Premenstrual Syndromes : PMS and PMDD - Rutuja :: The site ...

150 LH
FSH
100
mIU/ml
50
pg/ml
ng/ml
ng/ml
0
400
300
200
100
0
60
45
30
15
0
8
6
4
2
0
E 2
E 1
P
17-OHP
9 days
hCG
1 5 9 13 17 21 25 29
Day of cycle
Figure 8.3 Hormonal changes during a conception
cycle and the first week of pregnancy. LH, luteinizing
hormone; FSH, follicle-stimulating hormone;
E 2 , estradiol; E 1 , estrone; P, progesterone; 17-OHP,
17-hydroxyprogesterone. (Reproduced with
permission from Yen. 26 )
Total T (nmol/L)
1.8
1.6
1.4
1.2
1.0
0.8
Free T (pmol/L)
18 30
16
Total T
Free T
LH
14
12
10
8
0
–12 –9 –6 –3 0 3 6 9 12
Day relative to LH peak
PHYSIOLOGY OF THE MENSTRUAL CYCLE 67
follicular phase. In the luteal phase, the predominance
of progesterone results in decidualization of the
endometrium – the increase in vascularity and secretory
vacuoles that would be integral to implantation and early
embryonic development. Cytosolic vacuoles containing
prostaglandins rupture and release their contents when
progesterone levels fall late in the luteal phase. These
prostaglandins, in turn, cause blood vessels within the
endometrium to constrict, resulting in ischemic necrosis
and sloughing of the superficial endometrium. The
basal layer of endometrium is preserved and the deeper
glands constitute the source for new endometrial cells
that resurface the denuded endometrial cavity. Bleeding
typically subsides as small vessels that supply the
endometrium constrict and develop a platelet and fibrin
plug. Aberrations of coagulation (either congenital, like
von Willebrand’s disease, or acquired, such as idiopathic
thrombocytopenic purpura) or fibrinolysis can
result in exaggerated flow in some women. More commonly,
women with pathological abnormalities of the
endometrium (endometrial polyps) or myometrium
(leiomyomata) will report unusually heavy menstrual
flow. In the normal situation the endometrium is rapidly
resurfaced in the 5–6 days after menstruation abates.
Synchronous time-limited shedding of the endometrium
results when progesterone levels decline in ovulatory
women and asynchronous (incomplete) sloughing
of endometrium may result from temporary declines in
estrogen that occur in ovulatory cycles coincident with
ovulation 22 but more commonly at unpredictable times
in anovulatory women. Accordingly, the pattern of
menstruation will usually confirm whether or not a
woman is ovulatory. Regular predictable cycles with an
intermenstrual interval of 24–35 days are the hallmark
of ovulatory menstrual cycles, whereas unpredictable
bleeding at intervals of weeks to months that lasts for
different durations (sometimes several weeks) is highly
predictive of anovulatory or oligo-anovulatory cycles.
20
10
LH (IU/L)
Figure 8.4 Graph showing mean
serum concentrations of testosterone
(Total T) and free testosterone (Free
T) related to luteinizing hormone (LH)
levels during the menstrual cycle in 34
healthy women. (Reproduced with
permission from Sinha-Hikim et al. 29 )