A new tool for predicting the probability of chronic kidney disease from a specific value of estimated GFR

Abstract

Objective. To demonstrate how patients’ probability of having chronic kidney disease (CKD) stage 3–5 (measured GFR <60 mL/min/1.73 m²) can be predicted from a specific value of estimated glomerular filtration rate (eGFR). Material and methods. The probability of CKD stage 3–5 was predicted from a logistic regression model (n = 850) using three different eGFR prediction equations: Lund-Malmö, MDRD and CKD-EPI. Population weighting was used to illustrate how this probability varies in three different populations: original sample (55% true prevalence of CKD stage 3–5), a screening (6.7% prevalence) and a CKD population (84% prevalence). Results. All three eGFR-equations had high classification ability (area under the receiver-operating-characteristic curve = 97%). The probability of CKD stage 3–5 increased with decreasing eGFR, varied substantially among the populations studied and to some extent between the eGFR-equations. Using the Lund-Malmö equation as illustration, the probability of CKD stage 3–5 is > 90% only when eGFR is <38 mL/min/1.73 m² in a screening population, whereas it is > 90% already when eGFR is <51 mL/min/1.73 m² in a CKD population. Conversely, the probability of CKD stage 3–5 is <10% if eGFR > 59 mL/min/1.73 m² in a screening population, whereas it is <10% only when eGFR is > 88 mL/min/1.73 m² in a CKD population. Conclusion. Instead of reporting diagnostic accuracy as sensitivity, specificity, and predictive values, actual eGFR supplemented with the probability that it represents a true GFR <60 mL/min/1.73 m² may be more valuable for physicians. Clinical (pre-test) probability in the population must be considered when predicting this probability.     

Different equations to combine creatinine and cystatin C to predict GFR. Arithmetic mean of existing equations performs as well as complex combinations

Abstract

Purpose: To test various ways of combining creatinine and cystatin C in equations to predict glomerular filtration rate (GFR). Material and methods: Performance of the following expressions to predict GFR was compared with measured GFR (iohexol clearance, mL/min/1.73 m²) in 857 patients: (i) Lund-Malmö creatinine equation, (ii) Grubb cystatin C equation, (iii) arithmetic mean of (1) and (2), (iv) geometric mean of (1) and (2), (v) linear regression on (1) and (2), (vi) regression on (1) and cystatin C, and (vii) regression on creatinine, cystatin C, age and gender. Results: For the entire cohort median percent error (bias) was <5% for all expressions, though all expressions tended to underestimate (?8.3 to 15.8%) GFR at levels ≥90 mL/min/1.73 m². The five expressions combining creatinine and cystatin C significantly improved correlation and accuracy (p<0.001) within 15 and 30% of measured GFR compared with the equations based on the separate analytes and with no significant difference between the five expressions. In a subgroup of patients with neurological disease and muscle atrophy the cystatin C equation performed better than the expressions combining creatinine and cystatin C. Conclusion: Simply calculating the arithmetic mean of predicted GFR based on separate creatinine and cystatin C equations performs equally well as more complex equations. Reporting GFR based on separate creatinine and cystatin C equations, and their arithmetic mean also has the definite advantage that the physician can choose the estimated GFR, most appropriate depending on the clinical setting and patient characteristics.     

Revised equations for estimating glomerular filtration rate based on the Lund-Malmö Study cohort

