Comparison of Dialysis Unit and Home Blood Pressures: An Observational Cohort Study.

RATIONALE & OBJECTIVE: Prior studies of patients receiving maintenance hemodialysis have shown that, on average, blood pressure (BP) measured predialysis is higher than BP measured at home. We hypothesized that a subset of hemodialysis patients has BP that is higher when measured at home than when measured predialysis and this subgroup of patients has a higher prevalence of left ventricular hypertrophy. STUDY DESIGN: Prospective cohort. SETTING & PARTICIPANTS: 97 hypertensive hemodialysis patients enrolled in the Blood Pressure in Dialysis Study (BID), a randomized trial of comparing target predialysis BP ≤140/90 to 155-165/90 mm Hg. EXPOSURE: Differences between predialysis and next-day home systolic BP measured ≥6 times over 1 year. OUTCOME: Left ventricular mass index (LVMI) by cardiac magnetic resonance imaging. ANALYTICAL APPROACH: A hierarchical clustering analysis divided patients into 3 clusters based on the average and variability of differences in systolic predialysis and home BP. Clusters were compared with respect to clinical factors and LVMI. RESULTS: Mean differences between predialysis and home systolic BP were 19.1 (95% CI, 17.0 to 21.1) mm Hg for cluster 1 ("home lower"), 3.7 (95% CI, 1.6 to 5.8) mm Hg for cluster 2 ("home and predialysis similar"), and -9.7 (95% CI, -12.0 to -7.4) mm Hg for cluster 3 ("home higher"). Systolic BP declined during dialysis in clusters 1 and 2 but increased in cluster 3. Interdialytic weight gains did not differ. After adjusting for sex and treatment arm, LVMI was higher in cluster 3 than in clusters 1 and 2: differences in means of 10.6 ± 4.96 (SE) g/m2 (P = 0.04) and 12.0 ± 5.08 g/m2 (P = 0.02), respectively. LIMITATIONS: Limited statistical power. CONCLUSIONS: Nearly one-third of participants had home BPs higher than predialysis BPs. These patients had LVMI higher than those with similar or lower BPs at home, indicating that their BP may have been undertreated.

Longitudinal Evolution of Markers of Mineral Metabolism in Patients With CKD: The Chronic Renal Insufficiency Cohort (CRIC) Study.

RATIONALE & OBJECTIVE: The pathogenesis of disordered mineral metabolism in chronic kidney disease (CKD) is largely informed by cross-sectional studies of humans and longitudinal animal studies. We sought to characterize the longitudinal evolution of disordered mineral metabolism during the course of CKD. STUDY DESIGN: Retrospective analysis nested in a cohort study. SETTING & PARTICIPANTS: Participants in the Chronic Renal Insufficiency Cohort (CRIC) Study who had up to 5 serial annual measurements of estimated glomerular filtration rate, fibroblast growth factor 23 (FGF-23), parathyroid hormone (PTH), serum phosphate, and serum calcium and who subsequently reached end-stage kidney disease (ESKD) during follow-up (n = 847). EXPOSURE: Years before ESKD. OUTCOMES: Serial FGF-23, PTH, serum phosphate, and serum calcium levels. ANALYTICAL APPROACH: To assess longitudinal dynamics of disordered mineral metabolism in human CKD, we used "ESKD-anchored longitudinal analyses" to express time as years before ESKD, enabling assessments of mineral metabolites spanning 8 years of CKD progression before ESKD. RESULTS: Mean FGF-23 levels increased markedly as time before ESKD decreased, while PTH and phosphate levels increased modestly and calcium levels declined minimally. Compared with other mineral metabolites, FGF-23 levels demonstrated the highest rate of change (velocity: first derivative of the function of concentration over time) and magnitude of acceleration (second derivative). These changes became evident approximately 5 years before ESKD and persisted without deceleration through ESKD onset. Rates of changes in PTH and phosphate levels increased modestly and without marked acceleration around the same time, with modest deceleration immediately before ESKD, when use of active vitamin D and phosphate binders increased. LIMITATIONS: Individuals who entered the CRIC Study at early stages of CKD and who did not progress to ESKD were not studied. CONCLUSIONS: Among patients with progressive CKD, FGF-23 levels begin to increase 5 years before ESKD and continue to rapidly accelerate until transition to ESKD.

Concomitant monoclonal immunoglobulin deposition disease and crystalglobulin-induced nephropathy with a membranoproliferative pattern of glomerular injury
.

