Comparative evaluation of iohexol and inulin clearance for glomerular filtration rate determinations

We evaluated iohexol as a filtration marker in 150 children. The clearance of iohexol was compared with that of inulin or with a formula clearance. The single-sample clearance of iohexol showed a good correlation with the clearance of inulin ( r = 0.834). The clearance of iohexol correlated well ( r = 0.672) with the formula clearance. The optimal blood sampling time for iohexol clearance determinations appears to be between 120 and 180 min after injection, at least in patients with relatively normal filtration rates. We conclude that iohexol clearance is an accurate method of determining the glomerular filtration rate in clinical practice.     

Comparison of Tc-99 measurement of glomerular filtration rate vs. calculated creatinine clearance to assess renal function pretransplant in pediatric patients undergoing hematopoietic stem cell transplantation

We compared the results of Tc-99 evaluation of glomerular filtration rate (GFR) vs. the calculation of the creatinine clearance (CCrC) as a predictor for the development of renal insufficiency in pediatric patients following hematopoietic stem cell transplantation (HSCT). We reviewed 95 consecutive patients receiving autologous (n = 37) or allogeneic (n = 58) HSCT at Children's Memorial Hospital between January, 1995 and February, 1998. Diagnoses included leukemia (n = 43), solid tumor (n = 27), bone marrow failure syndrome (n = 12), non-malignant disease (n = 8), CNS tumors (n = 5) and immunodeficiency (n = 3). Tc-99 GFR was compared with a calculated creatinine clearance derived from the Schwartz formula (CCrC) prior to HSCT. These measures of renal function were compared with the patient's subsequent clinical course to determine if patients who developed renal insufficiency of sufficient magnitude as to require continuous veno-venous hemofiltration (CVVH) or dialysis, could have been identified. Overall comparison of the two methods of evaluation of renal function showed low correlation with values obtained by CCrC, which were consistently higher in most patients (r-value 0.01 in the regression analysis and a p = 0.08 95% CI -24.15 to 1.48). When stratified for age, correlation between the two methods was excellent only in children younger than 5 yr of age p = 0.02 95%, CI 0.032-0.49). Eleven patients required therapy with CVVH or dialysis but neither CCrC nor Tc-99 GFR prior to transplant predicted this event. Patients who received TBI were statistically more prone to develop renal insufficiency than those without TBI (p < 0.0001, 95% CI 0.25-0.008). Neither the Tc-99 GFR nor the CCrC was predictive of the development of renal insufficiency in HSCT patients as the majority of patients who required dialysis had normal Tc-99 GFR prior to transplant. The characteristics found in the patients who developed renal insufficiency and required dialysis include: the use of total body irradiation as part of the transplant-conditioning regimen (p < 0.0001) and the use of continuous infusion CSA (p = 0.04).     

Assessment of glomerular filtration rate and effective renal plasma flow in cystic fibrosis

A study was conducted to examine renal function in 10 healthy control subjects and eight patients with cystic fibrosis in stable condition. Sequential bolus injections of 99mTc-DTPA and 125I-OIH were administered to assess glomerular filtration rate and effective renal plasma flow, respectively. Blood was subsequently collected for 3 hours, and urine for 24 hours. Renal clearances of both radioisotope markers were virtually identical in patients and controls. Inasmuch as neither glomerular filtration rate nor effective renal plasma flow was enhanced in patients with cystic fibrosis, increased clearance of drugs in these patients is unlikely to be the result of enhanced glomerular filtration or tubular secretion.     

PAH clearance, sodium excretion, and PAH extraction ratio in acidotic near-term lambs treated with hypertonic sodium bicarbonate.

The electrolyte changes and renal hemodynamic adjustment to hypertonic sodium bicarbonate (NaHCO3) correction of a metabolic acidosis were studied in 4 neonatal lambs and in 2 controls. PAH clearance increased from 0.92 to 1.65 ml/min/kg (p less than 0.05), urine flow from 0.37 to 0.61 ml/min/kg (p less than 0.05), and Na excretion from 8.4 to 23.7 muEq/min/kg (p less than 0.05) during the NaHCO3 infusion. These increases were transient and returned to pre-infusion levels following NaHCO3 infusion. Calculation of Na intake and output revealed a net retention of 5.1 mEq/kg in the study lambs which was reflected in a rise of serum Na and osmolarity (Osm) during the post-NaHCO3 -infusion period. The extraction ratio of sodium p-aminohippurate (EPAH) and its relationship to arterial pH were studied in 4 additional lambs. The EPAH did not change with metabolic acidosis but for unknown reasons, the infusion of NaHCO3 resulted in a temporary depression of EPAH (p less than 0.001).     

