Observations with regard to the National Kidney Foundation K/DOQI clinical practice guidelines concerning serum transthyretin in chronic renal failure.

The National Kidney Foundation K/DOQI Guidelines state that, "Serum prealbumin is a valid and clinically useful measure of protein-energy nutritional status in maintenance dialysis (MD) patients." Prealbumin, also known as serum transthyretin (TTR), was not recommended as a nutritional parameter of the same usefulness as the serum albumin. This decision was made, in part, because published research at that time suggested that serum TTR was not a more sensitive index of nutritional status than serum albumin and there was much more clinical and research experience with serum albumin as a nutritional and inflammatory marker. Evidence, including more recently published research data, which is reviewed in this paper has led to the following conclusions by the current authors: 1) In MD patients either protein-energy malnutrition or inflammation can lead to a reduction in serum TTR concentrations. 2) Hence, in MD patients, serum TTR concentrations can be used as a measure of both nutritional and inflammatory status. 3) Serum TTR concentrations are typically increased in MD patients. 4) In maintenance hemodialysis (MHD) patients, serum TTR is a risk factor for mortality that is somewhat independent of serum albumin. 5) Current epidemiological evidence suggests that a serum TTR value of 25 or 30 mg/dl or greater is associated with increased survival and, hence, is desirable in MHD patients. 6) MHD patients with serum TTR levels less than 25-30 mg/dl should be evaluated for protein-energy malnutrition and inflammation.     

Protein status in pancreatitis--transthyretin is a sensitive biomarker of malnutrition in acute and chronic pancreatitis.

Malnutrition may develop in acute pancreatitis (AP), accompanied by hypermetabolism and high nutritional requirements, and in chronic pancreatitis (CP). We measured the incidence of protein malnutrition in AP and CP by comparing different serum biomarkers of protein metabolism and inflammation. Thirty-five patients with acute (27 moderate, 8 severe), and 35 with chronic, pancreatitis were enrolled in the study. Serum transthyretin, albumin, transferrin and C-reactive protein (CRP) concentrations were measured in AP at admission, after 1 and 2 weeks of jejunal feeding, and in patients with CP at follow-up. In AP, at admission the transthyretin level was low in 74%, transferrin in 48%, and albumin in 29% of patients. In severe pancreatitis, transthyretin levels were significantly lower than in moderate forms (7.5 +/- 2.43 vs. 14.39 +/- 6.8 mg/dl, p < 0.005). Transthyretin levels increased significantly after 2 weeks of jejunal feeding (p < 0.05). In CP, transthyretin levels were decreased in 37%, transferrin in 27%, and albumin in 12% of patients. We found significantly lower transthyretin levels in alcohol-related CPthan in other forms (18.5 +/- 8.3 vs. 30.2 +/- 5.7, p < 0.01). Transthyretin correlated positively with albumin and transferrin and negatively with CRP Transthyretin seems to be a sensitive biomarker of protein status and metabolic stress. Monitoring nutritional status through measurement of serum proteins is important for optimal treatment of AP and CP.     

Age- and sex-specific pediatric reference intervals and correlations for zinc, copper, selenium, iron, vitamins A and E, and related proteins

Age- and sex-specific reference intervals based on the 0.025 and 0.975 fractiles of data derived from a healthy pediatric population are presented for zinc, copper, selenium, iron, ferritin, retinol, alpha-tocopherol, and related analytes in serum. Age was an important covariate for copper, selenium, retinol, and tocopherol, and ferritin in boys. Strong correlations were found between retinol and retinol-binding protein, prealbumin (transthyretin), alpha-tocopherol, and selenium. Tocopherol was highly correlated with both cholesterol and triglycerides. We found no relationship between serum zinc and either retinol or retinol-binding protein. Despite exclusion of children in whom anemia, microcytosis, or variant hemoglobins were found, the 0.025 fractile for iron in several age groups was even less than the concentration considered to indicate poor iron nutritional status.     

Laser immunonephelometry reference intervals for eight serum proteins in healthy children.

