Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P01034 (cystatin C)
 3,397 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Homocysteinemia is an independent risk factor for cardiovascular disease, but information on its association with type 2 diabetes and mild renal dysfunction is limited. Plasma total homocysteine (tHcy) concentration is partly determined by renal plasma clearance. Serum cystatin C (Cys C) concentration has been introduced as a marker of renal function, specifically as an indicator of glomerular filtration rate (GFR). The aim of this study was to explore the relationships among tHcy, creatinine clearance (Ccr), serum Cys C, and microalbuminuria in a population with type 2 diabetes. Fasting plasma tHcy, serum homocysteine-related vitamins (folate and vitamin B12), serum Cys C, serum creatinine, urine microalbumin, and creatinine clearance were determined in 75 type 2 diabetic patients and 40 healthy control subjects. The patients were assigned to two groups based on urinary albumin excretion (UAE): normoalbuminuric (NAU, UAE < 30 mg/24 hr, n = 35) and microalbuminuric (MAU, UAE 30-300 mg/24 hr, n = 40). Ccr was calculated using the Cockroft-Gault formula. Plasma Hcy levels were determined by HPLC with fluorescence detection and serum Cys C by automated particle enhanced immunoturbidimetry. Plasma tHcy levels were significantly higher in normoalbuminuric and microalbuminuric patients than in controls (10.64 +/- 0.53, 13.29 +/- 0.78, 6.91 +/- 0.37 mmol/L, respectively). Serum Cys C levels in microalbuminuric diabetics were higher than in normoalbuminurics and controls (1.36 +/- 0.06, 1.12 +/- 0.04, 1.10 +/- 0.06 mg/ L, respectively). Positive correlations were noted between tHcy and Cys C levels in normoalbuminuric and microalbuminuric diabetics (r = 0.72, r = 0.64, respectively). Homocysteine and creatinine concentrations were correlated in both diabetic groups (r = 0.89, r = 0.93, NAU and MAU, respectively). Elevated plasma total homocysteine concentrations in type 2 diabetics suggest an association between homocysteinemia and deterioration of renal function, evidenced by increased serum creatinine and Cys C, Ccr, and microalbuminuria. These findings implicate homocysteinemia in the relationship between diabetic nephropathy and cardiovascular complications of diabetes.
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PMID:Association between homocysteinemia and renal function in patients with type 2 diabetes mellitus. 1217 91

We determined the relationship between the levels of serum cystatin C or creatinine (s-Cr) and the grade of creatinine clearance (CCr) in patients with various glomerular diseases. Serum samples from 96 patients with glomerular diseases were obtained from our hospital. The levels of serum cystatin C were measured using the Dade Behring Cystatin C assay with the automated Dade Behring Nephelometer II (BNII). CCr levels were classified into six groups according to the Guidelines of the Japanese Society of Nephrology as follows: grade 1 (normal renal function); grade 2 (slight decrease of renal function); grade 3 (moderate decrease of renal function); grade 4 (severe decrease of renal function); grade 5 (renal failure), and grade 6 (uremia). The mean levels of serum cystatin C in grade 3 patients were significantly higher than those in grade 1. The mean levels of serum cystatin C in grades 4, 5 and 6 patients were also significantly higher than those in grade 1. However, the mean levels of serum Cr in grade 3 patients were not significantly higher than those in grade 1. The levels of s-Cr in grades 4, 5 or 6 patients were significantly higher than those in grade 1. In this study, an increase of serum cystatin C levels occurred earlier than that of s-Cr in various glomerular diseases. It appears that the levels of serum cystatin C may provide early prognostic marker of patients with various glomerular diseases rather than the levels of s-Cr.
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PMID:Serum cystatin C is a more sensitive marker of glomerular function than serum creatinine. 1218 9

Iohexol clearance is an accepted, but time-consuming assay for the measurement of glomerular filtration rate (GFR). We investigated if simpler methods could predict GFR. Sixty-nine children with hematological-oncological disorders participated. A linear relationship was established by regression analysis between iohexol clearance ( n=734) and 1/s-creatinine ( r=0.45, n=727), s-cystatin C ( r=0.41, n=518), and the Schwartz ( r=0.45, n=723), Counahan-Barratt ( r=0.48, n=723), and modified Counahan-Barratt formulae ( r=0.48, n=723). These correlations improved when one GFR measurement per individual was compared with each of the five parameters. We further investigated if iohexol clearance could accurately be replaced. The degree of variation in predicting GFR was estimated by the standard deviation of the residuals (S(res)). For 1/s-creatinine and s-cystatin C, S(res) was 39 and 38 ml/min per 1.73 m(2). For the formulae of Schwartz, Counahan-Barratt, and modified Counahan-Barratt, the S(res) was 43, 40, and 40 ml/min per 1.73 m(2), respectively. The wide variations of the S(res) were not reduced when one GFR measurement per child was compared with the five parameters. Due to the large deviation in predicting GFR, we conclude that the five alternative methods studied cannot replace iohexol clearance for measurement of GFR.
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PMID:Correct evaluation of renal glomerular filtration rate requires clearance assays. 1237 15