Effect of low dose 1 alpha-hydroxycholecalciferol on glomerular filtration rate in moderate renal failure.

Serial measurements of 51Cr edetic acid clearance were made over a period of one year in two groups of 8 children, in a double blind trial of 1 alpha-hydroxycholecalciferol (10 ng/kg/day) and calciferol (670 ng/kg/day). Glomerular filtration rate (GFR) at the beginning of the trial was 20-50 ml/min/1.73 m2; it rose in the children given 1 alpha-hydroxycholecalciferol (group A) after 6 months but was not appreciably different from the pretreatment value after 12 months. The GFR in the children given calciferol (group B) showed no significant difference at 6 or 12 months. Parathyroid hormone values fell markedly in group A after 6 months but not in group B. Quantitative bone histology improved considerably in group A but not in group B at 12 months. Low dose 1 alpha-hydroxycholecalciferol may be used effectively for renal osteodystrophy in children with moderate but stable renal failure without jeopardising renal function.     

Experimental focal segmental glomerulosclerosis: correlation with protein excretion, glomerular filtration rate, and renal plasma flow

A rat model of focal segmental glomerulosclerosis (FSGS) produced by repeated injections of aminonucleoside (AMN) of puromycin was used to evaluate the relative roles of hemodynamic alterations and AMN-induced glomerular visceral epithelial cell injury in the development of FSGS. Twenty rats received three intraperitoneal injections of AMN on days 1, 21, and 28 and developed significant proteinuria. On day 50, 14 rats (group 1) underwent selective left renal perfusion with AMN and six rats (group 2) received left renal perfusion with saline. At sacrifice on day 70 or 110, group 2 rats had similar values in left and right kidneys for glomerular filtration rate (GFR), effective renal plasma flow (ERPF), and the amount of FSGS (13.1 +/- 5.6% in left and 12.9 +/- 7.8% in right). In contrast, group 1 rats manifested a significantly higher amount of FSGS in right kidneys as compared to left kidneys (3.1 +/- 1.3% in left and 6.3 +/- 2.0% in right, as well as significantly diminished GFR and ERPF in left as compared to right kidneys. A higher degree of FSGS was seen in kidneys with a higher GFR and ERPF. A positive correlation was observed between the mean 24-h protein excretion of the rats and the percentage of FSGS in left and right kidneys (r = 0.66, p less than 0.01).     

Prenatal programming of renal function: the estimated glomerular filtration rate is influenced by size at birth in apparently healthy children

Prenatal growth is known to affect glomerular function in adult life. It is unknown, however, whether this association is also present in children. In a cross-sectional study, we examined whether birth weight (BW) is associated with serum creatinine (measured by an improved Jaffe method) and GFR (estimated by the Haycock-Schwartz formula; eGFR) in 73 apparently healthy school-age children (35 boys and 38 girls; age 9.5 +/- 0.4 yr). All children were born after singleton term pregnancies (gestational age 39.6 +/- 0.2 wk) with normal BW (3.2 +/- 0.04 kg). A significant decrease in serum creatinine and increase in the eGFR was evident by tertiles of BW-SD score (SDS) (p = 0.001 and p < 0.0001). eGFR was correlated with BW-SDS (r = 0.45; p < 0.0001), so that each unit increase in BW-SDS was associated with an increase in eGFR of 10 (95% CI 5-14) ml/min per 1.73 m. In summary, estimates of glomerular function are in apparently healthy school-age children influenced by size at birth. These findings suggest early effects for the prenatal programming of renal function in humans.     