Eight serum proteins were analyzed with the Behring nephelometer in samples from 479 healthy French children, ages three to 16 years. Girls had higher concentrations of IgM and albumin than boys had. Age appeared to be a main factor of variation for the proteins tested. Reference intervals are presented for IgG, IgA, IgM, albumin, transthyretin (prealbumin), retinol-binding protein, alpha 1-acid glycoprotein, and C-reactive protein. The significance of increased concentrations of C-reactive protein within a community is discussed.     

Kinetic nephelometric determination of transthyretin and retinol-binding protein in neonatal serum

We have developed a kinetic immunonephelometric method for the determination of retinol-binding protein and modified the method of Jacob et al (Clin Chem 1983; 29: 564) for the determination of transthyretin (prealbumin) in neonatal serum specimens from small, premature infants. The methodologies allow detection of 17.5 mg/l transthyretin and 1.7 mg/l retinol-binding protein in 25 microliter of serum. Between-run precision studies using pooled neonatal serum gave CV values of 3% and 5-6% for transthyretin and retinol-binding protein, respectively. Results obtained for neonatal specimens using this method agreed well with those obtained for the same specimens using radial immunodiffusion. Mean (SD) serum concentrations for 39 neonatal specimens were 100.4 (46.6) and 26.3 (10.8) mg/l for transthyretin and retinol-binding protein, respectively.     

Residual renal function in a large cohort of peritoneal dialysis patients: change over time, impact on mortality and nutrition.

OBJECTIVE: Residual renal function contributes importantly to total solute clearance in peritoneal dialysis (PD) patients. This study was designed to examine the progression of residual renal function over time and its impact on nutrition and mortality in PD patients in the six New England states (ME, NH, VT, CT, MA, RI) comprising End Stage Renal Disease (ESRD) Network 1. DESIGN: As part of the ESRD Clinical Indicators Project, data on 990 PD patients in Network 1 were abstracted from data supplied by dialysis units in the fourth quarter of 1997. This included demographic information; dose of PD in L/day; weekly renal, dialysis, and total Kt/V urea; weekly renal, dialysis, and total creatinine clearance (CCr); serum albumin level; and mortality and transplantation information. Data collection was repeated in the second and fourth quarters of 1998 and in the second quarter of 1999. PATIENTS: 990 PD patients in Network 1. OUTCOME MEASURES: The change in total and renal solute clearances over time, the relationship between renal clearance and mortality, and the relationship between renal clearance and nutritional status, as represented by serum albumin. RESULTS: Over the 2-year period, mean weekly renal Kt/V urea and weekly renal CCr dropped significantly. To examine the effect of residual renal function on mortality, patients were divided into high and low (above and below the median) weekly renal Kt/V urea and weekly renal CCr groups. Patients above the median levels of both weekly renal Kt/V urea and weekly renal CCr had a significantly decreased risk of dying during the observation period, after controlling for age, gender, serum albumin level, and diabetic status [OR for high vs low renal Kt/V urea 0.54 (CI 0.34 - 0.84), OR for high vs low renal CCr 0.61 (CI 0.40 - 0.94)]. The mean weekly renal Kt/V urea was significantly and directly correlated with the mean serum albumin level by Spearman rank correlation (R = 0.133, p < 0.001), as was the mean weekly renal CCr (R = 0.115, p < 0.001). CONCLUSIONS: Residual renal function is an important contributor to total solute clearance in PD patients. Even at low levels it is linked to decreased mortality and better nutritional status.     

腹膜透析治疗糖尿病肾病尿毒症患者的临床分析

目的　探讨影响糖尿病终末期肾病 (ESRD)患者腹膜透析生存率的因素。方法　对糖尿病ESRD患者 2年存活组与死亡组开始透析时的肾功能、营养状态及合并症情况进行对比分析。结果　糖尿病ES RD患者 2年死亡组开始透析时的尿素氮 (BUN)、血肌酐 (Scr)高于存活组 ,内生肌酐清除率低于存活组 ;与存活组相比 ,2年死亡组开始透析时的血红蛋白 (Hb)、血浆白蛋白 (Alb)明显较低 ;2年死亡组开始透析时的合并症数目多于存活组。结论　糖尿病ESRD患者的腹膜透析生存率与开始透析时的肾功能、营养状态及合并症情况密切相关 ,应根据患者透析前肾功能、营养状态及合并症情况综合考虑 ,选择适当的透析时机。     

