Estimating GFR in children with 99mTc‐DTPA renography: a comparison with single‐sample 51Cr‐EDTA clearance

Glomerular filtration rate (GFR) measurement by ⁵¹Cr‐ethylenediaminetetraacetic acid (EDTA) and blood sampling in children is usually cumbersome for the patient, parents and laboratory technicians. We have previously developed a method accurately estimating GFR in adults. The aim of the present study was to evaluate the accuracy of this non‐invasive method in children. We calculated GFR from ^99mTc‐diethylene triamine pentaacetic acid (DTPA) renography and compared with ⁵¹Cr‐EDTA plasma clearance of 29 children between the age of 1 month and 12 years (mean 4·7 years). The correlation between ^99mTc‐DTPA renography and ⁵¹Cr‐EDTA plasma clearance was for all children R = 0·96 (n = 29, P<0·0001), for children above 2 years of age R = 0·96 (n = 18, P<0·0001) and for children <2 years R = 0·84 (n = 11, P<0·001). We conclude that assessment of GFR from ^99mTc‐DTPA renography is reliable and comparable to GFR calculated from ⁵¹Cr‐EDTA plasma clearance. Because our method is non‐invasive and only takes 21 min, it may be preferable in many cases where an assessment of renal function is needed in children especially when renography is performed anyhow.     

Clearance and renal extraction of technetium-99m- L, L-ethylenedicysteine,I-131-ortho-iodohippurate and I-125-iothalamate in pigs

99mTc- L , L -ethylenedicysteine (^99mTc-EC) has been proposed as a ^99mTc-labelled alternative to radio-iodinated ortho-iodohippurate (OIH) for renal imaging and evaluation of renal function. The kinetics of this new renal function agent were studied by a single-injection plasma clearance technique in pigs. ^99mTc-EC, ¹³¹I-OIH and ¹²⁵I-iothalamate were injected and the plasma concentration of the three tracers was followed for 240 min. Renal, hepatic and total plasma clearance were calculated. There was no difference between the renal plasma clearance of ^99mTc-EC and ¹³¹I-OIH (175 ± 9 versus 178 ± 8 ml min^?1, P=0·43), whereas the difference between the total plasma clearance of ^99mTc-EC and ¹³¹I-OIH was highly significant (268 ± 16 versus 185 ± 9 ml min^?1, P=0·0001). ^99mTc-EC had a significant hepatic clearance of 83 ± 10 ml min^?1 whereas the hepatic clearance of ¹³¹I-OIH was negligible. Renal plasma extraction of both ^99mTc-EC and ¹³¹I-OIH decreased significantly between 2 and 240 min post-injection from 0·85 to 0·45% for ^99mTc-EC and from 0·93 to 0·57% for ¹³¹I-OIH. Red blood cell binding of ^99mTc-EC and ¹³¹I-OIH was 6·1% and 20%, respectively. The protein binding of ^99mTc-EC and ¹³¹I-OIH was 32% for both tracers. We conclude that ^99mTc-EC is not a suitable tracer for measuring renal function by the single-injection plasma clearance technique in pigs. This is due to a decreasing renal extraction and a significant hepatic clearance.     

Endothelin‐1: increased plasma clearance,pulmonary affinity and renal vasoconstriction in young smokers

Pulmonary and renal haemodynamics and elimination of endothelin‐1 (ET‐1) were studied in six young smokers in response to 20 min intravenous infusion of ET‐1 (4 pmol kg^–1 min^–1) after smoking. At 20 min of ET‐1 infusion fractional ET‐1 extractions in the lungs and kidneys were 60 ± 2 and 60 ± 7%, respectively. Cardiac output and renal blood flow (RBF) fell by 18 ± 4% (P<0·05) and 34 ± 5% (P<0·01). Mean systemic arterial pressure increased (P<0·05) whereas pulmonary pressures were unchanged. Compared with previously published data in non‐smokers ( 38 , 39 ) basal arterial ET‐1 and ET‐1‐values during ET‐1 infusion were lower with a more rapid return to basal value. Smokers had higher pulmonary extraction of ET‐1 at the same pulmonary arterial concentration (P<0·05). RBF reduction was more pronounced (P<0·05). Systemic vascular resistance increased while pulmonary vascular resistance did not increase as in non‐smokers. Increased plasma clearance and more efficient pulmonary elimination of ET‐1 lowers the arterial level in young smokers. In addition ET‐1 evokes more pronounced renal vasoconstriction in these individuals.     

