title: Effects of normalization of plasma testosterone levels in hypogonadal men on plasma levels and urinary excretion of asymmetric dimethylarginine (ADMA).
abstract: Elevated plasma levels of asymmetric dimethylarginine (ADMA) inhibit nitric oxide formation and exert a proatherogenic action. Low testosterone (T) levels are associated with increased cardiovascular risks. This study analyzed the effects of normalization of plasma T levels on plasma levels and urinary excretion of ADMA in hypgonadal men (n=10) receiving transdermal T administration. Plasma T levels, starting from clearly hypogonadal T plasma concentrations with a mean level of 4.0+/-2.72 nmol/l at baseline, rose to >10 nmol/l after 2 weeks, with plasma T levels within the normal range of men (mean level of 22.5+/-11.3 nmol/l) over the last 16 weeks of the 24 weeks of T administration. Normalization of plasma T led to a small but significant fall of plasma ADMA (519+/-55 vs. 472+/-59 nmol/l, p=0.031). The outcome of this study may be viewed as a favorable effect of normalization of plasma testosterone on plasma ADMA since even small elevations of plasma ADMA significantly increase cardiovascular risk. While this effect of normalization of plasma T may impress as favorable, most available studies on effects of T administration to hypogonadal men have not shown beneficial effects on functions of the vascular wall.
authors.affiliation: Department of Gastroenterology, Hepatology & Endocrinology, Hannover Medical School, Hannover, Germany. eleifke@tgrd.com
authors.forename: E
authors.initials: E
authors.lastname: Leifke
authors.forename: M
authors.initials: M
authors.lastname: Kinzel
authors.forename: D
authors.initials: D
authors.lastname: Tsikas
authors.forename: L
authors.initials: L
authors.lastname: Gooren
authors.forename: J C
authors.initials: JC
authors.lastname: Frölich
authors.forename: G
authors.initials: G
authors.lastname: Brabant
mesh_terms: D000328:Adult; D000368:Aged; D001120:Arginine / Q000031:analogs & derivatives* / Q000097:blood / Q000652:urine; D015992:Body Mass Index; D006801:Humans; D007006:Hypogonadism / Q000097:blood* / Q000652:urine*; D008297:Male; D008875:Middle Aged; D009566:Nitrates / Q000097:blood; D009573:Nitrites / Q000097:blood; D013739:Testosterone / Q000097:blood*
chemical_list: D009566:Nitrates; D009573:Nitrites; D013739:Testosterone; C018524:N,N-dimethylarginine; D001120:Arginine