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Munoz Mendoza J, Isakova T, Ricardo AC, Xie H, Navaneethan SD, Anderson AH, Bazzano LA, Xie D, Kretzler M, Nessel L, Hamm LL, Negrea L, Leonard MB, Raj D, Wolf M. Fibroblast growth factor 23 and Inflammation in CKD. Clin J Am Soc Nephrol 2012; 7:1155-62. [PMID: 22554719 DOI: 10.2215/cjn.13281211] [Citation(s) in RCA: 194] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
BACKGROUND AND OBJECTIVES Levels of fibroblast growth factor 23 (FGF23) and inflammatory markers are commonly elevated in CKD, and each is associated with adverse clinical outcomes. This study tested the hypothesis that FGF23 is independently associated with inflammation in CKD. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS The association between levels of FGF23 and the inflammatory markers IL-6, C-reactive protein (CRP), TNF-α, and fibrinogen was assessed in a cross-sectional analysis of 3879 participants enrolled in the Chronic Renal Insufficiency Cohort (CRIC) study between June 2003 and September 2008. RESULTS FGF23 correlated directly with IL-6 (r=0.4), CRP (r=0.2), TNF-α (r=0.4), and fibrinogen (r=0.3; P<0.001 for each). In univariate and multivariable-adjusted linear regression analyses, natural log (ln) transformed FGF23 was significantly associated with lnIL-6, lnCRP, lnTNF-α, and fibrinogen (P<0.001 for each). Each unit higher lnFGF23 was associated with severe inflammation, defined as levels of all inflammatory markers in the highest 25th percentile, in univariate (odds ratio [OR], 2.4 [95% confidence interval (CI), 2.0-2.9]) and multivariable-adjusted (OR, 2.0 [95% CI, 1.6-2.5]) logistic regression analyses. Ascending FGF23 quartiles were independently associated with severe inflammation (OR, 5.6 for the highest versus lowest FGF23 quartile [95% CI, 2.3-13.9]; P for trend < 0.001). CONCLUSIONS Higher FGF23 levels are independently associated with higher levels of inflammatory markers in patients with CKD and with significantly greater odds of severe inflammation. Future studies should evaluate whether inflammation modifies the association between FGF23 and adverse outcomes in CKD.
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Affiliation(s)
- Jair Munoz Mendoza
- Division of Nephrology and Hypertension, Department of Medicine, University of Miami, Miller School of Medicine, Miami, FL 33136, USA
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Wahl P, Xie H, Scialla J, Anderson CAM, Bellovich K, Brecklin C, Chen J, Feldman H, Gutierrez OM, Lash J, Leonard MB, Negrea L, Rosas SE, Anderson AH, Townsend RR, Wolf M, Isakova T. Earlier onset and greater severity of disordered mineral metabolism in diabetic patients with chronic kidney disease. Diabetes Care 2012; 35:994-1001. [PMID: 22446176 PMCID: PMC3329844 DOI: 10.2337/dc11-2235] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
OBJECTIVE Disordered mineral metabolism is a common complication of chronic kidney disease (CKD) and a novel risk factor for CKD progression, cardiovascular disease, and mortality. Although diabetes is the leading cause of CKD and is associated with worse clinical outcomes than other etiologies, few studies have evaluated mineral metabolism in CKD according to diabetes status. RESEARCH DESIGN AND METHODS Using the Chronic Renal Insufficiency Cohort Study, we tested the hypothesis that diabetes is independently associated with lower serum calcium and higher serum phosphate, parathyroid hormone (PTH), and fibroblast growth factor 23 (FGF23). RESULTS Compared with participants without diabetes (n = 1,936), those with diabetes (n = 1,820) were more likely to have lower estimated glomerular filtration rate (eGFR), lower serum albumin, and higher urinary protein excretion (all P < 0.001). Unadjusted serum phosphate, PTH, and FGF23 levels were higher and calcium was lower among those with compared with those without diabetes (all P < 0.001). After multivariate adjustment, diabetes remained a significant predictor of serum phosphate, PTH, and FGF23 but not calcium. The eGFR cut point at which 50% of participants met criteria for secondary hyperparathyroidism or elevated FGF23 was higher in participants with diabetes compared with those without (PTH: eGFR 30-39 vs. 20-29, P < 0.001; FGF23: eGFR 50-59 vs. 40-49, P < 0.001). CONCLUSIONS Disordered mineral metabolism begins earlier in the course of CKD and is more severe among CKD patients with compared with those without diabetes. Future studies should explore mechanisms for these differences and whether they contribute to excess risks of adverse clinical outcomes among diabetic patients with CKD.
