There are few studies examining the association between homocysteine (Hcy) level and the risk of hypertension with consideration for folate and vitamin B₁₂ as related to Hcy level. We simultaneously examined the associations of plasma levels of Hcy, folate, and vitamin B₁₂, and dietary folate intake with the prevalence of hypertension. Participants included 1046 men and 1033 women (mean age ± standard deviation: 56.0 ± 8.9 years) in the Japan Multi-Institutional Collaborative Cohort Study. Dietary folate intake was estimated using a validated food frequency questionnaire. Hypertension was defined based on measured blood pressure and use of antihypertensive medication. A total of 734 participants (35.3%) had hypertension. Multivariate-adjusted odds ratios of hypertension for the highest quartile group of Hcy were 2.36 (95% CI 1.41-3.96) in men and 1.86 (95% CI 1.11-3.11) in women, as compared with the lowest group (P for trend = 0.014 and 0.005, respectively). Dietary folate intake was not correlated with hypertension in both men and women (P for trend = 0.099 and 0.703, respectively). Plasma vitamin B₁₂ was positively associated with hypertension only in women (P for trend = 0.027). Plasma Hcy level was positively linked with hypertension after controlling for covariates, including folate and vitamin B₁₂.

Life-threatening course in coronavirus disease 2019 (COVID-19): Is there a link to methylenetetrahydrofolic acid reductase (MTHFR) polymorphism and hyperhomocysteinemia?

As the current COVID-19 pandemic develops and epidemiological data reveals differences in geographical spread as well as risk factors for developing a severe course of illness, hypotheses regarding possible underlying mechanisms need to be developed and tested. In our hypothesis, we explore the rational for a role of MTHFR polymorphism C677T as a possible explanation for differences in geographical and gender distribution in disease severity. We also discuss the role of the resulting hyper-homocysteinemia, its interaction with the C677T polymorphism and its influence on immune state as well as risk factors for severe disease. Finally, we consider possible dietary ways to influence the underlying pathomechanisms prophylactically and supportively.

C677T MTHFR Gene Polymorphism is Contributing Factor in Development of Renal Impairment in Young Hypertensive Patients

Homocysteine concentration affected by the activities of the enzymes methylene tetra-hyrdofolate reductase (MTHFR). Polymorphisms in MTHFR gene associated with an impairment of MTHFR activity. Hyperhomocysteinemia is a result of single nucleotide polymorphisms (SNPs) in MTHFR 677 C>T that can cause homocysteine levels in the blood to increase. The purpose of this study is to investigate the relationships between MTHFR C677T (rs1801133) gene polymorphism, changes in homocysteine concentrations and progress of renal impairment in young adult hypertensive patients. Two hundred young hypertensive patients (age 21-24 years) were involved in this study; they were classified into patients with and without renal impairment in addition to 200 age and sex matched healthy controls. All participants were submitted to laboratory investigations as assay of MTHFR gene polymorphism C677T (rs1801133) by PCR/RFLP, determination of lipid profile, homocysteine and folic acid concentrations in addition to urinary albumin creatinine ratio (UACR). The levels of both homocysteine and UACR in the TT genotype patients were higher than those in the CC genotype group. Individuals who carry the T allele were more risky to hypertension and progress to early renal impairment in young age compared with those carrying the C allele [OR 2.02 (1.33-3.08), P < 0.001]. Genetic variants of C677T MTHFR gene and hyperhomocysteinemia may be responsible for rapid progress of renal impairment in Egyptian young age hypertensive patients. TT genotype or T allele may be considered as a predisposing factor for both elevated Hcy levels and the development of renal impairment. This study believed that lowering of homocysteine level can reduce renal impairment of hypertensive patients.

