Glomerular Filtration Rate In Subjects Research Articles

El continuo cardiorrenal: una propuesta para la prevención de las enfermedades cardiovasculares y renales

Cardiovascular risk factors such as arterial hypertension, type 2 diabetes mellitus (DM2) and dyslipidemia are commonly involved with chronic kidney disease (CKD) and its contribution to long-term cardiovascular morbidity. Diffuse endothelial dysfunction and atherosclerosis are believed to be part of the common pathophysiology in diabetic and non-diabetic CKD, particularly in the elderly. Age is the main determinant of glomerular filtration rate (GFR) and effective renal plasma flow and has been reported that the presence of hypertension at baseline enhances the yearly decline in creatinine clearance. Dyslipidemia may directly affect the kidney by causing deleterious renal lipid disturbances (renal lipotoxicity), as well as indirectly through systemic inflammation and oxidative stress, vascular injury, hormones change and other signaling molecules with renal action. Several cross-sectional studies found that impaired glucose tolerance, as well as the presence of left ventricular hypertrophy, was associated with an increase in the slope of the inverse relationship between age and GFR in subjects with never-treated essential hypertension. Most of the drugs used to reduce the burden of risk factor on cardiovascular disease also benefit the renal function. So, we propose the cardiorenal continuum as a preventive strategy to protect both organ and reduce the deleterious impact of the cardiovascular risk factor on the renal function considering both organs as a functional and physiopathological binomial.

Prevalence and Determinants of Diabetic Foot Ulcers and Lower Extremity Amputations in Three Selected Tertiary Hospitals in Ghana.

Background The occurrence and complications of diabetes are increasing worldwide. This study examined the prevalence and determinants of diabetic foot ulcers and lower extremity amputations in three selected tertiary hospitals in Ghana. Methods A cross-sectional multicenter study involving 100 subjects was carried out. Subjects were selected through simple random sampling from three selected tertiary hospitals in Ghana. A structured questionnaire was used to document information on sociodemographic, medical history, lifestyle, and physical characteristics of subjects. Foot ulcers and lower extremity amputations were also investigated. Total cholesterol, triglycerides, low-density lipoproteins, high-density lipoproteins, serum urea, serum creatinine, and estimated glomerular filtration rate of subjects were assessed. Data analysis was done using SPSS version 22. Results The study revealed that 31% and 69% were males and females, respectively, with a mean age of 53.8 ± 13.8 years. Among the patients, 11% had diabetic foot ulcers whilst 3% had lower extremity amputations. In the multivariate binary logistic regression analysis, previous history of foot ulcers (OR = 40.4, 95% CI = 5.5-299.9) and foot deformities (OR = 14.4, 95% CI = 1.3-161.2) were identified as independent predictors of diabetic foot ulcers. Foot deformity (p = 0.043) and serum urea (p = 0.002) were associated with diabetic lower extremity amputations in the univariate analysis. Conclusion This study showed that the prevalences of diabetic foot ulcers and lower extremity amputations are high among diabetes patients. Foot deformities and previous history of foot ulcers are determinants of diabetic foot ulcers. Foot deformity and serum urea are associated with diabetic lower extremity amputations.

Changes in antioxidant status associated with haemodialysis in chronic kidney disease.

We evaluated the effects of one session of HD on the antioxidant capacity and lipid peroxidation in CKD patients. Thirty-six CKD patients requiring HD were recruited into this study. Participants were naïve to HD and each completed a session of three hours using polysulfone membrane dialyzers. Blood samples were collected before and after dialysis. Total antioxidant capacity (TAC) was measured by ferric reducing antioxidant power (FRAP) while malondialdehyde (MDA) was measured using thiobarbituric acid-reactive substance (TBARS). Comparison was made between pre-HD and post-HD values of TAC and MDA respectively, p value of <0.05 was taken as significant. Mean age and estimated glomerular filtration rate of subjects were 45 ±15 years and 6.3± 4.7mls/1.73m2 respectively. There was significant decrease in the mean TAC from 1232.2 ± 495.6 µmol Trolox equiv/ to 832.4 ± 325.7 µmol Trolox equiv/L post-dialysis (p< 0.001) while MDA values were similar before and after HD (11.8 ± 1.8 vs 11.8 ± 2.331)µmol/L (p> 0.05). There was no significant association between changes in antioxidant status following HD with blood flow rate, ultrafiltration volume nor dialyzer per size. A session of HD in patients with CKD is associated with significant reduction of the total antioxidants capacity; and no effect on MDA levels. No external funding received.

