Serum cystatin-C Research Articles

Chemotherapy-induced suppression of serum holotranscobalamin

e20639 Purpose: Chemotherapy-induced damage to the stomach and small intestine may inhibit the absorption of vitamin B12. To assess the risk of chemotherapy causing acute vitamin B12 deficiency, we primarily measured the active form of vitamin B12, holotranscobalamin, but also total serum B12, methylmalonic acid, and total homocysteine. Experimental Design: We studied 21 patients that were actively on chemotherapy and recorded values for holotranscobalamin, total serum B12, methylmalonic acid, total homocysteine, and cystatin-c. Measurements were taken both before and after four doses of chemotherapy. T-tests were employed to determine statistical significance. Results: There was a statistically significant drop in holotranscobalamin after chemotherapy in eighteen out of twenty-one patients (p = 2.64x10–3). Three patients were vitamin B12 deficient as defined by total B12 < 300 pg/ml. Neither methylmalonic acid (p = 3.95x10–1), nor total homocysteine (p = 4.34x10–1), showed any significant changes. Conclusions: Chemotherapy caused an acute deficiency of the only metabolically active form of vitamin B12, holotranscobalamin, despite B12 supplementation. We suggest monitoring patients for changes in holotranscobalamin to ensure that prolonged deficiency does not occur. The clinical implications of acute lowering of holotranscobalamin remain unknown. No significant financial relationships to disclose.

M1717 Serum Cystatin-C and Creatinine Compared with Standard GFR in Cirrhotic Patients

Background: Assessment of glomerular filtration rate (GFR) by common creatinine-based methods is potentially inaccurate in patients with cirrhosis. Cirrhotic patients have several underlying conditions that contribute to falsely low serum creatinine concentrations, even in the presence of moderate to severe renal impairment, therefore creatinine-based methods usually overestimate true GFR in these patients. Cystatin-C is a low molecular weight protein and an endogenous marker of GFR. We compared the accuracy of plasma cystatin-C and creatinine in assessing renal function in cirrhotic patients. Methods: We serially enrolled cirrhotic patients admitted in our ward if they met the inclusion criteria and consented to participate. Child-Pugh (CP) score was calculated for all patients. GFR was calculated using serum creatinine, serum Cystatin-C, and 99mTc-DTPA clearance with the last one serving as the gold standard. The area under curve (AUC) on Receiver-operating characteristic curves were used to compare the diagnostic accuracy of each calculated GFR with that measured by DTPA. Results: Fourty-eight patients were enrolled (32 males, 66.7%). Nine were in class-A, 20 in class-B and 19 in class-C of CP score. Cystatin-C did not perform well in predicting the true GFR, while serum creatinine performed relatively accurate at GFR 20 a GFR<80 could also be predicted by serum creatinine (ROC curve AUC=0.739, p=0.034). Serum creatinie could also predict GFR<80ml/min in patients with CP class A & B (ROC curve AUC=0.795, p=0.01), but not in patients with CP class C. Conclusion: Neither serum creatinine nor Cystatin-C are good predictors of GFR in cirrhostic patients, although serum creatinine seems to perform better in selected subgroups.

Cystatin C Provides More information Than Other Renal Function Parameters for Stratifying Risk in Patients With Acute Coronary Syndrome

The protein cystatin C has a stable plasma concentration and is eliminated exclusively by the kidneys. The aim of this study was to determine the prognostic value of cystatin C in patients with acute coronary syndrome (ACS). The prospective study included 203 hospitalized ACS patients. Clinical evaluation during the first 24 hours of hospitalization included a hemogram and measurement of creatinine, cystatin C, total and fractionated cholesterol and markers of myocardial necrosis. The glomerular filtration rate (GFR) was estimated using the MDRD (Modification of Diet in Renal Disease) equation. A comparison was made between two groups of patients divided according to a serum cystatin-C level above or below 0.95 mg/L. The mean follow-up period was 151 days. In total, 90 patients (44.3%) had a cystatin-C level < or =0.95 mg/L and 113 (55.7%) had a level >0.95 mg/L. Those with a cystatin-C level >0.95 mg/L had poorer in-hospital outcomes, including more frequent heart failure (51.3% vs. 13.3%; P=.001) and higher in-hospital mortality (17.6% vs. 3.3%; P=.001), as well as higher mortality throughout follow-up (22.0% vs. 5.6%; P=.001). Multivariate analysis adjusted for age, ejection fraction and troponin-I and high-sensitivity C-reactive protein concentrations showed that cystatin C was the most powerful independent predictor of a cardiovascular event (relative risk=1.91; 95% confidence interval, 1.03-3.53). Patients with a GFR >60 mL/1.73 m(2) and a cystatin-C level >0.95 mg/L had higher in-hospital mortality (10.2% vs. 3.9%; P=.001). Measurement of cystatin C in high-risk ACS patients may be clinically useful for risk stratification during hospitalization, particularly in those with a normal GFR.

