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)

There has been considerable recent interest in the potential use of serum cystatin C as a diagnostic tool. Here we examined the hypothesis that the cystatin C level in the pleural effusion can differ from the corresponding serum level. We evacuated pleural effusion fluids from 47 patients by thoracentesis. Cystatin C, beta(2)-microglobulin, inorganic phosphate, creatinine and total protein were quantified in both pleural effusion fluids and corresponding sera. We determined cystatin C levels in pleural effusions and calculated the ratio of cystatin C levels in serum and effusion, to discriminate between effusions caused by severe renal impairment and other types of effusion. Extremely high concentrations of cystatin C in serum/effusion pairs were only measured in patients with renal failure (6.0 +/- 0.8/6.0 +/- 0.8 mg/l, means +/- S.D., n=11). A clearly defined region was found to correspond to pleural effusion caused by renal failure (r=0.954). The quantification of cystatin C in the effusion was justified by the discovery that there were some patients with a high serum cystatin C level but a low effusion concentration, or a low serum cystatin C but a high effusion concentration, indicating causes other than renal failure. In conclusion, the pilot data indicate a relationship between the cystatin C concentration in pleural fluid and the underlying disease. Thus cystatin C levels in pleural effusion and serum may be a valuable criterion for the differential diagnosis of pleural diseases of different aetiologies.
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PMID:Cystatin C of pleural effusion as a novel diagnostic aid in pleural diseases of different aetiologies. 1186 79

Recently, cystatin C (cyst C) was proposed for the assessment of glomerular filtration rate, being more accurate than creatinine determination. Reference intervals for cyst C do not vary with age and sex, like creatinine values. Elevated values of cyst C were reported for pre- and full-term infants. Nevertheless, the age cut-off for stable cyst C values i.e., age independence, remains under discussion. Therefore, we conducted a prospective study in 98 healthy children, 51 being under 18 months of age. Cyst C was determined by the nephelometric method. The infants under the age of 18 months had a higher mean serum cyst C value (0.94 +/- 0.24 mg/l) than the older children (0.65 +/- 0.19 mg/l). There was a negative correlation between age and cyst C in the infant group under the age of 18 months (r(2)=0.631, P<0.01). Our results indicate that mean serum cyst C is higher in infants than older children; the age cut-off appears over the age of 1 year of life, presumably reflecting kidney maturation. Our study does not allow accurate assessment of the age cut-off at 18 months or 36 months.
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PMID:Impact of age on reference values for serum concentration of cystatin C in children. 1187 72

Clinical biochemists have long known the analytical and clinical limitations of creatinine and creatinine clearance measurement in the assessment of glomerular filtration rate (GFR). This background is reviewed in the article before assessing the utility of cystatin C, the most promising replacement biochemical marker yet identified. Cystatin C has been used in clinical research studies for more than 20 years and yet has been introduced into clinical practice in very few centres, firstly in Lund in Sweden and now Carshalton in the UK. Why is this? The review compares our ability to measure creatinine and cystatin C and their relative sensitivity and specificity for changes in GFR. Comparison is made of cystatin C with creatinine as screening tests for early renal dysfunction and for monitoring its progression where issues of reference ranges and within-individual variation are important. The superiority of cystatin C as a screening test is probably accepted but there are still concerns about non-renal influences upon its circulating concentration, particularly steroid therapy, insufficient data on the influence of malignancy and a general lack of prospective clinical studies confirming the prognostic significance of cystatin C.
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PMID:Cystatin C. 1266 66

It has been suggested that hyperhomocysteinemia observed in patients with occlusive vascular disease is caused by reduced renal function secondary to renovascular disease. We have therefore used serum cystatin C, a new sensitive marker for glomerular filtration, in 59 patients with acute coronary syndromes and high plasma homocysteine (tHcy) concentration to measure renal function. Samples were also obtained from 34 patients with low-normal plasma tHcy and 50 control subjects. The patients with low-normal plasma tHcy concentration showed decreased concentrations of serum cystatin C and serum creatinine and increased concentrations of blood folate and serum cobalamin compared to the controls and to the patients with high plasma tHcy. There was a large overlap in cystatin C concentrations between patients with high and low-normal plasma tHcy. None of the parameters investigated except plasma tHcy were significantly different in the group of patients with high plasma tHcy concentration compared to the control group. In order to further demonstrate the importance of renal impairment, a subgroup of the patients with high plasma tHcy was supplemented daily with folic acid 5 mg, pyridoxine 40 mg and cyancobalamin 1 mg for 3 months. Vitamin therapy reduced plasma tHcy from 18.3+/-4.6 pmol/l to 9.6+/-2.2 pmol/l (p<0.0001). However, vitamin treatment did not strengthen the correlation between cystatin C and plasma tHcy concentrations. These findings do not support the hypothesis that subtle renal dysfunction is an important cause of high plasma tHcy concentration in patients with acute coronary syndromes.
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PMID:Renal function exerts only a minor influence on high plasma homocysteine concentrations in patients with acute coronary syndromes. 1193 86