Filtrado glomerular estimado por fórmulas en pacientes obesos

IntroductionEstimating glomerular filtration rate (GFR) in obese subjects is a challenge. An analysis is made of the performance of equations to estimate GFR in this population. Material and methodsThis cross-sectional study included 100 obese subjects evaluated between 2008 and 2015. The GFR was measured with urinary iothalamate clearance (reference standard) and estimated using creatinine-based formulas: Cockroft Gault, MDRD, CKD-EPI, MCQ,and CKD-MCQ (mean of these). A Global Performance Score (G-P-Score) was created to unify all the analysis criteria. ResultsCKD-MCQ equation had the best performance in obesity grade I (n=53) [bias=1.6+/- 17.4ml / min x 1.73 m2; Correlation (r)=0.87; Area under the curve (AUC)=0.978; Sensitivity (S)=100%; Specificity (E)=87.8%]. MCQ and CKD-MCQ had the lowest bias in obesity grade II (n=25) (bias=1.8+/- 22.3 and -4.4+/- 21.9ml / min x 1.73m2), and CKD-MCQ the highest r (r=0.89), with the same AUC, S, and E (AUC=0.976, S=85.7%, E=100%). MDRD equation had the lowest bias in obesity grade III (n=22) (bias=-0.2+/- 31.1ml/min x 1.73 m2), and CKD-MCQ had the highest r and AUC (r=0.66, AUC=0.929), with the same S and E (S=80%, E=94.1%) than MDRD.CKD-MCQ was the only equation without significant differences compared to the reference standard in any of the obesity levels. The highest score was obtained in the G-P-Score (39/48). ConclusionCKD-MCQ had the better overall performance for estimating GFR in subjects with different degrees of obesity.

A high-protein diet reduces liver fat content and improves glomerular filtration rate in subjects with type 2 diabetes

High-protein diet has shown favourable but also adverse effects in type 2 diabetic subjects. Nevertheless, the origin of the protein and its role in metabolism needs further investigation. A clinical study compared two isocaloric high-protein diets of animal (AP) and respectively plant (PP) origin and evaluated in detail their effects in type 2 diabetes.

Effect of Cobicistat on Glomerular Filtration Rate in Subjects With Normal and Impaired Renal Function

This study evaluated the effect of cobicistat (COBI) on glomerular filtration rate in subjects with normal renal function (RF) or with mild/moderate renal impairment, by comparing creatinine clearance [estimated glomerular filtration rate (eGFR)] with actual GFR (aGFR) using iohexol, a probe drug excreted by glomerular filtration. COBI is a potent CYP3A inhibitor (pharmacoenhancer) currently in phase 3 testing with elvitegravir, atazanavir, and darunavir. Normal RF subjects received COBI 150 mg QD, ritonavir (RTV) 100 mg QD, or placebo for 7 days; subjects with mild/moderate renal impairment received COBI 150 mg QD. The eGFR and aGFR were measured on days 0, 7, and 14 and within-subject changes calculated relative to day 0. COBI and RTV pharmacokinetics were analyzed on day 7. All 36 subjects in cohort 1 and 17 of 18 subjects in cohort 2 completed all study treatments. Study treatments were well tolerated. Small increases in serum creatinine with corresponding mean decreases in eGFR (∼10 mL/min or mL/min per 1.73 m) were observed on day 7 relative to day 0 in subjects receiving COBI (P < 0.05). The decreases were reversible on COBI discontinuation; mean eGFR values returned to baseline on day 14 (P > 0.05). No statistically significant changes in aGFR on days 7 or 14 relative to day 0 were seen with COBI (P > 0.05). No statistically significant decreases in aGFR or eGFR were observed with RTV or placebo. COBI affects eGFR but not the actual GFR. The time to onset, magnitude, and time to resolution of changes in eGFR are consistent with altered proximal tubular secretion of creatinine through inhibition of drug transporters.

