β-Trace Protein: From GFR Marker to Cardiovascular Risk Predictor

β-Trace protein, also known as Lipocalin type prostaglandin D synthase, is a low-molecular mass glycoprotein (between 23,000 and 29,000 Da depending on the degree of glycosylation) that converts prostaglandin H2 into prostaglandin D2. β-Trace protein was initially isolated from cerebrospinal fluid and served as a marker of cerebrospinal fluid leakage; however, its cDNA and gene have been isolated in numerous human body tissues, including central nervous system, retina, melanocytes, heart, and male genital organs. In recent years, β-trace protein has emerged as a promising novel endogenous marker of GFR, representing a more sensitive marker for mild kidney dysfunction than serum creatinine. In this regard, β-trace protein has been proposed as an alternative marker to Cystatin C for measuring kidney function. Beyond its role for estimating renal function, β-trace protein is also emerging as a novel biomarker in cardiovascular risk. It has been associated with several cardiovascular disorders, playing a potential role for prognostic stratification in patients with acutely decompensated heart failure and acute coronary syndromes and being advocated as a novel marker for cardiovascular risk prediction.