Fibroblast Growth Factor 23 and Mortality Among Prevalent Hemodialysis Patients in the Japan Dialysis Outcomes and Practice Patterns Study

PTH may predict early mortality in incident patients on hemodialysis: results from a large cohort

PURPOSE

Parathyroid hormone (PTH) is merit as a risk factor for mortality in patients with chronic kidney disease in prevalent hemodialysis patients in a U shape. Most studies, however, do not focus on incident patients and those who died within the first 90 days of therapy. We evaluated PTH as a risk factor for mortality in a large cohort population in Brazil.

METHODS

This is an observational cohort study that included 4317 adult patients who initiated hemodialysis between July 1st, 2012 and June 30, 2017. The main outcome was all-cause mortality. Fine-gray sub-distribution hazard models were used to evaluate survival in the presence of a competing event (kidney transplant).

RESULTS

Median PTH levels of 252 (118, 479) pg/mL. There were 331 deaths during the first 90 days of therapy (6.7%), 430 in a 1-year follow-up (10.7%) and 1282 (32%) during the 5-year study period. Deaths according to PTH < 150, 150-600 and > 600 pg/mL corresponded to 38.1%, 33.0% and 28.5%, respectively (p < 0.001). In an adjusted model, patients who started dialysis with PTH < 150 pg/mL had a higher mortality risk within the first 90 days, but not in 1 year and 5 years after starting dialysis. Analyses in a subset of patients with a repeated PTH in 1 year (N = 1954) showed that although persistent PTH low levels (< 150 pg/mL) at 1 year were significantly associated with all-cause mortality, this result was not sustained after multiple adjustments.

CONCLUSION

PTH < 150 pg/mL confers a high mortality risk in the first 90 days of dialysis. If this result reflects poor nutritional conditions, it deserves further investigations.

Roles of Parathyroid Hormone and Fibroblast Growth Factor 23 in Advanced Chronic Kidney Disease

Parathyroid hormone (PTH) and fibroblast growth factor 23 (FGF23) each play a central role in the pathogenesis of chronic kidney disease (CKD)-mineral and bone disorder. Levels of both hormones increase progressively in advanced CKD and can lead to damage in multiple organs. Secondary hyperparathyroidism (SHPT), characterized by parathyroid hyperplasia with increased PTH secretion, is associated with fractures and mortality. Emerging evidence suggests that these associations may be partially explained by PTH-induced browning of adipose tissue and increased energy expenditure. Observational studies suggest a survival benefit of PTHlowering therapy, and a recent study comparing parathyroidectomy and calcimimetics further suggests the importance of intensive PTH control. The mechanisms underlying the regulation of FGF23 secretion by osteocytes in response to phosphate load have been unclear, but recent experimental studies have identified glycerol-3-phosphate, a byproduct of glycolysis released by the kidney, as a key regulator of FGF23 production. Elevated FGF23 levels have been shown to be associated with mortality, and experimental data suggest off-target adverse effects of FGF23. However, the causal role of FGF23 in adverse outcomes in CKD patients remains to be established. Further studies are needed to determine whether intensive SHPT control improves clinical outcomes and whether treatment targeting FGF23 can improve patient outcomes.

Diabetes mellitus modifies the association between chronic kidney disease-mineral and bone disorder biomarkers and aortic stiffness in peritoneal dialysis patients

This study aimed to investigate the relationship of four chronic kidney disease-mineral and bone disorder (CKD-MBD) biomarkers, including intact parathyroid hormone (PTH), fibroblast growth factor 23 (FGF23), soluble klotho, and fetuin-A, with aortic stiffness in peritoneal dialysis (PD) patients, comparing those with and without diabetes mellitus (DM). A total of 213 patients (mean age 58 ± 14 years; 81 (38.0%) patients with DM) were enrolled. Their aortic pulse wave velocity (PWV) was measured using pressure applanation tonometry, while serum intact PTH, FGF23, α-klotho, and fetuin-A levels were measured using enzyme-linked immunosorbent assay. Overall, patients with DM had higher aortic PWV than those without (9.9 ± 1.8 vs. 8.6 ± 1.4 m/s, p < 0.001). Among the four CKD-MBD biomarkers, FGF23 levels were significantly lower in DM group (462 [127-1790] vs. 1237 [251-3120] pg/mL, p = 0.028) and log-FGF23 independently predicted aortic PWV in DM group (β: 0.61, 95% confidence interval: 0.06-1.16, p = 0.029 in DM group; β: 0.10, 95% confidence interval: - 0.24-0.45, p = 0.546 in nonDM group; interaction p = 0.016). In conclusion, the association between FGF23 and aortic PWV was significantly modified by DM status in PD patients.