In previous studies a high frequency of elevated plasma tHcy concentrations has been observed in psychogeriatric patients (40-50%), but the main cause of these increased concentrations could not be established with certainty. Impaired renal function could partly contribute to elevated plasma tHcy concentrations in psychogeriatric patients. Therefore, in the present study, cystatin C was used as a sensitive marker for glomerular filtration. A linear regression analysis including age, blood folate, serum cobalamin, serum cystatin C and serum creatinine showed that only serum creatinine (p<0.001) and blood folate (p<0.001) independently predicted plasma tHcy concentration. However, about 44% of the patients with elevated plasma tHcy concentrations had signs of reduced glomerular filtration rate, as judged by increased serum cystatin C, whereas only about 13% of the patients with normal concentrations of plasma tHcy had signs of reduced glomerular filtration rate. This finding indicates that renal impairment may to some extent contribute to the elevated plasma tHcy concentration, even though serum cystatin C did not independently predict plasma tHcy concentration.
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PMID:Role of impaired renal function as a cause of elevated plasma homocysteine concentration in psychogeriatric patients. 1238 85

Serum cystatin C more accurately reflects glomerular filtration rate (GFR) in pediatric renal transplant recipients than serum creatinine. Nineteen pediatric renal transplant recipients, 15 male and 4 female, ranging in age from 8.35 yr to 19.06 yr (median 13.52 yr), were enrolled in the study over an 18-month period. Twenty-eight measurements of 99mTc-DTPA GFR were compared with simultaneous measurements of serum cystatin C and Cr. Linear regression analysis, Pearson correlation coefficients and analysis of variance (anova) were used to determine the relationship between creatinine, cystatin C and GFR. The correlation coefficients (R2) for the relationship of 1/Cr to DTPA-GFR and for 1/cystatin C to DTPA-GFR were 0.63 and 0.58, respectively. There was no significant difference between serum cystatin C and serum creatinine as markers of GFR. Serum cystatin C, which costs more to measure than serum creatinine, offers no advantage in monitoring the renal function of pediatric renal transplant recipients.
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PMID:The relationship between serum creatinine, serum cystatin C and glomerular filtration rate in pediatric renal transplant recipients: a pilot study. 1239 Apr 19

OBJECTIVE-Assessment and follow-up of early renal dysfunction is important in diabetic nephropathy. Plasma creatinine is insensitive for a glomerular filtration rate (GFR) >50 ml/min and creatinine clearance is unwieldy and subject to collection inaccuracies. We aimed to assess the reproducibility, reliability, and accuracy of plasma cystatin C as a measure of GFR ranging from normal to moderate impairment due to type 1 diabetes in the presence of a normal plasma creatinine concentration. RESEARCH DESIGN AND METHODS-A sensitive immunoturbidimetric cystatin C assay was examined in 29 subjects with type 1 diabetes and 11 nondiabetic subjects. Duplicate measurements of the following were collected from each subject, 2 weeks apart: cystatin C, enzymatic plasma creatinine, 24-h creatinine clearance, GFR estimated from plasma creatinine by the Cockcroft-Gault equation, and iohexol clearance as a gold standard. RESULTS-Iohexol clearance ranged from 35 to 132 ml. min(-1). 1.73 m(-2). Plasma cystatin C compared well with the other clinically used tests. The reliability of cystatin C, as assessed by the discriminant ratio, was superior to creatinine clearance (3.4 vs. 1.5, P < 0.001) and the correlation of cystatin C with iohexol clearance (Rs -0.80) was similar to that of creatinine clearance (Rs -0.74) and superior to that of plasma creatinine and the Cockcroft-Gault estimate (Rs -0.54 and 0.66, respectively). Duplicate estimations were used to provide an unbiased equation to convert plasma cystatin C to GFR. CONCLUSIONS-Based on this study, cystatin C is a more reliable measure of GFR than creatinine clearance, is more highly correlated with iohexol clearance than plasma creatinine, and is worthy of further investigation as a clinical measure of GFR in type 1 diabetes.
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PMID:Clinical usefulness of cystatin C for the estimation of glomerular filtration rate in type 1 diabetes: reproducibility and accuracy compared with standard measures and iohexol clearance. 1240 47