Effect of Banxia Baizhu Tianma Tang for H-type hypertension: A protocol for a systematic review

BACKGROUND

H-type hypertension is a kind of cardiovascular disease that threatens human life and health seriously. Banxia Baizhu Tianma Tang (BBTT) has been used widely for H-type hypertension while its effective evidence is not clear. Hence, we provide a systematic review protocol to evaluate the efficacy and safety of BBTT in the treatment of H-type hypertension.

METHODS

Nine databases including Cochrane Library, PubMed, EMBASE, WOS, Medline, CNKI, WangFang, CBM, and VIP will be searched from their inception to October 2019. All randomized controlled trials (RCTs) of BBTT for H-type hypertension will be included. The language is limited to Chinese and English. The primary outcome measure will be the major adverse cardiac and cerebral events (MACCE). The entire process will include study selection, data extraction, assessment of bias risk, data synthesis. Data analysis will be performed using RevMan V.5.3.5 (The Cochrane Collaboration, Oxford, UK).

RESULTS

This study will evaluate the efficacy and safety of BBTT in the treatment of H-type hypertension from several aspects, including MACCE, blood pressure (BP), blood lipids, inflammation indicators and homocysteine (Hcy).

CONCLUSION

This systematic review will provide evidence for determining whether or not BBTT is an effective and safe intervention for H-type hypertension.

PROSPERO REGISTRATION NUMBER

PROSPERO CRD 42019131491.

Evidence on the causal link between homocysteine and hypertension from a meta-analysis of 40 173 individuals implementing Mendelian randomization

Numerous researchers have investigated the associations among methylenetetrahydrofolate reductase gene (MTHFR) C677T polymorphism, homocysteine (Hcy) concentration, and hypertension. However, the results are controversial. Thus, a meta-analysis implementing Mendelian randomization approach was conducted to examine the hypothesis that elevated Hcy concentration plausibly contributes to increased risk of hypertension. Based on several inclusion and exclusion criteria, eligible studies were selected to explore the correlation between MTHFR C677T and hypertension risk, MTHFR C677T and Hcy concentration in hypertension, and Hcy concentration and hypertension, and they were evaluated by odds ratios (ORs), effect size (ES), and standard mean difference with their corresponding 95% confidence intervals (95% CIs), respectively. Moreover, Mendelian randomization was implemented to evaluate the relationship between Hcy and hypertension. Consequently, 14 378 cases and 25 795 controls were involved in this study and the results showed that MTHFR C677T led to an elevated risk of hypertension (for T vs C: OR = 1.27, 95% CI = 1.17-1.37; for TT vs CC: OR = 1.53, 95% CI = 1.30-1.79). Additionally, in hypertensive subjects, the pooled Hcy concentration in individuals of TT genotype was 7.74 μmol/L (95% CI: 5.25-10.23) greater than that in individuals of CC genotype. Moreover, the pooled Hcy concentration in hypertensive was 0.69 μmol/L (95% CI: 0.50-0.87) greater than that in controls. The estimated causal OR associated with hypertension was 1.32 for 5 μmol/L Hcy increment. Via MTHFR C677T polymorphism, the findings in the present study demonstrated that there exists evidence on causal link between Hcy concentration and the risk of hypertension.

Association between homocysteine level and blood pressure traits among Tibetans: A cross-sectional study in China

Studies on hypertension (HTN) in Tibetans who live in high altitude areas are less and whether total homocysteine level (tHcy) is associated with blood pressure (BP) levels or HTN status in Tibetans is unknown.A total of 1486 Tibetans with complete information from a cross-sectional survey conducted in Lhasa Chengguan County of Tibet were included in this study. Demographic data, self-reported history of disease, and life styles were collected using a questionnaire. Blood tHcy, creatinine, fasting plasma-glucose, total cholesterol, triglycerides, and BP were measured with equipment.The median tHcy level of the whole population was 14.60 (13.17-16.50) μmol/L, and the prevalence of HTN was 26.99%. Regression models, adjusted for possible covariates, showed that an average increase of 1 lnHcy (log transformation of tHcy level) was associated with an increase of 3.78 mmHg of systolic BP (SBP, P = .011) and 3.02 mmHg of diastolic BP (DBP, P = .003). The prevalence of HTN, levels of SBP and DBP in the third (OR for HTN: 1.60, P = .026; β for SBP: 3.41, P = .004; β for DBP: 2.57, P = .002) and fourth (OR for HTN: 2.19, P < .001; β for SBP: 5.08, P < .001; β for DBP: 3.09, P < .001) quartile of tHcy level were higher than those in the first quartile.THcy is associated with BP levels and HTN status among Tibetans. Both HTN management and tHcy level should be paid more attention in Tibetans.