FGF23 and klotho at the intersection of kidney and cardiovascular disease

Cardiovascular disease is the leading cause of death in patients with chronic kidney disease (CKD). As CKD progresses, CKD-specific risk factors, such as disordered mineral homeostasis, amplify traditional cardiovascular risk factors. Fibroblast growth factor 23 (FGF23) regulates mineral homeostasis by activating complexes of FGF receptors and transmembrane klotho co-receptors. A soluble form of klotho also acts as a 'portable' FGF23 co-receptor in tissues that do not express klotho. In progressive CKD, rising circulating FGF23 levels in combination with decreasing kidney expression of klotho results in klotho-independent effects of FGF23 on the heart that promote left ventricular hypertrophy, heart failure, atrial fibrillation and death. Emerging data suggest that soluble klotho might mitigate some of these effects via several candidate mechanisms. More research is needed to investigate FGF23 excess and klotho deficiency in specific cardiovascular complications of CKD, but the pathophysiological primacy of FGF23 excess versus klotho deficiency might never be precisely resolved, given the entangled feedback loops that they share. Therefore, randomized trials should prioritize clinical practicality over scientific certainty by targeting disordered mineral homeostasis holistically in an effort to improve cardiovascular outcomes in patients with CKD.

Fibroblast growth factor-23 and cardiovascular disease among prevalent hemodialysis patients focusing on residual kidney function

Background

In patients undergoing incident hemodialysis, increased fibroblast growth factor-23 (FGF-23) levels are associated with the development of cardiovascular disease (CVD), but the influence of residual kidney function (RFK) on this association is unclear. This study aimed to investigate the association between FGF-23 levels, RKF, and CVD in patients undergoing prevalent hemodialysis.

Methods

This cross-sectional and longitudinal observational study included 296 patients undergoing maintenance hemodialysis for at least three months who were followed up for a median of 44 months. RKF was defined as 24-h urine output >200 mL, left ventricular (LV) diastolic dysfunction as E/E' >15 on echocardiographic parameters. CVD was defined as hospitalization or emergency room visits due to cardiovascular causes, such as angina, myocardial infarction, or congestive heart failure.

Results

The median intact FGF-23 (iFGF-23) level was 423.8 pg/mL (interquartile range, 171-1,443). Patients with an FGF-23 level > 423.8 pg/mL significantly had a lower proportion of RKF (39.2% vs. 60.1%, P < 0.001) and a higher proportion of LV diastolic dysfunction (54. 1% vs. 29.1%, P < 0.001) than those with an iFGF-23 level ≤ 423.8 pg/mL. The odds ratio (OR) for LV diastolic dysfunction was significantly higher in patients with RFK (OR per one-unit increase in the natural log-transformed iFGF-23 levels, 1.80; 95% confidence interval [CI]: 1.11-2.93) than in patients without RKF (OR per one-unit increase in the natural log-transformed iFGF-23 levels: 1.42; 95% CI: 1.01-1.99) in multivariate analysis (p < 0.001). During the follow-up period, 55 patients experienced CVD. The hazard ratio (HR) for CVD development was also significantly higher in patients with RKF (HR per one-unit increase in the natural log-transformed iFGF-23 levels, 2.64; 95% CI: 1.29-5.40) than those without RKF (HR per one-unit increase in the natural log-transformed iFGF-23 levels: 1.44; 95% CI: 1.04-1.99) in multivariate analysis (p = 0.05).