腹膜透析患者血清白蛋白水平影响因素分析

目的通过对持续性非卧床腹膜透析(CAPD)患者的研究,探讨影响患者血清白蛋白(Alb)水平的可能因素。方法选择北京大学第一医院腹膜透析中心217例患者,按照其血清白蛋白水平分为两组:Alb≤35g/L组和Alb>35g/L组,分析血清白蛋白与其它营养指标之间的关系及其影响因素。结果血清白蛋白水平与握力、血肌酐显著相关,营养不良的患者血清白蛋白显著降低。多因素回归分析发现血清C-反应蛋白、容量状态、合并症、年龄对血清白蛋白水平有显著影响(P<0.05)。结论本研究发现血清白蛋白水平与营养指标密切相关,但除营养指标之外的一些因素也可显著影响血清白蛋白水平,这包括炎症、体内液体容量负荷过多、合并症等等。因此,在将血清白蛋白作为评估患者营养状态时应注意排除这些因素的影响。     

Peritoneal membrane transport and hypoalbuminemia: cause or effect?

OBJECTIVE: Peritoneal membrane transport has been associated with serum albumin and clinical outcome. We examined the relationship between serum albumin and peritoneal membrane transport status before and after the initiation of peritoneal dialysis. SETTING: Patients were followed at a tertiary-care regional nephrology program at St. Joseph's Hospital, McMaster University, Hamilton, Ontario, Canada. METHODS: Incident peritoneal dialysis patients between 1 January 1995 and 31 May 1998 were eligible if there was a peritoneal equilibration test within 180 days of starting dialysis, and a serum albumin value measured within 90 days prior to, and 20 to 70 days after initiating dialysis. MAIN OUTCOME MEASURES: Serum albumin, before and after the initiation of dialysis, and the presence of proteinuric renal disease were compared with the peritoneal equilibration test results. RESULTS: Among 67 identified patients, there were 7 high, 27 high-average, 26 low-average, and 7 low transporters and the mean serum albumin values before dialysis were 35.1, 37.4, 37.8, and 40.4 g/L, respectively (p < 0.001). Serum albumin values prior to the initiation of dialysis correlated significantly with the 4-hour D/P creatinine ratio (r = -0.251, p = 0.040). After initiation of dialysis, the correlation was stronger (r= -0.447, p< 0.001). Serum albumin prior to initiation of dialysis was lower for those with proteinuric than nonproteinuric renal disease (36.4 g/L vs 38.8 g/L, p = 0.04). The trend to lower serum albumin in high transporters was seen in patients with both proteinuric and nonproteinuric renal disease. CONCLUSION: The association between higher peritoneal membrane transport and lower serum albumin is present before initiation of dialysis in both proteinuric and nonproteinuric renal disease.The poor outcomes associated with low serum albumin and higher peritoneal membrane transport might be explained by other underlying factors. The contribution of inflammation, malnutrition, and fluid overload requires further study.     

Laboratory monitoring of nutritional status in burn patients.

Most nutrition laboratory testing relies on serum concentrations of ingested nutrients, their coenzymes, proteins, or lipids. Alternatively, functional tests measure a specific physiological process or biochemical reaction. We compared these two approaches to nutritional assessment in intensive-care burn patients, in whom the serum concentrations of transthyretin (prealbumin), albumin, transferrin, carotene, retinol, ascorbic acid, copper, cholesterol, iron, and calcium were all below established reference ranges. In contrast, serum triglyceride concentrations were often above the reference range. Functional tests for thiamin, riboflavin, pyridoxine, and iron (by zinc protoporphyrin/heme ratio) in these patients all showed normal values. Dietary intake, weight trends, and nitrogen balances all indicated that these patients' estimated caloric and protein needs had been met. These findings suggest that static measurements of serum concentrations may be unreliable indicators of nutritional status in burn patients.     

