Diagnostic accuracy study of urine dipstick in relation to 24-hour measurement as a screening tool for proteinuria in lupus nephritis

OBJECTIVE: Early detection of renal involvement in lupus prevents poor outcomes. Although published guidelines recommend urine dipstick as an appropriate screening test and evidence suggests a majority of American rheumatologists use dipstick to screen for proteinuria, the performance of this diagnostic approach in lupus has not been reported. We examined the validity of qualitative urine dipstick versus quantitative 24-hour measurement to accurately detect proteinuria, including low-level proteinuria. METHODS: We performed a diagnostic accuracy study using paired samples from the Johns Hopkins University School of Medicine and the Ohio State University School of Medicine lupus cohorts. All qualitative urine dipstick values were obtained within 1 day of a 24-hour urine collection. RESULTS: We analyzed the performance of 3 urine dipstick assays to detect proteinuria compared to 24-hour protein/creatinine ratios, using 2224 dipstick measures from 296 patients. The sensitivity of a > or = 1+ dipstick result to detect quantitative proteinuria (> or = 0.50 g protein/g creatinine) was 82.7% for the Clinitek, 97.7% for the Atlas, and 85.5% for the Bayer assay. The corresponding sensitivity to detect low-level proteinuria, (0.50-0.99 g protein/g creatinine) was 63.1%, 96.4%, and 80.7%, respectively. The specificity to correctly exclude proteinuria (< 0.50 g protein/g creatinine) with negative/trace results was 86.1%, 62.2%, and 59.4%. There was considerable variability in the range of protein/creatinine ratios detected at each dipstick level of proteinuria. CONCLUSION: Urine dipsticks demonstrate substantial variability and often poor validity to accurately detect proteinuria at quantitative levels; this warrants further diagnostic evaluation. Clinicians should consider quantified proteinuria assays as a more accurate screening tool in the diagnostic evaluation of lupus nephritis.     

Urine protein-to-creatinine ratio in an untimed urine collection is a reliable measure of proteinuria in lupus nephritis

OBJECTIVE: To evaluate the accuracy of urine protein-to-creatinine (P/C) ratio in an untimed urine specimen as compared with 24 h total protein excretion for measurement of proteinuria in patients with lupus nephritis. METHODS: Proteinuria in patients with lupus nephritis was assessed by 24 h total protein excretion and spot urine P/C ratio. Correlation and limits of agreement between the two methods were evaluated. The discriminant cutoff values for spot urine P/C ratio in predicting 24 h protein 'threshold' excretion of > or =0.3, > or =0.5, > or =1.0 and > or =3.5 g/day were determined using receiver operating characteristic curves. RESULTS: A total of 165 samples were available for assessment with 21.8% excluded due to inadequate collection. A strong correlation (r = 0.91, P < 0.0001) was found between spot urine P/C ratio and 24 h urine protein excretion. Bland-Altman plot showed the two tests had acceptable limits of agreement in low level of protein excretion (-0.86 to +0.92 g/day when protein excretion was <2.0 g/day). The limits became wider as the protein excretion increased. The spot urine P/C ratios of 0.45 (sensitivity 0.92; specificity 0.88), 0.7 (0.92; 0.89) and 1.84 (1.0; 0.86) mg/mg reliably predicted 24 h urine total protein equivalent 'thresholds' at > or =0.5, 1.0 and 3.5 g/day. CONCLUSION: This study supports the recommendation of using spot urine P/C ratio in screening and monitoring proteinuria in patients with lupus nephritis. However, in assessing the exact amount of proteinuria, the urine P/C ratio may have unacceptably wide limits of agreement in high protein excretion range.     

