Unstably controlled systolic blood pressure trajectories are associated with markers for kidney damage in prediabetic population: results from the INDEED cohort study.

BACKGROUND: The association between blood pressure change and kidney damage in patients with abnormal blood glucose remains unclear. The current study aimed to identify systolic blood pressure (SBP) trajectories among the prediabetic population and to determine their association with kidney damage after a long-term follow-up. METHODS: The incidence, development, and prognosis of diabetic kidney disease (INDEED) study is nested in the Kailuan cohort study with a focus on population with diabetes and prediabetes. We screened out people with prediabetes in 2006 and with more than three SBP records from 2006 to 2014 biennially. We used the latent mixture modeling to fit five groups of trajectories of SBP. In 2016, estimated glomerular filtration rate (eGFR), urinary albumin creatinine ratio (uACR), and urinary α1-microglobulin (α1MG), transferrin and α1-acid glycoprotein were measured, and the association between SBP trajectories and these markers was analyzed by linear regression and logistic regression models. RESULTS: Totally, 1451 participants with prediabetes and without kidney damage were identified in 2006. Five heterogeneous SBP trajectories were detected based on the longitudinal data from 2006 to 2014, as low-stable group (n = 323), moderate-stable group (n = 726), moderate-increasing group (n = 176), moderate-decreasing group (n = 181), and high-stable group (n = 45). Linear regression analysis showed that the moderate and high SBP groups had lower eGFR, higher uACR, higher urinary α1MG, higher transferrin, and higher α1-acid glycoprotein than the low-stable group. Multivariable analysis attenuated the association but did not change the statistical significance. CONCLUSIONS: Prediabetic patients with persistent high-level SBP trajectory or gradually increased SBP trajectory had severer kidney damage during follow-up.

Associations of urinary epidermal growth factor and monocyte chemotactic protein-1 with kidney involvement in patients with diabetic kidney disease.

BACKGROUND: In diabetic kidney disease (DKD), it is important to find biomarkers for predicting initiation and progression of the disease. Besides glomerular damage, kidney tubular injury and inflammation are also involved in the development of DKD. The current study investigated the associations of urinary epidermal growth factor (uEGF), monocyte chemotactic protein-1 (MCP-1) and the uEGF:MCP-1 ratio with kidney involvement in patients at early and advanced stages of DKD. METHODS: The concentration of uEGF and uMCP-1 was measured in two Chinese population-based studies. The associations of uEGF, uMCP-1 and uEGF/MCP-1 with occurrence of DKD were studied in a cross-sectional study (n = 1811) of early stage DKD. Associations of baseline uEGF, uMCP-1 and uEGF/MCP-1 with kidney outcome were assessed in a longitudinal cohort (n = 208) of advanced-stage DKD. RESULTS: In both studies, positive correlations were found between uEGF/urine creatinine (Cr) and estimated glomerular filtration rate (eGFR) at sampling and between uMCP-1/Cr and urinary albumin:creatinine ratio (uACR). In the cross-sectional study, uEGF/Cr and uEGF/MCP-1 were negatively associated with the occurrence of DKD {odds ratio (OR) 0.65 [95% confidence interval (CI) 0.54-0.79], P < 0.001; 0.82 (0.71-0.94), P = 0.005, respectively}. In the longitudinal cohort, the uEGF:MCP-1 ratio correlated more closely with the percentage change of eGFR slope (r = 0.33, P < 0.001) as compared with uEGF/Cr or uMCP-1/Cr alone. The composite endpoint was defined as end-stage renal disease or 30% reduction of eGFR. These three markers were independently associated with composite endpoint after adjusting for potential confounders [hazard ratio 0.76 (0.59-1.00), P = 0.047 for uEGF/Cr; 1.18 (1.02-1.38), P = 0.028 for uMCP-1/Cr; 0.79 (0.68-0.91), P = 0.001 for uEGF/MCP-1]. CONCLUSION: In Chinese patients, urinary EGF/MCP-1 was negatively associated with the occurrence of DKD. Moreover, uEGF/MCP-1 had a better ability to predict the composite endpoint and correlated more closely with kidney function decline in advanced DKD as compared with uEGF/Cr or uMCP-1/Cr alone.