Cystatin-C is an independent prognostic factor for survival in multiple myeloma and is reduced by bortezomib administration

Renal impairment is a common complication of multiple myeloma. Cystatin-C is considered an accurate marker of glomerular filtration rate in several renal disorders. Microarray analysis has revealed that cystatin-C is one of the most highly up-regulated genes in multiple myeloma. The aim of this study was to evaluate the serum levels of cystatin-C in myeloma patients, explore possible correlations with clinical data, including survival, and assess the effect of bortezomib on cystatin-C in relapsed multiple myeloma. We measured serum cystatin-C in 157 newly diagnosed, previously untreated myeloma patients, in 28 patients with relapsed disease pre- and post-bortezomib therapy and in 52 healthy controls, using a latex particle-enhanced nephelometric immunoassay. In newly diagnosed patients, cystatin-C was elevated and showed strong correlations with advanced ISS stage, extensive bone disease, high beta(2)-microglobulin, high serum creatinine, and low creatinine clearance. Multivariate analysis revealed that only cystatin-C and lactate dehydrogenase had an independent prognostic impact on patients' survival. The combination of cystatin-C and lactate dehydrogenase revealed three prognostic groups of patients: a high-risk group (both elevated cystatin-C and lactate dehydrogenase) with a median survival of 24 months, an intermediate-risk group (elevated cystatin-C or elevated lactate dehydrogenase) with a median survival of 48 months and a low-risk group (both low cystatin-C and lactate dehydrogenase) in which median survival has not yet been reached (p<0.001). Cystatin-C could also identify a subset of ISS-II patients with worse outcome. Relapsed patients had higher cystatin-C levels even compared to newly diagnosed patients. Treatment with bortezomib produced a significant reduction of cystatin-C, mainly in responders. Serum cystatin-C is not only a sensitive marker of renal impairment but also reflects tumor burden and is of prognostic value in myeloma. Its reduction after treatment with bortezomib reflects bortezomib's anti-myeloma activity and possibly bortezomib's direct effect on renal function.

Association of kidney function and uncarboxylated matrix Gla protein: Data from the Heart and Soul Study

Vascular calcification is highly prevalent in persons with chronic kidney disease (CKD) and predicts cardiovascular disease (CVD) events. Matrix Gla protein (MGP) is a potent inhibitor of vascular calcification, and lower levels of its precursor-uncarboxylated MGP (ucMGP)--are associated with vascular calcification and atherosclerosis. Whether mild to moderate decrements in kidney function are associated with lower serum ucMGP is unknown. In a cross-sectional study among 842 outpatients with stable CVD, estimated glomerular filtration rate (eGFR), serum cystatin-C and urine albumin-to-creatinine ratio (ACR) were measured and serum ucMGP levels were determined by ELISA. Multivariate linear regression evaluated the association of each kidney function measure with serum ucMGP levels. The mean eGFR was 76 +/- 23 mL/min/1.73 m(2), and 186 subjects (22%) had moderate CKD (eGFR <60 mL/min/1.73 m(2)). The mean +/- SD ucMGP level was 3289 +/- 1177 nM. In unadjusted analysis, each 10 mL/ min/1.73 m(2) lower eGFR was associated with 101 nM lower ucMGP level. This association was only minimally attenuated in final multivariate models wherein each 10 mL/ min/1.73 m(2) lower eGFR was associated with 79 nM lower ucMGP (95% confidence interval [CI]; 44 to 115; P < 0.001) after adjustment for age, sex, race, body mass index, blood pressure, smoking, hypertension, diabetes; and serum albumin, calcium, phosphorus, and fetuin-A levels. Similarly, in models adjusted for identical covariates, each 0.1 mg/L higher cystatin-C was associated with 39 nM lower ucMGP (95% CI 23 to 55; P < 0.001). In contrast, no significant association was observed between ACR and ucMGP in either unadjusted or adjusted analyses (adjusted P = 0.17). All associations were similar among subjects with or without diabetes (P-values for interaction > 0.50). Among outpatients with stable CVD, a reduced glomerular filtration rate is associated with a decreased serum ucMGP level. In contrast, ACR is not associated with ucMGP levels. Whether ucMGP is a useful marker of vascular calcification and CVD event risk in persons with CKD deserves future study.