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Affiliation(s)
- Patricia Wahl
- Division of Nephrology and Hypertension, Department of Medicine, University ofMiami Miller School of Medicine, Miami, Florida, USA
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53
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Jamal SA, West SL, Miller PD. Fracture risk assessment in patients with chronic kidney disease. Osteoporos Int 2012; 23:1191-8. [PMID: 21901475 DOI: 10.1007/s00198-011-1781-0] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/08/2011] [Accepted: 08/04/2011] [Indexed: 10/17/2022]
Abstract
Fractures are common in patients with chronic kidney disease (CKD) and associated with substantially high morbidity and mortality. Bone mass measurements are commonly used to assess fracture risk in the general population, but the utility of these measurements in patients with CKD, and specifically among those on hemodialysis, is unclear. This review will outline the epidemiology and etiology of fractures in patients with CKD with a particular emphasis on men and women on hemodialysis. As well, we will summarize the published data, which describes the association between risk factors for fracture (including bone mass measurements, biochemical markers of mineral metabolism, and muscle strength) and fractures in patients with CKD. Patients with CKD suffer from fractures due to impairments in bone quantity, bone quality, and abnormalities of neuromuscular function. There is a paucity of evidence on the associations between bone quality, bone turnover markers, neuromuscular function, and fractures in patients with CKD. Furthermore, the complex etiology of fractures combined with the technical limitations of bone mineral density testing, both by dual energy X-ray absorptiometry (DXA) and by peripheral quantitative tomography (pQCT), limits the clinical utility of bone mass measurements for fracture prediction in CKD; this is particularly true among patients with stages 4 and 5 CKD. Further prospective studies to identify noninvasive measures of bone strength that can be used for fracture risk assessment are needed.
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Affiliation(s)
- S A Jamal
- Department of Medicine, University of Toronto, Toronto, ON, Canada.
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Bone-specific alkaline phosphatase concentrations are less variable than those of parathyroid hormone in stable hemodialysis patients. Kidney Int 2012; 82:100-5. [PMID: 22456600 PMCID: PMC3376309 DOI: 10.1038/ki.2012.77] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Abnormalities of bone mineral metabolism and vascular calcification are prevalent in patients with kidney failure. Clinical management is based on biochemical targets, in particular parathyroid hormone (PTH) concentrations, but this has many limitations including high biological variation. A possible alternative is bone-specific alkaline phosphatase (ALP); therefore, we evaluated the biological variation of this marker in patients undergoing hemodialysis. Bone ALP was measured in non-fasting serum samples taken twice a week over a 6-week period in 22 stable hemodialysis patients and 12 healthy volunteers. The within-individual coefficients of variance were calculated and used to derive the critical difference required to be certain that an observed change was significant. The coefficient of variance for bone ALP was significantly higher in hemodialysis patients compared to healthy individuals. Seven samples were required to estimate the homeostatic set point of bone ALP, within 10%, in a hemodialysis patient. The concentration of serial bone ALP measurements would need to change by 36% between any two measurements before it can be considered a significant change. Since the biological variation of bone ALP is less than half that reported for PTH, our study provides further support for the use of bone ALP as an alternative marker of bone mineral metabolism in the setting of chronic kidney disease–mineral and bone disorder.
