Hair magnesium, but not serum magnesium, is associated with left ventricular wall thickness in hemodialysis patients

BACKGROUND

Extracellular magnesium (Mg) accounts for approximately 1% of the total body Mg. Clinically, serum Mg concentration is measured, but it does not necessarily reflect total body Mg status. Although relationships have been reported between reduced Mg and cardiovascular disease in non-dialysis patients, there have been few such studies in hemodialysis patients. It was hypothesized that reduced Mg, as represented by lower Mg concentration in the hair, would be associated with echocardiographic parameters in chronic hemodialysis patients.

METHODS AND RESULTS

Hair Mg concentration was measured in 79 male hemodialysis patients using inductively coupled plasma mass spectrometry, and the relationships between hair Mg concentration and echocardiographic parameters were investigated. There was no significant correlation between Mg concentration in the hair and in serum. Hair Mg concentration in the patients with high-left ventricular mass index (LVMI) was significantly lower than that in the low-LVMI patients. Hair Mg concentration correlated significantly and negatively with posterior left ventricular wall thickness, interventricular septum thickness, left ventricular wall thickness (LVWT), and relative wall thickness. Serum Mg concentration, however, did not correlate with any of these echocardiographic parameters.

CONCLUSIONS

In hemodialysis patients, hair Mg concentration is a biomarker, independent of serum Mg concentration. Hair Mg, but not serum Mg, was significantly and negatively associated with LVWT. Reduced tissue Mg concentration, as measured in the hair, may be associated with left ventricular hypertrophy in hemodialysis patients.

Serum n-3 and n-6 polyunsaturated fatty acid profile as an independent predictor of cardiovascular events in hemodialysis patients

BACKGROUND

Unlike the n-6 polyunsaturated fatty acid (PUFA) arachidonic acid (AA), n-3-PUFAs such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) appear to have beneficial effects on inflammation, thrombosis, and cardiovascular disease (CVD). We examined possible alterations in serum PUFA profiles in patients on maintenance hemodialysis therapy and its association with CVD risk.

STUDY DESIGN

An observational study including cross-sectional and longitudinal analyses.

SETTING & PARTICIPANTS

Single-center study of 517 maintenance hemodialysis patients in an urban area in Japan.

PREDICTORS

Serum EPA, DHA, and AA concentrations and EPA:AA, DHA:AA, and (EPA+DHA):AA ratios.

OUTCOMES

CVD events, including ischemic heart disease, stroke, peripheral artery disease, pulmonary edema, and valve disease.

RESULTS

Hemodialysis patients showed lower (EPA+DHA):AA, EPA:AA, and DHA:AA ratios than 122 controls similar in age and sex. During follow-up, 190 CVD events were recorded. (EPA+DHA):AA ratio was not associated significantly with CVD in unadjusted analysis, but was associated significantly and inversely with CVD in Cox models adjusted for age and other confounding variables, with HRs in the range of 1.71-1.99 in the lowest versus highest quartile of (EPA+DHA):AA ratios. Similarly, EPA:AA and DHA:AA ratios showed inverse associations with CVD, whereas serum EPA, DHA, and AA concentrations were not predictive of CVD.

LIMITATIONS

No information for dietary intake, use of dietary supplements, or cell membrane PUFA content.

CONCLUSIONS

In hemodialysis patients, serum PUFA profile is unfavorably altered, and the low n-3-PUFA:AA ratios are independent predictors of CVD.

Decreased serum adrenal androgen dehydroepiandrosterone sulfate and mortality in hemodialysis patients

BACKGROUND

Endocrine and metabolic abnormalities may affect the survival of hemodialysis patients. Serum dehydroepiandrosterone sulfate (DHEA-S), an adrenal androgen with anabolic properties, is known to be lowered in ill patients and predicts poor outcome in the general population and in those with cardiac disease. The aims of this study were to examine a possible change in the DHEA-S level in dialysis patients and its association with survival in this population.

METHODS

This was an observational cohort study in 494 prevalent hemodialysis patients (313 men and 181 women) in urban area of Osaka, Japan. The main exposure was the baseline DHEA-S level in December 2004 and the key outcome was all-cause mortality during the subsequent 5 years. Also, DHEA-S levels were compared between the hemodialysis patients and 122 matched healthy controls.

RESULTS

The median (inter-quartile range) DHEA-S levels were 771 (447-1351) and 414 (280-659) ng/mL for male and female dialysis patients, respectively, and these values were significantly lower by 40-53% than the healthy control levels. Among the hemodialysis patients, DHEA-S was lower in women, those with older age, pre-existing cardiovascular disease, lower serum albumin and higher C-reactive protein. During the follow-up, we recorded 101 deaths. A low DHEA-S level was a significant predictor of all-cause mortality independent of potential confounders in male, but not in female, hemodialysis patients.

