Fibroblast growth factor-23 levels are associated with uric acid but not carotid intima media thickness in renal transplant recipients

Nutritional Predictors of Cardiovascular Risk in Patients after Kidney Transplantation-Pilot Study

Asymmetric dimethylarginine (ADMA) is a marker of endothelial damage. Research confirms the association of ADMA with an increased cardiovascular risk (CVR) among kidney transplant recipients (KTRs). Additionally, increased circulating levels of fibroblast growth factor 23 (FGF-23) are associated with pathological cardiac remodeling and vascular alterations. The aim of the study is the analysis of the relationship between ADMA, FGF-23, nutritional, biochemical parameters in healthy subjects and KTRs. 46 KTRs and 23 healthy volunteers at mean age of 50.8 ± 15.4 and 62.5 ± 10.7 years were enrolled. The anthropometric and biochemical parameters such as ADMA, FGF-23, albumin, prealbumin were assessed. Fat tissue mass among KTRs was 30.28 ± 9.73%, lean body mass 64.5 ± 14.8%. Overweight and obesity was presented by 65.2% of recipients. Albumin level was 38.54 ± 3.80 g/L, prealbumin 27.83 ± 7.30 mg/dL and were significantly lower than in the control (p < 0.05). Patients with ADMA > 0.66 µmol/L had a lower concentration of prealbumin, albumin and increased concentration of oxidized low density lipoprotein (oxLDL), high sensitive C-reactive protein (hsCRP) and FGF-23. FGF-23 was significantly higher in patients with higher hsCRP (p < 0.05). KTRs with elevated ADMA had a longer transplantation vintage, lower eGFR and higher albuminuria. Diabetes mellitus (DM) was associated with higher levels of ADMA and FGF-23. Even in stable KTRs a relationship between inflammatory state, nutritional status, graft function and endothelial dysfunction biomarkers was observed.

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.

Meta-analysis of the correlation between serum uric acid level and carotid intima-media thickness

Objective

Recently, increasing epidemiological evidence has shown that there is a correlation between serum uric acid level (SUA) and carotid intima-media thickness (CIMT). This paper explored the relationship between them through meta-analysis.

Methods

PubMed, Cochrane Library, EMBASE, Web of Science and Google Scholar were searched to obtain literature. The keywords used to retrieve the literature were carotid intima thickness, intima-media thickness, carotid atherosclerosis, carotid stenosis, carotid artery, uric acid, blood uric acid, and hyperuricaemia. The retrieval time was from the establishment of the database through July 2020. Stata15.0 and RevMan5.3 software were used for statistical analysis. The standardized mean difference (SMD) and 95% confidence interval (95% CI) were calculated by a random effect model to estimate the correlation. Publication bias was assessed using the Begg and Egger tests. The stability of these results was evaluated using sensitivity analyses.

Results

Fifteen studies were included with a total sample size of 11382, including 7597 participants in the high uric acid group and 3785 in the control group, on the basis of the inclusion and exclusion criteria. According to the evaluation of the JBI scale, the literature was of high quality. The average age ranged from 42 to 74. Meta-analysis showed that CIMT in the high uric acid group was significantly higher than that in the control group (SMD = 0.53, 95% CI: [0.38, 0.68]), and the difference was significant (z = 6.98, P < 0.00001). The heterogeneity among the 15 articles was obvious (I² = 89%, P < 0.00001). Subgroup analysis by disease status illustrated a positive relationship between SUA and CIMT in healthy people and people with diseases. SUA was shown to be positively correlated with CIMT in people aged 45–60 years and ≥60 years by subgroup analysis by age. SUA was also found to be positively correlated with CIMT in a population with BMI>24 kg/m² by subgroup analysis by BMI. In addition, subgroup analysis of other risk factors for CIMT, including TC, SBP, DBP, triglycerides, and LDL-C, all showed a positive correlation between SUA and CIMT.

Conclusions

There is a significant correlation between serum uric acid level and carotid intima-media thickness, and a high concentration of serum uric acid is related to carotid artery intima-media thickness.