Prevalence and Disease Burden of Chronic Kidney Disease.

Chronic kidney disease (CKD) has been recognized as a leading public health problem worldwide. The global estimated prevalence of CKD is 13.4% (11.7-15.1%), and patients with end-stage kidney disease (ESKD) needing renal replacement therapy is estimated between 4.902 and 7.083 million. Through its effect on cardiovascular risk and ESKD, CKD directly affects the global burden of morbidity and mortality worldwide. The global increase in this disease is mainly driven by the increase in the prevalence of diabetes mellitus, hypertension, obesity, and aging. But in some regions, other causes such as infection, herbal and environmental toxins are still common. The large number of deaths for poor access to renal replacement therapy in developing countries, and also large increase of patients with ESKD in future, will produce substantial financial burden for even the most wealthy countries. Cost-effectiveness of preventive strategies to reduce the disease burden should be evaluated in relation to the local economic development and resource. Strategies reducing the cardiovascular risk in CKD still need further evaluation in large trials especially including patients with advanced kidney disease or end-stage kidney disease.

Sphingosine-1-phosphate and its receptors in anti-neutrophil cytoplasmic antibody-associated vasculitis.

BACKGROUND: C5a plays a crucial role in anti-neutrophil cytoplasmic antibody (ANCA)-mediated neutrophil recruitment and activation. Our previous studies found that the interaction between sphingosine-1-phosphate (S1P) and C5a plays an important role in the ANCA-mediated activation of neutrophils. In the current study, the expression levels of S1P in plasma and its receptors (S1PR1-5) in kidneys were analysed in patients with ANCA-associated vasculitis (AAV). METHODS: Plasma samples from 32 AAV patients in active stage and 20 AAV patients in remission were collected. The plasma levels of S1P were determined by an enzyme-linked immunosorbent assay (ELISA). The expression of S1PR1-5 in the renal specimens from 24 AAV patients was detected by immunohistochemistry. The associations of the plasma levels of S1P and renal expression of S1PRs with clinical and pathological parameters were analysed. RESULTS: The level of plasma S1P was significantly higher in AAV patients in active stage than it was in both patients in remission and in normal controls. Correlation analysis showed that the plasma levels of S1P correlated with the initial serum creatinine levels (r = 0.502, P = 0.003) and inversely correlated with the estimated glomerular filtration rate (eGFR; r = -0.358, P = 0.044) in AAV patients. Double-labelling immunofluorescence assay suggested that S1PR1-5 were expressed on endothelial cells in the glomeruli and that S1PR1, 4 and 5 were expressed on neutrophils. CONCLUSIONS: In AAV patients, the circulating S1P levels were elevated and the renal expression of S1PR2-5 was upregulated. The levels of circulating S1P and the renal expression of S1PR were associated with the renal involvement and disease activity of AAV.

Prevalence and risk factors for cardiovascular disease among chronic kidney disease patients: results from the Chinese cohort study of chronic kidney disease (C-STRIDE).

