title: Proteinuria and plasma total homocysteine levels in chronic renal disease patients with a normal range serum creatinine: critical impact of true glomerular filtration rate.
abstract: Conflicting data have been reported concerning the independent association between proteinuria and plasma total homocysteine (tHcy) levels, particularly among chronic renal disease (CRD) patients with a normal range serum creatinine. Studies of this potential relationship have been limited by failure to assess true GFR, failure to assess proteinuria in a quantitative manner, or arbitrary restriction of the range of proteinuria examined. We examined the potential independent relationship between plasma tHcy levels and a wide range of quantitatively determined proteinuria (i.e., 0.000-8.340 g/day), among 109 CRD patients with a normal range serum creatinine (range; 0.8-1.5 mg/dl; median=1.2 mg/dl). Glomerular filtration rate (GFR) was directly assessed by iohexol clearance, and plasma status of folate, pyridoxal 5'-phosphate, and B12, along with serum albumin, were also determined. Linear modeling with ANCOVA revealed that proteinuria was not independently associated with tHcy levels (partial R=0.127; P=0.201), after adjustment for potential confounding by GFR (partial R=0.408; P<0.001), age, sex, plasma B-vitamin status, and serum albumin. Moreover, descending across quartiles (Q) [from Q4 to Q1] of GFR, ANCOVA-adjusted (i.e., for age, sex, and folate status) geometric mean tHcy levels (micromol/l) were significantly increased: tHcy Q4 GFR=9.6; tHcy Q3 GFR=10.5; tHcy Q2 GFR=11.9; tHcy Q4 GFR=14.5; P<0.001 for overall Q difference. We conclude that across a broad spectrum of quantitatively determined proteinuria, after adjustment for true GFR, in particular, there is no independent relationship between proteinuria and tHcy levels among CRD patients with a normal range serum creatinine.
authors.affiliation: Division of General Internal Medicine, Memorial Hospital of Rhode Island, 111 Brewster Street, Pawtucket, RI, USA. abostom@loa.com
authors.forename: A G
authors.initials: AG
authors.lastname: Bostom
authors.forename: F
authors.initials: F
authors.lastname: Kronenberg
authors.forename: P F
authors.initials: PF
authors.lastname: Jacques
authors.forename: E
authors.initials: E
authors.lastname: Kuen
authors.forename: E
authors.initials: E
authors.lastname: Ritz
authors.forename: P
authors.initials: P
authors.lastname: König
authors.forename: G
authors.initials: G
authors.lastname: Kraatz
authors.forename: K
authors.initials: K
authors.lastname: Lhotta
authors.forename: J F
authors.initials: JF
authors.lastname: Mann
authors.forename: G A
authors.initials: GA
authors.lastname: Müller
authors.forename: U
authors.initials: U
authors.lastname: Neyer
authors.forename: W
authors.initials: W
authors.lastname: Riegel
authors.forename: V
authors.initials: V
authors.lastname: Schwenger
authors.forename: P
authors.initials: P
authors.lastname: Riegler
authors.forename: J
authors.initials: J
authors.lastname: Selhub
mesh_terms: D000328:Adult; D000368:Aged; D002908:Chronic Disease; D003404:Creatinine / Q000097:blood*; D005260:Female; D005492:Folic Acid / Q000097:blood; D005919:Glomerular Filtration Rate; D006710:Homocysteine / Q000097:blood*; D006801:Humans; D007668:Kidney / Q000503:physiopathology; D007674:Kidney Diseases / Q000378:metabolism / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D011507:Proteinuria; D011732:Pyridoxal Phosphate / Q000097:blood; D012709:Serum Albumin / Q000032:analysis; D014805:Vitamin B 12 / Q000097:blood
chemical_list: D012709:Serum Albumin; D006710:Homocysteine; D011732:Pyridoxal Phosphate; D005492:Folic Acid; D003404:Creatinine; D014805:Vitamin B 12