M. Spitzer et al., PATTERN OF DEVELOPMENT OF HYPERPROLACTINEMIA AFTER INITIATION OF HALOPERIDOL THERAPY, Obstetrics and gynecology, 91(5), 1998, pp. 693-695
Objective: To determine the time it takes for prolactin (PRL) levels t
o increase after initiation of therapy with haloperidol (a neuroleptic
medication) and the pattern and extent of the increase. Methods: Seve
nteen individuals scheduled to be given treatment with neuroleptic dru
gs were enrolled. Baseline blood specimens were collected for PRL and
TSH levels. Follow-up samples for PRL determinations were obtained eve
ry 3 days for 18 days after initiation of haloperidol therapy. Results
: There were 17 subjects: 14 women and three men. Two of the subjects
were found to have hyperprolactinemia due to hypothyroidism and were e
xcluded from the basic study. The 15 remaining subjects all had normal
baseline PRL levels and normal TSH values. The PRL levels in all 15 s
howed a similar pattern: a rapid increase in PRL levels in the first 6
-9 days, followed by a plateau that remained, with minor fluctuations,
throughout the study. The highest mean peak level of PRL was 37.4 ng/
mL and the maximum was 77 ng/mL. The two individuals with hypothyroidi
sm had somewhat elevated baseline PRL levels; although they showed the
same initial pattern of increase after haloperidol administration, th
eir PRL levels reached values well above 100 ng/mL. Conclusion: There
is a distinct pattern of response of PRL to haloperidol. The PRL level
increases for 6-9 days, then plateaus, the peak being between 30 and
50 ng/mL, and always remains below 77 ng/mL. In our study, levels that
continued to increase, or increased above 77 ng/mL, indicated the pre
sence of hypothyroidism. The patterns and levels of the increase were
uninfluenced by the therapeutic dose of the medication given. Given th
at the patients in our study with elevated levels of TSH had such high
levels of PRL, all patients should have TSH determinations at the ini
tiation of therapy with neuroleptic medications such as haloperidol. (
C) 1998 by The American College of Obstetricians and Gynecologists.