BACKGROUND: Although a high incidence of cardiovascular disease (CVD) is observed among chronic kidney disease (CKD) patients in developed countries, limited information is available about CVD prevalence and risk factors in the Chinese CKD population. The Chinese Cohort of Chronic Kidney Disease (C-STRIDE) was established to investigate the prevalence and risk factors of CVD among Chinese CKD patients. METHODS: Participants with stage 1-4 CKD (18-74 years of age) were recruited at 39 clinical centers located in 28 cities from 22 provinces of China. At entry, the socio-demographic status, medical history, anthropometric measurements and lifestyle behaviors were documented, and blood and urine samples were collected. Estimated glomerular filtration rate (eGFR) was calculated by the CKD-EPI creatinine equation. CVD diagnosis was based on patient self-report and review of medical records by trained staff. A multivariable logistic regression model was used to estimate the association between risk factors and CVD. RESULTS: Three thousand four hundred fifty-nine Chinese patients with pre-stage 5 CKD were enrolled, and 3168 finished all required examinations and were included in the study. In total, 40.8% of the cohort was female, with a mean age of 48.21 ± 13.70 years. The prevalence of CVD was 9.8%, and in 69.1% of the CVD cases cerebrovascular disease was observed. Multivariable analysis showed that increasing age, lower eGFR, presence of hypertension, abdominal aorta calcification and diabetes were associated with comorbid CVD among CKD patients. The odds ratios and 95% confidence intervals for these risk factors were 3.78 (2.55-5.59) for age 45-64 years and 6.07 (3.89-9.47) for age ≥65 years compared with age <45 years; 2.07 (1.28-3.34) for CKD stage 3a, 1.66 (1.00-2.62) for stage 3b, and 2.74 (1.72-4.36) for stage 4 compared with stages 1 and 2; 2.57 (1.50-4.41) for hypertension, 1.82 (1.23-2.70) for abdominal aorta calcification, and 1.70 (1.30-2.23) for diabetes, respectively. CONCLUSIONS: We reported the CVD prevalence among a CKD patient cohort and found age, hypertension, diabetes, abdominal aorta calcification and lower eGFR were independently associated with higher CVD prevalence. Prospective follow-up and longitudinal evaluations of CVD risk among CKD patients are warranted.

Heat exposure and hospitalizations for chronic kidney disease in China: a nationwide time series study in 261 major Chinese cities.

BACKGROUND: Climate change profoundly shapes the population health at the global scale. However, there was still insufficient and inconsistent evidence for the association between heat exposure and chronic kidney disease (CKD). METHODS: In the present study, we studied the association of heat exposure with hospitalizations for cause-specific CKD using a national inpatient database in China during the study period of hot season from 2015 to 2018. Standard time-series regression models and random-effects meta-analysis were developed to estimate the city-specific and national averaged associations at a 7 lag-day span, respectively. RESULTS: A total of 768,129 hospitalizations for CKD was recorded during the study period. The results showed that higher temperature was associated with elevated risk of hospitalizations for CKD, especially in sub-tropical cities. With a 1 °C increase in daily mean temperature, the cumulative relative risks (RR) over lag 0-7 d were 1.008 [95% confidence interval (CI) 1.003-1.012] for nationwide. The attributable fraction of CKD hospitalizations due to high temperatures was 5.50%. Stronger associations were observed among younger patients and those with obstructive nephropathy. Our study also found that exposure to heatwaves was associated with added risk of hospitalizations for CKD compared to non-heatwave days (RR = 1.116, 95% CI 1.069-1.166) above the effect of daily mean temperature. CONCLUSIONS: Short-term heat exposure may increase the risk of hospitalization for CKD. Our findings provide insights into the health effects of climate change and suggest the necessity of guided protection strategies against the adverse effects of high temperatures.

Association between alkaline phosphatase/albumin ratio and the prognosis in patients with chronic kidney disease stages 1-4: results from a C-STRIDE prospective cohort study.

Background: The alkaline phosphatase-to-albumin ratio (APAR) has been demonstrated to be a promising non-invasive biomarker for predicting prognosis in certain diseases. However, the relationship between APAR and prognosis in non-dialysis chronic kidney disease (CKD) patients remains unclear. This study aims to identify the association between APAR and prognosis among CKD stages 1-4 in China. Methods: Patients with CKD stages 1-4 were consecutively recruited from 39 clinical centers in China from 2011 to 2016. New occurrences of end-stage kidney disease (ESKD), major adverse cardiovascular and cerebrovascular events, and all-cause deaths were the outcome events of this study. Subdistribution hazard competing risk and Cox proportional hazards regression models were adopted. Results: A total of 2,180 participants with baseline APAR values were included in the analysis. In the primary adjusted analyses, higher APAR level [per 1-standard deviation (SD) increase in natural logarithm transformed (ln-transformed) APAR] was associated with 33.5% higher risk for all-cause deaths [adjusted hazard ratio (HR) 1.335, 95% confidence interval (CI) 1.068-1.670]. In addition, there was evidence for effect modification of the association between APAR and ESKD by baseline estimated glomerular filtration rate (eGFR) (P interaction < 0.001). A higher APAR level (per 1-SD increase in ln-transformed APAR) was associated with a greater risk of ESKD among participants with eGFR ≥ 60 ml/min/1.73 m2 (adjusted SHR 1.880, 95% CI 1.260-2.810) but not in eGFR < 60 ml/min/1.73 m2. Conclusion: Higher APAR levels in patients with CKD stages 1-4 seemed to be associated with an increased risk of all-cause death. Thus, APAR appears to be used in risk assessment for all-cause death among patients with CKD stages 1-4.