Estimation of glomerular filtration rate in children using 99m-technetium DTPA. A comparison with 51-chromium EDTA clearance

The usefulness of radionuclide imaging studies with 99m-technetium diethylenetriaminepentaacetic acid (Tc-DTPA) for quantitating the glomerular filtration rate (GFR) in children was studied. This was compared to the conventional methods for measuring GFR using 51-chromium-EDTA clearance (Cr-EDTA), creatinine clearance and a height/plasma creatinine formula. In the 22 children studied, the correlation coefficient between renal uptake of DTPA and Cr-EDTA was 0.90 (p less than 0.001). In contrast, there was a poorer correlation between Cr-EDTA and creatinine clearance (r = 0.69) or the derived GFR using height/creatinine formula (r = 0.83). The regression line between Tc-DTPA uptake and Cr-EDTA clearance was used to derive a formula for calculating the predicted GFR. This was tested in 10 additional children, and the correlation between the predicted GFR and measured GFR (using Cr-EDTA clearance studies) was 0.92 (p less than 0.001). Quantitative estimation of the GFR during renal imaging studies is a feasible and convenient method of assessing renal function.     

Postnatal development of renal function in very low birthweight infants

The postnatal development of renal function was compared in infants with a gestational age of 25-30 weeks, mean 27.8 weeks (GA 28), and in infants with a gestational age of 31-34 weeks, mean 32.5 weeks (GA 32). The infants were comparable with regard to postnatal course, fluid, caloric and salt intake. Observations were made during the 1st, 2nd and 4th-7th (mean 5th) postnatal weeks. From the 1st to the 5th postnatal week the creatinine clearance (CCr ml/min/1.73 m2), increased from 11 to 20 in GA 28 and from 15 to 30 in GA 32. At 2 weeks of age CCr was significantly lower in GA 28 than in GA 32. During the first week of life diuresis was lower in GA 28 than in GA 32 but thereafter was the same in both groups. We interpret this as a sign of dehydration in GA 28. Serum arginine vasopressin (S-AVP) concentrations were high in both groups at all ages. Mean urine osmolality was low (less than 300) regardless of postnatal age and S-AVP. Urinary sodium excretion was high at 1 week of age in both groups and decreased with increasing postnatal age. Na excretion was slightly higher in GA 28 than in GA 32 at 1 but not at 2 and 5 weeks. UK/UNa was below 1 in both groups during the first week of life and increased with postnatal age. Urinary aldosterone excretion was high in both GA 28 and GA 32 at all ages. Serum sodium levels were lower in GA 28 than in GA 32 at all ages.(ABSTRACT TRUNCATED AT 250 WORDS)     

Variables affecting estimated glomerular filtration rate after renal transplantation in children: A NAPRTCS data analysis

Moudgil A, Martz K, Stablein DM, Puliyanda DP. Variables affecting estimated glomerular filtration rate after renal transplantation in children: A NAPRTCS data analysis.
Pediatr Transplantation 2010: 14:288–294. © 2009 John Wiley & Sons A/S. Abstract: Short‐term graft survival has improved in renal transplants without significant effect on long‐term graft survival. As GFR decline precedes graft loss, an understanding of variables affecting eGFR after TX may help improve graft survival. NAPRTCS data were analyzed to assess effects of donor, recipient, and other variables on Schwartz eGFR after transplantation. For 8438 children with a functioning graft at day 30, data were censored for children dying with a functioning graft, and those with <3 yr follow‐up. Multivariate linear regression and repeated measures analyses identified factors related to eGFR at day 30 after TX and during follow‐up. Young, female, non‐black, children without ATN and acute rejection in the first 30 days, TX after 1995, those with better eGFR at day 30, and receiving tacrolimus had better long‐term eGFR. Transplant from ideal (6–35 yr) donors had best short‐term eGFR, young donors (<5 yr) had lower eGFR and poor graft survival. After one yr, eGFR improved in surviving grafts of young donors and matched ideal donors. Acute rejection, BP medications, and hospitalizations in prior six months had negative association with subsequent eGFR. Regardless of variables, eGFR deteriorated with time. Slope of eGFR decline has not changed in the recent era indicating the need for innovative therapies.     