随机尿 晨尿 24 h尿视黄醇结合蛋白/尿肌酐与24 h尿蛋白的相关性研究

目的研究用肌酐校正随机尿、晨尿、24h尿视黄醇结合蛋白（UaBP）后与24h尿蛋白（UP）定量的相关性。方法收集泌尿内科住院或门诊患者同一天内随机尿、晨尿和24h尿标本,分别测定三种不同类型尿液中的视黄醇结合蛋白（RBP）、肌酐（Cr）以及UP含量,其中晨尿和随机尿的结果分别以肌酐比值表示。结果24hURBP与24hUP的相关性为0．955（P=0．000）;随机尿、晨尿URBP与24hURBP的相关系数分别为0．663、0．707（P=0．000）,与24hUP的相关系数分别为0．673、0．738（P=0．000）,其结果经尿肌酐校正后与24hUP的相关系数分别为0．792、0．880（P=0．ooo）。结论晨尿、随机尿URBP／UCr比值与24h尿蛋白有良好的相关性,且标本收集方便易行。     

Screening for proteinuria in a rheumatology clinic: comparison of dipstick testing, 24 hour urine quantitative protein, and protein/creatinine ratio in random urine samples.

Measurements of protein/creatinine ratio in 'spot' urine samples were compared with measurements of 24 hour quantitative proteinuria and side room 'dipstick' testing in 104 samples from 90 patients presenting consecutively to a rheumatology unit. Linear regression analysis showed a highly significant correlation between the random urinary protein/creatinine ratio and total protein excretion in 24 hour urine samples (r = 0.92, p less than 0.001, y = 6.55x + 0.04). Although an approximation of 24 hour urinary protein excretion could have been made from the regression line: 24 hour urine protein = 6.55 x protein/creatinine ratio + 0.04 (g/l), there was a wide scatter of values, particularly in patients with greater than 1 g/24 h urinary protein excretion. Nevertheless, significant proteinuria (greater than 300 mg/24 h) could have been confirmed or excluded with a sensitivity and specificity of 97% by adopting random protein/creatinine values of less than 0.04 as 'normal'. Specificity and sensitivity could have been increased to 100%, however, by excluding patients with values lying between 0.01 and 0.10 as all the false negatives (n = 3) and false positives (n = 3) lay within this range. In comparison, dipstick testing, although 100% sensitive, had a poor specificity due to the high false positive rate (40/83 (48%] in patients with 1+ to 3+ readings. Assessment of random urinary protein/creatinine ratio may obviate the need for 24 hour urine collections in the initial assessment of suspected proteinuria. A wider application of this technique seems indicated in view of the obvious advantages in terms of cost, time, and patient convenience.     

Urinary cortisol in the assessment of pituitary-adrenal function: utility of 24-hour and spot determinations

To more conveniently assess dynamic changes in the biologically active fraction of cortisol, we measured cortisol in 1-h urine samples obtained from 0700-0800 and from 2200-2300 h. In 20 normal subjects, morning 1-h urinary cortisol levels were 78 +/- 36 ng/mg creatinine (mean +/- SD), whereas levels from 2200-2300 h were 22 +/- 12 ng/mg creatinine, demonstrating diurnal variability. In 14 patients with Cushing's syndrome, mean morning urinary cortisol was elevated (207 +/- 176 ng/mg creatinine), but there was overlap with values in normal subjects. In contrast, evening values in Cushing's syndrome (248 +/- 208 ng/mg creatinine) were elevated in each patient; there was no diurnal variation and no overlap with normal subjects. Similarly, the morning urinary cortisol response to dexamethasone (1 mg, orally, at 2300 h) clearly separated normal subjects from those with Cushing's syndrome (5 +/- 6 vs. 169 +/- 149 ng/mg creatinine, respectively). In 10 patients with secondary hypoadrenalism, urinary cortisol levels were less than 2 ng/mg creatinine in both morning and evening 1-h samples. Thus, the determination of cortisol in 1-h samples is a practical and simple method of assessing cortisol secretion and allows multiple sampling without hospitalization. It is effective in assessing dynamic cortisol responses, such as diurnal variation and responsiveness to suppression, and it is an effective screening test for Cushing's syndrome and hypoadrenalism.     

