Reference intervals and factors contributing to serum cystatin C levels in a Chinese population

Estimating eGFR using serum creatinine or cystatin C in healthy Vietnamese population

Very few studies worldwide have assessed the estimated glomerular filtration rate (eGFR) using serum cystatin C (ScysC) in comparison to the gold standard measured glomerular filtration rate (mGFR) with a gamma camera technique using 99m-Technetium-Diethylene Triaminepentoacetic Acid (99mTc-DTPA). To determine the eGFR formula with the most accurate estimate of glomerular filtration rate when compared with mGFR in a healthy population in Vietnam. We conducted a cross-sectional descriptive study of more than 100 adults without hypertension. The study subjects were examined for general characteristics and blood biochemistry tests to assess eGFR, and the glomerular filtration rate was measured using 99mTc-DTPA with the Gates technique to record mGFR. The estimated values of the eGFR formula were evaluated and compared with the actual mGFR using 99mTechnetium-DTPA. Serum creatinine (Scr) concentration showed a significant difference between males and females: 0.9 ± 0.1 versus 0.8 ± 0.1 (P < .001), while ScysC concentration did not show this difference. The mGFR in the age groups < 40, 40 to 59, and ≥ 60: 105.0 ± 9.9, 94.8 ± 8.6, and 93.4 ± 10.6, respectively (P < .001). The eGFR-CKD-EPI-cystatin C 2012 formula showed the highest positive correlation with mGFR (ΔGFR = -1.6, R = 0.68, P < .001). eGFR calculated using cystatin C does not require sex adjustment, whereas, for creatinine, sex adjustment is necessary. The eGFR-CKD-Epi-CysC formula showed the lowest difference and a strong correlation with mGFR.

Transcriptomics-based analysis reveals the nephrotoxic effects of triphenyltin (TPT) on SD rats by affecting RAS, AQPs and lipid metabolism

Triphenyltin (TPT) is a class of organotin compounds that are extensively used in industry and agriculture. They have endocrine-disrupting effects and cause severe environmental contamination. Pollutants may accumulate in the kidneys and cause pathological complications. However, the mechanism of TPT's toxicological effects on the kidney remains unclear. This study aimed to investigate the toxic effects and mechanism of action of TPT exposure on renal impairment in rats. Male SD rats were divided into four groups: the Ctrl group (control group), TPT-L group (0.5 mg/kg/d), TPT-M group (1 mg/kg/d), and TPT-H group (2 mg/kg/d). After 28 days of exposure to TPT, we observed the morphology and structure of kidney tissue using HE, PASM, and Masson staining. We also detected serum biochemical indexes, performed transcriptome sequencing of rat kidney tissue using RNA-seq. Furthermore, protein expression levels were measured through immunohistochemistry and gene expression levels were determined using RT-qPCR. The study results indicated a decrease in kidney weight and relative kidney weight after 28 days of exposure to TPT. Additionally, TPT caused damage to kidney structure and function, as evidenced by HE staining, PASM staining, and serum biochemical tests. Transcriptomics identified 352 DEGs, and enrichment analyses revealed that TPT exposure primarily impacted the renin-angiotensin system (RAS). The expression levels of water channel proteins were reduced, and the expression levels of RAS and lipid metabolism-related genes (Mme, Ace, Fasn, Cyp4a8, Cpt1b and Ppard) were significantly decreased in the TPT-treated group. In summary, exposure to TPT may impair renal structure and function in rats by affecting RAS, AQPs, and lipid metabolism.

Age-adjusted reference values and influencing factors of cystatin C in healthy Chinese population

BACKGROUND

Normative distribution of serum cystatin C and relationship with sex and age in healthy adult Chinese population is unknown.

METHODS

This is a prospective cohort study. Adult subjects (18 years of age and older) who underwent annual health examination at the Health Management Center in Sir Run Run Hospital were eligible. Subjects with major diseases, e.g., hypertension, diabetes, chronic kidney disease, obesity (body mass index ≥ 28 kg/m²) were excluded from the analysis. Multivariate logistic regression analysis was conducted to identify risk factors of elevated cystatin C (> 1.03 mg/L). Data are shown as median and 95% confidence interval (CI).

RESULTS

The final analysis included a total of 10,640 subjects (40 ± 12 years, 52% men). The median serum cystatin C concentration was 0.73 mg/L (95% CI 0.52-1.03 mg/L) in the overall analysis, 0.79 (95% CI 0.59-1.07 mg/L) in men, and 0.67 (95% CI 0.49-0.95 mg/L) in women. In the multivariate regression analysis, elevated cystatin C was independently associated with the male sex (odds ratio 1.94; 95% CI 1.07-3.52), older age (odds ratio 1.04 every year; 95% CI 1.02-1.06), higher body mass index (odds ratio 1.70; 95% CI 1.01-2.83), uric acid (odds ratio 1.00; 95% CI 1.00-1.01), and β2-microglobulin (odds ratio 39.35; 95% CI 22.90-67.64).