Abstract

Objective. To increase the accuracy of estimated GFR (eGFR) from creatinine overall and at measured GFR ≥90 mL/min per 1.73 m² by revising the Lund-Malmö (LM) equations, to elaborate on more complex forms to improve the LM and CKD-EPI equations further, and to assess benefits of adding lean body mass (LBM). Material and methods. Swedish Caucasians (n = 850, 376 women; median 60, range 18–95 years) referred for GFR measurement (plasma iohexol-clearance: median 55, range 5–173 mL/min/1.73 m²) constituted the Lund-Malmö Study cohort. Bias, precision, accuracy, expressed as median absolute percentage difference and percentage of estimates ±10% (P₁₀) and ±30% (P₃₀) of measured GFR, and classification ability with respect to five GFR stages were compared with the original LM, CKD-EPI and MDRD equations. Results. LM Revised overall performed better than LM Original without LBM due to increased accuracy at measured GFR ≥90 mL/min/1.73 m². Further extensions of the CKD-EPI or LM equations did not substantially improve overall performance. In particular, the performance of LM Revised at measured GFR ≥90 mL/min/1.73 m² could not be improved further without decreasing accuracy and classification ability at lower GFR-levels. Adding LBM to the equations had no strong effect on accuracy. Conclusion. Comparisons with the CKD-EPI and MDRD equations suggest that the LM equations are superior for the present Swedish population, due to markedly higher accuracy of the LM equations at measured GFR <30 mL/min/1.73 m². However, the LM equations cannot be recommended for use in general clinical practice until validated in other populations.     

The Lund–Malmö creatinine‐based glomerular filtration rate prediction equation for adults also performs well in children

Objective. To evaluate the clinical performance in a paediatric population of the Lund–Malmö creatinine‐based glomerular filtration rate (GFR) prediction equations, primarily developed for adults. Material and methods. Iohexol clearance was used as the gold standard in 85 paediatric Caucasian patients (0.3–17 years; 37 F/48?M). One Lund–Malmö equation was based on age and gender (LM) and one included lean body mass (LM‐LBM). Comparisons focused on correlation (adjusted R²), bias (median percent error) and accuracy (proportions of predicted GFR differing ?30?% from measured GFR) (mL/min/1.73?m²). The performances were compared with those of the Modification of Diet in Renal Disease (MDRD) Study equation, a dedicated paediatric creatinine equation, Counahan–Barratt (CB) and a cystatin C‐based equation. Results. The MDRD equation performed poorly with a median bias of 96?%. Of the remaining equations, only the LM‐LBM produced significant bias (+10?% in median) according to line of identity regression analysis. The LM equation yielded marginally higher accuracy (76?%) than the LM‐LBM equation (74?%) and the CB (73?%), but lower than the cystatin C‐based equation (82?%). However, the estimated accuracy figures for these four equations were generally imprecise and none of the differences compared with the LM equation was statistically significant. Conclusion. In contrast to most creatinine‐based GFR prediction equations, the LM equation performs adequately for both children and adults. This may be due to the unique model‐building principles used when the LM equation was established. Further validation in a larger paediatric population is necessary.     

Prediction of relative glomerular filtration rate in adults: New improved equations based on Swedish Caucasians and standardized plasma‐creatinine assays

Objective. To evaluate newly developed equations predicting relative glomerular filtration rate (GFR) in adult Swedish Caucasians and to compare with the Modification of Diet in Renal Disease (MDRD) and Mayo Clinic equations using enzymatic and zero‐calibrated plasma creatinine assays. Material and methods. GFR was measured with iohexol clearance adjusted to 1.73?m². One population sample (n = 436/Lund) was used to derive an equation based on plasma‐creatinine/age/gender, and a second with the addition of lean body mass (LBM). Both equations were validated in a separate sample (n = 414/Malmö). The coefficients of the equations were eventually fine‐tuned using all 850 patients and yielding Lund–Malmö equations without (LM) and with LBM‐term (LM_LBM). Their performance was compared with the MDRD_CC (conventional creatinine calibration), MDRD_IDMS (isotope dilution mass spectroscopy traceable calibration) and Mayo Clinic equations. Results. The Lund equations performed similarly in both samples. In the combined set, the Mayo Clinic/MDRD_CC resulted in +19.0/+10.2?% median bias, while bias for the other equations was<10?%. LM_LBM had the highest accuracy (86?% of estimates within 30?% of measured GFR), significantly (p<0.001) better than for MDRD_IDMS (80?%). In men with BMI<20?kg/m², MDRD_IDMS/LM had +46?%/+19?% median bias. MDRD_IDMS also overestimated GFR by 22?%/14?% in men/women above 80 years of age. The LM_LBM equation had<10?% bias irrespective of BMI, age or GFR except for a 15?% negative bias at GFR?90?mL/min/1.73?m². Conclusion. The newly developed Lund–Malmö equations for GFR estimation performed better than the MDRD_IDMS and Mayo Clinic equations in a Swedish Caucasian sample. Inclusion of an LBM term improved performance markedly in certain subgroups.     