Gamma‐variate plasma clearance versus urinary plasma clearance of 51Cr‐EDTA in patients with cirrhosis with and without fluid retention

In patients with fluid retention, the plasma clearance of ⁵¹Cr‐EDTA (Cl_exp obtained by multiexponential fit) may overestimate the glomerular filtration rate (GFR). The present study was undertaken to compare a gamma‐variate plasma clearance (Cl_gv) with the urinary plasma clearance of ⁵¹Cr‐EDTA (Cl_u) in patients with cirrhosis with and without fluid retention. A total of 81 patients with cirrhosis (22 without fluid retention, 59 with ascites) received a quantitative intravenous injection of ⁵¹Cr‐EDTA followed by plasma and quantitative urinary samples for 5 h. Cl_gv was determined from the injected dose relative to the plasma concentration‐time area, obtained by a gamma‐variate iterative fit. Cl_exp and Cl_u were determined by standard technique. In patients without fluid retention, Cl_gv, Cl_exp and Cl_u were closely similar. The difference between Cl_gv and Cl_u (Cl_gv – Cl_u = ΔCl) was mean ?0·6 ml min^?1 1·73 m^?2. In patients with ascites, ΔCl was significantly higher (11·8 ml min^?1 1·73 m^?2, P<0·0001), but this value was lower than Cl_exp – Cl_u (17·5 mL min^?1 1·73 m^?2, P<0·01). ΔCl increased with lower values of GFR (P<0·001). In conclusion, in patients with fluid retention and ascites Cl_gv and Cl_exp overestimates GFR substantially, but the overestimation is smaller with Cl_gv. Although Cl_u may underestimate GFR slightly, patients with ascites should collect urine quantitatively to obtain a reliable measurement of GFR.     

99mTc-DTPA清除率、肌酐清除率及彩色多普勒在评价肾功能中的价值比较

目的比较核素扫描、肌酐清除率及彩色多普勒在评价肾小球滤过功能中的价值.方法对11例健康体检者、163例慢性肾功能不全患者进行24 h肌酐清除率(CCR)、血肌酐(SCr)、核素扫描测量肾小球滤过率(GFRDTPA)等检查,并用彩色多普勒超声检查峰时肾血流量、肾动脉阻力指数(RI)、肾血流分布状况;分析GFRDTPA、CCR、RI和峰时肾血流量间的关系.结果 CCR和GFRDTPA在GFR≥90 ml/min组和GFR＜15 ml/min组无明显差异;但在15 ml/min≤GFR＜90 ml/min组,GFRDTPA明显低于CCR(P＜0.01).GFRDTPA、CCR均与彩超所测峰时肾血流量、肾血流丰富程度正相关,与肾动脉阻力负相关,且随肾功能下降肾血供减少.结论患者肾功能无明显异常和肾功能下降达终末期时由CCR评估肾小球滤过率结果可靠,当15 ml/min≤GFR＜90 ml/min时,CCR结果与核素扫描结果有较大偏差.彩色多普勒技术为监测肾功能不全肾功能变化状况的有效手段.     

Patlak plot analysis CT‐GFR for the determination of renal function: comparison of normal dogs with autologous kidney transplant dogs

Glomerular filtration rate (GFR) can be determined using Patlak plot analysis with single‐slice dynamic computed tomography (CT). Acute autologous graft failure has several causes, all of which induce a measurable decrease in glomerular filtration rate. This study demonstrated in an experimental model of canine autologous renal transplant that CT‐derived renal plasma clearance was significantly lower (p = 0.002) in dogs having undergone transplant (0.077 ± 0.058 ml min^?1 ml renal tissue^?1) compared with control dogs (0.396 ± 0.139 ml min^?1 ml renal tissue^?1). A significant negative curvilinear relationship was seen between serum creatinine and total renal plasma clearance (R² = 0.84, p = 0.0001). Alterations in renal time attenuation curve shape in dogs having undergone transplant may have been related to increased renal vascular resistance related to tubular necrosis. CT‐GFR may be a useful experimental tool in the evaluation of renal dysfunction in transplant models. Copyright © 2010 John Wiley & Sons, Ltd.     

