Measured GFR as "Gold Standard"-All that Glitters Is Not Gold?

Division of Nephrology, University of California, San Francisco, 513 Parnassus Avenue, 672 HSE, Box 0532, San Francisco, CA 94143-0532. .
Clinical Journal of the American Society of Nephrology (Impact Factor: 5.07). 08/2011; 6(8):1813-4. DOI: 10.2215/CJN.06040611
Source: PubMed
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    ABSTRACT: We congratulate the KDIGO (Kidney Disease: Improving Global Outcomes) work group on their comprehensive work in a broad subject area, and agreed with many of the recommendations in their clinical practice guideline on the evaluation and management of chronic kidney disease. We concur with the KDIGO definitions and classification of kidney disease, and welcome the addition of albuminuria categories at all levels of glomerular filtration rate (GFR) , the terminology of G categories rather than stages to describe level of GFR, the division of former stage 3 into new G categories 3a and 3b, and the addition of the underlying diagnosis. We agree with the use of the heat map to illustrate the relative contributions of low GFR and albuminuria to cardiovascular and renal risk, though we felt that the highest risk category was too broad, including as it does people at quite disparate levels of risk. We add an albuminuria category A4 for nephrotic-range proteinuria, and D and T categories for patients on dialysis or with a functioning renal transplant.We recommend target blood pressure of 140/90 mm Hg regardless of diabetes or proteinuria, and against the combination of angiotensin-receptor blockers with angiotensin-converting enzyme inhibitors. We recommend against routine protein restriction. We concur on individualization of HbA1C targets. We do not agree with routine restriction of sodium to less than 2 g/d, instead suggesting reduction of sodium intake in those with high intake (> 3.3 g/d). We suggest screening for anemia only when GFR < 30 mL/min/1.73 m2. We recognize the absence of evidence on appropriate phosphate targets and methods of achieving them, and do not agree with suggestions in this area. In drug dosing, we agree with the recommendation of using absolute clearance (ie, mL/min), calculated from the patient’s estimated GFR (which is normalized to 1.73 m2) and the patient’s actual anthropomorphic body surface area. We agree with referral to a nephrologist when GFR < 30 mL/min/1.73 m2 (and for many other scenarios), but suggest urine albumin-creatinine ratio > 60 mg/mmol or proteinuria > 1 g/d as the referral threshold for proteinuria.
    American Journal of Kidney Diseases 11/2014; DOI:10.1053/j.ajkd.2014.10.013 · 5.76 Impact Factor
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    ABSTRACT: The usefulness of estimated glomerular filtration rate may not be restricted to pre-dialysis patients, since we reported that estimated glomerular filtration rate was well correlated with measured total creatinine clearance in peritoneal dialysis patients. To clarify the clinical usefulness of estimated glomerular filtration rate as a parameter for peritoneal dialysis adequacy, we retrospectively surveyed estimated glomerular filtration rate and total creatinine clearance in peritoneal dialysis patients treated at JA Toride Medical Center. A total of 114 data sets of estimated glomerular filtration rate and total creatinine clearance from 21 PD patients treated at JA Toride Medical Center were collected from November 2010 to October 2011. The patients consisted of 15 men and six women with an average age of 66.6 ± 12.6 years (46-95 years old). The average number of samples was 5.4 ± 1.5 (2 to 7) per patient. The collected data showed less correlation of estimated glomerular filtration rate and total creatinine clearance (r. = 0.435) than that of a previous cross-sectional study (r. = 0.836). As reported in pre-dialysis patients, the differences between estimated glomerular filtration rate and total creatinine clearance were correlated with total creatinine excretion in urine and PD effluent (r. = 0.821). The differences were also correlated with normalized protein catabolic rate, which was one of the main determinant factors for total creatinine excretion (r. = 0.636). A similar tendency was apparently observed in one patient with poor compliance to diet therapy and fluctuating dietary intake. From the analysis of these data, serum creatinine seemed to fluctuate less possibly due to compensatory capacity of the residual renal function in small solute clearance. Consequently, estimated glomerular filtration rate was turned out to be a more stable parameter than total creatinine clearance, which might be a desirable feature in long-term follow-up of peritoneal dialysis patients.
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    ABSTRACT: Aims Improved early diagnostic methods are needed to identify risk for kidney disease in people with type 1 diabetes. We hypothesized that glomerular filtration rate (GFR) measured by iohexol clearance in dried blood spots (DBS) on filter paper would be comparable to plasma (gold-standard) and superior to estimated GFR (eGFR) and, second, that adjustment for ambient blood glucose would improve accuracy and precision of GFR measurement. Methods GFR was measured by iohexol clearance in plasma, DBS, and as estimated by the CKD-Epidemiology Collaboration equations in 15 adults with type 1 diabetes at two visits, one euglycemic and one hyperglycemic. Results GFR measured by DBS was more comparable and less biased than GFR cystatin C, serum creatinine, and both combined. GFR was higher during hyperglycemia. Correction for between visit glycemia statistically significantly reduced bias and mean squared error for GFR measured by DBS as compared to gold-standard during euglycemia. Conclusions Iohexol clearance measured with DBS performed better than eGFR methods. Correction for ambient blood glucose improved precision and accuracy of GFR measurement. This method is more convenient than the gold-standard GFR method and may improve screening and diagnostic capabilities in people with type 1 diabetes, especially when GFR is > 60 ml/min/1.73 m2.
    Journal of Diabetes and its Complications 09/2014; 28(5). DOI:10.1016/j.jdiacomp.2014.06.001 · 1.93 Impact Factor