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Garrett G, Sardiwal S, Lamb EJ, Goldsmith DJA. PTH--a particularly tricky hormone: why measure it at all in kidney patients? Clin J Am Soc Nephrol 2012; 8:299-312. [PMID: 22403273 DOI: 10.2215/cjn.09580911] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Plasma parathyroid hormone (PTH) concentrations are commonly measured in the context of CKD, as PTH concentration elevation is typical in this clinical context. Much has been inferred from this raised PTH concentration tendency, both about the state of skeletal integrity and health and also about the potential clinical outcomes for patients. However, we feel that reliance on PTH concentrations alone is a dangerous substitute for the search for, and use of, more precise and reliable biomarkers. In this article, we rehearse these arguments, bringing together patient-level and analytical considerations for the first time.
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Affiliation(s)
- Giorgia Garrett
- East Kent Hospitals University, NHS Foundation Trust, Canterbury, Kent, United Kingdom
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Fukumoto S, Shimizu Y. Fibroblast growth factor 23 as a phosphotropic hormone and beyond. J Bone Miner Metab 2011; 29:507-14. [PMID: 21822586 DOI: 10.1007/s00774-011-0298-0] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/10/2011] [Accepted: 06/20/2011] [Indexed: 01/16/2023]
Abstract
Fibroblast growth factor 23 (FGF23) is produced by bone and reduces serum phosphate by inhibiting proximal tubular phosphate reabsorption and intestinal phosphate absorption. Excess actions of FGF23 cause several kinds of hypophosphatemic rickets/osteomalacia while deficient actions of FGF23 result in hyperphosphatemic tumoral calcinosis. In addition, FGF23 has been shown to prevent the development of hyperphosphatemia during the progression of chronic kidney disease-mineral and bone disorder. Epidemiological studies have indicated that high FGF23 levels are associated with unfavorable events including higher mortality, cardiovascular events, progression of CKD and fracture; however, these associations are not observed unequivocally and it is not evident why they are present. While FGF23 has been shown to be a hormone that regulates phosphate metabolism, it remains to be established whether FGF23 has roles other than regulating mineral homeostasis.
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Affiliation(s)
- Seiji Fukumoto
- Division of Nephrology and Endocrinology, Department of Medicine, University of Tokyo Hospital, Bunkyo-ku, Tokyo, Japan.
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Abstract
Chronic kidney disease (CKD) is a major public health problem. The classification of CKD by KDOQI and KDIGO and the routine eGFR reporting have resulted in increased identification of CKD. It is important to be able to identify those at high risk of CKD progression and its associated cardiovascular disease (CVD). Proteinuria is the most sensitive marker of CKD progression in clinical practice, especially when combined with eGFR, but these have limitations. Hence, early, more sensitive, biomarkers are required. Recently, promising biomarkers have been identified for CKD progression and its associated CVD morbidity and mortality. These may be more sensitive biomarkers of kidney function, the underlying pathophysiological processes, and/or cardiovascular risk. Although there are some common pathways to CKD progression, there are many primary causes, each with its own specific pathophysiological mechanism. Hence, a panel measuring multiple biomarkers including disease-specific biomarkers may be required. Large, longitudinal observational studies are needed to validate candidate biomarkers in a broad range of populations prior to implementation into routine CKD management. Recent renal biomarkers discovered include neutrophil gelatinase-associated lipocalin, kidney injury molecule-1, and liver-type fatty acid-binding protein. Although none are ready for use in clinical practice, it is timely to review the role of such biomarkers in predicting CKD progression and/or CVD risk in CKD.