99mTc-MAG3 kinetics in the normal pig. A comparison to 131I-OIH and 125I-iothalamate after single injection and during continuous infusion

Summary. An invasive comparative study of some pharmacokinetic aspects of ^99mTc-mercaptoacetyltriglycine (MAG3), ¹³¹I-orthoiodohippurate (OIH), and ¹²⁵I-iothala-mate (iothalamate) was performed in six pigs 0–150 min after a simultaneous single injection (SI) and during a subsequent 90 min of continuous infusion (CI). The total plasma clearance and the renal clearance of MAG₃ were about 75% that of OIH. The renal clearance of MAG₃ was about 2¹/₂ times the glomerular filtration rate. The distribution volume of MAG₃ was 71% that of iothalamate and only 47% that of OIH. There was a significant hepatic plasma clearance of MAG₃ of 5.9 ml min^-1 and 3.9% of the injected dose was excreted in the bile. HPLC analysis revealed that technetium was excreted in urine and Me mainly labelled to MAG₃. The average red blood cell (RBC) binding after single injection/during continuous infusion was 1.0%/2.3% for MAG₃, 13.5%/9.0% for OIH, and 3.1%/5.3% for iothalamate. The binding of OIH to RBC in arterial blood increased from 8% at 1 min post-injection to 21% at 150 min post-injection. The RBC binding was higher in the renal vein, indicating incomplete back diffusion from RBC to plasma. The protein binding was 90% for MAG₃, 49% for OIH and 16% for iothalamate. The renal plasma extraction of MAG₃ was constant but significantly smaller after SI (0.54) than during CI (0.62). Following SI, the renal plasma extraction of OIH decreased continuously from 0.85 to 0.52, 3.150 min post-injection. On the average there was no significant difference in renal plasma extraction after SI and during CI of either OIH (0.72 versus 0.77) or iothalamate (0.26 versus 0.27). It is concluded that MAG₃ is preferential to OIH as a tracer for renal function studies using a single injection technique mainly due to the constant renal extraction of MAG₃.     

Arterio-venous concentration difference of [51Cr]EDTA after a single injection in man. Significance of renal function and local blood flow

Summary. The present investigation was undertaken in order to study (1) the difference in arterial (C_a) and venous (C_v) concentration of [⁵¹Cr]EDTA (ethylenediaminetetra-acetate) after a single intravenous injection, (2) the impact of different physiological variables on this difference, and (3) the error introduced in the measurement of renal plasma clearance and total plasma clearance by using venous blood samples instead of arterial. In 13 patients with GFR ranging from 29 to 150 ml min^-1, C_a was higher than C_v immediately after the injection. After mean 38 min (range 12–82 min) the two curves crossed, and 180–300 min post-injection (p.i.) C_v was 5·9% higher than C_a (range 0·5–13·9%, P<0·001). The more reduced renal function, the smaller was the concentration difference. The areas under the arterial and the venous plasma concentration curves did not differ significantly at either 0–∞ or 0–300 min p.i., whereas the venous area 0–100 min p.i. underestimated the arterial area in the same period by 4·1% (P<0·05). In a computer simulation model, variation in the forearm capillary permeability–surface area product did not have any significant influence on the C_v–C_a difference, whereas the difference was very sensitive to even small changes in forearm blood flow within the physiological range. For measurement of renal plasma clearance it is recommended to use one long period: from the time of injection until 300 min p.i. or longer. If the clearance period is too short, the use of venous samples will overestimate the true renal clearance. Plasma clearance determined by venous and arterial blood samples does not differ significantly as long as the concentration is followed from the time of injection and a long period is applied. When simplified plasma clearance techniques are used, different results may be obtained from venous and arterial samples. The simplified techniques using venous blood samples—which usually include some empirical corrections—should be sufficiently reliable in daily clinical practice provided the forearm blood flow is reasonably high, e.g. exposure to cold should be avoided.     

连黄降浊颗粒治疗高血压性肾损害的临床研究

目的：观察连黄降浊颗粒治疗高血压性肾损害肾功能衰竭期的疗效，并探讨其作用机制。方法：将96例中医辨证符合湿浊内蕴证的高血压性肾损害肾功能衰竭期患者随机分为试验组和对照组，各48例。试验组给予连黄降浊颗粒，对照组给予尿毒清颗粒，均每次1袋，每日3次，治疗2个月。观察治疗前后两组血压、24h尿蛋白定量、血红蛋白（Hb）、肾功能、一氧化氮（NO）、血浆内皮素（ET）、甲状旁腺激素（PTH）、N-乙酰-β-氨基葡萄糖苷酶（NAG）、湿浊内蕴证的症状积分及疗效变化。结果：治疗后试验组患者的血压、24h尿蛋白定量、ET、PTH、NAG、血肌酐（SCr）、尿素氮（BUN）、尿酸（UA）及中医症状积分均较治疗前显著下降（P〈0．05或P〈0．01），而Hb、肌酐清除率（CCr）、NO均显著上升（P〈0．05或P〈0．01），且连黄降浊颗粒作用较尿毒清颗粒更显著。试验组临床总有效率（91．7％）优于对照组（75．0％，x^2=4．8，P〈0．05）。结论：连黄降浊颗粒是治疗高血压性肾损害肾功能衰竭期的有效药物，具有降压、改善肾功能、调节内源性血管活性物质代谢、纠正甲状旁腺功能亢进、改善临床症状等作用。     

