Non-Albumin Proteinuria (NAP) as a Complementary Marker for Diabetic Kidney Disease (DKD).

Jaehyun Bae,Young Jun Won,Byung-Wan Lee

doi:10.3390/life11030224

Abstract

Diabetic kidney disease (DKD) is one of the most common forms of chronic kidney disease. Its pathogenic mechanism is complex, and it can affect entire structures of the kidney. However, conventional approaches to early stage DKD have focused on changes to the glomerulus. Current standard screening tools for DKD, albuminuria, and estimated glomerular filtration rate are insufficient to reflect early tubular injury. Therefore, many tubular biomarkers have been suggested. Non-albumin proteinuria (NAP) contains a wide range of tubular biomarkers and is convenient to measure. We reviewed the clinical meanings of NAP and its significance as a marker for early stage DKD.

Highlights

Diabetic kidney disease (DKD) is one of the most frequent complications of diabetes mellitus (DM), and the leading cause of end-stage renal disease (ESRD) [1]. It occurs in 20%~40% of patients with DM, and is diagnosed by the presence of persistently increased albuminuria and/or decreased estimated glomerular filtration rate [2]
The need for complementary markers to albuminuria for early stage DKD has been raised, and researchers have focused on urinary proteins other than albumin
When the researchers followed those patients for a median of 29 months, NAP-to-creatinine ratio (NAPCR) was significantly associated with an annual decline in estimated glomerular filtration rate (eGFR) and remained statistically associated in the multivariate regression analysis, even after adjusting for urinary albumin-to-creatinine ratio (UACR), baseline eGFR, and cystatin C

Summary

Introduction

Diabetic kidney disease (DKD) is one of the most frequent complications of diabetes mellitus (DM), and the leading cause of end-stage renal disease (ESRD) [1] It occurs in 20%~40% of patients with DM, and is diagnosed by the presence of persistently increased albuminuria and/or decreased estimated glomerular filtration rate (eGFR) [2]. Increased delivery of growth factors such as transforming growth factor-β, epidermal growth factor, and insulin-like growth factor-1 to renal tubules under diabetic conditions induces tubulointerstitial fibrosis in diabetic kidneys [30,37,38] These pathologic factors of tubular injury are associated with other chronic diseases such as non-alcoholic fatty liver (NAFLD) and hypertension. Based on the classical view of the natural history of DKD (Table 3) [5,42], it is considered to be an early marker of DKD, appearing prior to eGFR reduction

End stage renal disease

NAP and Tubular Injury

Findings

Clinical Significance of NAP in DKD