Update on Estimation of Kidney Function in Diabetic Kidney Disease

Abstract

The American Diabetes Association recommends annual assessment of glomerular filtration rate (GFR) to screen for diabetic nephropathy. GFR is measured indirectly using markers that, ideally, are eliminated only by glomerular filtration. Measured GFR, although the gold standard, remains cumbersome and expensive. GFR is therefore routinely estimated using creatinine and/or cystatin C and clinical variables. In pediatrics, the Schwartz creatinine-based equation is most frequently used even though combined creatinine and cystatin C-based equations demonstrate stronger agreement with measured GFR. In adults, the CKD Epidemiology Collaboration (CKD-EPI) equations with creatinine and/or cystatin C are the most accurate and precise estimating equations. Despite recent advances, current estimates of GFR lack precision and accuracy before chronic kidney disease stage 3 (GFR < 60 mL/min/1.73 m(2)). There is therefore an urgent need to improve the methods for estimating and measuring GFR. In this review, we examine the current literature and data addressing measurement and estimation of GFR in diabetes.

Renal and Cardiovascular Risk According to Tertiles of Urinary Albumin-to-Creatinine Ratio: The Adolescent Type 1 Diabetes Cardio-Renal Intervention Trial (AdDIT)

“…Estimated GFR (eGFR) was calculated from plasma creatinine with a modified Schwartz formula, based on our previous study in type 1 diabetes adolescents (15) (17).…”

Cystatin C in aging and in Alzheimer’s disease

“…Measurement of serum CysC, in addition to creatinine, is widely used to estimate glomerular filtration rates in older individuals, with an increase in serum CysC indicative of poor kidney function (Inker et al, 2012). The importance of readily accessible and informative markers for kidney disease is underscored by the overlay of an age-dependent increase in chronic kidney disease and the fact that studies have shown that in older people chronic kidney disease is associated with an increased risk of multiple adverse outcomes including end-stage kidney disease, cardiovascular events, acute kidney injury, severe infections, cognitive decline, and death, [recently reviewed in (Bjornstad et al, 2015; Joshi and Viljoen, 2015; Taal, 2015)]. That serum CysC levels can serve as more than a simple filterable protein marker of kidney function has been suggested by studies correlating cognitive function with CysC levels in the blood.…”

“…In contrast to this finding, a study of 3,030 elders showed that individuals with high levels of serum CysC had lower scores on cognitive tests compared with those with intermediate/low levels, and that those with high serum CysC levels were more likely to experience a decline in cognitive function (Yaffe et al, 2008). In this cohort, however, the brain magnetic resonance imaging and other clinical evaluation needed to determine whether the cognitive impairments were due to vascular disease, AD, or chronic kidney disease were not done (Yaffe et al, 2008), and multiple factors can drive cognitive decline associated with changes in serum CysC levels (Bjornstad et al, 2015; Joshi and Viljoen, 2015; Taal, 2015). Thus, CysC levels in the serum are affected by multiple conditions that may affect cognition, and abnormal CysC levels in the blood, either high or low, appear to be a peripheral biomarker for cognitive dysfunction and/or the development of AD.…”

Renin-angiotensin-aldosterone system activation in long-standing type 1 diabetes

“…Diabetic kidney disease (DKD) is the leading cause of end-stage renal disease and dialysis in North America (1)(2)(3) and is a strong predictor of cardiovascular disease and mortality (4,5). The cumulative lifetime incidence of DKD in type 1 diabetes (T1D) is approximately 50% (6,7), which means that a subset of patients with T1D do not develop clinical DKD (6,7).…”