Conclusions

Increased iFGF-23 levels were associated with LV diastolic dysfunction and CVD development in patients undergoing prevalent hemodialysis; however, the loss of RKF attenuated the magnitude of these associations. Therefore, in these patients, RKF strongly influenced the detrimental role of iFGF-23 in the development of CVD.

Roles of PTH and FGF23 in kidney failure: a focus on nonclassical effects

Parathyroid hormone (PTH) and fibroblast growth factor 23 (FGF23) each play a central role in the pathogenesis of chronic kidney disease-mineral and bone disorder (CKD-MBD). Both hormones increase as kidney function declines, presumably as a response to maintain normal phosphate balance, but when patients reach kidney failure, PTH and FGF23 fail to exert their phosphaturic effects, leading to hyperphosphatemia and further elevations in PTH and FGF23. In patients with kidney failure, the major target organ for PTH is the bone, but elevated PTH is also associated with mortality presumably through skeletal and nonskeletal mechanisms. Indeed, accumulated evidence suggests improved survival with PTH-lowering therapies, and a more recent study comparing parathyroidectomy and calcimimetic treatment further suggests a notion of "the lower, the better" for PTH control. Emerging data suggest that the link between SHPT and mortality could in part be explained by the action of PTH to induce adipose tissue browning and wasting. In the absence of a functioning kidney, the classical target organ for FGF23 is the parathyroid gland, but FGF23 loses its hormonal effect to suppress PTH secretion owing to the depressed expression of parathyroid Klotho. In this setting, experimental data suggest that FGF23 exerts adverse nontarget effects, but it remains to be confirmed whether FGF23 directly contributes to multiple organ injury in patients with kidney failure and whether targeting FGF23 can improve patient outcomes. Further efforts should be made to determine whether intensive control of SHPT improves clinical outcomes and whether nephrologists should aim at controlling FGF23 levels just as with PTH levels.

Biopsy-proven CKD etiology and outcomes: the Chronic Kidney Disease Japan Cohort (CKD-JAC) study

BACKGROUND

The Kidney Disease: Improving Global Outcomes guidelines advocate the cause-glomerular filtration rate (GFR)-albuminuria (CGA) classification for predicting outcomes. However, there is a dearth of data supporting the use of the cause of chronic kidney disease. This study aimed to address how to incorporate a prior biopsy-proven diagnosis in outcome prediction.

METHODS

We examined the association of biopsy-proven kidney disease diagnoses with kidney failure with replacement therapy (KFRT) and all-cause death before KFRT in patients with various biopsy-proven diagnoses (n = 778, analysis A) and patients with diabetes mellitus labeled with biopsy-proven diabetic nephropathy (DN), other biopsy-proven diseases and no biopsy (n = 1117, analysis B).

RESULTS

In analysis A, adding biopsy-proven diagnoses to the GFR-albuminuria (GA) classification improved the prediction of 8-year incidence of KFRT and all-cause death significantly regarding integrated discrimination improvement and net reclassification index. Fine-Gray (FG) models with KFRT as a competing event showed significantly higher subdistribution hazard ratios (SHRs) for all-cause death in nephrosclerosis {4.12 [95% confidence interval (CI) 1.11-15.2)], focal segmental glomerulosclerosis [3.77 (95% CI 1.09-13.1)]} and membranous nephropathy (MN) [2.91 (95% CI 1.02-8.30)] than in immunoglobulin A nephropathy (IgAN), while the Cox model failed to show significant associations. Crescentic glomerulonephritis had the highest risk of all-cause death [SHR 5.90 (95% CI 2.05-17.0)]. MN had a significantly lower risk of KFRT than IgAN [SHR 0.45 (95% CI 0.24-0.84)]. In analysis B, other biopsy-proven diseases had a lower risk of KFRT than biopsy-proven DN in the FG model, with death as a competing event [SHR 0.62 (95% CI 0.39-0.97)].

CONCLUSIONS

The CGA classification is of greater value in predicting outcomes than the GA classification.