A retrospective review of the outcome of plasma exchange and aggressive medical therapy in antibody mediated rejection of renal allografts: A single center experience

Antibody‐mediated rejection (AMR) has been recognized as a major cause of renal allograft loss. Protocols using plasma exchange (PE) to reverse rejection have mixed results. Methods: A retrospective chart review was performed to determine the clinical response to PE inpatients with AMR of renal allograft. A good response to treatment was defined as a decline in serum creatinine (SCr) to within 25% above the prerejection value or discontinuation of dialysis with a SCr <2 mg/dl within 3 months of discharge from the hospital and disappearance of donor‐specific alloantibodies (DSA). Results: Twenty‐two patients, treated with PE for biopsy proven AMR with or without acute‐cellular rejection (ACR), were included in the study. Sixty‐four percent of patients had concurrent AMR and ACR. Fifty‐two percent of all patients had a good response to antirejection therapy, whereas 63% of patients with only AMR and 46% of patients with both AMR and ACR had a good response. Good response to PE did not correlate with the number of plasma volumes exchanged (P = 0.09), but correlated with a shorter period from transplantation to the rejection episode (P = 0.002). Conclusion: Only a shorter interval between transplantation and the acute rejection episode correlated with a good response to PE. J. Clin. Apheresis, 2008. © 2008 Wiley‐Liss, Inc.     

Safety and efficacy of cryoprecipitate‐poor plasma as a replacement fluid for therapeutic plasma exchange in thrombotic thrombocytopenic purpura: A single center retrospective evaluation

Introduction: Thrombotic thrombocytopenic purpura (TTP) is a thrombotic microangiopathy caused by decreased activity of ADAMTS13, resulting in reduced clearance of ultralarge von Willebrand factor (VWF) multimers. Treatment of TTP is therapeutic plasma exchange (TPE) with replacement with fresh frozen plasma (FFP). Cryoprecipitate‐poor plasma (CPP) is a plasma product with lower concentrations of large VWF multimers, and similar amounts of ADAMTS13. CPP is regarded as at least as efficacious as FFP in TTP but evidence of additional benefits has not been demonstrated. Furthermore, there are limited data on the frequency of adverse events associated with CPP. Material and methods: In our center, the choice between CPP and FFP is performed before the 1st TPE session at the physicians' discretion. Here, we retrospectively evaluated the efficacy and safety of CPP based on the number of sessions, volume of plasma exposure, frequency of exacerbations/relapses, and adverse events. Results: Fourteen patients with newly diagnosed TTP were included in this analysis. The proportion of CPP:FFP use was 5:9. There were no significant differences in age, gender, initial hemoglobin, platelet count, LDH, or etiology of TTP between groups. We observed a trend toward a higher number of TPE sessions and higher plasma exposure in CPP, compared to FFP‐treated patients. Acute exacerbations were more frequent among patients treated with CPP (OR 26.6; 95%CI 1.01–703.51; P = 0.03). Mild allergic reactions were the most common treatment‐related adverse event in both groups. Discussion: Our data suggest that CPP should not be used as 1st line treatment for newly diagnosed TTP patients. J. Clin. Apheresis 29:311–315 2014. © 2014 Wiley Periodicals, Inc.     

肾移植术后病人随访方法与生活质量关系的研究

[目的]探讨肾移植术后病人最佳的随访方法,以提高病人远期生存质量。[方法]选择2003年10月—2005年9月在我院行肾移植术后病人60例,随机分为电话随访组、通信随访组和门诊随访组,每组20例。随访时间:出院后1个月内每周1次,出院后1个月～3个月2周随访1次,3个月～12个月每月随访1次,1年后3个月随访1次,随访内容相同,并于术后半年、1年采用生活质量指数评定量表(SF-36)对3组病人生活质量进行评分。[结果]电话随访组总体生活质量明显高于通信随访组和门诊随访组。[结论]电话随访法能及时准确给院外病人以医学健康指导,能及时发现早期并发症,明显提高病人远期生活质量。     

A single plasma sample method for estimation of the glomerular filtration rate in infants and children using iohexol, II: Establishment of the optimal plasma sampling time and a comparison with the 99Tcm-DTPA method

The glomerular filtration rate (GFR) can be determined from the plasma disappearance rate of the non-ionic contrast medium iohexol. A preceding study established the empirical formulae enabling the development of a single plasma sample method for estimation of GFR in infants and children. In the present study the validity of these empirical formulae was confirmed in examinations in 143 patients. The results of the single plasma sample method were similar to those of a standard 99Tcm-DTPA method, and also with those of a two plasma sample iohexol method. Evaluation of the results obtained with plasma sampling 1 h, 2 h, 3 h and 4 h after the injection of the contrast medium showed that the optimal sampling time was about 3 h after the injection.     