老年心血管病患者的肾功能状况及评估

目的研究老年心血管疾病患者肾功能状况及其影响因素。方法回顾性分析277例60~97(74.8±7.3)岁老年心血管病患者临床资料,以简化MDRD公式估计肾小球滤过率(GFR)。对年龄≥70岁、GFR<60 ml/min者(肾功能不全组)与GFR≥60 ml/min者进行年龄、性别配对比较。结果(1)277例血清肌酐(SCr)(100.3±55.7)μmol/L,GFR(76.5±28.3)ml/min。GFR<60 ml/min 73例,其中年龄≥70岁67例,占同年龄段(209例)32.1%,而仅14人临床诊断了慢性肾功能不全。⑵配对比较显示:肾功能不全组糖尿病、心力衰竭、高尿酸血症患者例数明显高于对照组,分别为29∶15、19∶5、27∶12,P≤0.01;高血压患病时间明显长于对照组[(21.9±14.5)年vs(15.6±13.7)年,P<0.05];血尿酸水平明显高于对照组[(405.0±122.4)μmol/L vs(336.9±83.2)μmol/L],P<0.01。结论70岁以上老年心血管病患者肾功能不全的发病率高。仅以SCr标准易使非专科人员误读老年患者的肾功能状态,简化MDRD公式估计的GFR可供临床医生参考。     

Comparison of methods for estimating glomerular filtration rate in head and neck cancer patients treated with cisplatin

Cisplatin is a chemotherapeutic agent widely used in the treatment of various solid tumors. Cisplatin induces nephrotoxicity and may lead to long-term reduction of kidney function. Consequently, determination of glomerular filtration rate (GFR) is used to monitor potential kidney damage. This study aimed to compare two commonly used algorithms for estimating GFR (eGFR) from plasma creatinine (PCr) with ⁵¹Cr-EDTA clearance (CrCl) as a reference method. This was a retrospective single center study of 94 head and neck cancer patients treated with cisplatin. CrCl was performed once before, during, and after treatment, and PCr was measured concurrently. eGFR was assessed from PCr applying the Cockcroft-Gault (CG) and the Chronic Kidney Disease-Epidemiology Collaboration (CKD-EPI) equations. Agreement was assessed applying the statistical methods of Bland and Altman. A predefined limit of clinically acceptable variation between CrCl and eGFR of 14% was applied. Comparison of CrCl and eGFR_CKD revealed a positive slope of the linear regression line, suggesting proportional bias (p?CG. Pre-treatment, 42 (46%), 53 (56%) and 48 (53%) observations were within the clinically acceptable limit of variation for standardized eGFR_CKD, BSA corrected eGFR_CKD, and eGFR_CG, respectively. The observed body weight changes were significant. In conclusion, estimated GFR_CKD cannot sufficiently replace CrCl in the assessment of GFR during treatment with cisplatin due to systematic bias. Consequently, if CrCl is unavailable, then the CG equation is the better choice provided proper attention is paid to the large variation between methods.     

应用放射性核素方法测量肾小球滤过率及相关技术问题

应用放射性核素功能测定或肾动态显像获得肾小球滤过率（GFR）是临床常用的测量方法，核素显像的特点在于获得肾血流和尿路排泄系列影像的同时计算GFR及其他参数，方法实用简便，GFR数值通常与临床判断或与其他计算GFR的方法相吻合。但核素显像测量GFR受多种因素的影响，包括测量放射性剂量的准确性、“弹丸”注射技术、患者的体形变异和肾脏位置差异、肾脏疾病严重程度和肾外因素干扰、计算机处理方法和操作技能因素等，因此计算GFR的精确度存在不确定性，临床要特别注重参考其他相关指标综合评估肾脏的功能状态。     