Association between plasma homocysteine and hypertension: Results from a cross-sectional and longitudinal analysis in Beijing's adult population from 2012 to 2017

Plasma homocysteine (Hcy) levels are associated with elevated blood pressure. However, the causal association between Hcy levels and the risk of hypertension remains ambiguous. Taking the study design effect into consideration, this study aimed to investigate this issue through a cross-sectional and longitudinal analysis. Data were obtained from the Beijing Health Management Cohort study, which conducted routine health check-ups from 2012 to 2017. Multivariate logistic regression was used for the cross-sectional analysis, and a quadratic inference function approach was performed for the longitudinal analysis. A total of 30 376 subjects (mean age = 50.0 years) were included in the cross-sectional analysis, and a subgroup of 3913 subjects without hypertension at baseline was included in the longitudinal analysis. After adjusting for potential confounders, the risk of hypertension increased with Hcy levels in the cross-sectional analysis using the traditional definition of hypertension (OR = 1.262, 95% CI: 1.155-1.378, Q2 vs Q1; OR = 1.458, 95% CI: 1.335-1.593, Q3 vs Q1; OR = 1.520, 95% CI: 1.388-1.664, Q4 vs Q1) and the 2017 hypertension definition (OR = 1.159, 95% CI: 1.067-1.259, Q2 vs Q1; OR = 1.328, 95% CI: 1.221-1.445, Q3 vs Q1; OR = 1.328, 95% CI: 1.217-1.449, Q4 vs Q1). The longitudinal analysis showed that hypertension risk increased in the third quartile of Hcy (OR = 1.268, 95% CI: 1.030-1.560, Q3 vs Q1). Elevated total plasma Hcy may be used as a predictive biomarker for hypertension. Attention should be paid to gender-specific mechanisms when issuing precise precautions.

Interactions of homocysteine and conventional predisposing factors on hypertension in Chinese adults

This study aimed to investigate whether conventional predisposing factors modify the associations of homocysteine with blood pressure levels and hypertension. A total of 2615 adults were recruited from Liaoning province. An elevated homocysteine level was significantly associated with increased hypertension risk and blood pressure (all P<.05). Interaction analyses showed that homocysteine acted synergistically with age, overweight/obesity, dyslipidemia, and family history of hypertension to affect hypertension risk, and the relative excess risk due to interaction was 1.21 (95% confidence interval, 0.07-2.35), 0.72 (95% confidence interval, 0.07-1.36), 0.45 (95% confidence interval, 0.06-0.85), and 1.87 (95% confidence interval, 0.77-2.97), respectively. Increases in blood pressure were higher in patients who were overweight/obese or had a family history of hypertension than in their counterparts (all Pinteraction <.05). This study provides some strong evidence for interactions of homocysteine with conventional predisposing factors on hypertension.