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Wolf M, Molnar MZ, Amaral AP, Czira ME, Rudas A, Ujszaszi A, Kiss I, Rosivall L, Kosa J, Lakatos P, Kovesdy CP, Mucsi I. Elevated fibroblast growth factor 23 is a risk factor for kidney transplant loss and mortality. J Am Soc Nephrol 2011; 22:956-66. [PMID: 21436289 PMCID: PMC3083317 DOI: 10.1681/asn.2010080894] [Citation(s) in RCA: 226] [Impact Index Per Article: 17.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2010] [Accepted: 12/10/2010] [Indexed: 12/11/2022] Open
Abstract
An increased circulating level of fibroblast growth factor 23 (FGF23) is an independent risk factor for mortality, cardiovascular disease, and progression of chronic kidney disease (CKD), but its role in transplant allograft and patient survival is unknown. We tested the hypothesis that increased FGF23 is an independent risk factor for all-cause mortality and allograft loss in a prospective cohort of 984 stable kidney transplant recipients. At enrollment, estimated GFR (eGFR) was 51 ± 21 ml/min per 1.73 m(2) and median C-terminal FGF23 was 28 RU/ml (interquartile range, 20 to 43 RU/ml). Higher FGF23 levels independently associated with increased risk of the composite outcome of all-cause mortality and allograft loss (full model hazard ratio: 1.46 per SD increase in logFGF23, 95% confidence interval: 1.28 to 1.68, P<0.001). The results were similar for each component of the composite outcome and in all sensitivity analyses, including prespecified analyses of patients with baseline eGFR of 30 to 90 ml/min per 1.73 m(2). In contrast, other measures of phosphorus metabolism, including serum phosphate and parathyroid hormone (PTH) levels, did not consistently associate with outcomes. We conclude that a high (or elevated) FGF23 is an independent risk factor for death and allograft loss in kidney transplant recipients.
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Affiliation(s)
- Myles Wolf
- Division of Nephrology and Hypertension, University of Miami, Miller School of Medicine, 1120 NW 14th Street, CRB 819, Miami, FL 33136, USA.
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Manghat P, Souleimanova I, Cheung J, Wierzbicki AS, Harrington DJ, Shearer MJ, Chowienczyk P, Fogelman I, Nerlander M, Goldsmith D, Hampson G. Association of bone turnover markers and arterial stiffness in pre-dialysis chronic kidney disease (CKD). Bone 2011; 48:1127-32. [PMID: 21281749 DOI: 10.1016/j.bone.2011.01.016] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/06/2010] [Revised: 01/17/2011] [Accepted: 01/19/2011] [Indexed: 12/15/2022]
Abstract
Vascular calcification (VC) is highly prevalent in CKD and leads to increased vascular stiffness and cardiovascular disease (CVD). Non-traditional cardiovascular risk factors include abnormal bone turnover and/or dysregulation of the calcification inhibitors, although their relative contribution remains unclear. We investigated the association between bone turnover, the calcification inhibitors (matrix gla protein; MGP and Fetuin-A), and the phosphate regulating hormone; fibroblast growth factor-23 (FGF-23) and arterial stiffness in pre-dialysis CKD patients. One hundred and forty-five patients with CKD stages 1-4 (74 M, 71 F) aged (mean [SD]) 53 [14] years were studied. Bone turnover markers (bone-specific alkaline phosphatase (BALP) and tartrate-resistant acid phosphatase (TRACP)) and MGP, Fetuin-A and FGF-23 were determined. BMD was measured at the lumbar spine (LS), femoral neck (FN), forearm (FARM) and total hip (TH). Arterial stiffness was assessed by contour analysis of digital volume pulse (SI(DVP)). There was a significant positive correlation between TRACP:BALP ratio and SI(DVP) ( r=0.19, p=0.023). Following multi-linear regression analysis, significant associations were seen between serum BALP (p=0.037), TRACP (p=0.009) and TRACP:BALP ratio (p=0.001) and SI(DVP) independently of traditional CVD risk factors. No significant relationship between SI(DVP) and MGP, Fetuin-A and FGF-23 was observed. A significant negative correlation was seen between BMD at the FARM and SI(DVP) in CKD stage 4 (r=-0.35, p=0.024). The association remained significant following correction for age, gender and cardiovascular risk factors (p=0.029). Our data suggest a link between imbalances in bone turnover and arterial stiffness in pre-dialysis CKD. Longitudinal studies are needed to evaluate the clinical usefulness of these bone turnover markers as predictors of CVD in CKD.
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Affiliation(s)
- P Manghat
- Department of Chemical Pathology, St Thomas' Hospital, London, UK
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