Urine albumin and serum uric acid are important determinants of serum 25 hydroxyvitamin D level in pre-dialysis chronic kidney disease patients

Low serum 25 hydroxyvitamin D (25 OH D) is common among chronic kidney disease (CKD) patients. This cross-sectional study is looking for the different factors associated with serum 25 OH D among pre-dialysis CKD. 1624 adult stage 3–5 CKD patients were studied beside 200 normal control subjects. All candidates were tested for body mass index (BMI), estimated glomerular filtration rate (eGFR), calcium (Ca), phosphorus (P), parathormone (PTH), 25 OH D, albumin, and uric acid (UA), and urine albumin/creatinine ratio (ACR). Multivariate linear regression analysis was done to determine predictors of 25 OH D. 98.6% of CKD patients have inadequate level of 25 OH D vs 48% of normal subjects. Serum 25 OH D was significantly lower in CKD patients (mean ± S.D = 16.54 ± 5.8 vs 37.79 ± 3.58 ng/mL for CKD vs control group respectively, p < .001). Serum level of 25 OH D has significant positive correlation with Ca (r = 0.337, p < .001), and significant negative correlation with P, PTH, UA, and ACR (r = −0.440, −0. 679, −0.724, and −0.781respectively, p < .001 in all). The independent predictors of 25 OH D were Ca, P, UA, PTH, and ACR (R square = 0.7, β = −0.087, −0.226, −0.313, −0.253, and −0.33 respectively, p < .001 in all). In conclusion, pre-dialysis CKD patients frequently suffer low 25 OH D. Among the different abnormalities related to CKD, urine albumin excretion rate and UA are the most important predictors of 25 OH D in these patients.

Uremic Toxins and Clinical Outcomes: The Impact of Kidney Transplantation

Non-transplanted and transplanted patients with chronic kidney disease (CKD) differ in terms of mortality and the risk of clinical events. This difference is probably due to the difference of both traditional and non-traditional risk factors. Uremic retention solutes may constitute important non-traditional risk factors in this population. In the present review, we selected a set of uremic toxins that have been associated with harmful effects, and are an appealing target for adjuvant therapy in CKD. For each toxin reviewed here, relevant studies were selected and the relationship with hard clinical outcomes of uremic toxins were compared between non-transplanted CKD patients and transplanted patients taking into account the level of glomerular filtration rate in these two situations.

Effect of hydrochlorothiazide on serum uric acid concentration: a genome-wide association study

AIM

To recognize genetic associations of hydrochlorothiazide-induced change in serum uric acid (SUA) concentration.

PATIENTS & METHODS

We conducted a genome-wide association study on hydrochlorothiazide-induced change in SUA in 214 Finnish men from the GENRES study. Replication analyses were performed in 465 Finns from the LIFE study.

RESULTS

In GENRES, we identified 31 loci associated with hydrochlorothiazide-induced change in SUA at p < 5 × 10^-5. rs1002976 near VEGFC associated with the change in GENRES and in LIFE. rs950569 near BRINP3 associated with the change in SUA in GENRES and LIFE. The analysis of previously reported SNPs and candidate genes provided some proof for PADI4 and ABCC4.

CONCLUSION

We report genetic markers that may predict the increase in SUA concentration during thiazide treatment.

Associations of fibroblast growth factor 23 with urate metabolism in patients with chronic kidney disease

OBJECTIVE

In patients with preserved kidney function, a positive association of fibroblast growth factor 23 (FGF23) with serum uric acid (SUA) has been reported; however, the relationship in overall chronic kidney disease (CKD) patients has not been investigated. No report has examined the relationship between FGF23 and uric acid clearance (CUA). The aim of the present study was to determine whether FGF23 is independently associated with urate metabolism in patients with CKD stages 1-5.

MATERIALS AND METHODS

In this cross-sectional study, 537 CKD patients were enrolled. SUA, CUA, FGF23, parathyroid hormone (PTH), and 1,25-dihydroxyvitamin D (1,25(OH)2D) were measured. Multivariable linear regression analysis was applied to determine independent factors associated with SUA or CUA.