Performance of serum cystatin C versus serum creatinine as a marker of glomerular filtration rate as measured by inulin renal clearance

Serum cystatin C was recently proposed as an alternative marker of glomerular filtration rate (GFR), with a suggested better performance than creatinine. However, detailed studies are limited. We evaluated the performance of cystatin C as a GFR marker. GFR was measured by inulin clearance in 763 Japanese subjects. Factors other than GFR influencing serum cystatin C or serum creatinine were analyzed by multivariate analyses. After adjustment for GFR, the value of serum creatinine was 25.2% lower in females than males, and decreased by 5.2% for every 20 years of age. Serum cystatin C was 8.2% lower in females, and did not change significantly with aging. Creatinine but not cystatin C was significantly affected by body weight, height and body mass index after adjustment for GFR, gender and age. The correlation coefficient between GFR and 1/cystatin C was significantly higher than that of 1/creatinine in total subjects (0.866 and 0.810, respectively, p < 0.001). Unlike serum creatinine, serum cystatin C did not increase in association with the reduction of GFR in subjects with very low GFR. The regression line of 1/cystatin C against GFR showed a significantly negative intercept of about -8 ml/min/1.73 m(2). The performance of serum cystatin C was not good in the subjects with very low GFR. Non-renal elimination of cystatin C may contribute to the result. The correlation between reciprocal cystatin C and GFR suggested its superiority in predicting GFR compared to creatinine in subjects with normal and mildly reduced GFR.

Efficacy and safety of pitavastatin in Japanese patients with hypercholesterolemia: LIVES study and subanalysis

The Livalo Effectiveness and Safety (LIVES) study was an observational study to examine the efficacy and safety of pitavastatin, a newly developed drug, in approximately 20,000 Japanese patients with hypercholesterolemia. During a 2-year follow-up period, no significant problems concerning safety were observed upon treatment with pitavastatin. Pitavastatin demonstrated potent and stable lowering of the LDL-cholesterol level. The LIVES study subanalyses revealed significant and continuous elevation of HDL-cholesterol in association with pitavastatin treatment and also showed that the drug did not adversely affect glycemic control as evaluated by the glycohemoglobin A1c level. Moreover, pitavastatin treatment was associated with an increase in estimated glomerular filtration rate in subjects with chronic kidney disease. These results suggest the usefulness of pitavastatin in hypercholesterolemic patients from various backgrounds. The ongoing LIVES study extension is expected to provide further data on cardiovascular outcome in subjects treated with pitavastatin.

Lower HDL-C and apolipoprotein A-I are related to higher glomerular filtration rate in subjects without kidney disease