CONCLUSIONS

The serum DHEA-S level is decreased in hemodialysis patients and associated with mortality in men. These results support the growing observational evidence that uremia-induced endocrine alterations including decreased sex hormones may be linked to adverse clinical outcomes.

Elemental concentrations in scalp hair, nutritional status and health-related quality of life in hemodialysis patients

Elemental concentrations in hair from hemodialysis (HD) patients have not been well investigated. We examined the relationships between the elemental concentrations in scalp hair and health-related quality of life (HRQOL) and nutritional status in HD patients. Twenty six elemental concentrations were measured in scalp hair samples from 60 male HD patients using inductively-coupled plasma mass spectrometry. To evaluate HRQOL, the Short Form 36 item health survey (SF36) was used. As indices of nutritional status, body mass index, serum parameters, and geriatric nutritional risk index (GNRI) were used. Phosphorus correlated positively with serum creatinine, blood urea nitrogen (BUN), GNRI and the physical domains of the SF36. Zinc correlated positively with serum creatinine, BUN and the physical domains of the SF36. Mercury and arsenic correlated positively with BUN. Cadmium correlated negatively with serum albumin, BUN and GNRI. Copper correlated positively with the physical domains of the SF36. Iodine correlated negatively with the physical domains of the SF36. Selenium correlated negatively with the mental domains of the SF36. In conclusion, phosphorus and zinc concentrations in scalp hair can be additional biomarkers of HRQOL and/or nutritional status in HD patients. Cadmium accumulation correlated with malnutrition. Iodine and selenium accumulation may adversely affect HRQOL. Further investigation is necessary to determine precisely how these elements affect these measures.

Trace elements in the hair of hemodialysis patients

Trace element disturbance is often observed in hemodialysis patients. While trace element concentrations have been reported in blood samples from hemodialysis patients, they have not been well investigated in scalp hair. In the present study, 22 trace elemental concentrations were measured by inductively coupled plasma-atomic emission spectrometry in the scalp hair of 80 male hemodialysis patients and compared with those of 100 healthy male subjects. In hemodialysis patients, the concentrations of beryllium, arsenic, magnesium, chromium, manganese, iron, selenium, molybdenum, iodine, vanadium, and cobalt were significantly higher than those in healthy subjects, while lead, mercury, copper, germanium, and bromine were significantly lower than those in the former group. No significant differences were observed for lithium, aluminum, cadmium, zinc, boron, or nickel. There were significant positive correlations between the duration of hemodialysis and the magnesium and manganese concentrations. There was a significant negative correlation between cadmium concentration and the duration of hemodialysis. There were significant positive correlations between dialysis efficacy (Kt/V) and magnesium, manganese, zinc, and selenium concentrations. In conclusion, trace element concentrations of the scalp hair are different between hemodialysis patients and healthy subjects. Essential trace elements, such as magnesium, manganese, zinc, and selenium, may be affected by the duration of hemodialysis and Kt/V.

Advanced glycation end products, carotid atherosclerosis, and circulating endothelial progenitor cells in patients with end-stage renal disease

Numbers of endothelial progenitor cells (EPCs) have been shown to be decreased in subjects with end-stage renal disease (ESRD), the mechanism of which remained poorly understood. In this study, mutual association among circulating EPC levels, carotid atherosclerosis, serum pentosidine, and skin autofluorescence, a recently established noninvasive measure of advanced glycation end products accumulation, was examined in 212 ESRD subjects undergoing hemodialysis. Numbers of circulating EPCs were measured as CD34+ CD133+ CD45(low) VEGFR2+ cells and progenitor cells as CD34+ CD133+ CD45(low) fraction by flow cytometry. Skin autofluorescence was assessed by the autofluorescence reader; and serum pentosidine, by enzyme-linked immunosorbent assay. Carotid atherosclerosis was determined as intimal-medial thickness (IMT) measured by ultrasound. Circulating EPCs were significantly and inversely correlated with skin autofluorescence in ESRD subjects (R = -0.216, P = .002), but not with serum pentosidine (R = -0.079, P = .25). Circulating EPCs tended to be inversely associated with IMT (R = -0.125, P = .069). Intimal-medial thickness was also tended to be correlated positively with skin autofluorescence (R = 0.133, P = .054) and significantly with serum pentosidine (R = 0.159, P = .019). Stepwise multiple regression analyses reveal that skin autofluorescence, but not serum pentosidine and IMT, was independently associated with low circulating EPCs. Of note, skin autofluorescence was also inversely and independently associated with circulating progenitor cells. Thus, tissue accumulated, but not circulating, advanced glycation end products may be a determinant of a decrease in circulating EPCs in ESRD subjects.