Influence of Renal Function on the Urinary Excretion of Amylase

Urinary excretion of endogenous amylase was studied during osmotic diuresis in normal rats and in rats with different kinds of induced kidney damage. In normal rats the amylase excretion varied almost proportionally with respect to plasma concentration of amylase and to glomerular filtration rate (GFR), estimated as clearance for polyethylene glycol 1000 (PEG 1000). The ratio between amylase clearance and GFR varied only slightly with body weight and was independent of urine flow in normal rats. Both increased glomerular permeability to proteins in aminonucleoside-nephrosis and tubular dysfunction after sodium maleate treatment augmented the ratio of amylase clearance to GFR. A considerable tubular reabsorption of amylase in normal rats is concluded. In unilateral pyelonephritis or unilateral ischemic kidney damage this ratio remained constant, but when the functional kidney mass was reduced by removal of the intact kidney, it increased considerably, possibly owing to decreased fractional reabsorption of fluid in the proximal tubules and increased glomerular filtration of proteins per nephron.     

Assessing the impact of inadequate hydration on isotope-GFR measurement

Guidelines state that patients undergoing isotope glomerular filtration rate (GFR) tests should maintain adequate hydration, but pragmatically these tests can coincide with procedures requiring the patient not to eat or drink (‘nil-by-mouth’) for up to 12?hours beforehand. This study investigated the impact of a 12-hour nil-by-mouth regime on GFR measurement. Twelve healthy volunteers were recruited from our institution. Exclusion criteria included diabetes mellitus, being under 18?years of age and pregnancy. Isotope GFR measurements were carried out on these volunteers twice. One of the tests adhered strictly to the British Nuclear Medicine Society (BNMS) guidelines for GFR measurement and the other test was carried out after the volunteers had refrained from eating or drinking anything for 12?hours. The order of these tests was randomly assigned. The results show that after a nil-by-mouth regime, participants’ average absolute GFR fell from 108?ml/min to 97?ml/min (p?<?.01), while normalised GFR fell from 97?ml/min/1.73 m² to 88?ml/min/1.73m² (p?<?.01). Serum creatinine rose from 68?mmol/L to 73?mmol/L (p?<?.05). There were no changes in blood pressure, serum hydration markers or bio-impedance measured fluid status. Urine analysis showed statistically significant increases in urea, creatinine and osmolality levels after the nil-by-mouth regime. The results highlight the importance of following current guidelines recommending fluid intake during the procedure. Practitioners should consider what other outpatient appointments are being scheduled concurrently with a GFR test.     

正确应用肾小球滤过功能检验十分重要

肾小球滤过率（GFR）是判断有无慢性肾脏病的重要指标。目前有多种GFR检验方法，包括放射性核素标记物检测、内生肌酐清除率检测、血清β2微球蛋白及胱蛋白酶抑制物检测等。近年，又提倡用公式估算GFR（eGFR）替代上述检验，国外成人常用的估算公式有Cockcroft—Gault公式及简化肾脏病膳食改良试验（MDRD）公式，它们并不完全适用于国人，所以国内也开发了几个国人eGFR估算公式。这么多GFR检测方法在临床上如何正确应用？在不同慢性肾脏病分期中它们的检测结果可能出现什么偏差？这些问题都非常值得研究。     

Estimating glomerular filtration rate in hypertensive subjects: Comparison of the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) and Modification of Diet in Renal Disease (MDRD) Study equations

Abstract

Background.The Modification of Diet in Renal Disease (MDRD) Study equation is the most commonly used formula for estimation of glomerular filtration rate (eGFR). Recently, the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) developed a new equation to provide a more accurate estimate of GFR among individuals with normal or mildly reduced renal function.

Aim. To compare the MDRD and CKD-EPI equations in hypertensive population treated in general practice.

Methods. The MDRD and CKD-EPI equations were applied to a cohort of 994 hypertensive subjects aged 45–70 years without cardiovascular or renal disease or previously known diabetes.

