The role of uric acid in mineral bone disorders in chronic kidney disease

Changes in Bone Mineral Density in Patients With Non-dialysis-Dependent Chronic Kidney Disease Are Associated With Body Composition

OBJECTIVE

Chronic kidney disease (CKD) and low bone mineral density (BMD) are highly prevalent and can co-exist. Parameters of mineral metabolism are associated with BMD in CKD, but other contributing factors may contribute. The aim of this study was to assess changes in BMD and its determinants in patients with nondialysis-dependent CKD (NDD-CKD).

METHODS

Body composition and biochemical profiles were assessed in a retrospective hospital-based cohort study of patients with NDD-CKD. BMD, lean soft tissue (LST), appendicular LST (ALST), and percentage fat mass were assessed by dual-energy X-ray absorptiometry. The ALST index (ALSTI, ALST/height2) and load-capacity index (LCI, fat mass/LST) were calculated. Low BMD was defined as T-score ≤ -1.0.

RESULTS

The mean time between assessments was 2.8 ± 1.3 years; 46 patients were included. A reduction in renal function was observed. Changes in body composition included reductions in ALST (P = .031), ALSTI (P = .021), a trend for BMD (P = .053), and an increase in percentage fat mass (P = .044) and LCI (P = .032). Females had a reduction in BMD (P = .034), ALST (P = .026), and ALSTI (P = .037). Patients with low BMD at baseline had lower LST (P = .013), ALST (P = .023), and percentage fat mass (P = .037) than those with normal BMD. Additionally, reductions in LST (P = .041), ALST (P = .006), and ALSTI (P = .008) were observed in patients who had low BMD at baseline, while no significant changes in body composition were observed in those with normal BMD at baseline. The following body composition parameters at baseline were determinants of BMD status at follow-up: LST (odds ratio [OR]: 0.899, 95% confidence interval [CI]: 0.829-0.976, P = .010), ALST (OR: 0.825, 95% CI: 0.704-0.967, P = .017), and ALSTI (OR: 0.586, 95% CI: 0.354-0.968, P = .037), independent of fat mass and LCI.

CONCLUSIONS

Detrimental body composition changes were observed without changes in body weight; these were more significant in females. Moreover, this is the first longitudinal study showing a protective effect of LST against BMD loss in patients with NDD-CKD.

The relationship between uric acid and bone mineral density in the intermediate stage of CKD 1-3

BACKGROUND

Some studies have suggested that uric acid has antioxidant properties that can prevent bone loss, but the relationship between uric acid and bone mineral density is controversial. The aim of this study was to investigate the relationship between UA and BMD in patients with CKD stage 1-3.

METHODS

We extracted 13,047 participants from the NHANES database, including 7342 male subjects and 5705 female subjects. Weighted multiple linear regression analysis was used to investigate the correlation between UA and BMD in patients with CKD stages 1-3.

RESULTS

In patients with CKD stage 1-3, UA was significantly correlated with BMD. In the male group, UA was positively associated with BMD (β, 7.94 [95%CI, 4.95, 10.94]). In the female group, there was a negative relationship between them (β, -5.33 [95%CI, -8.77, -1.89]). The relationship between UA and BMD in male group showed an inverted U-shaped curve, and UA was positively correlated before 6.1 mg/dl and negatively correlated after 6.1 mg/dl. The relationship was basically negative in the female group.

CONCLUSIONS

For the patients with CKD stage 1-3, the relationship between UA and BMD showed an inverted U-shaped curve in the males, while the relationship was largely negative in the females.

Association of serum uric acid levels with bone mineral density and the presence of osteoporosis in Chinese patients with Parkinson's disease: a cross-sectional study

INTRODUCTION

As the population ages, the incidence of osteoporosis among patients suffering from Parkinson's disease (PD) will surge continually, and the ensuing disability from falls is becoming a serious social burden. Due to its antioxidant properties, much literature has indicated the possible ability of serum uric acid (UA) to prevent ageing-related diseases caused by oxidative stress, including osteoporosis and PD. Therefore, this study was for exploring the connection of serum UA levels with bone mineral density (BMD) and the osteoporosis presence in Chinese PD patients.

MATERIALS AND METHODS

A cross-sectional design was used to statistically analyze 42 clinical parameters obtained from 135 patients with PD treated in Wuhan Tongji Hospital during 2020-2022. Multiple stepwise linear regression and multiple logistic regression analyses were constructed for identifying the association of serum UA levels with BMD as well as osteoporosis in PD patients, respectively. With receiver operative characteristic (ROC) curves, the optimal cutoff value was acquired for serum UA in the diagnosis of osteoporosis.

RESULTS

According to the regression analysis adjusted for confounders, serum UA levels in PD patients had positive correlation with BMD at each site and negative correlation with the presence of osteoporosis (P < 0.05 for all). ROC curves determined that the optimal cutoff value for UA to perform well in diagnosing osteoporosis in PD patients was 284.27 μmol/L (P < 0.001).

