Plasma creatine concentration is associated with incident hypertension in a cohort enriched for the presence of high urinary albumin concentration: the Prevention of Renal and Vascular Endstage Disease study

A Prospective Study of the Association Between Plasma Calprotectin Levels and New-Onset CKD in the General Population

Introduction

Systemic inflammation has been associated with chronic kidney disease (CKD). In this study, we aimed to investigate a potential association between the plasma biomarker of inflammation calprotectin and new-onset CKD in a population-based cohort study.

Methods

Individuals without CKD at baseline (n = 4662) who participated in the Prevention of REnal and Vascular ENd-stage Disease (PREVEND) prospective population-based cohort study in the Netherlands were included. Baseline plasma calprotectin levels were assessed in samples that had been stored at -80 °C. Occurrence of new-onset CKD was defined as a composite outcome of an estimated glomerular filtration rate (eGFR) <60 ml/min per 1.73 m2, urinary albumin excretion (UAE) >30 mg/24h, or both.

Results

Baseline median (interquartile range) plasma calprotectin levels were 0.49 (0.35-0.68) mg/l and baseline median eGFR was 95.9 (interquartile range: 85.0-105.7) ml/min per 1.73 m2. After median follow-up of 8.3 (7.8-8.9) years, 467 participants developed new-onset CKD. Baseline plasma calprotectin levels were significantly associated with an increased risk of new-onset CKD (hazard ratio [HR] per doubling 1.28 [95% confidence interval, CI: 1.14-1.44], P < 0.001), independent of potentially confounding factors (HR 1.14 [95% CI: 1.01-1.29], P = 0.034), except for baseline high-sensitive C-reactive protein (hs-CRP) (HR 1.05 [0.91-1.21], P = 0.494). In secondary analyses, the association between plasma calprotectin and occurrence of UAE >30 mg/24h remained significant (HR 1.17 [1.02-1.34], P = 0.027), but not significantly so for the incidence of eGFR <60 ml/min per 1.73 m2 as individual outcome (HR 1.15 [0.92-1.43], P = 0.218).

Conclusion

Higher plasma calprotectin levels are associated with an increased risk of developing CKD in the general population. This association is mitigated after adjustment for hs-CRP, and more pronounced with new-onset CKD defined by UAE.

Plasma Calprotectin Levels Associate With New-Onset Hypertension in the General Population: A Prospective Cohort Study

BACKGROUND

Low-grade systemic inflammation is a relevant pathogenic mechanism underlying the development of hypertension. In this study, we hypothesized that plasma calprotectin levels, as a biomarker of neutrophil-mediated inflammation, is associated with developing new-onset hypertension in the general population.

METHODS AND RESULTS

Plasma calprotectin levels were determined in 3524 participants who participated in the PREVEND (Prevention of Renal and Vascular End-Stage Disease) study, a prospective population-based cohort study. Plasma calprotectin levels were studied for associations with the risk of new-onset hypertension, defined as systolic blood pressure of at least 140 mm Hg, diastolic blood pressure of at least 90 mm Hg, or the first recorded use of antihypertensives. Participants with hypertension at baseline were excluded. Median plasma calprotectin levels were 0.48 (0.34-0.66) mg/L, and median systolic blood pressure was 117 (109-126) mm Hg. Plasma calprotectin levels were significantly associated with the risk of new-onset hypertension (hazard ratio [HR], per doubling 1.30 [95% CI, 1.21-1.41]; P<0.001), also after adjustment for age and sex (HR, 1.26 [95% CI, 1.16-1.37]; P<0.001), but not after additional adjustment for potentially confounding factors, including baseline systolic blood pressure (HR, 1.00 [95% CI, 0.90-1.11]; P=0.996). Stratified analyses showed significant effect modification by sex (Pinteraction=0.023) and urinary albumin excretion (Pinteraction=0.004), with higher HRs in men (compared with women) and in individuals with higher urinary albumin excretion (>9.3 mg per 24 hours) compared with lower urinary albumin excretion (≤9.3 mg per 24 hours).