脑梗死患者脑白质疏松与24小时尿微量白蛋白排泄率的相关研究

目的分析脑梗死患者脑白质疏松(leukoaraiosis,LA)与24 h尿微量白蛋白排泄率(urine microalbumin excretion,UAER)的相关性。方法选择2011年6～12月住南京军区南京总医院所有首次急性脑梗死患者120例,根据是否合并LA分为LA组45例,无LA组75例,详细记录患者一般临床资料,检测24 h UAER及空腹血糖、血脂等生化指标。比较2组一般临床危险因素及24 h UAER,并进行多因素回归分析。结果 120例脑梗死患者中,合并LA 45例,占37.5%。与无LA组比较,LA组患者年龄、高血压发生率、24 h UAER水平明显升高,差异有统计学意义(P<0.05,P<0.01);LA与24 h UAER水平呈正相关(r=0.681,P<0.01);24 h UAER(OR=1.100,95%CI:1.03～1.17,P=0.002)是LA的独立危险因素。结论 LA与24 h UAER密切相关,24 h UAER可以作为小血管病损伤的一个标记物,对LA的诊断和治疗有重要意义。     

Comparison of overnight, morning and 24-hour urine collections in the assessment of diabetic microalbuminuria

With the aim of comparing different urine collection periods in the assessment of micro-albuminuria, urinary albumin excretion rates (AERs) were measured in samples from 24 h, overnight, and morning urine collections in 54 patients aged 17 to 62 years with insulin-dependent diabetes mellitus with a mean duration of 15 years. The AER in overnight urine was found to be reduced by 25% compared to the rate in 24 h and morning urine. Assessing the ability to predict a 24 h AER within the microalbuminuric range (20-200 micrograms/min) we found a sensitivity of 90% and a specificity of 88% for both overnight and morning urine samples. These values were slightly improved by relating AER to the excretion of creatinine and it is concluded that overnight as well as morning urine collections can be used when diagnosing microalbuminuria in insulin-dependent diabetics. Furthermore the results show that the albumin to creatinine ratio in morning urine is a reliable estimate of 24 h AER and better than measurement of the albumin concentration alone.     

糖尿病肾病患者尿足细胞脱落及其与尿蛋白的关系

目的 通过观察糖尿病肾病(DN)患者尿中足细胞及肾活检标本足细胞脱落情况,探讨尿中足细胞脱落与尿蛋白、空腹血糖、肌酐的关系.方法 选取2005年1月至2006年12月间天津医科大学总医院收治的DN患者50例,微小病变(MCD)患者25例及正常人对照组10例,按照慢性肾脏病(CKD)分期将DN患者分为5组,其中CKD I期15例,CKD Ⅱ期10例,CKD Ⅲ期8例,CKD IV期9例,CKD V期8例;另按尿蛋白量将DN患者分为3组,其中少量蛋白尿组(<1.0 g/d)13例,中量蛋白尿组(1-3.5 g/d)20例,大量蛋白尿组(>3.5 g/d)17例,采用间接免疫荧光法检测尿足细胞数目及肾小球足细胞特异性蛋白(podocalyxin,PCX)表达;分别统计各组中尿足细胞数目;同时检测各组患者24h尿蛋白、肌酐、空腹血糖,多组计量指标比较采用单因素方差分析,双变量分析采用Pearson相关分析.结果 DN组尿中足细胞的阳性率为88%(44/50);微小病变(MCD)组及正常对照组中阳性率为0;DN组患者的肾活检标本中,肾小球足细胞PCX表达缺失,MCD组肾活检标本足细胞PCX呈完整连续性表达.少量蛋白尿组尿足细胞数目(1.5±1.0)个/ml,中等量蛋白尿组(2.2±0.7)个/ml及大量蛋白尿组(3.5±1.3)个/ml,除少量蛋白尿与中量蛋白尿组差别不具有统计学意义外,其他组间差别均具有统计学意义(P<0.05).DN患者尿足细胞数目与蛋白尿(r=0.785,P<0.05)、I-Ⅲ期患者同期SCr呈正相关(r=0.466,P<0.05);而与FBG无相关性(P>0.05).结论 DN进展过程中存在足细胞损伤.DN足细胞脱落与尿蛋白、CKD I至Ⅲ期同期SCr呈正相关,与Ⅳ至V期SCr、FBG无关.     