Urinary soluble CD90 predicts renal prognosis in patients with diabetic kidney disease.

BACKGROUND: Diabetic kidney disease (DKD), the major cause of chronic kidney disease, is associated with progressive renal fibrosis. The expression of CD90 correlated with fibrogenesis. However, the association between urinary soluble CD90 and renal disease severity, and whether it predicts outcomes in patients with DKD are still unclear. METHODS: Urinary sCD90 was measured in 285 patients with DKD in a longitudinal cohort. The composite endpoint was defined as end-stage renal disease (ESRD) or 40% reduction of estimated glomerular filtration rate (eGFR). The associations between urinary sCD90/Cr and clinical parameters, as well as renal outcomes were evaluated. Moreover, we detected the intrarenal CD90 expression, and demonstrated the correlation of intrarenal CD90 with clinico-pathological parameters. RESULTS: The urinary sCD90 level of DKD patients is significantly higher than diabetes patients without kidney injuries and healthy controls. We further showed urinary sCD90/Cr had significantly correlations with eGFR (r=-0.373, P<0.001), uACR (r=0.303, P<0.001), serum creatinine (r=0.344, P<0.001), and the eGFR slope (r=-0.27, P<0.001). Elevated urinary sCD90/Cr was an independent risk factor for the composite endpoint, adjustment for potential confounders in DKD patients (HR 1.20, 95% CI: 1.04-1.38, P=0.015). However, the CD90 expression in the renal tubulointerstitial compartment in DKD patients was significantly lower than healthy controls, and showed significant negative correlations with the interstitial fibrosis and tubular atrophy score (IFTA) (r=-0.3, P=0.047), and urinary sCD90/Cr (r=-0.399, P=0.029). CONCLUSIONS: This study provided evidence that urinary sCD90 could reflect the disease severity and serve as a valuable factor for renal outcome prediction in patients with DKD.

Association between serum uric acid level and mortality in China.

BACKGROUND: Whether there is an association between serum uric acid (SUA) level and risk of mortality in the general population remains unclear. Based on the China National Survey of Chronic Kidney Disease linked to mortality data, a population-based cohort study was performed to investigate the association between SUA level and all-cause mortality, cardiovascular disease (CVD) mortality, and cancer mortality in China. METHODS: The survival status of participants in the cross-sectional survey was identified from January 1, 2006 to December 31, 2017. Only 33,268 individuals with complete SUA data among the 47,204 participants were included in the analysis. We determined the rates of all-cause mortality, CVD mortality, and cancer mortality. We used Cox proportional hazards regression models to evaluate the effect of the SUA level on mortality. RESULTS: During a total of 297,538.4 person-years of follow-up, 1282 deaths occurred. In the Cox proportional hazards regression model, the rate of all-cause mortality, CVD mortality, and cancer mortality had a U-shaped association with SUA levels only in men, whereas no significant associations were detected in women. For all-cause mortality in men, the multivariable-adjusted hazard ratios (HRs) in the first, second, and fourth quartiles compared with the third quartile were 1.31 (95% confidence interval [CI] 1.04-1.67), 1.17 (95% CI 0.92-1.47), and 1.55 (95% CI 1.24-1.93), respectively. For CVD mortality, the corresponding HRs were 1.47 (95% CI 1.00-2.18), 1.17 (95% CI 0.79-1.75), and 1.67 (95% CI 1.16-2.43), respectively. For the cancer mortality rate, only a marginally significant association was detected in the fourth quartile compared with the third quartile with an HR of 1.43 (95% CI 0.99-2.08). CONCLUSIONS: The association between SUA and mortality differed by sex. We demonstrated a U-shaped association with SUA levels for all-cause and CVD mortalities among men in China.