Serum C-reactive protein and thioredoxin levels in subjects with mildly reduced glomerular filtration rate

Background

Chronic kidney disease (CKD) is a newly recognized high-risk condition for cardiovascular disease (CVD), and previous studies reported the changes in inflammation and oxidative stress in advanced stages of CKD. We compared the levels of serum biomarkers for inflammation and oxidative stress between subjects with normal and mildly reduced glomerular filtration rate (GFR).

Methods

The subjects were 182 participants of a health check-up program including those with normal (≥ 90 mL/min/1.73 m², N = 79) and mildly reduced eGFR (60-89 mL/min/1.73 m², N = 103) which was calculated based on serum creatinine, age and sex. We excluded those with reduced eGFR < 60 mL/min/1.73 m². No one had proteinuria. We measured serum levels of C-reactive protein (CRP) and thioredoxin (TRX) as the markers of inflammation and oxidative stress, respectively.

Results

As compared with subjects with normal eGFR, those with mildly reduced eGFR had increased levels of both CRP and TRX. Also, eGFR was inversely correlated with these biomarkers. The associations of eGFR with these biomarkers remained significant after adjustment for age and sex. When adjustment was done for eight possible confounders, CRP showed significant association with systolic blood pressure, high density lipoprotein cholesterol (HDL-C) and non-HDL-C, whereas TRX was associated with sex significantly, and with eGFR and systolic blood pressure at borderline significance.

Conclusions

We showed the increased levels of CRP and TRX in subjects with mildly reduced eGFR. The eGFR-CRP link and the eGFR-TRX link appeared to be mediated, at least partly, by the alterations in blood pressure and plasma lipids in these subjects.

Skin autofluorescence, a marker for advanced glycation end product accumulation, is associated with arterial stiffness in patients with end-stage renal disease

Elevated cardiovascular mortality has been shown to be associated with increased arterial stiffness. However, the contribution of tissue accumulation of advanced glycation end products (AGEs) to increased arterial stiffness is unclear. We examined whether skin autofluorescence, a recently developed marker of tissue accumulation of AGEs, is associated with arterial stiffness in 120 Japanese patients with end-stage renal disease (ESRD) and 110 age- and sex-matched control subjects. The ESRD patients had significantly higher pulse wave velocity (PWV), a noninvasive measure of arterial stiffness, and skin autofluorescence than the control subjects. Skin autofluorescence was significantly associated with age in the group of all subjects (R(s) = 0.255, Spearman rank correlation test) and that of control subjects (R(s) = 0.493), but not in the group of ESRD subjects (R(s) = 0.046). The PWV was significantly and positively associated with skin autofluorescence in the group of all subjects (R(s) = 0.335), controls (R(s) = 0.246), and ESRD subjects (R(s) = 0.205). Multiple regression analyses showed that, in the group of all subjects, association of skin autofluorescence with PWV was significant even after adjustment for other covariates including the presence of ESRD and age. Moreover, for ESRD subjects, a significant association between skin autofluorescence and PWV was found, independent of age. Our findings demonstrate the potential usefulness of skin autofluorescence in people of color and demonstrate clinically for the first time the potential involvement of tissue accumulation of AGEs in the pathophysiology of arterial stiffness.

Low Circulating Endogenous Secretory Receptor for AGEs Predicts Cardiovascular Mortality in Patients With End-Stage Renal Disease

OBJECTIVE

Receptor for advanced glycation end-products (RAGE) is involved in diabetic vascular complications. We have recently shown that plasma endogenously secretory RAGE (esRAGE), an alternatively spliced form of RAGE, is closely associated with metabolic syndrome and atherosclerosis. Here, we evaluated if plasma esRAGE is a predictor of cardiovascular mortality in a cohort of 206 (171 nondiabetic) patients with end-stage renal diseases (ESRD).

METHODS AND RESULTS

The cohort was followed for a median of 111 months, and 74 deaths including 34 cardiovascular deaths were recorded. Plasma esRAGE was measured at baseline. Cumulative incidence of cardiovascular death by Kaplan-Meier estimation was significantly higher in subjects in the lowest tertile of plasma esRAGE than those in the middle or the highest tertile both in all and nondiabetic subjects alone. In all subjects, as compared with the lowest tertile of plasma esRAGE, the hazards ratios for the highest and middle tertile were 0.40 (95% CI, 0.18 to 0.89) and 0.26 (0.10 to 0.66), respectively. The higher risk for lower esRAGE was still significant even after adjusted either with body mass index, hypertension, dyslipidemia and vascular complications, but was confounded by age and diabetes.