Results. The prevalence of CKD stage 3 (eGFR 30–59 mL/min per 1.73 m²) was 6.7% (95% CI 5.3–8.5) (67/994) according to the MDRD formula and 3.7% (95% CI 2.6–5.1) (37/994) according to the CKD-EPI formula. Of the 67 subjects classified as having CKD stage 3 according to the MDRD equation, 30 (44.8%) were reclassified as ‘no-CKD’ by the CKD-EPI equation. These subjects were mostly women 26/30 (87.7%).

Conclusion. Using the CKD-EPI equation leads to lower prevalence estimates for CKD than the MDRD equation in a hypertensive population treated in general practice.     

Applicability of estimated glomerular filtration rate in stratifying chronic kidney disease

Objective. The aim of this audit was to evaluate the degree of glomerular filtration rate (GFR) among inpatients and outpatients in a District General Hospital, with special attention given to laboratory testing and impact on health delivery. Background. UK Chronic Kidney Disease guidelines recommend that investigation of renal function should be accompanied by an estimation of GFR (eGFR) in order to identify and manage patients with chronic kidney disease (CKD). The estimated GFR forms the basis for classification of CKD and appropriate action plans for patient management and follow‐up. Method. A retrospective audit of 8160 results from a predominantly British Caucasian population was carried out; extracting creatinine results from two isolated months in years 2001 and 2004. The estimated GFR (eGFR) was calculated using the MDRD formula. The data were classified according to demography, serum creatinine and eGFR. Patients from the 2001 database were classified according to eGFR and those with a value of <60?mL/min/1.73m² were followed up in 2004. Results. The difference in eGFR between the men and women was significantly different with medians (confidence intervals) of 80.1 (41–109) and 64.4 (30–84.6) (p<0.0001), respectively. There was an inverse association between age and eGFR in both genders (p<0.0001), with a decrease in eGFR of around 7?% for each decade increase in age. 1926 patients (24?%) of results studied had eGFR <60?mL/min, of whom 64?% were females and 36?% males. Follow‐up of patients with eGFR<60?mL/min from 2001 showed that 4?% progressed to stages 4 and 5 CKD. Conclusion. eGFR is inversely associated with increasing age and female gender. MDRD derived eGFR fails to completely compensate for age and gender variations and thus different action limits may be required. Small but significant numbers of patients progressed to stages 4 and 5 CKD. Additional clarity in describing “progressive fall in eGFR” in the guidelines would improve identification of the population most at risk.     

Plasmatic cystatin C for the estimation of glomerular filtration rate in intensive care units

Objective To compare the sensitivity of cystatin C and creatinine in detecting decreased glomerular filtration rate.Design Prospective observational study.Setting Medical intensive care unit at a university hospital.Patients and participants Fourteen patients hospitalised in a medical intensive care unit.Interventions Cystatin C and creatinine plasmatic levels were measured in 40 blood samples taken with an interval of at least 24 h.Measurements and results Glomerular filtration rate was estimated by creatinine clearance using 24-h urine collection and the classical Cockcroft-Gault equation. The ability of cystatin C to detect a glomerular filtration rate under 80 ml/min per 1.73 m² was significantly better than that of creatinine (p<0.05).Conclusions Cystatin C, a new plasmatic marker of renal function, could be used to detect renal failure in intensive care in the future.     