Associations of plasma homocysteine levels with peripheral systolic blood pressure and noninvasive central systolic blood pressure in a community-based Chinese population

Previous studies indicated that homocysteine (Hcy) is associated with higher peripheral systolic blood pressure (pSBP). There have been few data on the relationship between Hcy and central SBP (cSBP). A total of 4,364 Chinese subjects from the Shijingshan community in Beijing were included. cSBP and pSBP were measured with an Omron HEM-9000AI device. Subjects were 57.20 ± 8.9 years old, 37.9% were male. The median of Hcy was 11.96 μmol/L. The mean of cSBP and pSBP was 129.94 ± 18.03 mmHg and 133.25 ± 18.58 mmHg. lnHcy was associated with cSBP (adjusted β = 2.17, SE = 0.80, P = 0.007) and pSBP (adjusted β = 2.42, SE = 0.75, P = 0.001). With increasing Hcy, there were enhanced correlations of Hcy with pSBP and cSBP (p for trend between quartiles <0.01). Using Q1 for reference, the Q4 was associated with cSBP (adjusted β = 1.77, SE = 0.89, P = 0.047) and pSBP (adjusted β = 2.15, SE = 0.84, P = 0.011). The correlations were more significant in non-obese subjects than in obese subjects (cSBP: β = 4.30 vs 0.46, pSBP: β = 5.04 vs 1.18, P for interaction <0.001). Our study showed that Hcy was associated with higher cSBP and pSBP, especially in non-obese subjects.

Homocysteine levels and risk of essential hypertension: A meta-analysis of published epidemiological studies

BACKGROUND

Plasma homocysteine (Hcy) levels may be associated with essential hypertension (EH). However, the results of previous studies on this association are inconsistent.

METHODS

In this meta-analysis, we performed a systematic literature search of the Embase, PubMed, Cochrane Library, and Web of Science for the relevant articles dated up to March 2016. Pooled odds ratios (ORs) and corresponding 95% confidence intervals (CIs) were used to evaluate the estimates.

RESULTS

We included 11 studies with a total of 16,571 participants (4,830 EH cases). We found that elevated Hcy levels were associated with the risk of EH (pooled OR: 1.36, 95% CI: 1.02-1.80 in the random-effects model). However, subsequent subgroup analyses showed that elevated Hcy levels increased the EH risk in retrospective studies (OR: 1.82, 95% CI: 1.53-2.16; p < 0.001) and unadjusted studies (OR: 1.72, 95% CI: 1.43-2.07; p < 0.001), but not in perspective studies (OR: 0.99, 95% CI: 0.73-1.28; p = 0.939) and adjusted studies (OR: 1.21, 95% CI: 0.85-1.72; p = 0.297). No significant publication bias was found (p = 0.876 for Begg's test, p = 0.144 for Egger's test).

CONCLUSION

Plasma Hcy levels are associated with EH risk. However, our findings do not support a causal association between Hcy levels and EH.

Homocysteine and hydrogen sulfide in epigenetic, metabolic and microbiota related renovascular hypertension

Over the past several years, hydrogen sulfide (H₂S) has been shown to be an important player in a variety of physiological functions, including neuromodulation, vasodilation, oxidant regulation, inflammation, and angiogenesis. H₂S is synthesized primarily through metabolic processes from the amino acid cysteine and homocysteine in various organ systems including neuronal, cardiovascular, gastrointestinal, and kidney. Derangement of cysteine and homocysteine metabolism and clearance, particularly in the renal vasculature, leads to H₂S biosynthesis deregulation causing or contributing to existing high blood pressure. While a variety of environmental influences, such as diet can have an effect on H₂S regulation and function, genetic factors, and more recently epigenetics, also have a vital role in H₂S regulation and function, and therefore disease initiation and progression. In addition, new research into the role of gut microbiota in the development of hypertension has highlighted the need to further explore these microorganisms and how they influence the levels of H₂S throughout the body and possibly exploiting microbiota for use of hypertension treatment. In this review, we summarize recent advances in the field of hypertension research emphasizing renal contribution and how H₂S physiology can be exploited as a possible therapeutic strategy to ameliorate kidney dysfunction as well as to control blood pressure.