CONCLUSION

The median serum cystatin C concentration was 0.73 (95% CI 0.52-1.03 mg/L) in healthy adult Chinese population, 0.79 (95% CI 0.59-1.07 mg/L) in men, and 0.67 (95% CI 0.49-0.95 mg/L) in women. Elevated cystatin C was associated with the male sex, older age and higher body mass index.

Correlation between retinal vascular parameters and cystatin C in patients with type 2 diabetes

AIMS

To investigate the relationship between retinal vascular parameters and cystatin C in patients with type 2 diabetes in northwestern China.

METHODS

This was a cross-sectional study of 1689 patients with type 2 diabetes. A validated fully automated computer program was used to extract retinal vascular parameters from the entire vascular tree. Multiple logistic regression analyses were conducted to investigate the relationship between these vascular measurements and cystatin C.

RESULTS

For retinal vascular geometrical measurements, smaller arteriolar fractal dimension was related to high cystatin C after adjusting for multiple variables (odds ratio [OR] 0.149, 95% CI 0.042-0.532). For retinal vascular caliber measurements, narrower central and middle arteriolar calibers were related to high cystatin C after adjusting for multiple variables (central: OR 0.922, 95% CI 0.886-0.960; middle: OR 0.940, 95% CI 0.901-0.981). Wider central, middle and peripheral venular calibers were associated with high cystatin C after adjusting for multiple variables (central: OR 1.058, 95% CI 1.003-1.117; middle: OR 1.094, 95% CI 1.040-1.150; peripheral: OR 1.075, 95% CI 1.023-1.130).

CONCLUSIONS

Multiple retinal vascular geometrical and caliber measurements are associated with cystatin C in type 2 diabetic patients. Further studies are needed to explore whether these retinal vascular changes can predict the incidence and progress of diabetic nephropathy.

Reference intervals for serum cystatin C in neonates and children 30 days to 18 years old

BACKGROUND

Serum cystatin C (CysC) is a promising biomarker of kidney function, which has higher accuracy and sensitivity when compared with creatinine. To better utilize serum CysC in clinical practice, this study aimed to establish continuous paediatric reference intervals (RIs) for serum CysC.

METHODS

The study subjects consisted of healthy term neonates and children aged 30 days to 18 years. Venous blood samples were collected and serum CysC levels were measured using the immunoturbidimetric measurement principle. Fractional polynomial regression model and quantile regression was applied in the statistical analysis to generate continuous RIs.

RESULTS

A total of 378 samples with equal numbers of males and females were analysed for serum CysC. No outliers were found in this analysis. The continuous RIs are presented as equations and graphical scatterplots.

CONCLUSIONS

This study established continuous paediatric reference intervals (RIs) for serum CysC in healthy term neonates and children. The continuous RIs generated from this study show age-based dynamic changes as well as blood group and gender-specific differences for serum CysC. Graphical abstract.

Reference intervals for serum cystatin C and serum creatinine in an adult sub-Saharan African population

Background

Serum cystatin C (SCysC) and serum creatinine (SCr) are two biomarkers used in common practice to estimate the glomerular filtration rate (GFR). For SCysC and SCr to be used in a given population, normal values need to be determined to better assess patients. This study aimed to determine SCysC and SCr reference intervals (RIs) in a Cameroonian adult population and factors susceptible of influencing them.

Methods

We carried-out a cross-sectional study from November 2016 to May 2017 in Yaoundé, Cameroon. Participants were Cameroonians aged 18 years and above, residing inside the country and found in good health at study inclusion. SCysC and SCr were determined by particle-enhanced turbidimetric immunoassay standardized against the ERM-DA471/IFCC reference material and by the IDMS reference modified Jaffe kinetic method, respectively. RIs were determined using the 2.5th and 97.5th percentiles and their respective 90% confidence intervals (CIs). The quantile regression served to identify potential factors likely influencing SCysC and SCr values.

Results

We included 381 subjects comprising 49.1% females.. RIs for SCysC varied between 0.57 (90%CI: 0.50–0.60) and 1.03 mg/L (90%CI: 1.00–1.10) for females, and from 0.70 (90%CI: 0.60–0.70) to 1.10 mg/L (90%CI: 1.10–1.20) for males. Concerning SCr, its RIs ranged from 0.58 (90%CI: 0.54–0.61) to 1.08 mg/dL (90%CI: 1.02–1.21) for females, and from 0.74 (90%CI: 0.70–0.80) to 1.36 mg/dL (90%CI: 1.30–1.45) for males. Men had significantly higher SCysC and SCr values than women (p <  0.001). Likewise, subjects aged 50 years and above had higher SCysC values in comparison to younger age groups (p <  0.001), which was not the case for SCr values (p = 0.491). Moreover, there was a positive and significant correlation between SCysC and SCr in women (ρ = 0.55, p < 0.001), in men (ρ = 0.39, p < 0.001) and globally (ρ = 0.58; p < 0.001). Furthermore, the sex influenced both biomarkers’ values across all quantile regression models while age and body surface area (BSA) influenced them inconsistently.