Monoclonal immunoglobulin paraproteins can deposit in the kidney in variable forms and eliciting differing patterns of injury. Crystalglobulin-induced nephropathy is a rare form of monoclonal immunoglobulin deposition in the kidney, characterized by glomerular capillary endoluminal crystalline material evident by light and electron microscopy that exhibits immunoglobulin restriction via immunofluorescence studies. We present a case of a patient with acute kidney injury, and a subsequent kidney biopsy notably revealed concurrent monoclonal immunoglobulin deposition disease (MIDD) and crystalglobulin-induced nephropathy secondary to an IgM/κ monoclonal protein that resulted in a membranoproliferative pattern of glomerular injury. The two process were distinctly evident by ultrastructural crystalline and non-crystalline (as seen with cases of more conventional MIDD) deposits in the glomeruli. The paraprotein constituency is novel (IgM/κ) for crystalglobulin-induced nephropathy (prior cases exhibited IgG/κ restriction) as was the finding of the two monoclonal immunoglobulin deposition processes contributing to development of an active glomerulitis characterized by a membranoproliferative pattern of glomerular injury (crystalglobulin-induced nephropathy has not been associated with an active glomerulitis before).

Effect of Oat ß-Glucan Supplementation on Chronic Kidney Disease: A Feasibility Study.

OBJECTIVE: Dietary supplementation with grains containing high ß-glucan fiber has been shown to attenuate the progression of chronic kidney disease (CKD) and vascular calcification in animal models. The aim of this study was to investigate the feasibility of consuming an oat ß-glucan supplement and to assess its effects on certain uremic toxins and markers of mineral metabolism in patients with CKD. DESIGN: This is a 20-week, nonrandomized, single-center, pretest-posttest study. Twenty-eight subjects with CKD stages 3-4 were enrolled. The mean age was 67.6 ± 8.9 years, and the mean estimated glomerular filtration rate was 35 ± 14 mL/min/1.73 m2. Subjects received a dietary supplement containing 3 g of oat ß-glucan per day for 12 weeks. The 4-week period before the start of the intervention was used as a baseline comparison for each subject. The primary outcome was pre-post supplement changes in plasma levels of two uremic toxins: trimethylamine N-oxide (TMAO) and asymmetric dimethylarginine. Secondary outcomes were pre-post supplement changes in serum calcium, phosphorus, and Klotho levels. Repeated-measures analysis of variance was used to test the differences in outcomes over the three-month-long intervention. RESULTS: Serum levels of TMAO decreased by a median of -17% (interquartile range: -46%, 7%) at the end of the intervention. A nonstatistically significant change was observed for asymmetric dimethylarginine (median -0.6% [-12%, 20%]) and serum Klotho (median -3% [-8%, 7%]). There were no changes in serum levels of calcium and phosphorus. One month after discontinuation of ß-glucan therapy, TMAO levels increased by a median of 16% (-12%, 36%) but remained slightly below the pretreatment levels. Eight subjects experienced side effects and discontinued the treatment. CONCLUSION: A diet supplemented with ß-glucan is safe and potentially efficacious in lowering serum concentrations of TMAO in patients with CKD. Larger trials with longer follow-up times are needed to determine whether such reductions translate into clinical benefits.

BP in Dialysis: Results of a Pilot Study.

The optimal BP target for patients receiving hemodialysis is unknown. We randomized 126 hypertensive patients on hemodialysis to a standardized predialysis systolic BP of 110-140 mmHg (intensive arm) or 155-165 mmHg (standard arm). The primary objectives were to assess feasibility and safety and inform the design of a full-scale trial. A secondary objective was to assess changes in left ventricular mass. Median follow-up was 365 days. In the standard arm, the 2-week moving average systolic BP did not change significantly during the intervention period, but in the intensive arm, systolic BP decreased from 160 mmHg at baseline to 143 mmHg at 4.5 months. From months 4-12, the mean separation in systolic BP between arms was 12.9 mmHg. Four deaths occurred in the intensive arm and one death occurred in the standard arm. The incidence rate ratios for the intensive compared with the standard arm (95% confidence intervals) were 1.18 (0.40 to 3.33), 1.61 (0.87 to 2.97), and 3.09 (0.96 to 8.78) for major adverse cardiovascular events, hospitalizations, and vascular access thrombosis, respectively. The intensive and standard arms had similar median changes (95% confidence intervals) in left ventricular mass of -0.84 (-17.1 to 10.0) g and 1.4 (-11.6 to 10.4) g, respectively. Although we identified a possible safety signal, the small size and short duration of the trial prevent definitive conclusions. Considering the high risk for major adverse cardiovascular events in patients receiving hemodialysis, a full-scale trial is needed to assess potential benefits of intensive hypertension control in this population.