Evaluation of serum cystatin-C in dogs with visceral leishmaniasis

Serum Cystatin C (sCys-C) is one of the most important serum markers of renal function assessment in dogs. The purpose of this study was to determine the sCys-C concentration in dogs with visceral leishmaniasis (VL). In the study, 16 dogs with VL and 10 clinical healty dogs (control) were used. Mean sCys-C concentration of the infected dogs was significantly higher than that of the control group (p < 0.05). Mean serum creatinine concentration was lower and mean blood urea nitrogen, albumin and globulin concentrations were higher in dogs with VL; however, these changes were not statistically significant. Mean total protein and phosphorus concentrations were found to be higher in dogs with VL than healthy dogs (p < 0.05). No significant correlation had been determined between sCys-C and other variables. Visceral leishmaniasis in dogs has increased sCys-C concentration indicating a possible renal impairment; however, further studies are needed to be performed together with renal biopsies in the investigation sCys-C in dogs with VL.

血清シスタチンＣ濃度を用いた塩酸バンコマイシン簡易初回投与法の設定

A recent meta-analysis has shown that the serum cystatin-C concentration is a superior marker to serum creatinine for estimating the glomerular filtration rate (GFR).In this study,we investigated the relationship between serum vancomycin (VCM) and cystatin-C concentrations to establish a simple method of setting initial doses for VCM therapy.We conducted a non-parametric analysis in which data from 140 patients treated with VCM for Methicillin-resistant Staphylococcus aureus (MRSA) infection were divided into 2 groups (a once-a-day group (n=54)and a twice-a-day group (n=86)).The GFR was estimated using the equation of Hoek based on the serum cystatin-C concentration.In the once-a-day group,VCM dose/serum VCM trough concentration (D/C) ratios were significantly different among 4 -subgroups established on the basis of GFR.The subgroups were GFR<20,20-40,40-50 and 50>mL/min and the average D/C ratios in them were 28.4,57.2,87.9 and 170.3,respectively.In the twice-a-day group,D/C ratios varied signifi-cantly among 3 subgroups based on GFR,which were GFR<50,50-80 and >80 mL/min,and the average D/C ratios in them were 75.0,149.9 and 264.0,respectively.Based on these findings,we simply established the following initial dosage regimens for VCM using GFRs estimated from serum cystatin-C concentrations : 500 mg q.o.d for GFR<20,500 mg s.i.d for GFR of 20-40,1000 mg s.i.d for GFR -of 40-50,1500 mg b.i.d for GFR of 50-80 and 2000 mg b.i.d for GFR>80.In conclusion,we consider that serum cystatin-C concentrations are a useful basis for setting initial doses of VCM,in particular for patients with a GFR<80.

Cystatin‐C, Renal Function, and Incidence of Hip Fracture in Postmenopausal Women

To evaluate the association between chronic kidney disease and incident hip fracture using serum cystatin-C as a biomarker of renal function calculated without reference to muscle mass. Case-control study nested within a prospective study. The Women's Health Initiative Observational Study conducted at 40 U.S. clinical centers. From 93,676 women aged 50 to 79 followed for an average of 7 years, 397 incident hip fracture cases and 397 matched controls were studied. Cystatin-C levels were measured on baseline serum using a particle-enhanced immunonepholometric assay. Estimated glomerular filtration rates (eGFR(cys-c)) were calculated using a validated equation and categorized into three groups (>or=90.0 mL/min per 1.73 m(2), 60.0-89.9 mL/min per 1.73 m(2), and <60.0 mL/min per 1.73 m(2) indicating chronic kidney disease Stages 3 to 4). The odds ratio (OR) for hip fracture was 2.50 (95% confidence interval (CI)=1.32-4.72) for eGFR(cys-c) less than 60 mL/min per 1.73 m(2) compared with Stages 0 to 1, after adjustment for body mass, parental hip fracture, smoking, alcohol consumption, and physical function. No association was observed for eGFR(cys-c) of 60 to 90 mL/min per 1.73 m(2) (OR=1.04, 95% CI=0.66-1.64). Additional adjustment for poor health status, hemoglobin, serum 25-hydroxy vitamin D, and bone metabolism markers did not affect these associations. Adjustment for plasma homocysteine reduced the OR for eGFR(cys-c) less than 60 mL/min per 1.73 m(2) to 1.83 (95% CI=0.93-3.61). Women with eGFR(cys-c) levels less than 60 mL/min per 1.73 m(2) have a substantially greater risk of hip fracture. Effects of renal function on homocysteine levels may partially mediate, or accompany, this association.