Animal experiments show that the kidney contributes to apolipoprotein (apo)A-I catabolism. We tested relationships of HDL cholesterol (HDL-C) and apo-I with kidney function in subjects without severe chronic kidney disease. Included was a random sample of the general population (part of the PREVEND cohort). Kidney function [estimated glomerular filtration rate (e-GFR) by two well-established equations and creatinine clearance], HDL-C, triglycerides, apoA-I and insulin resistance (HOMAir) were measured in 2,484 fasting subjects (e-GFR>or=45 ml/min/1.73 m2) without macroalbuminuria, cardiovascular disease, diabetes, or the use of anti-hypertensives and/or lipid-lowering agents. HDL-C (r=-0.056 to -0.102, P<0.01 to <0.001) and apo A-I (r=-0.096 to -0.126, P<0.001) were correlated inversely with both GFR estimates and creatinine clearance in univariate analyses. Multiple linear regression analyses also demonstrated inverse relationships of HDL-C and apoA-I with all measures of kidney function even after adjustment for age, sex, waist circumference, HOMAir, triglycerides, and urinary albumin excretion (P=0.053 to 0.004). In conclusion, HDL-C and apoA-I are inversely related to e-GFR and creatinine clearance in subjects without severely compromised kidney function, which fits the concept that the kidney contributes to apoA-I regulation in humans. High glomerular filtration rate may be an independent determinant of a pro-atherogenic lipoprotein profile.

Circulating methylarginine levels and the decline in renal function in patients with chronic kidney disease are modulated by DDAH1 polymorphisms

In patients with chronic kidney disease, high plasma levels of the endogenous nitric oxide synthase inhibitor, asymmetric dimethylarginine, are thought to contribute to decline in renal function. Here we took a candidate gene approach to determine any causal role of asymmetric dimethylarginine in the progression of chronic kidney disease. The impact of single-nucleotide polymorphisms in the genes encoding the two isoforms of the asymmetric dimethylarginine-degrading enzyme, dimethylarginine dimethylaminohydrolase (DDAH1 and DDAH2), on enzyme expression, plasma asymmetric dimethylarginine levels, and longitudinal changes in estimated glomerular filtration rate were determined in various patient groups. There was evidence suggesting that the rs17384213 DDAH1 GG genotype was associated with increased expression of its mRNA in kidney allografts. Healthy subjects carrying the rs17384213 G allele had lower plasma asymmetric dimethylarginine, and a similar borderline association was found in patients with chronic kidney disease. This allele, however, was independently associated with a steeper decline in renal function in two separate cohorts of patients with chronic kidney disease. We conclude that polymorphisms in DDAH1 alter the rate of decline of glomerular filtration rate in subjects with chronic kidney disease. Our findings show that DDAH1 modulates plasma asymmetric dimethylarginine and contributes to the decline in renal function. However, it appears that increases in circulating methylarginine did not mediate progressive kidney injury.

MR determination of glomerular filtration rate in subjects with solitary kidneys in comparison to clinical standards of renal function: feasibility and preliminary report

This study was conducted to demonstrate the feasibility of quantifying single kidney glomerular filtration rate (skGFR) by magnetic resonance (MR) by comparison to the clinical estimates of GFR in volunteer subjects with a single kidney. Seven IRB-approved subjects with a solitary kidney, stable serum creatinine (SCr) and a 24 h creatinine clearance (CrCl) volunteered to undergo an MR examination that determined renal extraction fraction (EF) with a breathhold inversion recovery echo planar pulse sequence and renal blood flow with a velocity encoded phase imaging sequence. The product of EF and blood flow determines GFR. These values were compared with the 24 h CrCl, estimated GFR by the modification of diet in renal disease (MDRD) regression analysis and the Cockroft-Gault (CG) determination of CrCl. The mean and standard deviation of differences between the MR GFR, MDRD and CG vs the 24 h CrCl were 12.3+/-35.7, -8.9+/-18.5 and 1.2+/-19.6, respectively. The Student t-test showed that none of the mean differences were statistically significant between techniques. This clinical investigation shows that MR can be used for skGFR determination in human subjects with comparable values to those derived from clinically used serum-based GFR estimation techniques.