血清胱抑素c与视黄醇结合蛋白检测在糖尿病肾病早期诊断中的应用价值

目的探讨血清胱抑素C（CysC）与血清视黄醇结合蛋白（RBP）检测在糖尿病肾病早期诊断中的意义。方法采用免疫速率散射比浊法,检测50例2型糖尿病肾病患者的血清胱抑素C与血清视黄醇结合蛋白。同时,用酶法检测血清尿素（Urea）、血清肌酐（cr）。结果糖尿病‘肾病组血清胱抑素C、血清视黄醇结合蛋白均显著高于正常对照组（P〈0．01）。结论胱抑素C与视黄醇结合蛋白可作为诊断糖尿病早期肾损害的血清学指标。     

老年肾衰竭透析患者合并感染的临床分析

目的　探讨老年肾衰竭血液透析患者感染的临床特点、相关因素及防治对策。方法　回顾分析82例老年血液透析患者的感染部位、病原菌种类、营养状况、透析充分性、原发病等与感染的关系。结果　感染组 4 4例患者共发生感染 6 0例次 ,肺部感染和尿路感染最常见 ,其次为肠道感染及中心静脉置管处局部感染 ,感染组血红蛋白、血清白蛋白及营养状况较非感染组明显减低 ,透析时间 /周感染组较非感染组明显减少。结论　慢性肾衰血液透析患者感染发病率高 ,积极改善营养状况 ,加强透析 ,注意个人卫生习惯 ,有助于预防感染。     

The sensitivity and specificity of nutrition-related variables in relationship to the duration of hospital stay and the rate of complications

We assessed the nutritional status at the time of hospital admission of 74 patients who were admitted for elective gynecologic or urologic operations. Nutritional assessment included measurement of serum albumin, thyroxine-binding prealbumin, retinol-binding protein, weight-change history, estimate of daily protein and total calorie intake, and a global estimate of nutritional risk. The sensitivity, specificity, false-positive rate, likelihood ratio, and positive predictive value of these nutrition-related variables were analyzed in patients who stayed in the hospital for longer than 10 days and in those patients with recognized complications. In the analysis of patients who remained in the hospital longer than 10 days, the finding of a low serum protein concentration or a low protein intake was most sensitive, and a low serum albumin concentration was the most specific. A receiver-operating-characteristic diagram that depicts the sensitivity and false-positive rates for the single variables and the combinations of variables is probably the most clinically useful summary of our study. Using the information in such a diagram, a clinician might choose variables that are more sensitive to identify hospitalized patients who should receive special nutritional attention in comparison with another clinician who might need fewer false-positive results for a prospective study of nutritional intervention.     

高龄肾功能衰竭患者血液透析的疗效分析

目的评估高龄肾功能衰竭患者血液透析的临床疗效.方法观察总结65例高龄肾功能衰竭患者血液透析治疗后的生存率和死亡原因,心脑血管并发症的发生情况及与透析充分性和营养状况相关的指标.结果高龄血液透析患者的长期存活率逐步提高,死亡原因主要为心血管疾病、感染及严重营养不良,常见心血管并发症为低血压,透析充分性和营养情况有改善,但血清白蛋白仍明显低于非老年组.结论施行个体化的透析和治疗,积极改善营养,减少感染,有助于减少高龄透析患者的并发症发生和提高生存率.     

Usefulness of data on albumin and prealbumin concentrations in determining effectiveness of nutritional support

In this ongoing study, albumin and prealbumin (transthyretin) changes were compared in 40 patients managed with enteral and (or) parental support with attainment of caloric/protein goals. The concentration of prealbumin in serum changed rapidly and more accurately reflected current nutritional status of these patients than did that of albumin. We determined concentrations of albumin and prealbumin that reflected significant improvement in nutritional status, using Rudolph's approach based on Shannon information measures. Reference values for albumin and prealbumin in the treatment populations were 25 g/L and 107 mg/L, respectively. A prealbumin concentration of 135 mg/L or greater reflected a return to stable status.     