CONCLUSIONS

Higher plasma calprotectin levels are associated with an increased risk of new-onset hypertension in the general population. This association is dependent on baseline systolic blood pressure and is particularly prominent in men compared with women.

Creatine and creatinine quantified using nuclear magnetic resonance: A method validation study and clinical associations between circulating creatine and fatigue in kidney transplant recipients

BACKGROUND

A potential contributor to fatigue in kidney transplant recipients (KTR) may be impaired creatine homeostasis. We developed and validated a high-throughput NMR assay allowing for simultaneous measurement of circulating creatine and creatinine, and determined plasma creatine and estimated intramuscular creatine concentrations in KTRs, delineated their determinants and explored their associations with self-reported fatigue.

METHODS

An NMR assay was developed and validated for measurement of circulating creatinine and creatine concentrations. Plasma creatine and creatinine concentrations were measured in 618 KTR. Fatigue was assessed using the checklist individual strength. Associations of creatine parameters with fatigue was assessed using linear mixed effect models.

RESULTS

The NMR-based assay had good sensitivity, precision and demonstrated linearity across a large range of values. Among KTR, the mean age was 56 ± 13 years, 62% were men and eGFR was 54 ± 18 ml/min/1.73 m2. Plasma creatine concentration was 27 [19-39] µmol/L. Estimated intramuscular creatine concentration was 27 ± 7 mmol/kg. Higher plasma creatine concentration and higher estimated intramuscular creatine concentration were independently associated with a lower total fatigue score and less motivation problems.

CONCLUSION

An NMR method for measurement of circulating creatine and creatinine which offers the potential for accurate and efficient quantification was developed. The found associations suggest that improving creatine status may play a beneficial role in mitigating fatigue.

Plasma Neutrophil Gelatinase-Associated Lipocalin Associates with New-Onset Chronic Kidney Disease in the General Population

Circulating levels of neutrophil gelatinase-associated lipocalin (NGAL) have been associated with acute kidney injury and the severity and progression of chronic kidney disease (CKD). This study investigated its potential utility as a biomarker for the risk of new-onset CKD in a population-based cohort study. Individuals without CKD at baseline (n = 4660) who participated in the Prevention of REnal and Vascular ENd-stage Disease (PREVEND) prospective population-based cohort study in the Netherlands were included. Baseline plasma NGAL concentrations were investigated for their associations with new-onset CKD, defined as a composite outcome of an estimated glomerular filtration rate (eGFR) < 60 mL/min/1.73 m², urinary albumin excretion (UAE) > 30 mg/24-h, or both. Mean (±SD) plasma NGAL concentrations were 104.0 (±34.7) μg/L and median eGFR was 96 [IQR: 85.3-105.8] mL/min/1.73 m². After median follow-up of 8.3 [IQR: 7.8-8.9] years, 467 participants developed new-onset CKD. Plasma NGAL concentrations were significantly associated with an increased risk of new-onset CKD (hazard ratio [HR] per doubling 1.35 [95% CI: 1.11-1.63], p = 0.002), even after adjustment for potentially confounding factors (1.37 [1.09-1.73], p = 0.007) except baseline eGFR (1.09 [0.86-1.37], p = 0.490). In secondary analyses, plasma NGAL concentrations were significantly associated with new-onset CKD as defined by eGFR < 60 mL/min/1.73 m² alone (adjusted HR per doubling 2.54 [1.69-3.80], p < 0.001), which was abrogated after adjustment for eGFR (1.05 [0.69-1.59], p = 0.828), also when UAE > 30 mg/24-h was set as individual outcome (1.05 [0.82-1.35], p = 0.705). Higher plasma NGAL concentrations are associated with an increased risk of developing CKD in the general population. This association is dependent on renal function, and mainly driven by new-onset CKD as defined by renal function decline.