Albuminuria and Renal Function in Homozygous Sickle Cell Disease

The glomerular filtration rate (GFR) in homozygous sickle cell (SS) disease is supranormal in childhood but falls steeply with age, often culminating in renal failure. The risk factors underlying these observations are unclear. We therefore sought to investigate the relationships between blood pressure, renal hemodynamics, and urinary albumin excretion in subjects with SS disease and matched controls with a normal AA genotype (hereinafter, controls) as a prelude to intervention studies. Serum creatinine level, GFR, effective renal plasma flow, blood pressure, and urinary albumin and creatinine excretion rates were measured in Jamaican individuals with SS disease aged 18 to 23 years and in controls followed from birth in a cohort study. Compared with controls, subjects with SS disease showed lower blood pressure and normal or supranormal GFR and effective renal plasma flow. Urinary albumin excretion exceeded 20 microg/min in 26% of subjects with SS disease and correlated positively with GFR and systolic blood pressure and negatively with hematocrit. A higher GFR and increased tubular secretion of creatinine combined to lower serum creatinine levels in patients with SS disease, giving an upper limit of the reference range of 0.90 mg/dL (80 micromol/L) in men and 0.77 mg/dL (68 micromol/L) in women. In addition, creatinine clearance measurements were consistently greater than GFR in subjects with SS disease. The GFR remained within reference range or elevated in patients with SS disease aged 18 to 23 years. The higher GFR in patients with albuminuria was consistent with the hypothesis that high glomerular flows cause renal damage. Lower serum creatinine levels characterize patients with SS disease, and a revised clinical definition based on serum creatinine level alone is proposed.

Acute Effect of Furosemide on Glomerular Filtration Rate in Diastolic Dysfunction

We sought to evaluate the acute effect of furosemide on glomerular filtration rate (GFR) in subjects with diastolic dysfunction. An equal number of subjects with documented diastolic dysfunction (DD) and healthy volunteers (controls) were enrolled and underwent a baseline GFR measurement via plasma clearance of technetium-99m-diethylenetriaminepentaacetic acid. Within three to seven days of the baseline, study subjects were scheduled for a second GFR study, which was performed immediately after administration of furosemide (20 mg orally and 20 mg intravenously). There were eight healthy volunteers (8 males with a mean age 42 ± 7.8 years; 6 white, 2 Asian) and eight subjects with diastolic dysfunction (7 males, 1 female, with a mean age 64.5 ± 9.3 years; 7 whites, 1 African-American). There was a significant post-furosemide decline in GFR in the healthy volunteers, baseline vs. post-furosemide 131.6 ± 19.8 vs. 117 ± 18.2 mL/min, respectively (p = 0.03), and the patients with DD, baseline vs. post-furosemide 117.5 ± 22.3 vs. 92 ± 21.7 mL/min, respectively (p = 0.0002). A strong trend was detected, though not statistically significant, of greater GFR decline in subjects with DD compared to the healthy volunteers, 25.5 ± 9.9 vs. 14.6 ± 15.6 mL/min, respectively (p = 0.12). To conclude, acute administration of furosemide might potentially cause a greater decline in GFR in subjects with diastolic dysfunction.

Lean body mass‐adjusted Cockcroft and Gault formula improves the estimation of glomerular filtration rate in subjects with normal‐range serum creatinine

Assessment of glomerular filtration rate (GFR) in individuals with normal-range serum creatinine is important in certain clinical situations, such as in potential living kidney donors. Accurate measurements of GFR invariably involve using an invasive method (e.g. inulin clearances), but is inconvenient. The aim of the present study was to determine whether serum creatinine-based prediction formulae adjusted for lean body mass (LBM) could improve the accuracy of GFR estimation in these subjects. Glomerular filtration rate was determined by the clearance of technetium-99m-labelled diethylenetriamine penta-acetic acid ((99m)Tc DTPA) from plasma in 56 subjects with normal serum creatinine. For each subject, GFR was estimated using prediction formulae +/- LBM adjustment and compared with measured GFR. Formulae analysed include Cockcroft-Gault, Levey, Gates, Mawer, Hull, Toto, Jellife and Bjornsson. All formulae +/- LBM adjustment underestimated measured GFR, with poor precision, poor agreement and correlation (r (2) <or= 0.25). Between 69% and 95% of the estimated GFR determined by the formulae correctly classified those with a normal measured GFR. LBM-adjusted formulae significantly improved the accuracy of GFR estimation compared with unadjusted formulae. The lean body mass-adjusted Cockcroft-Gault formula was the closest to measured GFR but is not accurate enough to replace radionuclide GFR measurement. Prediction formulae should be adjusted for LBM to improve GFR estimation.

