Physiology, Laboratory Testing, and Iodine
2
Figure
1A.
Thyroid
Physiology
During
Ovarian
Stimulation
a
Physiologic
alterations
of
serum
TSH,
FT4,
and
TBG
concentrations
are
expected
from
the
rise
of
estrogen
during
ovarian
stimulation.
yroxine
requirements
are
extracted
from
studies
of
hypothyroid
women
taking
fixed
levothyroxine
doses.
Before
ovarian
stimulation
4–7
days
after
ovarian
stimulation
At
time
of
hCG
stimulation
1
week
after
hCG
stimulation
2
weeks
after
embryo
transfer
2
weeks
pregnant
Thyroxine
degradation
by
D3
a
TBG
FT4
in
patients
on
fixed
LT4
dose
TSH
in
patients
on
fixed
LT4
dose
Estrogen
TSH
FT4