The predictive value of bioimpedance-derived fluid parameters for cardiovascular events in patients undergoing hemodialysis

Background

It is becoming increasingly evident that the accurate assessment of fluid status is critical to ensure optimal care in patients undergoing hemodialysis (HD). Various fluid parameters, including overhydration (OH) and overhydration/extracellular water (OH/ECW%), which can be obtained using a bioimpedance spectroscopy device have been used to indicate the hydration status in such patients. This study aimed to explore the effect of these fluid parameters on cardiovascular events and determine which parameter was a better predictor of cardiovascular events (CVEs).

Methods

A total of 227 patients who underwent HD at the Hangzhou Hospital of Traditional Chinese Medicine were enrolled in this prospective study between December 2017 and August 2018. Clinical data were collected, and the fluid status of patients was assessed using a body composition monitor. The patients were followed up until December 2020. The primary outcomes were CVEs. The association between fluid parameters and CVEs was analyzed using Cox proportional hazards models. The areas under the curve (AUCs) of receiver operating characteristic analysis and improvement in the global chi-squared value were used to compare the predictive values of fluid parameters for CVEs.

Results

During a median follow-up of 31 months, 66 CVEs were recorded. The patients with a higher absolute hydration index (OH) and a relative hydration index (OH/ECW%) exhibited an increased risk of developing CVEs. After adjusting for confounding factors, both OH [hazard ratio (HR) 1.279 per L, 95% confidence interval (CI) 1.047–1.562; p = 0.016] and OH/ECW% (HR 1.061 per %, 95% CI 1.017–1.108; p = 0.006) were independently associated with CVEs. The predictive ability of the absolute hydration index was superior to the relative hydration index based on AUC calculations for CVEs. Furthermore, a greater change in χ² in predicting CVEs was noted for the absolute hydration index.

Conclusions

Both absolute hydration index and relative hydration index were found to be independent predictors of CVEs in univariate and multivariate analyses. Furthermore, the absolute hydration index had a better additive predictive value than the relative hydration index in predicting CVEs.

Association of the modified creatinine index with muscle strength and mortality in patients undergoing hemodialysis

Background

In the updated consensus, low muscle strength overtook the role of low muscle mass, and probable sarcopenia was diagnosed once low muscle strength was detected. Whether the modified creatinine index (mCI) could identify persons with probable sarcopenia who may be at risk of adverse outcomes remains unknown. We aimed to evaluate the association of the mCI with probable sarcopenia and mortality in patients undergoing hemodialysis.

Methods

In the cross-sectional study (n = 346), univariate and multivariable logistic regression analyses were performed to study the association of mCI with probable sarcopenia. Modified Quantitative Subjective Global Assessment (MQSGA) was used to evaluate the nutritional status. The performance of the mCI value for identifying probable sarcopenia was analyzed using receiver operating characteristic (ROC) curve analysis. The appropriate cutoff points were determined using Youden’s method. In the longitudinal cohort study composed of an independent hemodialysis cohort (n = 218), cox proportional regression models were used to evaluate crude and adjusted hazard ratios and 95% confidence intervals (CIs) of death by mCI and MQSGA.

Results

Cross-sectional results showed that after adjusting for confounders, the association of mCI with low muscle strength remained significant. The area under the curve (AUC) of the mCI to predict probable sarcopenia was 0.804 (95% CI, 0.744–0.863; p < 0.001) for men and 0.787 (95% CI, 0.711–0.864; p < 0.001) for women. The optimal mCI cutoff values were 21.07 mg/kg/d for men and 19.57 mg/kg/d for women, respectively. Longitudinal results showed that compared with those in the high mCI group, subjects in the low mCI group had a higher risk of death for all causes (adjusted HR, 2.51; 95% CI, 1.16–5.41; p = 0.019). Adding the mCI significantly improved the predictive accuracy for death with an increase in C-index from 0.785 to 0.805 (p = 0.026) and improved the net reclassification index (38.6%, p = 0.021), while adding MQSGA did not.

