Abstract
High salt intake has been related to the development to chronic kidney disease (CKD) as well as hypertension. In its early stages, symptoms of CKD are usually not apparent, especially those that are induced in a “silent” manner in normotensive individuals, thereby providing a need for some kind of urinary biomarker to detect injury at an early stage. Because traditional renal biomarkers such as serum creatinine are insensitive, it is difficult to detect kidney injury induced by a high-salt diet, especially in normotensive individuals. Recently, several new biomarkers for damage of renal tubular epithelia such as neutrophil gelatinase-associated lipocalin (NGAL) and kidney injury molecule-1 (Kim-1) have been identified. Previously, we found a novel renal biomarker, urinary vanin-1, in several animal models with renal tubular injury. However, there are few studies about early biomarkers of the progression to CKD associated with a high-salt diet. This review presents some new insights about these novel biomarkers for CKD in normotensives and hypertensives under a high salt intake. Interestingly, our recent reports using spontaneously hypertensive rats (SHR) and normotensive Wistar Kyoto rats (WKY) fed a high-salt diet revealed that urinary vanin-1 and NGAL are earlier biomarkers of renal tubular damage in SHR and WKY, whereas urinary Kim-1 is only useful as a biomarker of salt-induced renal injury in SHR. Clinical studies will be needed to clarify these findings.
Highlights
Chronic kidney disease (CKD) is one of the serious health problems affecting millions of people and draining scarce health care resources
Stratified across high-income, middle-income, and low-income countries, the majority of the CKD population is found in low- and middle-income countries; the population consists of only 48 million men and 62 million women in high-income countries, whereas it consists of about 170 million men and 210 million women in low- and middle-income countries [1]
The importance of salt restriction is well recognized, and the World Health Organization (WHO) recommended that salt intake should be kept below 5 g/day in 2016, which is based on the WHO Guideline (WHO Guideline: Sodium intake for adults and children, 2012) in order to avoid health problems, especially those related to CKD as well as hypertension and the cardiovascular system
Summary
Chronic kidney disease (CKD) is one of the serious health problems affecting millions of people and draining scarce health care resources. Stratified across high-income, middle-income, and low-income countries, the majority of the CKD population is found in low- and middle-income countries; the population consists of only 48 million men and 62 million women in high-income countries, whereas it consists of about 170 million men and 210 million women in low- and middle-income countries [1]. A recently published double-blind controlled randomized trial in patients with CKD (stages 3 and 4) showed that dietary sodium restriction significantly decreased ambulatory BP by 10/4 mmHg, and consistent reductions in proteinuria and albuminuria were shown [3]. The importance of salt restriction is well recognized, and the World Health Organization (WHO) recommended that salt intake should be kept below 5 g/day in 2016, which is based on the WHO Guideline (WHO Guideline: Sodium intake for adults and children, 2012) in order to avoid health problems, especially those related to CKD as well as hypertension and the cardiovascular system. We refer to the salt-induced CKD under hypertension and normotension, from the classical to recent insights
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