运用主观评估法评价α酮酸对老年透析患者营养的改善作用

目的本研究采用主观评估（微型营养评估法与主观全面评估法）与客观指标结合的综合评估方法,初步探讨复方α酮酸制剂对于透析患者蛋白营养不良的治疗作用。方法选择上海交通大学附属第一人民医院透析中心血清白蛋白低于35g/L老年血液透析及腹膜透析患者各24例,透析时间均大于一年,其中,血液透析组及腹膜透析组各设对照组12例。除对照组外,所有患者均服用开同6个月。营养评估采用综合评估法,即客观营养指标结合主观营养评估。客观指标包括：体重指数（BMI）、血白蛋白（Alb）、血前白蛋白和平均每日每公斤体重能量与蛋白质摄入（DEI、DPI）。主观评估采用了两种评分方法：即通用的主观全面评估法（Subject Global Assessment,SGA）与专门用于老年患者的微型营养评估法（Mini NutritionalAssessment,MNA）,同时测定了患者饮食中的蛋白质与能量摄入情况。结果①伴营养不良的患者普遍存在SGA与MNA评分偏低,提示主客观的评估一致性较好;②与对照组相比,应用酮酸制剂治疗的透析患者3个月后,蛋白质与能量的摄入明显上升,虽体重指数改变不明显,但血清白蛋白水平明显升高,;治疗6个月以后,SGA评分、MNA评分明显上升;低血清白蛋白血症进一步改善,而蛋白质与能量的摄入未进一步增加,患者的体重指数BMI、透析充分性、C反应蛋白（CRP）、血脂改变仍不明显。结论复方酮酸制剂能够提高血清白蛋白水平,改善营养状况,微型营养评估法更适合老年透析患者的营养评估。     

Selective use of transthyretin and retinol-binding protein as markers in the postoperative assessment of protein nutritional status

We evaluated several markers to judge the postoperative state of protein nutriture in eight patients following surgery for cancer. Seven patients had a good prognosis and had no evidence of infections or other complications. Following surgery, all of the patients showed a shift toward abnormal values for the serum concentrations of albumin, transthyretin (TT), retinol-binding protein (RBP), and the amino acid (AA) ratio of nonessential to essential amino acids. In patients without complications, the AA ratio returned to normal first. When blood specimens were collected at 7-day intervals, concentrations of RBP and TT were revealed to be decreased and recovered at the same time, or TT was recovered after RBP was normalized. RBP and TT were usually abnormal until the AA ratio became normal. Although albumin moved toward normal concentrations after RBP and TT, the albumin concentrations in some patients were slightly above the lower reference value, whereas RBP and TT were significantly below their lower reference limits. In these patients, assessments over the next 7-14 days showed persistently low values for albumin, TT, and RBP. We recommend the selective use of TT and RBP for the postoperative assessment of protein nutriture in surgical patients.     

The prognostic value of nutritional and inflammatory indices in critically ill patients with acute respiratory failure.

In critically ill patients suffering from acute respiratory failure, weaning from ventilatory assistance is a key survival factor in intensive care units (ICU). The aim of this study was to provide deeper insight into laboratory methods allowing improved monitoring of that critical period. Eighty-three ICU patients (mean age 63.9 years), classified according to the Second Acute Physiology and Chronic Health Evaluation criteria, were submitted to mechanical ventilation, antibiotherapy and nutritional support. Weaning attempts required degressive pressure support ventilation. The biological status of the patients was assessed by the serial measurement of inflammatory (C-reactive protein and alpha1-acid glycoprotein) and of nutritional (albumin and transthyretin) indicators whose aggregation yields a prognostic inflammatory and nutritional index (PINI). Statistical analyses compared ventilatory and biological data recorded on admission and at the time of extubation. Results showed that vital capacity and plasma concentrations of albumin and transthyretin rose, whereas rapid shallow breathing index, C-reactive protein and PINI values declined during the tested period. Persistent low transthyretin concentrations were predictive of lethality while increased values were associated with improved ventilatory performances. The PINI scoring formula worked as an independent predictor of the weaning trial outcome. The study underlined the value of the PINI system for the successful management of the weaning procedure.