Gender differences in age-related decline in glomerular filtration rates in healthy people and chronic kidney disease patients.

BACKGROUND: Since men with chronic kidney disease (CKD) progress faster than women, an accurate assessment of CKD progression rates should be based on gender differences in age-related decline of glomerular filtration rate (GFR) in healthy individuals. METHODS: A Chinese sample population from a stratified, multistage, and clustered CKD screening study was classified into healthy, at-risk, and CKD groups. The gender differences in estimated GFR (eGFR) and age-related eGFR decline were calculated for each group after controlling for blood pressure, fasting glucose levels, serum lipids levels, education level, and smoking status. After referencing to the healthy group, gender-specific multivariate-adjusted rates of decline in eGFR and differences in the rates of decline were calculated for both CKD and at-risk groups. RESULTS: The healthy, at-risk, and CKD groups consisted of 4569, 7434, and 1573 people, respectively. In all the 3 groups, the multivariate-adjusted eGFRs in men were lower than the corresponding eGFRs in women. In addition, in the healthy and at-risk groups, the rates of decline in eGFR in men were lower than the corresponding rates of decline in women (healthy group: 0.51 mLxmin-1x1.73 m-2·yr-1 vs. 0.74 mLxmin-1x1.73 m-2xyr-1 and at-risk group: 0.60 mLxmin-1x1.73 m-2xyr-1 vs. 0.73 mLxmin-1x1.73 m-2xyr-1). However, in the CKD group, the rates of decline in eGFR in men were similar to those in women (0.96 mLxmin-1x1.73 m-2xyr-1 vs. 0.91 mLxmin-1x1.73 m-2xyr-1). However, after referencing to the healthy group, the rates of decline in eGFR in men in the at-risk and CKD groups were greater faster than the corresponding rates in women (at-risk group: 0.10 mLxmin-1x1.73 m-2·yr-1 vs. -0.03 mLxmin-1x1.73 m-2xyr-1 and CKD group: 0.44 mLxmin-1x1.73 m-2·yr-1 vs. 0.15 mLxmin-1x1.73 m-2xyr-1). CONCLUSION: To accurately assess gender differences in CKD progression rates, gender differences in age-related decline in GFR should be considered.

Prevalence and associated factors of depressive symptoms among chronic kidney disease patients in China: Results from the Chinese Cohort Study of Chronic Kidney Disease (C-STRIDE).

OBJECTIVE: Depression is the most common mental disorder in patients with chronic kidney disease (CKD), and previous studies have found that: (a) depression can accelerate the progression of CKD; and (b) depression is an independent risk factor for hospitalization and death among patients with CKD. Therefore, the objective of the current study was to investigate the prevalence of depression in Chinese patients with CKD, and to identify variables associated with depression. METHODS: The study analyzed baseline data from a multicenter prospective cohort study of Chinese patients with chronic kidney disease (the C-STRIDE study). In all, 2995 participants in CKD stages 1 to 4 who completed a survey of depressive symptoms were included in the analyses. Depressive symptoms were assessed by the Zung Self-Rating Depression Scale (ZSDS). A ZSDS ≥50 was used as the cut-off score for the presence of depressive symptoms. Multivariable logistic regression was used to identify variables associated with depression. RESULTS: The mean estimated glomerular filtration rate (eGFR) in the study sample was 51.59±29.49 ml/min/1.73 m2. The prevalence of depressive symptoms was 37.8% and increased significantly with CKD stage. Being female, a higher level of education, a low income, a larger economic impact of disease cost, comorbid cardiovascular disease, anemia, and impaired physical ability were independently associated with depressive symptoms. CONCLUSION: Our study revealed that depressive symptoms were common among patients with CKD in China. Sociodemographic variables and the clinical characteristics of disease severity were strongly associated with depressive symptoms.