Serum cystatin C level for better assessment of glomerular filtration rate in cystic fibrosis patients treated by amikacin

Monitoring of renal function in cystic fibrosis (CF) patients is essential. The dosage regimen of amikacin is regularly modified according to the patient's glomerular filtration rate (GFR). The aim of the study was to evaluate the use of cystatin C (CyC) for monitoring amikacin therapy along with other markers of renal tubular and glomerular function, and damage [N-acetyl-beta-d glucosaminidase (NAG), creatinine level and creatinine clearance]. We compared the GFR, estimated from the serum concentrations of creatinine (Cockcroft-Gault formula) and CyC (Grubb's formula). Seventy-one patients (mean age 12 years; range 4-28 years) with CF were treated by intermittent intravenous infusion of amikacin. Tubular nephrotoxicity was investigated by measurement of urine NAG/urine creatinine ratio (U-NAG/U-creatinine). Concentrations of all markers were measured before starting amikacin therapy and at days 3, 5, 7, 10 and 12. Fluorescence polarization analysis, turbidimetry, enzymatic phototometric creatinine deaminase method and fluorimetry were used for determination of serum amikacin, serum CyC, creatinine and urine NAG activity. Receiver operating characteristic (ROC) analysis was performed to assess the influence of GFR estimated from serum creatinine and serum CyC for the prediction of amikacin clearance during aminoglycoside therapy. Significant differences in the rate of U-NAG/U-creatinine were noted before and after treatment with amikacin (P < 0.001). Serum creatinine levels and creatinine clearance at the end of amikacin therapy (12th day) did not show any significant differences in comparison with the levels measured before the start of therapy (0th day). At days 5, 7, 10 and 12, serum CyC levels showed a significant elevation (P < 0.001), and CyC clearance showed a significant decrease (P < 0.001) in comparison with the levels measured at day 0. The ratio of amikacin clearance/creatinine clearance decreased with therapy whereas the amikacin clearance/CyC and amikacin clearance/CyC clearance increased. We showed that the rate of U-NAG/U-creatinine is a suitable marker for monitoring tubular nephrotoxicity in CF patients. Serum creatinine and estimated creatinine clearance are modest predictors of GFR in CF patients. CyC appears to be a better marker of GFR than serum creatinine concentration or creatinine clearance in our study. Serum CyC levels and CyC clearance showed greater ability to predict amikacin clearance during therapy than creatinine clearance.

A physiologic index of comorbidity: relationship to mortality and disability.

In older adults, there is often substantial undiagnosed chronic disease detectable on noninvasive testing, not accounted for by most comorbidity indices. We developed a simple physiologic index of comorbidity by scoring five noninvasive tests across the full range of values. We examined the predictive validity of this index for mortality and disability. There were 2928 (mean age 74.5 years, 60% women, 85% white, and 15% black) participants in the Cardiovascular Health Study (1992-1993) who had carotid ultrasound, pulmonary function testing, brain magnetic resonance scan, serum cystatin-C, and fasting glucose. These were combined into a single physiologic index of comorbid chronic disease on a scale of 0-10. Cox proportional hazard models were used to predict mortality, mobility limitation, and activities of daily living (ADL) difficulty after a maximum of 9 years. The range of the physiologic index was quite broad, with very few individuals having total scores of either 0 or 10. Those with an index of 7-10 had a hazard ratio of 3.80 (95% confidence interval, 2.82-5.13) for mortality compared to those with scores of 0-2, after adjustment for demographics, behavioral risk factors, and clinically diagnosed conditions. Associations with mobility limitation and ADL difficulty were also significant. The index explained about 40% of the age effect on mortality risk. Older adults with low levels of markers of chronic disease are rather rare but have remarkably good health outcomes. The ability of such an index to distinguish usual from low risk might provide an opportunity to better understand optimal health in old age.