223例慢性肾脏病患者胰岛素抵抗及其相关因素的研究

[目的]研究慢性肾脏病(chronic kidney disease,CKD)患者胰岛素抵抗(insulin resistance,IR)与肾脏病临床指标的相关性.[方法]选择近6个月在我院住院的CKD患者465例,测定身高、体重、血压;检测血生化、IR相关指标和24 h尿蛋白定量,计算身高体重指数(body mass index,BMI)和估算的肾小球滤过率(estimated glomerular filtration rate,eGFR),建立数据库.排除6个月内使用过糖皮质激素、有糖尿病及糖尿病家族史的患者,最终入选223例.通过稳态模型HOMA-IR指数评价患者1R,比较CKD各期IR发生率,应用多元回归分析研究CKD患者HOMA-IR指数升高的相关因素.[结果]CKD 4 ～5期患者IR发生率分别为44.44％和42.41％,显著高于CKD 1期患者(5.48％),P值均为0.000.在Pearson相关分析中,年龄(r=0.232,P=0.001)、BMI(r=0.227,P=0.002)、收缩压(r=0.343,P=0.000)、舒张压(r=0.293,P=0.000)、血尿酸(r=0.286,P=0.000)和甘油三酯(r=0.400,P=0.000)与HOMA-IR指数正相关,eGFR(r=-0.425,P=0.000)与该指数负相关,白蛋白(r=0.078,P=0.143)、总胆固醇(r=-0.006,P=0.937)和24h尿蛋白定量(r=0.002,P=0.177)与该指数无明显相关性.CKD 4 ～5期(B=0.512,P=0.000)、甘油三酯(B=0.089,P=0.006)、BMI(B=0.027,P=0.007)和高血压3级(B=0.444,P=0.030)最终进入多元回归方程.[结论]与CKD 1期相比,CKD 4～5期患者IR发生率显著升高.对于CKD患者,eGFR＜30 ml·min-1·(1.73m2)-1,血清甘油三酯升高、肥胖和高血压3级是IR的相关因素.     

Renal effects of urodilatin in healthy subjects are independent of blockade of the cyclooxygenase and angiotensin II receptor

Objective. Little is known about the role of the renin–angiotensin–aldosterone system and the renal prostaglandins in modulating the renal vasoconstrictive and natriuretic effects of synthetic urodilatin (URO) in healthy humans. Material and methods. Twelve volunteers were pretreated in a randomized, single‐blind, crossover study with losartan 50?mg a day or placebo for 5 days. Another 12 healthy subjects received indomethacin 25?mg three times a day or placebo for 4 days and a single dose on day 5. All subjects received a URO infusion (15?ng kg^?1?min^?1) on day 5. Radioactive tracers and the lithium clearance technique were used. Results. The effective renal plasma flow (ERPF) decreased significantly during URO infusion: losartan pretreatment 573±63 to 461±76?mL/min versus placebo 540±89 to 432±90?mL/min. The urinary sodium excretion rate (UNa) increased significantly during URO infusion: losartan 335±115 to 502±134?umol/min (micromol/min) (UNa) versus placebo 386±142 to 476±137?umol/min (micromol/min) (UNa). In the indomethacin pretreated subjects, ERPF decreased significantly from 530±109 to 446±55?mL/min versus 533±89 to 449±69?mL/min in the placebo group. UNa increased significantly from 395±142 to 768±254?umol/min (micromol/min) (UNa) in the indomethacin group versus 282±117 to 552±242?umol/min (micromol/min) (UNa) in placebo. Conclusion. The renal vasoconstrictive and natriuretic effects of synthetic URO are not modified by sustained inhibition of the angiotensin II receptor or the cyclooxygenase in man in a sodium replete state.     

Exaggerated natriuretic response to isotonic volume expansion in hypertensive renal transplant recipients: evaluation of proximal and distal tubular reabsorption by simultaneous determination of renal plasma clearanceof lithium and 51Cr-EDTA

In fourteen hypertensive and fourteen normotensive renal transplant recipients, and in a group of thirteen healthy controls, changes in natriuresis, glomerular filtration rate (GFR), and tubular reabsorption of sodium were determined in relation to intravenous infusion of 2 mmol isotonic sodium chloride per kg body weight. An exaggerated natriuresis was demonstrated in the hypertensive renal transplant recipients. This new finding indicates that the augmented natriuresis following plasma volume expansion, which is a characteristic finding in subjects with arterial hypertension, is not mediated by the renal nerves. Investigation of the tubular reabsorption rates of sodium by simultaneous determination of the renal clearance of 51Cr-EDTA and lithium showed that in the hypertensives the changes in tubular handling of sodium were different from those registered in the normotensive subjects. The increased sodium excretion in the hypertensive renal transplant recipients was caused by an increased output of sodium from the proximal tubules which was not fully compensated for by an increased distal reabsorption. Whether this increased delivery of sodium to the distal segments was caused by changes in GFR or in the proximal tubular reabsorption of sodium could not be clarified in the present study and warrants further investigations.     