Incidence, Development, and Prognosis of Diabetic Kidney Disease in China: Design and Methods.

BACKGROUND: Although that glomerulonephritis is the major cause of end-stage renal disease in developing countries such as China, the increasing prevalence of diabetes has contributed to the changing spectrum of predialysis chronic kidney disease. Recent studies have revealed an increased proportion of patients with diabetic kidney disease (DKD) in hemodialysis populations in large cities in China. However, studies regarding the clinical phenotype of DKD in China are extremely limited. The incidence, development, and prognosis of diabetic kidney disease (INDEED) study aims to investigate the incidence, progression, and prognosis of DKD, as well as the associated genetic, behavioral, and environmental factors and biomarkers in patients with DKD in China. METHODS: INDEED study is a prospective cohort study based on all participants with diabetes in the Kailuan study, which is a general population-based cohort study in northern China. Altogether, over 10,000 participants with diabetes will be followed biennially. Questionnaires documenting general characteristics, behavioral and environmental factors, and medical history will be administrated. Anthropometric measurements and a series of laboratory tests will be performed in one central laboratory. The DNA, plasma, and urine samples of every participant will be stored in a biobank for future research. CONCLUSIONS: INDEED study will provide essential information regarding the clinical phenotype and prognosis of patients with DKD in China and will be valuable to identify factors and biomarkers associated with patients with DKD in China.

Characteristics and comparison between diabetes mellitus and non-diabetes mellitus among chronic kidney disease patients: A cross-sectional study of the Chinese Cohort Study of Chronic Kidney Disease (C-STRIDE).

Although the prevalence of chronic kidney disease (CKD) and diabetes mellitus (DM) is increasing globally, information on Chinese CKD patients with DM is lacking. A total of 3499 pre-dialysis CKD patients from across China were enrolled in the Chinese Cohort Study of Chronic Kidney Disease (C-STRIDE) between November 2011 and April 2016. We divided the C-STRIDE patients into CKD with DM and CKD without DM groups and compared their clinical, demographic, and laboratory data in this cross-sectional study. CKD patients with DM were older, had a higher male-to-female ratio, and had more complications than CKD patients without DM. Age, smoking, and 24-h urinary protein levels were associated with co-occurrence of CKD and DM. Less than 50% of patients in either group took antilipemic, cardiovascular, cerebrovascular, or anti-anemic drugs. In addition, only 18.38% of CKD patients with DM had undergone a renal biopsy, and diabetic nephropathy was confirmed in 35.4% of them. Our findings suggest that several types of medication and renal biopsies should be used more frequently in the treatment of Chinese CKD patients with DM.

Mineral and Bone Disorder and Its Association with Cardiovascular Parameters in Chinese Patients with Chronic Kidney Disease.

BACKGROUND: Mineral and bone disorder (MBD), especially hyperphosphatemia, is an independently risk factor for adverse prognosis in patients with chronic kidney disease (CKD). However, CKD-MBD among Chinese population was poorly studied. This study aimed to investigate the status of MBD and its association with cardiovascular parameters in Chinese patients with predialysis CKD. METHODS: Chinese Cohort Study of Chronic Kidney Disease (C-STRIDE) is a prospective multicenter cohort study involving predialysis CKD patients in China. Markers of MBD, including serum phosphorus, calcium, and intact parathyroid hormone, were measured in baseline samples at the patients' entry. The association between serum phosphorus and abdominal aortic calcification (AAC), left ventricular hypertrophy (LVH) were examined by logistic regression models. RESULTS: Altogether 3194 predialysis patients with mean estimated glomerular filtration of 51.8 ± 33.1 ml.min-1.1.73 m-2 were included. The proportion of patients with hyperphosphatemia were 2.6%, 2.9%, 6.8%, and 27.1% in CKD Stages 3a, 3b, 4, and 5, respectively. Moreover, 71.6% of the patients with hyperphosphatemia did not receive any phosphate-binder (PB). Lateral abdominal X-rays were obtained in 2280 patients, 9.8% of the patients were diagnosed as having AAC. Altogether 2219 patients had data of echocardiography, and 13.2% of them were diagnosed with LVH. Multivariate logistic regression analysis showed that serum phosphorus was independently associated with the presence of AAC and LVH. CONCLUSIONS: In Chinese patients with CKD, the percentage of hyperphosphatemia is comparable to that of other countries while the usage of PBs is suboptimal. The prevalence of vascular calcification in Chinese patients is relatively lower compared with the Caucasian population.