Increase of glomerular filtration rate and renal plasma flow by insulin-like growth factor-1 during euglycaemic clamping in anaesthetized rats

Renal function was studied in anaesthetized rats receiving i.v. infusions of recombinant human insulin-like growth factor-I (IGF-I) under euglycaemic clamp conditions. IGF-I increased glomerular filtration rate up to 35% and renal plasma flow up to 100%, this increase being dose dependent with half-maximal stimulation at serum IGF-I concentrations of about 24 pmol ml-1. Renal vascular resistance was reduced up to 50%, filtration fraction decreased up to 30% and urine flow increased up to three fold while arterial blood pressure was unchanged. Renal haemodynamics were affected at serum IGF-I concentrations that did not stimulate total body glucose disposal during euglycaemic clamping. IGF-I seemed to regulate renal function through IGF-I receptors apparently independent of acute changes of glucose metabolism.     

Comparison of perineural platelet‐rich plasma and dextrose injections for moderate carpal tunnel syndrome: A prospective randomized,single‐blind,head‐to‐head comparative trial

Recent studies demonstrated the utility of perineural injection with platelet‐rich plasma (PRP) and 5% dextrose (D5W) as novel strategies for treatment of carpal tunnel syndrome (CTS). The present study comprised a prospective, randomized, single‐blind, head‐to head comparative trial to compare the 6‐month outcome of perineural injection with PRP or D5W in patients with moderate CTS. Fifty‐two patients with unilateral moderate CTS were enrolled and randomized into two groups: The PRP group received a single 3‐cc perineural injection of PRP under ultrasound guidance, and dextrose group received a single 3‐cc perineural injection of D5W under ultrasound guidance. The Boston Carpal Tunnel Syndrome Questionnaire score was used as the primary outcome. Secondary outcomes included cross‐sectional area (CSA) of the median nerve and electrophysiological assessments. Evaluations were performed at baseline and at 1, 3, and 6 months postinjection. All patients (26 patients per group) completed the study. Compared with the dextrose group, the PRP group demonstrated significant reductions in Boston Carpal Tunnel Syndrome Questionnaire function at 3 months (p = .044), distal motor latency at 6 months (p = .028), and CSA at 3 and 6 months (p = .010 and.018, respectively). A single perineural injection of PRP reduced the CSA of the median nerve more effectively than injection of D5W at 3 and 6 months postinjection for patients with moderate CTS.     

A comparison of washed and volume‐reduced platelets with respect to platelet activation,aggregation, and plasma protein removal

BACKGROUND: Washed or volume‐reduced platelets (PLTs) are occasionally requested for patients with a history of allergic or anaphylactic transfusion reactions. However, conclusive data are not available as to which method is more suitable. STUDY DESIGN AND METHODS: A direct comparison of saline‐washed and volume‐reduced PLTs was performed by splitting 11 units of 6‐day‐old apheresis PLT units. PLT activation, aggregation, plasma protein, and PLT count were determined before and after each procedure. To assess whether washing using neutral, calcium‐free Ringer's acetate (NRA) would better preserve PLT function, 8 additional units of apheresis PLTs were split and were washed in saline or NRA. RESULTS: Saline washing resulted in significantly increased number of activated, P‐selectin–expressing PLTs compared to volume reduction (24.2% vs. 10.3%, p = 0.001). Aggregation was also significantly reduced (?40.6% vs. ?0.8%, p = 0.004). Plasma protein removal was significantly better for saline‐washed than volume‐reduced PLTs (96% vs. 51.1%, p < 0.001). PLT recovery was not significantly different for saline‐washed versus volume‐reduced PLTs (70.5% vs. 80.7%, p = 0.079). There was no difference between washing in saline or NRA with regard to PLT activation and loss of aggregation. CONCLUSIONS: PLT washing with saline or NRA significantly increases PLT activation and decreases PLT aggregability. On the other hand, volume reduction does not adequately remove plasma proteins. Therefore, PLT washing should be reserved for patients with a history of severe allergic or anaphylactic transfusion reactions. We suggest that fresher PLTs be selected to improve the functionality of washed PLTs.