Association of Intradialytic Hypertension with Left Ventricular Mass in Hypertensive Hemodialysis Patients Enrolled in the Blood Pressure in Dialysis (BID) Study.

BACKGROUND/AIMS: Intradialytic hypertension (IDH), or paradoxical rise in blood pressure (BP) during hemodialysis (HD) is associated with increased morbidity and mortality. The association between IDH and increased left ventricular mass (LVM), a well-known risk factor for adverse cardiovascular outcomes in HD patients, has not been studied. The aim of our study is to evaluate the cross-sectional association of intradialytic change in BP with cardiac structure and function measured by cardiac MRI in hypertensive HD patients enrolled in the multi-center Blood Pressure in Dialysis (BID) clinical trial. METHODS: Participants in the BID study were categorized into 3 groups based on average change (Δ) in systolic blood pressure (SBP) (post-HD SBP minus pre-HD SBP) during HD over a 1 month period: group 1 - patients with an increase in SBP ≥ 10mm Hg during HD (IDH); group 2 -patients with SBP decrease of greater ≥10mm Hg during HD; group 3 - patients with SBP increase or decrease by < 10mm Hg during HD. LVM index (LVMI) was measured using cardiac MRI, which were centrally read. Baseline characteristics were compared in the 3 groups and multivariable regression models were fitted for the adjusted association of IDH with LVMI. RESULTS: Among the 80 participants, 7 (8.8%) had IDH and had average Δ SBP 17.0 ± 10.1 mmHg during HD. Patients with IDH were less likely to be diabetic, had lower pre-dialysis SBP and lower percent interdialytic weight gain as compared to the other 2 groups (p=0.02, p< 0.001 and p=0.02 respectively). In multivariable regression analyses, IDH was significantly associated with LVMI (adjusted mean difference relative to SBP decreased group [95% confidence interval (CI)] = 12.5 [3.6, 21.5], p=0.01) after adjusting for age, sex, diabetes, IDWG%, pre-HD SBP and beta blocker use. Every 1 mm rise in ΔSBP during HD was associated with 0.2 g/m2 increase in LVMI in adjusted models (p=0.04). CONCLUSION: IDH is independently associated with higher LVMI in hypertensive HD patients and may contribute to increased cardiovascular events.

Inflammation and elevated levels of fibroblast growth factor 23 are independent risk factors for death in chronic kidney disease.

Inflammation is a consequence of chronic kidney disease (CKD) and is associated with adverse outcomes in many clinical settings. Inflammation stimulates production of fibroblast growth factor 23 (FGF23), high levels of which are independently associated with mortality in CKD. Few large-scale prospective studies have examined inflammation and mortality in patients with CKD, and none tested the interrelationships among inflammation, FGF23, and risk of death. Therefore, we conducted a prospective investigation of 3875 participants in the Chronic Renal Insufficiency Cohort (CRIC) study with CKD stages 2 to 4 to test the associations of baseline plasma interleukin-6, high-sensitivity C-reactive protein, and FGF23 levels with all-cause mortality, censoring at the onset of end-stage renal disease. During a median follow-up of 6.9 years, 550 participants died (20.5/1000 person-years) prior to end-stage renal disease. In separate multivariable-adjusted analyses, higher levels of interleukin-6 (hazard ratio per one standard deviation increase of natural log-transformed levels) 1.35 (95% confidence interval, 1.25-1.46), C-reactive protein 1.28 (1.16-1.40), and FGF23 1.45 (1.32-1.60) were each independently associated with increased risk of death. With further adjustment for FGF23, the risks of death associated with interleukin-6 and C-reactive protein were minimally attenuated. Compared to participants in the lowest quartiles of inflammation and FGF23, the multivariable-adjusted hazard ratio of death among those in the highest quartiles of both biomarkers was 4.38 (2.65-7.23) for interleukin-6 and FGF23, and 5.54 (3.04-10.09) for C-reactive protein and FGF23. Thus, elevated levels of interleukin-6, C-reactive protein, and FGF23 are independent risk factors for mortality in CKD.

The effect of vitamin d on aldosterone and health status in patients with heart failure.

