Introduction: The association between testosterone
replacement therapy and cardiovascular risk remains unclear.
Most recent reports suggest that low testosterone level is
associated with increased male morbidity and mortality. The
objective of the present study was to evaluate the effect of
testosterone undecanoate (TU) in physiologic dose on blood hematocrit, haemoglobin, fibrinogen and viscosity.
Materials and Methods: Twenty four male New Zealand
White rabbits (2-2.5 kg) were involved in this study, of which
16 underwent orchiectomy and the other 8 underwent a sham
procedure. The 16 rabbits were randomly divided into 2 groups
(8/group): Castrated group and castrated TU injection group.
The 8 rabbits in TU injection group were administrated 6
mg/kg TU i.m at 1 day and 6 weeks after orchiectomy. The
blood viscosity, testosterone, hematocrit, haemoglobin, blood
chemistry and fibrinogen levels were measured at 0 week, 6
weeks and 18 weeks after orchiectomy.
Results: In control group, the blood viscosity, testosterone and
fibrinogen levels were significantly increased at 6 and 18 weeks
(P<0.01). In castrated group, the blood viscosity decreased and
the fibrinogen level increased but without statistical significance
compared with before orchiectomy. In TU injection group,
the blood viscosity was significantly decreased compared with
either before orchiectomy or control group (P<0.01), altogether
the fibrinogen level significantly increased. In all groups, the
hematocrit and haemoglobin had no significant difference.
Conclusions: The patients who received physiologic dose of TU
may also have a beneficial effect in lowing cardiovascular risk.
Further study is needed to find out the underlying mechanism.