title: Association of the cystatin C/creatinine ratio with the renally cleared hormones parathyroid hormone (PTH) and brain natriuretic peptide (BNP) in primary care patients: a cross-sectional study.
abstract: The ratio of cystatin C to creatinine (cysC/crea) is regarded as a marker of glomerular filtration quality and predicts mortality. It has been hypothesized that increased mortality may be mediated by the retention of biologically active substances due to shrinking glomerular pores. The present study investigated whether cysC/crea is independently associated with the levels of two renally cleared hormones, which have been linked to increased mortality. We conducted a multicenter, cross-sectional study with a random selection of general practitioners (GPs) from all GP offices in seven Swiss cantons. Markers of glomerular filtration quality were investigated together with estimated glomerular filtration rate (eGFR), albuminuria and urinary neutrophil gelatinase associated lipocalin (uNGAL) as well as two renally cleared low-molecular-weight protein hormones (i.e. BNP and PTH), Morbidity was assessed with the Charlson Comorbidity Index (CCI). A total of 1000 patients (433 males; mean age 57 ± 17 years) were included. There was a significant univariate association of BNP (r = 0.36, p < 0.001) and PTH (r = 0.18, p < 0.001) with cysC/crea. An adjusted model that accounted for kidney function (eGFR), altered glomerular structure (albuminuria), renal stress (uNGAL), and CCI showed that BNP and PTH were independently associated with cysC/crea as well as with the ratio of cystatin C-based to creatinine-based eGFR. In conclusion, in primary care patients, BNP and PTH are independently associated both with markers of glomerular filtration quality and eGFR regardless of structural kidney damage or renal stress. These findings offer an explanation, how altered glomerular filtration quality could contribute to increased mortality.
authors.affiliation: a Kantonsspital Graubünden, Zentrallabor , Chur , Switzerland ;|b Labormedizinisches Zentrum Dr. Risch , Liebefeld , Switzerland ;
authors.forename: Martin
authors.initials: M
authors.lastname: Risch
authors.affiliation: b Labormedizinisches Zentrum Dr. Risch , Liebefeld , Switzerland ;|c Faculty of Medical Sciences, Private University , Triesen , Liechtenstein ;|d University Institute of Clinical Chemistry, University Hospital and University of Bern , Bern , Switzerland ;
authors.forename: Lorenz
authors.initials: L
authors.lastname: Risch
authors.affiliation: e Faculty of Science , Tallinn University of Technology , Tallinn , Estonia ;
authors.forename: Mette-Triin
authors.initials: MT
authors.lastname: Purde
authors.affiliation: f Institute of Laboratory Medicine , Philipps University Marburg , Marburg , Germany ;
authors.forename: Harald
authors.initials: H
authors.lastname: Renz
authors.affiliation: g Division of Nephrology , Stadtspital Waid , Zurich , Switzerland ;
authors.forename: Patrice
authors.initials: P
authors.lastname: Ambühl
authors.affiliation: h European Center of Pharmaceutical Medicine , University of Basel , Basel , Switzerland ;
authors.forename: Thomas
authors.initials: T
authors.lastname: Szucs
authors.affiliation: i Epidemiology , Biostatistics and Prevention Institute, University of Zurich , Zurich , Switzerland.
authors.forename: Yuki
authors.initials: Y
authors.lastname: Tomonaga
mesh_terms: D000328:Adult; D000368:Aged; D015415:Biomarkers / Q000652:urine; D003404:Creatinine; D003430:Cross-Sectional Studies; D055316:Cystatin C; D005260:Female; D005919:Glomerular Filtration Rate; D006801:Humans; D007668:Kidney / Q000502:physiology; D007674:Kidney Diseases / Q000503:physiopathology*; D000071068:Lipocalin-2 / Q000652:urine; D008297:Male; D008875:Middle Aged; D009017:Morbidity; D020097:Natriuretic Peptide, Brain / Q000378:metabolism*; D010281:Parathyroid Hormone / Q000378:metabolism*; D011320:Primary Health Care; D011897:Random Allocation
chemical_list: D015415:Biomarkers; D055316:Cystatin C; D000071068:Lipocalin-2; D010281:Parathyroid Hormone; D020097:Natriuretic Peptide, Brain; D003404:Creatinine
keywords: Brain natriuretic peptide; creatinine; cross-sectional study; cystatin C; glomerular filtration quality; glomerular filtration rate; morbidity; neutrophil gelatinase-associated lipocalin; parathyroid hormone