The measurement of renal function in pre-dialysis patients is important in order to determine the appropriate time to begin renal replacement therapy, to forecast the start, and to compare, in groups of patients, the efficiency of different treatments that limit renal disease progression. The most reliable methods, such as inulin clearance or measurement by radioisotopes, are too awkward for the usual clinical follow-up of patients. Although much simpler and almost as reliable, the use of iohexol radiologic contrast does not allow the frequent monitoring of the patient either. The determinations of the plasmatic creatinine and its clearance or the estimate of the glomerular filtration rate by means of equations derived from the creatinine are the methods most often used in order to measure renal function, although not without problems in pre-dialysis. In order to try to overcome such problems, more precise equations and procedures, including the measurement of averaged urea-creatinine clearance or creatinine clearance with cimetidine, have been designed that better estimate the glomerular filtration rate. However, none of these methods is totally reliable in pre-dialysis. A new endogen marker, cystatin C, has advantages over creatinine, though more studies are needed in pre-dialysis in order to ascertain its use. The initial proposal of the National Kidney Foundation's Kidney Disease Outcome Quality Initiative (DOQI) guidelines to use weekly Kt/V and nutritional parameters to determine the time for starting renal replacement therapy has widened the prospects of the debate on the measurement of renal function in pre-dialysis, but further work is required to define their role in pre-dialysis patients' follow-up.
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PMID:Measurement of renal function in pre-ESRD patients. 1198 6

Cystatin C is a low molecular weight protein and the plasma level of cystatin C is mainly determined by glomerular filtration, making cystatin C an endogenous marker of glomerular filtration rate. The aim of the study was to elucidate the applicability of plasma cystatin C as a marker of renal function in patients with liver cirrhosis. Serum cystatin C and creatinine concentrations were compared with creatinine clearance. Thirty-six patients (14 females and 22 males aged between 33 and 81 years) with liver cirrhosis with normal to severely impaired kidney function were included. Plasma cystatin C was measured by an automated particle-enhanced nephelometric immunoassay (Dade Behring Diagnostics) and plasma creatinine by an enzymatic method. Plasma levels of cystatin C and creatinine were found to increase with decreasing values of creatinine clearance. The reciprocal values of cystatin C and creatinine were compared with those for creatinine clearance revealing an r2 of 0.37 and 0.18, respectively. Comparison of the areas under the curves (AUC) of the non-parametric receiver-operating characteristic plots for plasma cystatin C (AUC=0.7364; SE=0.0929) and plasma creatinine (AUC=0.6309: SF=0.1028) revealed a significant difference between plasma cystatin C and plasma levels of creatinine (p-value=0.03). The results demonstrate that the diagnostic accuracy of plasma cystatin C was better than plasma creatinine in identifying liver cirrhotic patients with reduced glomerular filtration rate.
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PMID:Plasma cystatin C as a marker of renal function in patients with liver cirrhosis. 1200 28

Serum cystatin C is believed to reflect the glomerular filtration rate (GFR) more closely than serum creatinine in many contexts and a reference interval for serum cystatin C in term pregnancy has been defined to enable its use also in pregnant women. However, serum cystatin C levels were not found to be decreased in term pregnancy, though GFR of low molecular mass substances is known to increase by at least 40% by the third trimester. The aim of this study was therefore to determine whether serum cystatin C is a reliable GFR marker also in pregnant women. GFR was determined by measurement of plasma clearance of iohexol in 48 previously healthy women in their third trimester and in 12 healthy nonpregnant women, and was compared with their serum levels of cystatin C and creatinine. Both serum cystatin C and creatinine levels were significantly related to GFR for both pregnant and non-pregnant women. However, the correlation between cystatin C and GFR was set at different levels for pregnant and nonpregnant women. Our results indicate a physiological difference between the filtration processes in kidneys of pregnant and non-pregnant women, whether it is size-dependent, configuration-dependent or charge-dependent. Nevertheless, serum cystatin C seems to reflect GFR reliably in both non-pregnant and pregnant, healthy and hypertensive women.
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PMID:Serum cystatin C for assessment of glomerular filtration rate in pregnant and non-pregnant women. Indications of altered filtration process in pregnancy. 1200 30