RESULTS

In all patients, both SUA and CUA were independently associated with male sex, use of diuretics, use of uric acid-lowering agents, estimated glomerular filtration rate, and log FGF23 (β=0.29, P<0.01 for SUA; β=-0.11, P<0.01 for CUA), but not with log PTH or log 1,25(OH)2D. Dyslipidemia and diabetes were also independent factors for SUA and CUA, respectively. In multivariable analyses by sex, log FGF23 was associated with SUA in both sexes (β=0.32, P<0.01 in males vs. β=0.20, P=0.02 in females). Conversely, log FGF23 was independently associated with CUA in males (β=-0.15, P<0.01), but not in females (β=-0.09, P=0.17).

CONCLUSIONS

FGF23 was independently associated with urate metabolism in this population of CKD patients. FGF23 might also have a stronger association with urate metabolism in males compared with females.

Phosphate and FGF-23 homeostasis after kidney transplantation

Dysregulated phosphate metabolism is a common consequence of chronic kidney disease, and is characterized by a high circulating level of fibroblast growth factor (FGF)-23, hyperparathyroidism, and hyperphosphataemia. Kidney transplantation can elicit specific alterations to phosphate metabolism that evolve over time, ranging from severe hypophosphataemia (<0.5 mmol/l) to hyperphosphataemia (>1.50 mmol/l) and high FGF-23 levels. The majority of renal transplant recipients develop hypophosphataemia during the first 3 months after transplantation as a consequence of relatively slow adaptation of FGF-23 and parathyroid hormone levels to restored renal function, and the influence of immunosuppressive drugs. By 3-12 months after transplantation, phosphate homeostasis is at least partially restored in the majority of recipients, which is paralleled by a substantially reduced risk of cardiovascular-associated morbidity and mortality compared with the pre-transplantation setting. Many renal transplant recipients, however, exhibit persistent abnormalities in phosphate homeostasis, which is often due to multifactorial causes, and may contribute to adverse outcomes on the cardiovascular system, kidney, and bone. Dietary and pharmacologic interventions might improve phosphate homeostasis in renal transplant recipients, but additional insight into the pathophysiology of transplantation-associated abnormalities in phosphate homeostasis is needed to further optimize disease management and improve prognosis for renal transplant recipients.

FGF-23 levels in patients with critical carotid artery stenosis

The aim of this study was to evaluate fibroblast growth factor (FGF)-23 serum levels and its tissue expression in patients with critical carotid artery stenosis (CAS). We selected 35 patients with critical CAS undergoing carotid thromboendoarterectomy. In each patient, FGF-23 serum levels were evaluated just prior to the surgery (t0) and 30 min (t1) thereafter. Moreover, macrophage cytokines were measured at baselines. Carotid artery specimens were used for immune histochemistry. On the basis of the histology, the patients were divided into 2 groups: A with complicated plaque and B with uncomplicated plaque. Twenty complicated plaques (57.14%, group A,) and 15 uncomplicated (42.86%, group B) were evaluated: calcifications were present in 16/20 (80%) complicated plaques and in 6/15 (40%) uncomplicated plaques. An inflammatory infiltrate was observed in 26/35 carotid samples: 18/26 (69.23%) complicated and 8/26 (30.76%) uncomplicated. FGF-23(+) cells were present in 17/20 complicated (85%) and in 8 uncomplicated (53%) plaques. The double-staining immunofluorescence confirmed that macrophage cells (CD68(+)) were also positive for FGF-23 staining. Serum levels of FGF-23 were significantly higher in group A versus group B at t0 (p < 0.05) and t1 (p 0.0047). Moreover, in group A patients a significant increase of FGF-23 serum levels was observed at t1 in comparison with t0 (p 0.0011). Our results suggest that FGF-23 acts in the late phases of atherosclerotic disease and may potentially represent a marker of complications in critical CAS.