Is Serum Cystatin-C a Reliable Marker for Metabolic Syndrome?

Purpose Chronic kidney disease and metabolic syndrome are recognized as major cardiovascular risk factors. It has been shown that cystatin C has a stronger association with mortality risk than creatinine-based estimations of glomerular filtration rate. We measured cystatin values in dyslipidemic patients and looked for correlations between renal function, cystatin, and metabolic syndrome. Methods There were 925 dyslipidemic patients prospectively included in this cross-sectional study and evaluated over 10 months. Each visit included clinical and biological assessment. Results Most patients exhibited cardiovascular risk factors other than dyslipidemia: hypertension in 34%, diabetes in 11%, and smoking in 18%. Mean triglycerides were 149 ± 136 mg/dL, mean high-density lipoprotein cholesterol 54 ± 14 mg/dL, and low-density lipoprotein 167 ± 48 mg/dL. Metabolic syndrome was present in 238 (26%) patients. Plasma creatinine did not differ between control group and metabolic syndrome patients (80 ± 26 vs 82 ± 20 μmol/L, respectively, P = .2), but creatinine clearance evaluated by abbreviated Modification of Diet in Renal Disease Study formula was lower in the metabolic syndrome group than in the non-metabolic-syndrome group (83.3 ± 18.8 mL/min/1.73m 2 vs 86.8 ± 16.9 mL/min/1.73m 2, respectively, P <.007). Cystatin value was significantly higher in metabolic syndrome patients than in others (0.86 ± 0.23 vs 0.79 ± 0.20 mg/L, respectively, P <.0001), independently of serum creatinine level and creatinine clearance. Furthermore, there was a progressive increase in cystatin, as a function of the number of metabolic syndrome components. Conclusions Our study shows that cystatin is associated with metabolic syndrome in dyslipidemic patients. Cystatin may be an interesting marker of metabolic syndrome and of increased cardiovascular and renal risk.

Diagnostic biomarkers of diabetic nephropathy

Clinical management and therapeutic intervention from the earlier stage of diabetic nephropathy (DN) is of major importance to prevent the progression of DN to end stage renal disease. At present, the measurement of albuminuria is used as a standardized non-invasive test for the diagnosis of early DN. Diabetic kidney disease, however, is not detected by this test in some cases. Hence, efforts have been made to find better diagnostic biomarkers of DN. These investigations have identified several proteins that can be used as diagnostic biomarkers of DN, including urinary immunoglobulin G, transferrin, ceruloplasmin and serum cystatin-C. Further, recent proteomics approaches have isolated potential biomarkers of DN. This review summarizes the diagnostic biomarkers developed over the last decade, and comments on their impacts in the diagnosis and management of this disease.

74: Incidence and Outcome of De-Novo Malignancy after Cardiac Transplantation – 20 Years Experience of a Single Center

measurement of renal function, which is usually assessed by measuring the glomerular filtration rate (GFR). The most commonly used marker for GFR is 24hr-creatinine clearance (24hr-Ccr). Serum creatinine level is widely used for evaluation of renal function, however, muscle volume and its wasting affect data. Serum concentrations of the low-molecular-weight proteins, cystatin-C and beta 2-microglobulin (B2MG) may afford useful markers to determine a reduced GFR. Methods and Materials: Serum creatinine, cystatin-C, B2MG and 24hr-Ccr were measured in 28 adult Japanese heart transplant recipients (19 to 58 years old, 10 females) who had been under care at least 2 years after transplantation. Results: Serum cystatin-C and B2MG negatively correlated with 24hr-Ccr (r .803, P .0001 and r .687, P .0001, respectively), and correlated with serum creatinine (r .738, P .0001 and r .593, P 0.0009, respectively). By receiver operating characteristic (ROC) analysis, both cystatin-C and B2MG showed 85.7% of sensitivity and 78.6% of specificity with using a cut off value of 70 ml/min of 24hr-Ccr. Conclusions: Serum cystatin-C or B2MG would be a better GFR marker than the widely used creatinine to detect renal dysfunction after heart transplantation.