BACKGROUND: Vitamin D deficiency is associated with heart failure (HF) events, and in animal models vitamin D down-regulates renin-angiotensin-aldosterone system hormones. METHODS: Patients with New York Heart Association (NYHA) functional class II-IV HF and a 25OH-D level ≤37.5 ng/mL received 50,000 IU vitamin D3 weekly (n = 31) or placebo (n = 33) for 6 months. Serum aldosterone, renin, echocardiography, and health status were determined at baseline and 6 months. RESULTS: Mean age of participants was 65.9 ± 10.4 years, 48% were women, 64% were African American, mean ejection fraction was 37.6 ± 13.9%, 36% were in NYHA functional class III, and 64% were in class II. The vitamin D group increased serum 25OH-D (19.1 ± 9.3 to 61.7 ± 20.3 ng/mL) and the placebo group did not (17.8 ± 9.0 to 17.4 ± 9.8 ng/mL). Aldosterone decreased in the vitamin D group (10.0 ± 11.9 to 6.2 ± 11.6 ng/dL) and not in the placebo group (8.9 ± 8.6 to 9.0 ± 12.4 ng/dL; P = .02). There was no difference between groups in renin, echocardiographic measures, or health status from baseline to 6 months. Modeling indicated that variables which predicted change in aldosterone included receiving vitamin D, increasing age, African American race, and lower glomerular filtration rate. CONCLUSIONS: Vitamin D3 repletion decreases aldosterone in patients with HF and low serum vitamin D. Vitamin D may be an important adjunct to standard HF therapy. Further study will assess if vitamin D provides long-term benefit for patients with HF.

Low socioeconomic status associates with higher serum phosphate irrespective of race.

Hyperphosphatemia, which associates with adverse outcomes in CKD, is more common among blacks than whites for unclear reasons. Low socioeconomic status may explain this association because poverty both disproportionately affects racial and ethnic minorities and promotes excess intake of relatively inexpensive processed and fast foods enriched with highly absorbable phosphorus additives. We performed a cross-sectional analysis of race, socioeconomic status, and serum phosphate among 2879 participants in the Chronic Renal Insufficiency Cohort Study. Participants with the lowest incomes or who were unemployed had higher serum phosphate concentrations than participants with the highest incomes or who were employed (P < 0.001). Although we also observed differences in serum phosphate levels by race, income modified this relationship: Blacks had 0.11 to 0.13 mg/dl higher serum phosphate than whites in the highest income groups but there was no difference by race in the lowest income group. In addition, compared with whites with the highest income, both blacks and whites with the lowest incomes had more than twice the likelihood of hyperphosphatemia in multivariable-adjusted analysis. In conclusion, low socioeconomic status associates with higher serum phosphate concentrations irrespective of race. Given the association between higher levels of serum phosphate and cardiovascular disease, further studies will need to determine whether excess serum phosphate may explain disparities in kidney disease outcomes among minority populations and the poor.

Serum Magnesium and Cardiovascular Outcomes and Mortality in CKD: The Chronic Renal Insufficiency Cohort (CRIC).

RATIONALE & OBJECTIVE: Low serum magnesium level has been shown to be associated with increased mortality, but its role as a predictor of cardiovascular disease is unclear. This study evaluates the association between serum magnesium level and cardiovascular events and all-cause mortality in a large cohort of individuals with chronic kidney disease (CKD). STUDY DESIGN: Prospective cohort study. SETTING & PARTICIPANTS: 3,867 participants with CKD, enrolled in the Chronic Renal Insufficiency Cohort (CRIC) Study. EXPOSURES: Serum magnesium measured at study baseline. OUTCOMES: Composite cardiovascular events (myocardial infarction, cerebrovascular accident, heart failure, and peripheral arterial disease) and all-cause mortality. ANALYTICAL APPROACH: Cox proportional hazards models adjusted for demographic, clinical, and laboratory characteristics. RESULTS: During the 14.6 (4.4) years (standard deviation) of follow-up, 1,384 participants died (36/1,000 person-years), and 1,227 (40/1,000 person-years) had a composite cardiovascular event. There was a nonlinear association between serum magnesium level and all-cause mortality. Low and high magnesium levels were associated with greater rates of all-cause mortality after adjusting for demographics, comorbid conditions, medications including diuretics, estimated glomerular filtration rate, and proteinuria (P < 0.001). No significant associations were observed between serum magnesium levels and the composite cardiovascular events. Low serum magnesium level was associated with incident atrial fibrillation (HR, 1.36; 95% CI, 1.01-1.82; P = 0.04). LIMITATIONS: Single measurement of serum magnesium. CONCLUSIONS: In this large CKD cohort, serum magnesium level < 1.9 mg/dL and >2.1 mg/dL was associated with increased risk for all-cause mortality. Low magnesium level was associated with incident atrial fibrillation but not with composite cardiovascular disease events. Further studies are needed to determine the optimal range of serum magnesium in CKD to prevent adverse clinical outcomes.

Hydralazine-induced ANCA-positive pauci-immune glomerulonephritis: a case report and literature review.