An evaluation of the body surface area correction for 51Cr-EDTA measurements of glomerular filtration rate

To interpret 51Cr-EDTA measurements of glomerular filtration rate (GFR) it is usual to correct results for a patient's body size by scaling values to a standard body surface area (BSA) of 1.73 m(2). To use 51Cr-EDTA data for a large group of healthy subjects to derive the optimum mathematical function for the body size correction that minimized the variance of the corrected GFR values. This function was then compared with the widely used Du Bois and Haycock BSA formulas to determine which of these two equations provided the better correction. GFR data for 428 healthy adults (218 female, 210 male) undergoing assessment as live kidney donors were evaluated. The body size correction was assumed to scale as the product of power laws of body mass index (BMI = weight/height(2)) and height. The corrected GFR figures were fitted to a model in which GFR was constant in subjects below 40 years of age and decreased linearly with age in older subjects. The scatter about the best fitting model was expressed as a percentage of the mean GFR in the younger group and the optimum power law indices derived from a least-squares fit were compared with the values for the Du Bois and Haycock formulas. The least-squares fit gave values of 0.444 (95% CI, 0.297-0.590) for the BMI power law index and 1.416 (95% CI, 1.027-1.802) for the height index with a 95% confidence error figure that included the points representing both the-Du Bois ([delta][chi]2 = 1.161, P = 0.560) and Haycock ([delta][chi]2 = 2.524, P = 0.283) formulas. For subjects of average height and a BMI in the middle of the normal range the Du Bois and Haycock equations agreed closely. Differences in BMI were found to explain 89% of the variance in the BSA estimates between the two formulas. Compared with the Du Bois formula the Haycock equation gave a 5% increase in corrected GFR in subjects with a BMI of 15 kg x m(-2) and a 10% decrease in subjects with a BMI of 40 kg x m(-2). Within the statistical errors both the Du Bois and Haycock BSA formulas were consistent with the optimum power law function that minimized the variance of the corrected GFR values for a group of 428 healthy adults.

Slowing the progression of chronic renal failure: Economic benefits and patients' perspectives

Because of the predicted increase in end-stage renal disease (ESRD) incidence (projected increase from 1998 to 2010; 86,825 to 172,667), prevalence (projected increase from 1998 to 2010; 326,217 to 661,330), and cost (total cost based on 1998 ratio of Medicare versus non-Medicare cost; $16.74 billion in 1998 to $39.35 billion in 2010), a cohesive national effort is needed to develop strategies to slow the progression of chronic renal failure (CRF). The question arises to how much reduction in the progression of CRF would lead to a meaningful decrease in the prevalence and cost of ESRD. There are no objective data that show the economic impact of slowing the progression of CRF. We developed a mathematical model to assess the economic impact of decreasing the progression of CRF by 10%, 20%, and 30%. US Renal Data System (USRDS) projections were used to model the rate of increase in ESRD incidence and prevalence. Glomerular filtration rate (GFR) at the initiation of ESRD therapy and cost per patient-year were based on USRDS data. The average decline in GFR in subjects with CRF was estimated to be 7.56 mL/min/y. All dollar savings reflect 1998 costs, discounted for the future at 3% per annum. We also determined how much slowing of the progression of CRF is important from patients' perspectives by means of a written questionnaire (which inquired about willingness to go on a restricted diet, take six extra medications per day, and make six extra office visits per year) and calculation of the pre-ESRD time gained for different degrees of reduction in the progression of CRF. If the rate of decline in GFR decreased by 10%, 20%, and 30% after December 31, 1999, in all patients with GFRs of 60 mL/min or less, cumulative direct healthcare savings through 2010 would equal approximately $18.56, $39.02, and $60.61 billion, respectively. For a 10%, 20%, and 30% decrease in the rate of decline in GFR in all patients with a GFR of 30 mL/min or less, estimated cumulative savings through 2010 equal $9.06, $19.98, and $33.37 billion, respectively. Responses to the questionnaire showed that approximately 79% of subjects with CRF (n = 113) perceived a few weeks' dialysis-free period significant (P ≤ 0.0001), a period corresponding to a 10% reduction in the rate of decline in GFR. Our data suggest that the cumulative economic impact of slowing the progression of CRF, even by as little as 10%, would be staggering. They provide strong support for the development and implementation of intensive reno-protective efforts beginning at the early stages of chronic renal disease and continued throughout its course. © 2002 by the National Kidney Foundation, Inc.