73: Serum Cystatin-C and beta 2-Microglobulin as Markers of Renal Dysfunction in Japanese Heart Transplant Recipients

73: Serum Cystatin-C and beta 2-Microglobulin as Markers of Renal Dysfunction in Japanese Heart Transplant Recipients

塩酸バンコマイシン注初回投与設計における血清シスタチンＣの有用性に関する検討

In clinical practice,the glomerular filtration rate (GFR) is often estimated from serum creatinine (Scr).However,several recent studies have shown that serum cystatin C (SCysC) is a better parameter for the diagnosis of early impaired renal function than Scr.In this study,we measured SCysC and 24 hour creatinine clearance (CLcr) levels in 102 in-hospital patients to determine if there was a relationship between the 2 parameters,finding that 1/SCysC was significantly positively correlated with CLcr.From the results,we derived the simple formula CLcr=65.45/SCysC-3.36(r=0.79,p<0.01).Using a formula including the one above we predicted vancomycin concentrations based on SCysC and compared them with actual vancomycin concentrations in 17 patients.Our analysis of the results showed that the formula had greater prediction accuracy for vancomycin concentrations than the Cockcroft&Gault equation which is based on Scr.These results suggest that SCysC is a better marker of renal function for setting initial doses of vancomycin and other drugs that are renally excreted.

Cystatin C: a potentially useful marker for identifying individuals with spina bifida and early renal insufficiency

Background Individuals with spina bifida (SB) are at risk for deterioration of their upper urinary tracts due to neurogenic bladder and subsequent progressive chronic renal insufficiency (CRI). Serum creatinine (SCr) is the most widely used marker to assess renal function and to estimate glomerular filtration rate (GFR), although it has significant limitations. SCr is dependent on age, height, gender and muscle mass and has been shown to be an unreliable marker of renal function in SB. Cystatin C (CyC) is a cysteine proteinase inhibitor of low molecular weight, produced at a constant rate by all nucleated cells, freely filtered at the glomerulus, and not secreted or reabsorbed at the renal tubule. CyC is independent of age, height, and gender and is believed to be independent of muscle mass. Over the past several years, serum CyC has been shown to be a better marker of renal function and GFR than SCr (using the Schwartz formula) in children. One study by Pham-Huy in 2003 showed that CyC was much better correlated with GFR than SCr in children with SB.

Reduced renal function and sleep-disordered breathing in community-dwelling elderly men

Background Sleep-disordered breathing (SDB) may increase the risk of cardiovascular disease (CVD) and death in chronic kidney disease (CKD). However, the association between mild reductions in renal function and SDB is uncertain. Methods We studied 508 community-dwelling men aged ⩾67 years (mean 76.0 ± 5.3) who were enrolled at the Minnesota site for the Minneapolis center of the Outcomes of Sleep Disorders in Older Men (MrOS) sleep study and had serum cystatin-C and creatinine measured coincident with overnight polysomnography. CKD was defined as estimated glomerular filtration rate (eGFR) <60 ml/min/1.73 m 2 using Cockcroft–Gault (CG), modification of diet in renal disease (MDRD) and Mayo Clinic formulae. SDB was defined by a respiratory disturbance index (RDI) ⩾15 events/h. Results Mean cystatin-C was 1.21 ± 0.30 mg/L, and mean creatinine was 1.09 ± 0.23 mg/dL. Median RDI was 7.0 events/h (range 0–73). Higher quartiles of cystatin-C were associated with higher mean RDI ( p for trend = 0.007). This association persisted after adjustment for age and race ( p for trend = 0.03), but not after adjustment for body mass index (BMI, p for trend = 0.34). After adjusting for age, race, BMI, diabetes, hypertension, and CVD, CKD defined by the Mayo Clinic formula, but not CG or MDRD, was associated with a higher odds of SDB [odds ratio (OR) 1.95, 95% confidence interval (CI) 1.04–3.65, p = 0.04]. Conclusions Older men with reduced renal function as defined by higher cystatin-C concentration have higher average RDI. This effect is explained by higher BMI in men with higher cystatin-C. CKD defined by the Mayo Clinic formula is independently associated with twofold higher odds for SDB. Therefore, reduced renal function may be associated with SDB in older men.

Abstract 1672: Glomerular Insufficiency, An Early Marker Of Renal Dysfunction In Patients With A Fontan Circulation.