应用Schwartz公式和99Tcm-DTPA肾动态显像评估肾小球滤过率的一致性研究

目的 评价应用Schwartz公式评估肾小球滤过率（GFR）的准确性,为儿科临床准确和便捷地评估GFR提供参考。方法 选择2002年 4月至2006 年12月在复旦大学附属儿科医院肾病科诊断为慢性肾脏病（CKD）的患儿为研究对象。患儿于入院后第2日早晨空腹采血,以碱性苦味酸法测定血肌酐（SCr）水平,测量身高,采用Schwartz公式计算GFR（eGFR）。入院后第2或3日行99Tcm-DTPA肾动态显像,获得GFR（mGFR）。采用NKF-K/DOQI推荐的CKD分期标准,依据mGFR分为CKD 1~5期。mGFR与eGFR的相关性采用Pearson相关分析;eGFR估算mGFR的准确性采用相对预测误差（MPE）和绝对预测误差(MAE)表示,eGFR和mGFR的一致性采用Bland-Altman检验。结果 170例CKD患儿进入分析,其中男100例,女70例;年龄2.3～17.8（9.3±3.9）岁。肾病综合征75例,肾小球肾炎28例,泌尿道感染49例,急性肾功能衰竭10例和慢性肾功能衰竭8例。CKD 1期 80例,2期 40例,3期 27例,4期 17例,5期6例。①eGFR和mGFR总体上有显著相关性（r＝0.871）;CKD 1期患儿的eGFR和mGFR呈显著弱相关性,CKD 2~4期患儿eGFR和mGFR无显著相关性。②eGFR预测mGFR的MPE和MAE随肾功能损害程度的加重呈增高趋势,CKD 1期79/80例（98.8%）、CKD 2期32/40例（80.0%）患儿eGFR预测mGFR的MPE均落在±30％内;CKD 3~5期患儿eGFR预测mGFR的准确性较差。③Bland-Altman检验结果提示,eGFR和mGFR的一致性CKD 1和2期患儿较好,CKD 3和4期患儿较差。结论 Schwartz公式对于肾功能损害较轻的CKD 1和2期患儿预测mGFR的准确性较高,CKD 3～5期患儿的准确性较差。对于CKD 3~5期患儿仍应行99Tcm-DTPA肾动态显像以获得准确的GFR。     

Retrospective study of the renal function using estimated glomerular filtration rate and congenital anomalies of the kidney-urinary tract in pediatric Turner syndrome

Although Turner syndrome (TS) is frequently associated with congenital anomalies of the kidney-urinary tract (CAKUT), which is a major cause of pediatric chronic kidney disease, renal function in TS is usually considered normal. The present study aimed to analyze the frequency of renal dysfunction and CAKUT in pediatric patients with TS. Our study included 122 patients with TS between the ages of 2 and 18 years from 30 hospitals across Japan. Clinical data related to renal function and CAKUT were retrospectively collected. The estimated glomerular filtration rate (eGFR) was calculated using the serum creatinine-based formula recommended by the Japanese Society for Pediatric Nephrology. An eGFR <90 mL/min/1.73 m² for two consecutive years was defined as renal dysfunction. Fifteen (13.5%) of 122 patients had CAKUT, and four patients had renal dysfunction (3.2%, 95% confidence interval: 0%-6.7%). Three of the four did not have CAKUT. Of the CAKUT manifestations, horseshoe kidney, renal hypodysplasia, and multicystic dysplastic kidney were seen in nine, two, and one patient, respectively. Eight of the nine patients with horseshoe kidney had a normal renal function; however, the remaining patient with renal hypodysplasia had renal dysfunction. A small percentage of patients with pediatric TS may had an eGFR below 90 mL/min/1.73 m² which was not necessarily associated with CAKUT.     

Estimation of glomerular filtration rate from plasma creatinine concentration in children.

The relation between the true plasma creatinine concentration (Pc) and the glomerular filtration rate corrected for body surface area (GFR/SA) was investigated in 108 individuals, and the following formula was derived: GFR/SA (ml/min per 1-73m2SA) = 0-43 Ht (cm)/Pc (mg/100 ml). This formula was tested in a second group of 83 children, and its accuracy and precision was compared to the 24-hour creatinine clearance. It was found to be superior to the creatinine clearance overall, and was as good, even if all results involving suspect 24-hour-urine collections were eliminated from analysis. The formula in SI usage is: GFR/SA (ml/min per 1-73 m2SA) = 38 Ht (cm)1Pc (mumol/l).     

Creatinine for evaluation of glomerular filtration rate in children

This report is to provide primary care physicians with a convenient method for identifying children with impaired kidney function. This is important because of the prevalence of chronic kidney disease in adults and because intervention may delay disease progression. The glomerular filtration rate (GFR) measured using cimetidine clearance and calculated using height and serum creatinine concentration were compared during 222 clearance studies in 32 pediatric patients over 8 years. A child 1 year or older with a calculated GFR<60 mL/min/1.73 m2 has a significantly reduced GFR and should be referred to a pediatric nephrologist for further evaluation.