A clinical investigation was conducted to clarify the reliability and efficacy of serum cystatin C measurement for estimation of the glomerular filtration rate (GFR). Two hundred twelve patients with various renal diseases enrolled in the study. All patients were evaluated for 24-hour creatinine clearance (24 h C(Cr)) and the standard sodium thiosulfate clearance test (C(Thio)) within a week of blood sample collection. Serum cystatin C concentration was determined by a particle-enhanced immunonephelometry method. C(Thio) and 1/cystatin C, 24 h C(Cr), 1/beta2-microglobulin and 1/creatinine were well correlated. The correlation coefficients for C(Thio) obtained by 24 h C(Cr) and 1/cystatin C were comparable to each other (0.701 vs. 0.679). Receiver-operated characteristic (ROC) analysis revealed that 24 h C(Cr) showed the highest area under the curve when C(Thio) = 60 ml/min or C(Thio) = 100 ml/min were applied as the discrimination point. However, the ROC value obtained by cystatin C was slightly greater than 24 h C(Cr) when C(Thio) = 80 ml/min was used as the discrimination point. Patient age, gender, glucose tolerance, presence of proteinuria, systemic inflammation, lupus, or systemic use of steroids did not interfere in the relationship between C(Thio) and 1/cystatin C. In conclusion, serum cystatin C measurement is an excellent diagnostic test for detecting patients with subclinical renal dysfunction.
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PMID:Serum cystatin C reliably detects renal dysfunction in patients with various renal diseases. 1202 14

Serum cystatin C often is used in humans as a rapid and more sensitive marker than serum creatinine for glomerular filtration rate. The purpose of the present study was to evaluate whether cystatin C-like immunoreactivity (CLI) could be measured reliably in canine serum and to investigate whether dogs with clinical renal insufficiency had higher CLI levels than did clinically healthy dogs and dogs with nonrenal diseases. A commercially available particle-enhanced turbidimetric immunoassay (PETIA) for human serum cystatin C was used to measure canine serum CLI in a linear and proportional manner, with a mean recovery of 104% +/- 7.5% and coefficients of variation of 1.7 to 9.6%. The assay was then applied to serum samples from 17 clinically healthy dogs, 12 dogs with nonrenal diseases, and 8 dogs with renal insufficiency. Serum CLI was significantly higher in dogs with renal insufficiency (median serum CLI = 5.01 mg/L) than in clinically healthy dogs and dogs with nonrenal diseases (median serum CLI = 1.06 mg/L and 1.62 mg/L, respectively). Thus, canine serum CLI could be reliably measured using a commercially available PETIA designed for human serum cystatin C, and dogs with clinical renal insufficiency had, as expected, significantly higher serum CLI levels.
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PMID:Preliminary evaluation of a particle-enhanced turbidimetric immunoassay (PETIA) for the determination of serum cystatin C-like immunoreactivity in dogs. 1202 21

Individuals after orthotopic liver transplantation (OLT) often show renal dysfunction, which may substantially affect the post-OLT course. Renal function after OLT is commonly assessed by means of serum creatinine (S(cr)) concentration or renal creatinine clearance (C(cr)). A glomerular filtration rate (GFR) estimate based on S(cr) level is not accurate enough because even a more marked decrease in GFR need not be associated with an increase in S(cr) level, especially in jaundiced patients. The study intends to try to estimate GFR in individuals after OLT by means of determining serum cystatin C (S(cyst)) concentrations. In 58 individuals (mean age, 49 +/- 7 years; 31 men, 27 women) at various intervals from OLT (mean, 14 +/- 10 months), GFR was estimated by using simultaneous determinations of S(cyst), S(cr), C(cr), and renal inulin clearance (C(in)). In most subjects (91.3%), C(in) was decreased to less than the lower limit of normal (80 mL/min/1.73 m(2)). A significant correlation (r = 0.70; P <.001) was found between 1/S(cyst) and C(in). Receiver operating characteristic analysis was performed on S(cyst) and S(cr) using a C(in) cutoff value of 80 mL/min/1.73 m(2). The area under the curve for S(cyst) was 0.912 +/- 0.044, and that for S(cr), 0.899 +/- 0.049. There was no statistically significant difference between these values. The sensitivity for a S(cyst) level of 1.20 mg/L (upper limit of normal value) to detect a decrease in GFR (measured as C(in)) below the lower limit of normal (80 mL/min/1.73 m(2)) was 96.1%. The sensitivity of S(cyst) level was significantly greater (P <.01) than the sensitivity of S(cr) level for men and at borderline significance for women (P =.05). Findings support the assumption that a S(cyst) level less than 1.2 mg/L indicates with a high degree of probability (P <.001) that GFR is not decreased to less than the normal limit. S(cyst) assessment in individuals after OLT could be proposed as a confirmatory test of a decrease in GFR in individuals with normal S(cr) levels.
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PMID:Glomerular filtration rate assessment in individuals after orthotopic liver transplantation based on serum cystatin C levels. 1208 13


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