CONCLUSIONS

Low circulating esRAGE is a predictor for cardiovascular mortality in ESRD patients.

Body fat mass and lean mass as predictors of survival in hemodialysis patients

A higher body mass index (BMI) is a predictor of better survival in hemodialysis patients, although the relative importance of body fat and lean mass has not been examined in the dialysis population. We performed an observational cohort study in 808 patients with end-stage renal disease on maintenance hemodialysis. At baseline, fat mass was measured by dual-energy X-ray absorptiometry and expressed as fat mass index (FMI; kg/m2). Lean mass index (LMI) was defined as BMI minus FMI. During the mean follow-up period of 53 months, 147 deaths, including 62 cardiovascular (CV) and 85 non-CV fatal events, were recorded. In univariate analysis, LMI was not significantly associated with CV or non-CV death, whereas a higher FMI was predictive of lower risk for non-CV death. Analyses with multivariate Cox models, which took other confounding variables as covariates, indicated the independent associations between a higher LMI and a lower risk of CV death, as well as between a higher FMI and a lower risk of non-CV death. These results indicate that increased fat mass and lean mass were both conditions associated with better outcomes in the dialysis population.

Non-high-density lipoprotein cholesterol (non-HDL-C) as a predictor of cardiovascular mortality in patients with end-stage renal disease

BACKGROUND

Patients with end-stage renal disease (ESRD) often show lipid abnormalities that may promote atherosclerosis. Although the standard lipid marker is low-density lipoprotein cholesterol (LDL-C) in official recommendations, the need of fasting blood sampling has prevented routine screening for plasma lipids in hemodialysis patients.

METHODS

We therefore evaluated the power of non-high-density lipoprotein cholesterol (non-HDL-C) in predialysis (non-fasting) serum as a predictor of cardiovascular mortality in a cohort of 525 hemodialysis patients.

RESULTS

During the mean follow-up of 64 months, 120 deaths, including 44 fatal cardiovascular events, occurred. Patients in the highest tertile of non-HDL-C (137 to 285 mg/dL) had a significantly higher risk for cardiovascular mortality (HR, 3.065; 95% CI, 1.357 to 6.925; P = 0.007) [correction] in a univariate Cox analysis. The association between non-HDL-C and cardiovascular mortality remained significant in multivariate Cox models, which included HDL-C, age, gender, duration of hemodialysis, blood pressure, presence of diabetes mellitus, serum albumin, C-reactive protein, and body mass index.

CONCLUSION

Non-HDL-C in predialysis serum was a significant and independent predictor of cardiovascular mortality in hemodialysis patients. Non-HDL-C may be a useful marker for risk assessment in routine practice, although predictive powers of this and the standard fasting LDL-C should be compared in future studies.

Diabetes mellitus, aortic stiffness, and cardiovascular mortality in end-stage renal disease

Cardiovascular mortality is elevated in patients with end-stage renal disease (ESRD), especially in those with diabetes mellitus. Although the higher cardiovascular death rate in diabetic ESRD patients may be the result of more advanced atherosclerotic changes of the arterial wall, this has not been documented previously. Aortic stiffness was compared between ESRD patients with and without diabetes, and the impact of aortic stiffness on cardiovascular mortality was examined in a prospective, observational cohort study. The cohort consisted of 265 ESRD patients on hemodialysis, including 50 diabetic patients studied between June 1992 and December 1998. At baseline, the diabetic ESRD patients had significantly higher aortic pulse wave velocity (PWV), a noninvasive measure of aortic stiffness, than the nondiabetic patients. During a mean follow-up period of 63 mo, 81 deaths, including 36 cardiovascular deaths, were recorded. Kaplan-Meier analysis revealed higher all-cause or cardiovascular mortality rates in the diabetic as compared with the nondiabetic patients and also in those with higher aortic PWV than those with lower aortic PWV. The effect of diabetes on cardiovascular death was significant in the Cox model, including age, years on hemodialysis, gender, smoking, C-reactive protein, hematocrit, and body mass index as covariates. However, when aortic PWV was included as a covariate, the impact of diabetes was no longer significant, whereas aortic PWV was a significant predictor. In a model including 13 covariates, aortic PWV remained a significant predictor for cardiovascular and overall mortality but not for non-cardiovascular death. These results demonstrate that the increased aortic stiffness of the ESRD patients with diabetes mellitus contributed to the higher all-cause and cardiovascular mortality rates.