Circulating Level of Neutrophil Extracellular Traps Is Not a Useful Biomarker for Assessing Disease Activity in Antineutrophil Cytoplasmic Antibody-Associated Vasculitis.

Antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) is a group of life-threatening disorders, and frequently affects the kidneys. This study investigated whether the circulating neutrophil extracellular traps (NETs) levels were associated with disease activity of AAV. We collected serum samples from 34 patients with AAV in active stage and 62 patients with AAV in remission. Cell free DNA in serum was quantified using the Quant-iT PicoGreen assay. NETs associated MPO-DNA complexes, citrullinated-histone H3-DNA (cit-H3-DNA) complexes and the concentration of deoxyribonuclease I (DNase I) were quantified using ELISA. The activity of DNase I was quantified using radial enzyme-diffusion method. Associations between circulating levels of NETs with clinico-pathological parameters were analyzed. Serum levels of NETs in active AAV patients were significantly higher than those in healthy controls, and the level of cell free DNA correlated with C-reactive protein (CRP). However, no correlation was found between MPO-DNA complexes or cit-H3-DNA complexes level and CRP. Also there was no significant correlation between NETs level and initial serum creatinine, estimated glomerular filtration rate (eGFR), crescents formation or Birmingham Vasculitis Activity Score (BVAS). Furthermore, there was no significant difference of serum levels of cell free DNA or MPO-DNA complexes between active stage and remission of AAV. In conclusion, circulating levels of NETs cannot be used as a biomarker to assess disease activity in AAV patients.

Immunofixation electrophoresis was highly specific for the diagnosis of renal light-chain amyloidosis.

BACKGROUND: Renal light-chain amyloidosis (AL) is one of the common causes of massive proteinuria and nephrotic syndrome, especially in elderly patients. This study aimed to evaluate the sensitivity and specificity of serum and urine using immunofixation electrophoresis (IFE) in the diagnosis of renal AL amyloidosis in patients older than 40 years. METHODS: Patients receiving native renal biopsy in the hospital who meet the following criteria were recruited in this retrospective study: (1) proteinuria excretion ≥3.5 g/24 hr; (2) age ≥ 40 years when receiving renal biopsy and (3) biopsy-proven glomerulopathy. Serum and urine monoclonal free immunoglobulin light chains were detected using IFE. RESULTS: A total of 625 patients were recruited. Of them, 32 patients (5.12%) were diagnosed as renal AL amyloidosis. The specificities of serum, urine and serum combined urine IFE in the total 625 patients (ie, monoclonal free immunoglobulin light chain in serum or urine) for diagnosis of renal AL amyloidosis were 98.6%, 98.0% and 97.6%, respectively. For patients older than 60 years, the specificities of serum, urine and serum combined urine IFE for diagnosis of renal AL amyloidosis were 98.5%, 98.0% and 97.6%, respectively and the sensitivity of serum, urine and serum combined urine IFE for diagnosis of renal AL amyloidosis were 68.6%, 81.3% and 81.3%, respectively. CONCLUSION: Serum or urine IFE was highly specific for renal AL amyloidosis for patients older than 40 years with nephrotic-range proteinuria. In older patients (>60 years), both the sensitivity and specificity of IFE for renal AL amyloidosis were high. Combination of serum and urine IFE could improve the sensitivity with comparable specificity.