Conclusion

This study has determined serum cystatin C and serum creatinine reference intervals in an adult Cameroonian population, whose interpretations might take into account the patient’s sex and to a certain extent, his/her age and/or BSA.

Electronic supplementary material

The online version of this article (10.1186/s12907-019-0086-7) contains supplementary material, which is available to authorized users.

The prevalence of hyperuricemia and its correlates in Ganzi Tibetan Autonomous Prefecture, Sichuan Province, China

Background

Hyperuricemia is a common and serious public health problem. There has been no broad epidemiological survey of hyperuricemia in China, especially in Tibetan area. This study was therefore investigated the prevalence of hyperuricemia and its correlated factors among people aged 18–85 years in Ganzi Tibetan Autonomous Prefecture, Sichuan Province, China.

Methods

We carried out a cross-sectional study among 3093 participants in Ganzi Tibetan Autonomous Prefecture using questionnaires in face-to-face interviews, anthropometric measurements and biochemical tests. We included 1416 subjects with complete data including serum uric acid and medical history to analyze the prevalence of hyperuricemia and correlated factors. Hyperuricemia was defined as a fasting serum uric acid level higher than 420 μmol/L in men and 360 μmol/L in women.

Results

The overall crude prevalence of hyperuricemia was 37.2%, and was greater in men than women (41% vs 34.4%, P = 0.011). The age-adjusted prevalence was 33.0%. Characteristics linked to hyperuricemia were farmers-herdsmen (OR: 1.749, 95% CI: 1.022–2.992), low to moderate education level (low OR:1.57, 95% CI: 1.102–2.237; moderate OR: 1.86, 95% CI: 1.167–2.963), current drinking (OR: 1.795, 95% CI: 1.193–2.702), hypertension (OR: 1.48, 95% CI: 1.091–2.006), higher body mass index (1 unit increase) (OR: 1.116, 95% CI: 1.077–1.156) and higher serum creatinine (1 unit increase) (OR: 1.046, 95% CI: 1.034–1.059). Serum uric acid was positively related to triglycerides and total cholesterol and negatively related to high density lipoprotein cholesterol in all subjects. Hyperuricemia was a risk factor for high triglyceride ((OR: 2.13, 95% CI: 1.156–3.9266) and high total cholesterol (OR: 2.313, 95% CI: 1.364–3.923) in men and for high low-density lipoprotein cholesterol (OR: 2.696, 95% CI: 1.386–5.245) in women.

Conclusion

There is a high prevalence of hyperuricemia in Ganzi Tibetan Autonomous Prefecture. The government needs to prevent and manage hyperuricemia in this area.

Are cystatin C-based equations superior to creatinine-based equations for estimating GFR in Chinese elderly population?

PURPOSE

Cystatin C has been proposed as a surrogate marker of kidney function. The elderly population accounts for the largest proportion of chronic kidney disease (CKD) patients. The aim of this study was to assess the diagnostic value of serum cystatin C and compare the applicability of cystatin C-based equations with serum creatinine (Scr)-based equations for estimating glomerular filtration rate (GFR).

METHODS

The estimated GFR (eGFR) values from six cystatin C-based equations (Tan, MacIsaac, Ma, Stevens1-3) and three Scr-based equations (CG, MDRD, CKD-EPI) were compared with the reference GFR (rGFR) values from 99mTc-DTPA renal dynamic imaging method.

RESULTS

A total of 110 elderly Chinese (60-92 year, 71.05±7.62 year) were enrolled. Cystatin C had better diagnostic value than Scr (relationship coefficient with rGFR: cystatin C -0.847 vs. Scr -0.729, P<0.01; sensitivity: cystatin C 0.90 vs. Scr 0.55, P<0.01; AUCROC: cystatin C 0.857 vs. Scr 0.757, P<0.01). All the equations predicted GFR more accurately for rGFR≥60 ml/min/1.73 m2 than for rGFR<60 ml/min/1.73 m2. Most equations had acceptable accuracy. The cystatin C-based equations deviated from rGFR by -12.78 ml/min/1.73 m2 to -2.12 ml/min/1.73 m2, with accuracy varying from 64.6 to 82.7%. The Scr-based equations deviated from rGFR by -5.37 ml/min/1.73 m2 to -0.68 ml/min/1.73 m2, with accuracy varying from 77.3 to 79.1%. The CKD-EPI, MacIsaac and Ma equations predicted no bias with rGFR (P>0.05), with higher accuracy and lower deviation in the total group. The MacIsaac, CKD-EPI and Stevens3 equations could be optimal for those with normal and mildly impaired kidney function, whereas the Ma equation for those with CKD.

CONCLUSION

Cystatin C is a promising kidney function marker. However, not all cystatin C-based equations could be superior to the Scr-equations.