CONCLUSION

Relatively higher serum UA levels in the physiological range can work as a biomarker of higher BMD, and were strongly linked to lower prevalence of osteoporosis in Chinese PD patients.

Uric acid plasma levels are associated with C-reactive protein concentrations and the extent of coronary artery lesions in patients with acute coronary syndromes

Many studies have pointed out that inflammation plays a pivotal role in pathophysiology of acute coronary syndromes (ACS) because several inflammatory molecules impair the endothelial functions in the coronary circulation and promote atherothrombotic events. Recently, many clinical/experimental evidences indicate that elevated plasma levels of uric acid (UA) might be considered a risk factor for developing ACS. It has been reported that elevated UA doses impair physiologic functions of endothelial cells, shifting them toward a pro atherothrombotic phenotype. In the present manuscript, we investigated the relationship between UA plasma levels, inflammatory burden, and extension of coronary atherosclerotic disease in patients with ACS. Patients with a clinical presentation of ACS (ST-elevated and non-ST-elevated myocardial infarction) admitted to the Vanvitelli Catheterization Laboratory at Monaldi Hospital in 2019, before the COVID-19 pandemia, were retrospectively analyzed. Biochemical profile, type of ACS presentation, as well as extension of coronary atherosclerosis were assessed. A total of 132 ACS patients were included in the analysis, and grouped into 3 tertiles according to the UA values (UA < 4.72 mg/dl, UA between 4.72 and 6.15 mg/dl, and UA > 6.15 mg/dl). Patients with UA plasma levels ≥ 6.15 mg/dL showed higher levels of C-reactive protein (mean of 5.1 mg/dL) as compared to patients with lower UA plasma levels. Moreover, the former group of patients showed higher levels of cardiac troponin and CPK, and presented more often with multivessel disease and complex coronary stenosis (type C of Ellis classification). Even though monocentric and with limited sample size, the present study shows that plasma levels of UA and hs-CRP are elevated in ACS patients and are associated with a more severe coronary disease, suggesting a potential role of UA in the pathophysiology of acute coronary events.

Uric Acid Induces a Proatherothrombotic Phenotype in Human Endothelial Cells by Imbalancing the Tissue Factor/Tissue Factor Pathway Inhibitor Pathway

BACKGROUND

 Several evidence show that elevated plasma levels of uric acid (UA) are associated with the increased risk of developing atherothrombotic cardiovascular events. Hyperuricemia is a risk factor for endothelial dysfunction (ED). ED is involved in the pathophysiology of atherothrombosis since dysfunctional cells lose their physiological, antithrombotic properties. We have investigated whether UA might promote ED by modulating the tissue factor (TF)/TF pathway inhibitor (TFPI) balance by finally changing the antithrombotic characteristics of endothelial cells.

METHODS

 Human umbilical vein endothelial cells were incubated with increasing doses of UA (up to 9 mg/dL). TF gene and protein expressions were evaluated by real-time polymerase chain reaction (PCR) and Western blot. Surface expression and procoagulant activity were assessed by FACS (fluorescence activated cell sorting) analysis and coagulation assay. The mRNA and protein levels of TFPI were measured by real-time PCR and Western blot. The roles of inflammasome and nuclear factor-κB (NF-κB) as possible mechanism(s) of action of the UA on TF/TFPI balance were also investigated.

RESULTS

 UA significantly increased TF gene and protein levels, surface expression, and procoagulant activity. In parallel, TFPI levels were significantly reduced. The NF-κB pathways appeared to be involved in modulating these phenomena. Additionally, inflammasome might also play a role.

CONCLUSION

 The present in vitro study shows that one of the mechanisms by which high levels of UA contribute to ED might be the imbalance between TF/TFPI levels in endothelial cells, shifting them to a nonphysiological, prothrombotic phenotype. These UA effects might hypothetically explain, at least in part, the relationship observed between elevated plasma levels of UA and cardiovascular events.

The relationship between uric acid and total femur bone mineral density in hypertensive and non-hypertensive populations

OBJECTIVE

This study aimed to explore the association between uric acid (UA) and total femur bone mineral density (BMD) in hypertensive and non-hypertensive groups.

METHODS

We conducted a cross-sectional study of 13,108 participants in the NHANES database, including 4,679 hypertensive and 8,429 non-hypertensive subjects. A weighted multiple linear regression analysis was conducted to explore the association between UA and total femur BMD.

RESULTS

In the hypertensive group, the relationship between UA and total femur BMD was positive [β, 3.02 (95% CI, -0.44 to 6.48), p = 0.0962). In the non-hypertensive group, the association was significantly positive [β, 5.64 (95% CI, 2.06-9.22), p = 0.0038]. In gender-stratified analysis, UA was analyzed as a continuous variable and a categorical variable (quartile). The significantly positive association was present in both the hypertensive male group [β, 5.10 (95% CI, 0.98-9.21), p for trend = 0.0042] and non-hypertensive male group [β, 10.63 (95% CI, 6.32-14.94), p for trend = 0.0001]. A smooth curve fitting showed that in the hypertensive male group, the relationship between UA and total femur BMD was an inverted U-shaped curve. In the hypertensive female group, the relationship was basically negative. In the non-hypertensive population, the relationship between UA and total femur BMD was an inverted U curve in both men and women.