This is a secondary analysis of data from a cross-sectional study to evaluate the diagnostic efficiency of cystatin C as a marker of the glomerular filtration rate in the elderly. Thirty patients (15 male, 15 female, mean age 75.4 +/- 7.1 years) attending a geriatric ward were enrolled. Exclusion criteria were previously diagnosed renal disease, dementia and heart failure (NYHA III or IV). Cystatin C in serum was determined by a particle-enhanced turbidimetric assay. Inulin clearance was assessed using a single-shot method. Also, Cockcroft-Gault formula was calculated. Twelve patients had a reduced glomerular filtration rate (<70 ml/min/ 1.73 m2). The mean values were 88.4 micromol/l (+/- 27.7) for serum creatinine, 1.57 mg/l (+/- 0.34) for cystatin C and 88.7 ml/min/1.73 m2 (+/- 34.6) for inulin clearance. Maximum efficiency was 0.73 for serum creatinine (cut-off limit 82 micromol/l), 0.67 for cystatin C (cut-off limit 1.63 mg/l) and 0.8 for Cockcroft and Gault estimation (cut-off limit 54 ml/min/1.73 m2). A receiver operating characteristics (ROC) analysis did not show any differences between the various methods. Therefore, cystatin C in serum may not improve the diagnostic efficiency in detecting a reduced glomerular filtration rate in the elderly. Furthermore, normal ranges for serum creatinine in the elderly might need to be adjusted.
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PMID:Diagnostic efficiency of cystatin C and serum creatinine as markers of reduced glomerular filtration rate in the elderly. 1252 Dec 32

Only with prospective randomized controlled trials is it possible to evaluate the several immunosuppressive regimens available to renal allograft recipients. Commonly used surrogate markers of clinical outcome, such as patient and graft survival, are constantly improving. Current immunosuppressive protocols have improved 1-yr graft survival to over 90%. The small differences in graft survival among the various immunosuppressive regimes require large patient cohorts in order to establish statistical significance. Such studies are often difficult to conduct in a timely manner, particularly in children. This necessitates the search for better surrogate markers sensitive enough to detect differences in smaller cohorts and in a shorter period of time. While the degree of fibrosis in transplant biopsies might well predict long-term graft survival, protocol biopsies are expensive, invasive, and unpopular among clinicians. In native kidneys, glomerular filtration rate (GFR) closely correlates with disease progression and interstitial fibrosis and appears to be well positioned as a less invasive surrogate marker for long-term outcome. Nonetheless, the ideal marker for GFR remains obscure. Serum creatinine has several major drawbacks, making it a poor predictor of GFR. This review discusses the several methods used to estimate or measure GFR with emphasis on 125I-iothalamate clearance and serum cystatin C (cys-C). Of all the serum markers, cys-C is the most reliable and the most promising. However, cys-C and other endogenous markers cannot replace the diagnostic sensitivity and reliability of radiolabeled markers of GFR such as 125I-iothalamate in renal transplant clinical trials. Unfortunately, clearance of most radiolabeled markers of GFR including 125I-iothalamate remain costly and time consuming.
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PMID:Glomerular filtration rate as a putative 'surrogate end-point' for renal transplant clinical trials in children. 1258 23

The assessment of glomerular filtration rate (GFR) is critical for the diagnosis and management of renal diseases in pediatric nephrology. Ideally, it requires the measurement of the renal clearance of a filtration marker. Inulin, an exogenous marker, is the only compound the excretion of which occurs exclusively by glomerular filtration, with no tubular handling. Therefore, inulin clearance provides the most accurate method to measure GFR and is considered as the "gold standard", at all ages including very premature neonates. However, inulin dearance is cumbersome and alternative methods are used in clinical practice. If urine is available, endogenous creatinine clearance is the most reliable method. When urine collection is difficult to obtain, GFR can be estimated by the plasma concentration of endogenous markers mainly eliminated by glomerular filtration, such as creatinine, or the more recently described cystatin C and beta 2-microglobulin. When the endogenous production of these markers is constant, their plasma concentration reflects glomerular filtration; it increases with decreasing renal function. However, in pediatric patients creatinine production depends on muscle mass, which significantly increases with linear growth, as well as age and gender. Mathematical formulas taking these parameters into account have thus been developed. Among these, the so-called "Schwartz formula" is often used and is a reliable estimate of GFR in children. Finally, radionuclide renal scans can be used to evaluate the separate glomerular function of each kidney.
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PMID:[Glomerular filtration markers in pediatrics]. 1261 Nov 89

Thiazides and angiotensin-converting enzyme (ACE) inhibitors are first-choice drugs for lowering elevated blood pressure and hence risk of cardiovascular disease. Homocysteine (tHcy) is another and independent cardiovascular risk factor and has been reported to be elevated in patients on antihypertensive therapy. As these studies reported only associations, a preliminary, randomized, prospective treatment study was performed in 40 hypertensive patients. We investigated the major determinants of tHcy concentrations after treatment with hydrochlorothiazide (HCT) or captopril: vitamins B6, B12, folic acid, and creatinine and cystatin C as parameters of renal function. A total of 21 Patients were treated with HCT and 19 with captopril, for, respectively, 31 and 29 days. HCT, but not captopril, raised tHcy by 16% (P =.003) and also creatinine and cystatin C (P =.025 and P =.004, respectively). This tHcy increase may offset the desired cardioprotection conferred by lowering the blood pressure.
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PMID:Antihypertensive treatment and homocysteine concentrations. 1264 60


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