Correlation between the indicators of blood coagulation and lipid metabolism in patients with stenocardia during the 24-hour period

The correlation between the main parameters of blood coagulation and lipid metabolism were examined dynamically during 24 hours in 49 patients with angina pectoris. Circadian fluctuations of varying degrees of direct and inverse correlation were found in the concentration of cholesterol, beta-lipoproteins, non-esterified fatty acids, lecitin, total lipids, triglycerids, on the one hand, and the level of free heparin, the fibrinolytic activity, fibrinogen, thrombine time, platelets count in 1 mm3 of blood, on the other hand.     

Comparative study of endocavitary recording and the 24-hour electrocardiogram in the study of sinus function. Apropos of 174 cases

We compared the results of electrophysiological investigations of sino-atrial node function in a series of 174 patients (including the sino-atrial conduction time (SACT) according to the method of Narula and Strauss, the corrected sino-atrial recovery time (CSART) and, in, 22 patients, the atropine test) with the results of 24 hour Holter monitoring. 73 patients presented a pathological Strauss curve, 47 had a prolonged SACT (Strauss' method) and 19 had a pathological CSART. Of the 22 bradycardic patients, the injection of atropine relieved the bradycardia in 45.5 per cent of cases. 19 patients showed signs of sino-atrial node dysfunction on the 24 hour Holter recording. Of the 35 patients with a surface electrocardiogram (ECG) suspicious of sino-atrial node dysfunction, 21 (60%) had a prolonged SACT and 13 (37.1%) had a pathological CSART: 15 of them (42.8%) showed major electrophysiological abnormalities and 19 (54.3%) had a positive Holter. In two-thirds of the cases of pure sino-atrial bradycardia, the results of electrophysiological and Holter investigations were normal; in 50 per cent of cases of sino-atrial block and/or pause on the surface ECG, major abnormalities were found on both electrophysiology and the Holter monitor. The SACT, estimated according to the method of Strauss, is discorsdant with the SACT estimated according to Narula's method in 46 p. cent of cases. It seems that Strauss' SACT was more sensitive in our study. In 102 cases (59.3%), the SACT and the CSART were concordant. In 10 cases, the SACT was normal while the CSART was pathological and in 42 cases, the SACT was pathological while the CSART was normal.(ABSTRACT TRUNCATED AT 250 WORDS)     

Serum C-reactive protein is rarely lost into urine in patients with secondary amyloidosis and proteinuria

We studied whether the low serum C-reactive protein (S-CRP) level in patients with inflammatory arthritis and proteinuria was due to the loss of CRP into urine. In 19 patients with secondary amyloidosis (14 with rheumatoid arthritis and five with juvenile chronic arthritis), S-CRP was measured with both immunoturbidimetric and radioimmunoassays. The concentration of urinary CRP was measured with a double-antibody radioimmunoassay. One patient with the most extensive proteinuria (12 g/24 h) excreted CRP at 14 mg/24 h, while in 18 of 19 patients only negligible, if any, amounts of CRP were found in 24-h urine samples. Proteinuria of <8 g/24 h did not reduce the S-CRP level. Proteinuria exceeding this level may result in increased excretion of CRP into urine and consequently may result in a reduced S-CRP level.     

原发性高血压患者24 h平均脉压与心脏损害的关系

目的探讨原发性高血压(EH)患者24 h平均脉压(ABPP)与心脏损害的关系.方法将486例EH患者行动态血压检测的结果按ABPP≥60 mmHg和ABPP＜60 mmHg分为两组,将两组的多普勒加二维超声心动图检测中主动脉内径、室间隔厚度、左心室舒张末期内径、左心室后壁厚度、左室重量、左室重量指数、EF、E/A,以及两组的心电图资料进行对比分析.结果随着脉压增大,出现心电图异常病例增多,心肌肥厚、心脏扩大、主动脉内径增大病例增多,心脏收缩和舒张功能减退,两组数据经统计学处理差异有明显的统计学意义.结论脉压增大,增加了对靶器官的损害,尤其是对心脏损害,进而造成心血管疾病发病率增高,因此在EH治疗中积极控制脉压将能有效减轻心脏损害.