Testosterone-induced suppression of lipoprotein(a) in normal men; relation to basal lipoprotein(a) level
Date
1996-04-26Author
Bremner, William J.
Bagatell, Carrie J.
Marcovina, Santica M.
Lippi, Giuseppe
Metadata
Show full item recordAbstract
The concentration of lipoprotein(a) [Lp(a)] in human plasma is largely
genetically determined and is inversely correlated to the size of
apolipoprotein(a) [apo(a)]. Additionally, Lp(a) values are relatively
stable within individuals and are only marginally susceptible to
therapeutic treatment. The aim of our study was to evaluate the effect of
exogenous testosterone on plasma Lp(a) concentration. The study was
carried out on 19 healthy men who were receiving weekly intramuscular
injections of 200 mg testosterone enanthate. Lp(a) values were determined
at multiple time-points by a double monoclonal antibody-based enzyme
immunoassay. This method is not sensitive to variation in Lp(a) size and
the values are expressed in nmol/l. Apo(a) size isoforms were determined
by agarose gel electrophoresis followed by immunoblotting. No correlation
was found between the baseline Lp(a) values and the baseline values of
testosterone or estradiol. The Lp(a) response to testosterone treatment
varied widely among subjects and was dependent upon the pretreatment Lp(a)
concentration. For 10 subjects with low Lp(a) values (< 25 nmol/l), no
significant decrease in Lp(a) was observed while, for the nine individuals
with Lp(a) values > 25 nmol/l, there was a significant and consistent
reduction in Lp(a) ranging from 25 to 59%. Lp(a) levels returned to
baseline values following cessation of testosterone administration. Apo(a)
size polymorphism did not appear to play a role in the determination of
Lp(a) response to testosterone.