Utility of Radioisotopic Filtration Markers in Chronic Renal Issufficiency: Simultaneous Comparison of 125I-Iothalamate, 169Yb-DTPA, 99mTc-DTPA, and Inulin

Assessment of glomerular filtration rate (GFR) with inulin is cumbersome and time-consuming. Radioisotopic filtration markers have been studied as filtration markers because they can be used without continuous intravenous (IV) infusion and because analysis is relatively simple. Although the clearances of 99mTc-diethylenetriamine-pentaacetic acid (DTPA), 169Yb-DTPA, and 125I-iothalamate have each been compared with inulin, rarely has the comparability of radioisotopic filtration markers been directly evaluated in the same subject. To this purpose, we determined the renal clearance of inulin administered by continuous infusion and the above radioisotopic filtration markers administered as bolus injections, simultaneously in four subjects with normal renal function and 16 subjects with renal insufficiency. Subjects were studied twice in order to assess within-study and between-study variability. Unlabeled iothalamate was infused during the second half of each study to assess its effect on clearances. We found that renal clearance of 125I-iothalamate and 169Yb-DTPA significantly exceeded clearance of inulin in patients with renal insufficiency, but only by several mL.min-1.1.73m-2. Overestimation of inulin clearance by radioisotopic filtration markers was found in all normal subjects. No differences between markers were found in the coefficient of variation of clearances either between periods on a given study day (within-day variability) or between the two study days (between-day variability). The true test variability between days did not correlate with within-test variability. We conclude that the renal clearance of 99mTc-DTPA, 169Yb-DTPA, or 125I-iothalamate administered as a single IV or subcutaneous injection can be used to accurately measure GFR in subjects with renal insufficiency; use of the single injection technique may overestimate GFR in normal subjects.

The effect of 1α-hydroxyvitamin D 3 on renal function in normal subjects

The effects of short-term administration of 1 μg daily of 1α-hydroxyvitamin D 3 (1αOHD 3) on plasma biochemistry and renal function have been studied in six normal subjects using the 51Cr-labelled edetic acid ( 51Cr-EDTA) infusion method to measure glomerular filtration rate. 1αOHD 3 was administered for two weeks, subjects being studied before treatment, at the end of the first and second weeks of treatment and one week after stopping treatment. Mean plasma creatinine concentration rose throughout the four weeks of the study, but this change was not statistically significant. Plasma creatinine levels in fact decreased in two subjects after 1αOHD 3 administration. There was no significant change in glomerular filtration rate as measured by the 51Cr-EDTA infusion method or in endogenous creatinine clearance. Plasma phosphate levels increased in all subjects during 1α0HD 3 administration and the maximum tubular reabsorption capacity for phosphate relative to the glomerular filtration rate (Tm po4/GFR) increased in five. There were no significant changes in plasma calcium or immunoreactive parathyroid hormone levels. It is concluded that short-term administration of 1αOHD 3, 1 μg daily, has no direct adverse effect on glomerular filtration rate in subjects with normal renal function.