CONCLUSION

In the hypertensive male group, the association between UA and total femur BMD was an inverted U-shaped curve. As to women, the relationship was basically negative. In the non-hypertensive group, the association between UA and total femur BMD was an inverted U-shaped curve in different genders.

The Role of Uric Acid in the Acute Myocardial Infarction: A Narrative Review

Increased serum uric acid (SUA) levels have been associated with various pathologic processes such as increased oxidative stress, inflammation, and endothelial dysfunction. Thus, it is not surprising that increased SUA is associated with various adverse outcomes including cardiovascular (CV) diseases. Recent epidemiological evidence suggests that increased SUA may be related to acute myocardial infarction (AMI). Accumulating data also showed that elevated UA has pathophysiological role in the development of AMI. However, there are also studies showing that SUA is not related to the risk of AMI. In this narrative review, we summarized the recent literature data regarding SUA and AMI after providing some background information for the association between UA and coronary artery disease. Future studies will show whether decreasing SUA levels is beneficial for outcomes related to AMI and the optimum SUA levels for best outcomes in CV diseases.

Hyperuricemia Is Associated with Left Ventricular Dysfunction and Inappropriate Left Ventricular Mass in Chronic Kidney Disease

Background. Hyperuricemia is common in patients with chronic kidney disease (CKD), and this may lead to poor cardiovascular (CV) outcomes. The aim of this cross-sectional study was to assess associations among serum uric acid (UA) and echocardiographic parameters, ankle-brachial index (ABI), and brachial-ankle pulse wave velocity (baPWV) in patients with CKD. Methods. A total of 418 patients with CKD were included. The echocardiographic measurements included left atrial diameter (LAD), left ventricular ejection fraction (LVEF) and the ratio of observed to predict left ventricular mass (LVM). ABI, baPWV and medical records were obtained. Results. Multivariable forward logistic regression analysis showed that a high UA level was significantly associated with LAD > 47 mm (odds ratio [OR], 1.329; p = 0.002), observed/predicted LVM > 128% (OR, 1.198; p = 0.008) and LVEF < 50% (OR, 1.316; p = 0.002). No significant associations were found between UA and ABI < 0.9 or baPWV > 1822 cm/s. Multivariate stepwise linear regression analysis showed that a high UA level correlated with high LAD (unstandardized coefficient β, 0.767; p < 0.001), high observed/predicted LVM (unstandardized coefficient β, 4.791; p < 0.001) and low LVEF (unstandardized coefficient β, −1.126; p = 0.001). No significant associations between UA and low ABI and high baPWV were found. Conclusion. A high serum UA level was associated with a high LAD, high observed/predicted LVM and low LVEF in the patients with CKD. A high serum UA level may be correlated with abnormal echocardiographic parameters in patients with stage 3–5 CKD.

Renal disorders in rheumatologic diseases: the spectrum is changing (part 2. Arthridides)

This review is devoted to rheumatologic diseases mainly characterized by different types of arthritis. They may involve also different organs, including the kidney, but renal disease is more frequently caused by the nephrotoxicity of drugs to relieve pain or to interfere with the pathophysiology of the underlying disease. Rheumatoid arthritis is the prototype of arthropathies. This autoimmune disease mainly attacks joints, tendons and ligaments but can also involve internal organs including the kidney. Psoriatic arthritis is a complex disease in which psoriasis, a chronic inflammatory disease, is associated with the development of peripheral arthritis or spondylitis. The disease or its treatment may lead to kidney complications. Gout is a form of inflammatory arthritis which is characterized by an increase in the serum uric acid deposits in and around the joints of the extremities, the so called tophi. The disease is often associated with a metabolic syndrome with diabetes, obesity, hypertension, and cardiovascular disease. Kidney injury is frequent. It may be caused by kidney stones, urinary tract obstruction, tubulointerstitial and vascular lesions leading to CKD and renal failure.

Uric acid in CKD: has the jury come to the verdict?

Epidemiological studies show that hyperuricemia independently predicts the development of chronic kidney disease (CKD) in individuals with normal kidney function both in the general population and in subjects with diabetes. As a matter of fact, an unfavorable role of uric acid may somewhat be harder to identify in the context of multiple risk factors and pathogenetic mechanisms typical of overt CKD such as proteinuria and high blood pressure. Although the discrepancy in clinical results could mean that urate lowering treatment does not provide a constant benefit in all patients with hyperuricemia and CKD, we believe that the inconsistency in the results from available meta-analysis is mainly due to inadequate sample size, short follow-up times and heterogeneity in study design characterizing the randomized controlled trials included in the analyses. Therefore, available data support the view that hyperuricemia has a damaging impact on kidney function, while preliminary evidence suggests that treatment of so-called asymptomatic hyperuricemia may be helpful to slow or delay the progression of chronic kidney.