Interactions of hyperhomocysteinemia and T cell immunity in causation of hypertension

Although hyperhomocysteinemia (HHcy) is an independent risk factor for cardiovascular diseases (CVD), there is a debate on whether HHcy is a risk factor or just a biomarker. Interestingly, homocysteine lowering strategies in humans had very little effect on reducing the cardiovascular risk, as compared with animals; this may suggest heterogeneity in human population and epigenetic alterations. Moreover, there are only few studies that suggest the idea that HHcy contributes to CVD in the presence of other risk factors such as inflammation, a known risk factor for CVD. Elevated levels of homocysteine have been shown to contribute to inflammation. Here, we highlight possible relationships between homocysteine, T cell immunity, and hypertension, and summarize the evidence that suggested these factors act together in increasing the risk for CVD. In light of this new evidence, we further propose that there is a need for evaluation of the causes of HHcy, defective remethylation or defective transsulfuration, which may differentially modulate hypertension progression, not just the homocysteine levels.

Homocysteine as a risk factor for hypertension: a 2-year follow-up study

Homocysteine (Hcy) is regarded as a risk factor for hypertension, but research on the causal relationship between Hcy and hypertension is limited. In the present study, we prospectively tracked the blood pressure progression of a normotensive population with different Hcy levels over a 2-year period. The incidence of hypertension with increasing Hcy quartiles produced an approximately U-shaped curve, with significance in males. Compared with the third quartile, the risk of hypertension in the first and second quartiles was increased by 1.55 (95% confidence interval [CI] 1.154–2.081) fold and 1.501 (95% CI 1.119–2.013) fold, respectively, with the increase being more significant in males. In conclusion, Hcy is related to hypertension incidence with the results approximating an U-shaped curve. Low Hcy levels might also increase the risk of hypertension.

Investigation of homocysteine-pathway-related variants in essential hypertension

Hyperhomocysteinemia (hHcy) has been associated with an increased risk of cardiovascular disease and stroke. Essential hypertension (EH), a polygenic condition, has also been associated with increased risk of cardiovascular related disorders. To investigate the role of the homocysteine (Hcy) metabolism pathway in hypertension we conducted a case-control association study of Hcy pathway gene variants in a cohort of Caucasian hypertensives and age- and sex-matched normotensives. We genotyped two polymorphisms in the methylenetetrahydrofolate reductase gene (MTHFR C677T and MTHFR A1298C), one polymorphism in the methionine synthase reductase gene (MTRR A66G), and one polymorphism in the methylenetetrahydrofolate dehydrogenase 1 gene (MTHFD1 G1958A) and assessed their association with hypertension using chi-square analysis. We also performed a multifactor dimensionality reduction (MDR) analysis to investigate any potential epistatic interactions among the four polymorphisms and EH. None of the four polymorphisms was significantly associated with EH and although we found a moderate synergistic interaction between MTHFR A1298C and MTRR A66G, the association of the interaction model with EH was not statistically significant (P = 0.2367). Our findings therefore suggest no individual or interactive association between four prominent Hcy pathway markers and EH.

Insulin resistance explains the relationship between novel cardiovascular risk factors and hypertension. The Telde Study

BACKGROUND

Most studies describing an association between hypertension and an inflammatory/pro-thrombotic state do not assess insulin resistance.

AIM

To examine the association between hypertension and new cardiovascular risk factors when considering both classical risk factors and insulin resistance.

METHODS

In a population-based sample of 1030 subjects, clinical information and blood samples were obtained. Subjects were classified according to the presence or absence of hypertension, and insulin resistance was estimated using the homeostasis model of assessment (HOMA). To identify variables independently associated with hypertension, a four-model multiple logistic regression was performed: model 1 included novel risk factors (Plasminogen Activator Inhibitor- 1 [PAI-1], fibrinogen, von Willebrand Factor [vWF], lipoprotein(a), homocysteine and C-reactive Protein [CRP]); model 2, novel risk factors plus HOMA; model 3 included both classical (smoking, triglycerides, HDL cholesterol, total cholesterol, waist circumference and diabetes) and novel risk factors and model 4, model 3 plus HOMA. All were adjusted for age, BMI and gender and compared using Akaike's Information Criterion (AIC).