We report a case of hydralazine-induced alveolar hemorrhage and anti-neutrophil cytoplasmic antibody (ANCA)-positive pauci-immune glomerulonephritis, with serum anti-histone antibodies present, features not previously described in the literature with this drug. A 50-year-old Caucasian female had hypertension treated with hydralazine 75mg TID for three years, and a lung nodule followed up periodically with chest-computed tomographies. She was admitted to the hospital for hemoptysis and newly discovered diffuse pulmonary ground-glass opacities. Transbronchial lung biopsy showed alveolar hemorrhage. Serum creatinine was 3.5 mg/dL and urinalysis showed 2+blood, 30-50RBC/hpf and red blood cell casts. ANCA against myeloperoxidase were present. Anti-double-stranded DNA, ANA, and anti-histone antibodies were positive. Serum complements were normal. Renal biopsy revealed focal crescentic necrotizing glomerulonephritis with negative immunofluorescence, consistent with pauci-immune ANCA-positive vasculitis. Serum creatinine returned to baseline three days after hydralazine was discontinued, and the hemoptysis resolved after treatment with cyclophosphamide and prednisone was started. We concluded that this case represents a hydralazine-induced small vessel vasculitis rather than an idiopathic one. The possibility of hydralazine-induced vasculitis should be considered when patients treated with hydralazine develop a pulmonary-renal syndrome. Anti-histone antibodies may be present in the absence of full classification criteria of drug-induced lupus.

Active Vitamin D in Chronic Kidney Disease: Getting Right Back Where We Started from?

BACKGROUND: The vitamin D system is essential for optimal health in humans. Circulating calcitriol, a key metabolite in maintaining calcium and phosphorus homeostasis, is produced in the kidney. In kidney failure, calcitriol levels progressively decrease, contributing to the development of renal secondary hyperparathyroidism (SHPT). SUMMARY: For years, SHPT had a central role in the disturbed mineral metabolism of renal patients. As calcitriol deficiency contributes to SHPT development, treatment with calcitriol or other compounds able to activate the vitamin D receptor (VDR) was one of the mainstays of therapy for renal patients in the last 40 years. In this review, we discuss how the treatment with VDR activators (VDRA) evolved during this time in the United States, as well as the main factors responsible for these changes. KEY MESSAGES: Management of SHPT with VDRA in renal patients has undergone a few paradigm shifts over the last 40 years. When treating SHPT, the newly developed therapies as well as VDRA need to be carefully considered and used appropriately. Nephrologists need to use an integrated approach that avoids excessive use of VDRA, ensures replenishment of vitamin D stores, and avoids hypercalcemia and hyperphosphatemia.

A pharmacokinetic analysis of cisplatin and 5-fluorouracil in a patient with esophageal cancer on peritoneal dialysis.

BACKGROUND: Very little is known about the pharmacokinetics of chemotherapeutic agents in patients also being treated with continuous ambulatory peritoneal dialysis. We sought to evaluate the pharmacokinetics of cisplatin and 5-fluorouracil in plasma and peritoneal dialysate in a patient being treated for esophageal adenocarcinoma. METHODS: A single patient with esophageal adenocarcinoma and on peritoneal dialysis for end-stage renal disease was treated with cisplatin 25 mg/m(2) on day 1 of weeks 1 and 5 and continuous infusional 5-fluorouracil 1000 mg/m(2)/day on days 1-4 of weeks 1 and 5 along with daily radiation therapy. Intense plasma and dialysate sampling was performed during the week 5 administration, followed by quantitation of platinum by atomic absorption spectrophotometry and 5-fluorouracil by LC-MS/MS. RESULTS: Following systemic administration, clearance of ultrafilterable (active) platinum over the first 6 h was 20.8 L/h, which is lower than previously reported clearance levels of ultrafilterable platinum. Total platinum AUC was 131 µg h/mL, also higher than an AUC previously reported for total platinum in patients with normal renal function. Platinum-related material was detected in the peritoneal cavity, but this is likely inactive. 5-Fluorouracil penetrated the intraperitoneal cavity, but the contribution of peritoneal dialysis to drug clearance was negligible at 0.072 %. CONCLUSIONS: Administration of intravenous cisplatin and 5-fluorouracil chemotherapy to a patient treated with continuous ambulatory peritoneal dialysis is feasible, but clearance in dialysate is nominal, thus suggesting that dose reduction is indicated for cisplatin. Systemic drug administration results in limited intraperitoneal penetration of 5-fluorouracil and inactive platinum species.

Fibroblast growth factor 23 and Inflammation in CKD.

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.

Earlier onset and greater severity of disordered mineral metabolism in diabetic patients with chronic kidney disease.

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.