Conclusion

The mCI is a predictor of muscle strength and survival in hemodialysis patients, and is preferable to the MQSGA for predicting death. Assessment of mCI could provide additional predictive and prognostic information to sarcopenia.

High-Dose Intravenous Iron with Either Ferric Carboxymaltose or Ferric Derisomaltose: A Benefit-Risk Assessment

The intravenous iron formulations ferric carboxymaltose (FCM) and ferric derisomaltose (FDI) offer the possibility of administering a large amount of iron in one infusion. This results in faster correction of anemia and the formulations being better tolerated than oral iron formulations. This triad of logistic advantages, improved patient convenience, and fast correction of anemia explains the fact that intravenous iron formulations nowadays are frequently prescribed worldwide in the treatment of iron deficiency anemia. However, these formulations may result in hypophosphatemia by inducing a strong increase in active fibroblast growth factor-23 (FGF-23), a hormone that stimulates renal phosphate excretion. This effect is much more pronounced with FCM than with FDI, and therefore the risk of developing hypophosphatemia is remarkably higher with FCM than with FDI. Repeated use of FCM may result in severe osteomalacia, which is characterized by bone pain, Looser zones (pseudofractures), and low-trauma fractures. Intravenous iron preparations are also associated with other adverse effects, of which hypersensitivity reactions are the most important and are usually the result of a non-allergic complement activation on nanoparticles of free labile iron-Complement Activation-Related Pseudo-Allergy (CARPA). The risk on these hypersensitivity reactions can be reduced by choosing a slow infusion rate. Severe hypersensitivity reactions were reported in < 1% of prospective trials and the incidence seems comparable between the two formulations. A practical guideline has been developed based on baseline serum phosphate concentrations and predisposing risk factors, derived from published cases and risk factor analyses from trials, in order to establish the safe use of these formulations.

Contribution of phosphate and FGF23 to CKD progression

PURPOSE OF REVIEW

Progressive forms of chronic kidney disease (CKD) exhibit kidney inflammation and fibrosis that drive continued nephron loss; however, factors responsible for the development of these common pathologic features remain poorly defined. Recent investigations suggest pathways involved in maintaining urinary phosphate excretion in CKD may be contributing to kidney function decline. This review provides an update on recent evidence linking altered phosphate homeostasis to CKD progression.

RECENT FINDINGS

High dietary phosphate intake and increased serum concentrations of fibroblast growth factor 23 (FGF23) both increase urinary phosphate excretion and are associated with increased risk of kidney function decline. Recent investigations have discovered high concentrations of tubular phosphate promote phosphate-based nanocrystal formation that drives tubular injury, cyst formation, and fibrosis.

SUMMARY

Studies presented in this review highlight important scientific discoveries that have molded our current understanding of the contribution of altered phosphate homeostasis to CKD progression. The collective observations from these investigations implicate phosphaturia, and the resulting formation of phosphate-based crystals in tubular fluid, as unique risk factors for kidney function decline. Developing a better understanding of the relationship between tubular phosphate handling and kidney pathology could result in innovative strategies for improving kidney outcomes in patients with CKD.

Impact of etelcalcetide on fibroblast growth factor-23 and calciprotein particles in patients with secondary hyperparathyroidism undergoing hemodialysis

BACKGROUND

Recently, we demonstrated the efficacy of etelcalcetide in the control of secondary hyperparathyroidism (SHPT). This post hoc analysis aimed to evaluate changes in fibroblast growth factor-23 (FGF23) and calciprotein particles (CPPs) after treatment with calcimimetics.

METHODS

The DUET trial was a 12-week multicenter, open-label, parallel-group, randomized (1:1:1) study with patients treated with etelcalcetide plus active vitamin D (E+D group; n = 41), etelcalcetide plus oral calcium (E+Ca group; n = 41), or control (C group; n = 42) under maintenance hemodialysis. Serum levels of FGF23 and CPPs were measured at baseline, and 6 and 12 weeks after the start.