Introduction : Fontan circulations have high central venous pressures and low dynamic cardiac output, risk factors for depressed renal perfusion. Objectives : Hypothesizing subclinical renal dysfunction, we sought to characterize renal pathophysiology and cardio-renal interaction in this group. Method: 17 Fontan patients were tested for early morning urine cystatin C, alpha-1-microglobulin (A 1 M), retinol binding protein (RBP), protein:creatinine and albumin:creatinine ratio; serum cystatin C (S.Cys-C) and creatinine; echocardiography including Tissue Doppler (TDI); and renal Doppler. Results : 6 (mean age 22.8 ± 5.0years) of 17 patients (mean age 23.5 ± 4.2years) had subclinical renal dysfunction, mean S.Cys-C-derived glomerular filtration rate (GFR S.Cys-C ) 77.31 ± 7.82ml/min/1.73m 2 , vs. 114.21 ± 36.38ml/min/1.73m 2 in the remainder. Whilst GFR S.Cys-C correlated highly with 2-D visual assessment of systemic ventricular function (correlation=0.618; p=0.014) this was not the case for any TDI parameters. Tubular function indices (urine cystatin C, RBP and A 1 M) were normal. Glomerular function indices were abnormal for S.Cys-C, with mean 1.04 ± 0.06mg/L, range 0.97–1.11mg/L; (normal range:0.53–0.95mg/L). Gross morphological renal abnormalities included 3 abnormal bipolar sizes in both right (mean 9.13 ± 0.49cm) and left (mean 9.38 ± 0.66cm) kidneys (normal range&gt;10cm), 6 and 5 abnormal renal cortical thicknesses in right (mean 11.61 ± 1.27mm) and left (mean 12.31 ± 0.92mm) kidneys respectively (normal range&gt;13mm) and 1 mild scarring of the right kidney. Abnormal resistive indices were present in the right kidney of 3 patients (mean 0.79 ± 0.01, range 0.78–0.80), and in the left kidney of 2 patients (mean 0.83 ± 0.02, range 0.81–0.84). Patients with abnormal resistive indices (&gt;0.77) had lower arterial saturations (mean 88.67 ± 2.08%, range 87–91% vs. mean 94.77 ± 2.46%, range 90–97% in those without) and higher haematocrit (mean 0.49 ± 0.01L/L, range 0.48–0.49L/L vs. mean 0.46 ± 0.03L/L, range 0.42–0.52L/L in those without). Conclusion : Fontan patients often have subclinical renal dysfunction mainly due to glomerular insufficiency. Ventricular function, cyanosis and polycythemia appear to be important drivers for renal dysfunction.

Serum Cystatin-C Evaluation in Dogs Affected by Different Diseases Associated or Not with Renal Insufficiency

Antognoni, M.T., Siepi, D., Porciello, F., Rueca, F. and Fruganti, G., 2007. Serum cystatin-C evaluation in dogs affected by different diseases associated or not with renal insufficiency. Veterinary Research Communications, 31(Suppl. 1), 269–271

Assessment of Glomerular Filtration Rate in Renal Transplant Patients Using Serum Cystatin C

Aim Serum cystatin C (SCysC) has been proposed as a better marker of glomerular filtration rate (GFR) than serum creatinine (Scr). However, few data are available in renal transplant patients, especially, during the early postoperative phase. Methods Thirty-nine renal transplant patients (22 men/17 women) were recruited for determination of SCysC and Scr before operation, at 1 week and at 4 weeks after operation. SCysC was determined by particle-enhanced turbidimetric immunoassay. Creatinine clearance (Ccr) was calculated using the Cockcroft-Gault formula. Results SCysC and Scr levels significantly decreased with the recovery of allograft function. SCysC showed a significant correlation with Scr and Ccr. The relationship between SCysC and Scr showed a positive correlation ( r = .849 preoperation, and r = .940 postoperation). The relationship between SCysC and Ccr revealed a negative correlation ( r = .857 preoperation, and r = .876 postoperation). At the Ccr level of 50 to 80 mL/min/1.73 m 2, the correlation between SCysC and Ccr ( r = .778) was significantly better than that between Scr and Ccr ( r = .553; P = .032). The concentration of SCysC was not affected by age, gender, height, body weight, hemoglobin, serum protein, glucose, or mycophenolate mofetil or azathioprine dosage. However, corticosteroids slightly increased the level of SCysC and cyclosporine (CsA) decreased it. The area under the curve of the receiver operating characteristic curve for SCysC and Scr are 0.964 and 0.915, respectively ( P < .05). Conclusion Although the concentration may be slightly influenced by prednisolone and CsA, SCysC is more sensitive than Scr to detect early and moderate deterioration of GFR in adult renal transplant recipients.