慢性肾脏病患者血清胱抑素C测定临床观察及意义

目的 探讨血清胱抑素C（CysC）在慢性肾脏病（CKD）患者肾功能评估中的临床价值,为临床应用提供更多的理论依据.方法 以2011年12月至2012年12月肾内科住院治疗的80例CKD患者为观察对象,测定CysC、血肌酐（SCr）、血尿素氮（BUN）及血白蛋白（ALB）,以MDRD公式计算所得肾小球滤过率（GFR）为诊断标准,评价CysC在CKD早期诊断中的意义.结果 CysC在各组间差异均有统计学意义（P〈0.05）,相关分析CysC与SCr、BUN呈正相关,与GFR呈负相关,且相关系数最高.结论 CysC可作为评价早期慢性肾脏病患者的敏感指标,与SCr、BUN相比能更早、更客观地反映肾小球滤过功能.     

检测血清胱抑素C诊断急性肾衰竭的研究

目的:探讨血清胱抑素C(cystatin C)在诊断急性肾衰竭(acute renal failure,ARF)中的临床价值。方法:收集215例ICU病人的血标本,用酶法测定血清肌酐(serum creatinine,Scr),用颗粒增强透射免疫比浊法测定血清cystatinC,用Cockroft-Gault公式计算肾小球滤过率(glomerular filtration rate,GFR),ARF诊断按ADQI标准。比较ARF病人与非ARF病人上述各指标。结果:41例ARF病人(观察组)血清cystatinC水平较174例非ARF病人(对照组)明显升高(P<0·01);ARF病人血清cys-tatinC与Scr呈正相关(r1=0·747,P<0·001)、与GFR呈负相关(r2=-0·808,P<0·001);以Scr升高达到或超过150%作为ARF的诊断标准时,ROC曲线分析显示血清cystatinC对ARF的诊断准确度高(曲线下面积为0·983)。结论:ARF时血清cystatinC明显升高,cystatinC可作为ICU危重病人并发ARF的诊断指标之一。     

基于半胱氨酸蛋白酶抑制素C建立的肾小球滤过率预测公式的适用性研究

目的 探讨基于Cys C建立的GFR预测公式在我国CKD患者及其分期中的适用性.方法 选择2007年9月至2009年7月我国不同区域(北京、上海、大连、长沙)4家三级甲等医院就诊的CKD患者176例,其中男90例,女86例.通过双血浆法99mTc-二乙三胺五乙酸(99mTc-DTPA)血浆清除率测定入选对象rGFR.应用PETIA和PENIA两种方法检测血浆Cys C浓度,分别将Larsson公式、Grubb公式、Hoek公式、Filler公式、Rule公式、Stevens公式和Hojs公式的eGFR与rGFR进行一致性、偏差、精确度、准确度和分期正确性比较.结果 176例CKD患者rGFR水平为[40.70 (19.09～86.49)] ml·min-1·(1.73 m2)-1.同一公式采用不同Cys C检测方法计算的eGFR结果差异有统计学意义(P均＜0.01).各公式的eGFR与rGFR存在相关,组内相关系数(ICC)在0.874～0.938之间.所有预测公式应用两种方法检测eGFR的30％准确性均低于60％;CKD各期正确分期百分比不理想,2～4期正确分期百分比低于65％.在CKD1期,由PENIA法建立的预测公式低估GFR水平;在CKD5期,由两种方法建立的公式均高估GFR水平.结论 本研究验证的8个基于Cys C建立的GFR预测公式不是我国CKD人群GFR预测的理想公式,不能直接应用于我国CKD患者,需综合种群及年龄等多方面因素进一步修正基于Cys C的GFR预测公式.