RESULTS

In the linear mixed model, serum levels of FGF23 in etelcalcetide users were significantly lower than those in non-users at week 6 (p < 0.001) and week 12 (p < 0.001). When compared the difference between the E+Ca group and the E+D group, serum levels of FGF23 in the E+Ca group were significantly lower than those in the E+D group at week 12 (p = 0.017). There were no significant differences in the serum levels of CPPs between etelcalcetide users and non-users at week 6 (p = 0.10) and week 12 (p = 0.18), while CPPs in the E+Ca group were significantly lower than those in the E+D group (p < 0.001) at week 12.

CONCLUSION

Etelcalcetide may be useful through suppression of FGF23 levels among hemodialysis patients with SHPT. When correcting hypocalcemia, loading oral calcium preparations could be more advantageous than active vitamin D for the suppression of both FGF23 and CPPs.

In-center Nocturnal Hemodialysis Reduced the Circulating FGF23, Left Ventricular Hypertrophy, and All-Cause Mortality: A Retrospective Cohort Study

Fibroblast growth factor 23(FGF23) is the most important biomarker and pathogenic factor in Chronic Kidney Disease–Mineral and Bone Disorder (CKD–MBD). In the moderate and severe stages of chronic renal failure, abnormally elevated circulating FGF23 can lead to some complications, including myocardial hypertrophy, which is positively correlated with all-cause mortality. However, the circulating FGF23 level of different hemodialysis modalities, the underlying essential regulatory factors, and potential clinical benefits remain to be elucidated. In this retrospective cohort study, 90 in-center nocturnal hemodialysis (INHD) and 90 matched conventional hemodialysis (CHD) patients were enrolled. The complete blood count, intact FGF23(iFGF23), calcium, phosphorus, PTH, and other biochemical and echocardiographic parameters of INHD and CHD patients were collected and analyzed at 1-year follow-up. The all-cause mortality was recorded during the 7-year follow-up. Furthermore, the regulatory factors of iFGF23 and its association with echocardiographic parameters and mortality were investigated by multivariate regression. The levels of iFGF23 and serum phosphate in patients undergoing INHD were significantly lower than those in patients undergoing CHD. The left ventricular volume index (LVMI) in patients with INHD was significantly attenuated and positively correlated with the drop of serum iFGF23. The INHD group had reduced all-cause mortality compared to the CHD group. Multivariate analysis showed that iFGF23 was positively correlated with serum calcium, serum phosphorus, and calcium-phosphate product. The calcium-phosphate product is an independent determining factor of serum iFGF23. Compared with the CHD group, the INHD group presented with a significantly reduced circulating iFGF23 level, which was closely associated with attenuation of left ventricular hypertrophy, but INHD reduced all-cause mortality in an FGF23 independent manner.

Fibroblast growth factor-23 rs7955866 polymorphism and risk of chronic kidney disease

Background

A missense gain-of-function fibroblast growth factor-23 (FGF23) gene single nucleotide polymorphism (SNP) (rs7955866) has been associated with FGF23 hypersecretion, phosphaturia, and bone disease. Excess circulating FGF23 was linked with atherosclerosis, hypertension, initiation, and progression of chronic kidney disease (CKD).

Methods

The study included 72 CKD stage 2/3 Egyptian patients (27–71 years old, 37 females) and 26 healthy controls matching in age and sex. Repeated measures of blood pressure were used to quantify hypertension on a semiquantitative scale (grades 0 to 5). Fasting serum urea, creatinine, uric acid, total proteins, albumin, calcium, phosphorus, vitamin D3, intact parathyroid hormone (iPTH), and intact FGF23 (iFGF23) were measured. DNA extracted from peripheral blood leucocytes was used for genotyping of FGF23 rs7955866 SNP using the TaqMan SNP genotyping allelic discrimination method.

Results

Major causes of CKD were hypertension, diabetic kidney disease, and CKD of unknown etiology. There was no significant difference in minor allele (A) frequency between the studied groups (0.333 in GI and 0.308 in GII). Median (IQR) serum iFGF23 was significantly higher in GI [729.2 (531.9–972.3)] than in GII [126.1 (88.5–152.4)] pg/mL, P < 0.001. Within GI, the minor allele (A) frequency load, coded for codominant inheritance, had a significant positive correlation with both hypertension grade (r = 0.385, P = 0.001) and serum iFGF23 (r = 0.259, P = 0.028). Hypertension grade had a significant positive correlation with serum phosphorus and iFGF23.