RESULTS

In model 1, only PAI-1, age and BMI showed association with hypertension.When HOMA and classical risk factors were also included, PAI-1 was replaced by triglyceride, smoking and diabetes. The lowest AIC value (best adjustment) was displayed by model 4, comprising all of the variables. Only age, BMI, HOMA and smoking remained significantly associated with hypertension.

CONCLUSIONS

The novel cardiovascular risk factors assessed do not add information as markers of hypertension when classical risk factors or insulin resistance are included in the evaluation.

Uric acid and insulin sensitivity and risk of incident hypertension

BACKGROUND

Uric acid, insulin sensitivity, and endothelial dysfunction may be important in the development of hypertension. Corresponding circulating biomarkers are associated with risk of hypertension, but because these factors may be interrelated, whether they independently affect risk is unknown.

METHODS

In 1496 women aged 32 to 52 years without hypertension at baseline, we prospectively analyzed the associations between fasting plasma levels of uric acid, insulin, triglycerides, the insulin sensitivity index, and 2 biomarkers associated with endothelial dysfunction (homocysteine and soluble intercellular adhesion molecule-1) and the odds of incident hypertension. Odds ratios were adjusted for standard risk factors and then for all biomarkers plus estimated glomerular filtration rate and total cholesterol level. Population-attributable risk was estimated for biomarkers significantly associated with hypertension.

RESULTS

All the biomarkers were associated with incident hypertension after adjustment for standard hypertension risk factors. However, after simultaneously controlling for all the biomarkers, estimated glomerular filtration rate, and total cholesterol level, only uric acid and insulin levels were independently associated with incident hypertension. Comparing the highest and lowest quartiles of uric acid levels, the odds ratio was 1.89 (95% confidence interval, 1.26-2.82). A similar comparison yielded an odds ratio of 2.03 (95% confidence interval, 1.35-3.05) for insulin levels. Using an estimated basal incidence rate of 14.6 per 1000 annually, 30.8% of all hypertension occurring in young women annually is associated with uric acid levels of 3.4 mg/dL or greater (to convert to micromoles per liter, multiply by 59.485). For insulin levels of 2.9 microIU/mL or greater (to convert to picomoles per liter, multiply by 6.945), this proportion is 24.2%.

CONCLUSIONS

Differences in uric acid and insulin levels robustly and substantially affect the risk of hypertension in young women. Measuring these biomarkers in clinical practice may identify higher-risk individuals.

Positive association between plasma homocysteine level and chronic kidney disease

BACKGROUND

Increasing experimental evidence, including recently developed animal models, supports a role for homocysteine in the development of chronic kidney disease (CKD). However, relatively few clinical/epidemiological studies have examined this hypothesis in humans. We examined the relationship between plasma homocysteine level and CKD in a population-based study of older Australians.

METHODS

Community-based study (1992-1994) among 2,609 individuals (58.6% women), aged 49-98 years, free of clinical cardiovascular disease in the Blue Mountains region, west of Sydney, Australia. The main outcome-of-interest was CKD (n = 461), defined as estimated glomerular filtration rate of <60 ml/min/1.73 m(2).

RESULTS

Higher plasma homocysteine levels were positively associated with CKD, independent of smoking, body mass index, diabetes mellitus, hypertension, cholesterol levels, and other confounders. The multivariable odds ratio (OR; 95% confidence intervals, CI) comparing quartile 4 of plasma homocysteine (>14 micromol/l) to quartile 1 (< or =9 micromol/l) was 10.44 (6.99-15.60), p-trend <0.0001. This association persisted in both men and women separately. The results were also consistent in subgroup analyses by categories of diabetes mellitus and hypertension.

CONCLUSIONS

Higher plasma homocysteine levels are associated with CKD in a community-based sample of older Australians. This association appeared to be independent of diabetes mellitus and hypertension.