Sm. Marcovina et al., TESTOSTERONE-INDUCED SUPPRESSION OF LIPOPROTEIN(A) IN NORMAL MEN - RELATION TO BASAL LIPOPROTEIN(A) LEVEL, Atherosclerosis, 122(1), 1996, pp. 89-95
The concentration of lipoprotein(a) [Lp(a)] in human plasma is largely
genetically determined and is inversely correlated to the size of apo
lipoprotein(a) [apo(a)]. Additionally, Lp(a) values are relatively sta
ble within individuals and are only marginally susceptible to therapeu
tic treatment. The aim of our study was to evaluate the effect of exog
enous testosterone on plasma Lp(a) concentration. The study was carrie
d out on 19 healthy men who were receiving weekly intramuscular inject
ions of 200 mg testosterone enanthate. Lp(a) values were determined at
multiple time-points by a double monoclonal antibody-based enzyme imm
unoassay. This method is not sensitive to variation in Lp(a) size and
the values are expressed in nmol/l. Apo(a) size isoforms were determin
ed by agarose gel electrophoresis followed by immunoblotting. No corre
lation was found between the baseline Lp(a) values and the baseline va
lues of testosterone or estradiol. The Lp(a) response to testosterone
treatment varied widely among subjects and was dependent upon the pret
reatment 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 signif
icant 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 rol
e in the determination of Lp(a) response to testosterone.