Conclusions

For the first time in an Egyptian cohort, we report a relatively high frequency of the rs7955866 SNP. It may remain dormant or become upregulated in response to some environmental triggers, notably dietary phosphorus excess, leading to increased circulating iFGF23 with ensuing hypertension and/or renal impairment. Subjects with this SNP, particularly in the homozygous form, are at increased risk for CKD of presumably “unknown” etiology, with a tendency for early onset hypertension and increased circulating iFGF23 out of proportion with the degree of renal impairment. Large-scale population studies are needed to confirm these findings and explore the role of blockers of the renin–angiotensin–aldosterone system and sodium chloride cotransporters in mitigating hypertension associated with FGF23 excess.

Iron Deficiency is Associated With Platelet Count Elevation in Patients With Dialysis-dependent Chronic Kidney Disease

OBJECTIVE

Iron deficiency is common in patients with end-stage renal disease (ESRD). Platelet count changes may reflect iron status, but the relationship between platelet count and iron indices is unclear in patients with ESRD.

METHODS

We conducted a retrospective study in 1,167 patients with ESRD from 2012 to 2017 in West China Hospital. Baseline data were used to analyze the relationship between the platelet count and iron indices. Patients were followed up for 3 years.

RESULTS

Patients with iron deficiency (both absolute and functional) had a higher platelet count than those without iron deficiency (174 ± 61 × 10⁹/L vs. 153 ± 58 × 10⁹/L, P < .001). Receiver operating characteristic analysis showed a weak predictive power of platelet count on absolute iron deficiency (area under curve 0.620; cutoff value > 137 × 10⁹/L, sensitivity 76%, specificity 43%) and functional iron deficiency (area under curve 0.540; cutoff value > 124 × 10⁹/L, sensitivity 77%, specificity 32%). Platelet count was negatively correlated with ferritin (Spearman's rho [ρ] -0.1547, P < .001), transferrin saturation (ρ = -0.1895, P < .001), and serum iron (ρ = -0.1466, P < .001). The abovementioned correlations remained significant in multivariate regression (β -0.7285, 95% confidence interval [CI] -1.0757 to -0.3814; β -.00347, 95% CI -0.0520 to -0.0174; β -0.0097, 95% CI -0.0159 to -0.0035, respectively). In unadjusted and adjusted Cox regression models, neither baseline platelet count nor relative thrombocytosis was associated with 3-year mortality.

CONCLUSION

There was a weak but significant platelet count elevation in patients with ESRD and with iron deficiency.

KEY WORDS

end-stage renal disease; iron deficiency; iron supplement; mortality; platelet count.

Cardiac Calcifications: Phenotypes, Mechanisms, Clinical and Prognostic Implications

There is a growing interest in arterial and heart valve calcifications, as these contribute to cardiovascular outcome, and are leading predictors of cardiovascular and kidney diseases. Cardiovascular calcifications are often considered as one disease, but, in effect, they represent multifaced disorders, occurring in different milieus and biological phenotypes, following different pathways. Herein, we explore each different molecular process, its relative link with the specific clinical condition, and the current therapeutic approaches to counteract calcifications. Thus, first, we explore the peculiarities between vascular and valvular calcium deposition, as this occurs in different tissues, responds differently to shear stress, has specific etiology and time courses to calcification. Then, we differentiate the mechanisms and pathways leading to hyperphosphatemic calcification, typical of the media layer of the vessel and mainly related to chronic kidney diseases, to those of inflammation, typical of the intima vascular calcification, which predominantly occur in atherosclerotic vascular diseases. Finally, we examine calcifications secondary to rheumatic valve disease or other bacterial lesions and those occurring in autoimmune diseases. The underlying clinical conditions of each of the biological calcification phenotypes and the specific opportunities of therapeutic intervention are also considered and discussed.