The
Hormone human Chorionic Gonadotropin
(better known as hCG)
is
produced during pregnancy. It is made
by cells that form the placenta, which
nourishes the egg after it has been
fertilized and becomes attached to
the uterine wall.
hCG can first be detected
by a normal blood test about 11 days
after conception and about 12 - 14
days by a urine test. In general the
hCG level will double every 72 hours.
The levels will reach their peak in
the 8 - 11 weeks of pregnancy (the
third month) and then will decline
and level off for the remainder of
the pregnancy.
Key
points about hCG levels: |
-
About
80% of normal pregnancies
will have the hCG
level double every
48 - 72 hours. As
you get further along
into pregnancy and
the hCG level gets
higher, the time it
takes to double can
increase to about
every 96 hours.
-
Caution must be used
in making too much
of hCG numbers. A
normal pregnancy may
have low hCG levels
and deliver a perfectly
healthy baby. The
results on an ultrasound
after 5 - 6 weeks
gestation are much
more accurate than
using hCG numbers.
-
An
hCG level of less
than 5mIU/ml is considered
negative for pregnancy,
and anything above
25mIU/ml is considered
positive for pregnancy.
-
hCG is measured in
milli-international
units per milliliter
(mIU/ml).
-
A
transvaginal ultrasound
should be able to
see at least a gestational
sac once the hCG levels
have reached between
1,000 - 2,000mIU/ml.
Because levels can
differentiate so much
and conception dating
can be wrong, a diagnosis
should not be made
by ultrasound findings
until the level has
reached at least 2,000.
-
A
single hCG reading
is not enough information
for most diagnoses.
When there is a question
regarding the health
of the pregnancy,
multiple testings
of hCG done a couple
of days apart give
a more accurate look
at assessing the situation.
-
hCG
levels should not
be used to date a
pregnancy since these
numbers can vary so
widely.
-
There
are two common types
of hCG tests. A qualitative
hCG test just looks
to see if hCG is present
in the blood. A quantitative
hCG test (or beta
hCG) measures the
amount of hCG actually
present in the blood.
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hCG
levels in weeks from LMP (gestational
age)
|
- 3
weeks LMP: 5 - 50 mIU/ml
- 4
weeks LMP: 5 - 426 mIU/ml
- 5
weeks LMP: 18 - 7,340
mIU/ml
- 6
weeks LMP: 1,080 - 56,500
mIU/ml
- 7
- 8 weeks LMP: 7, 650
- 229,000 mIU/ml
- 9
- 12 weeks LMP: 25,700
- 288,000 mIU/ml
- 13
- 16 weeks LMP: 13,300
- 254,000 mIU/ml
- 17
- 24 weeks LMP: 4,060
- 165,400 mIU/ml
- 25
- 40 weeks LMP: 3,640
- 117,000 mIU/ml
- Non-pregnant
females: <5.0 mIU/ml
- Postmenopausal:
<9.5 mIU/ml
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Note:
These numbers are just a GUIDELINE--
every woman’s level of hCG can
rise differently. It is not necessarily
the level that matters but rather
the change in the level.
Should
I check my hCG levels on a regular
basis?
It is not common for doctors to normally
re-check your hCG levels unless you
are showing signs of a possible problem.
A health care provider may re-check
your levels if you are bleeding, having
severe cramping or have a history
of miscarriage.
What
can low hCG levels mean?
A low hCG level can mean any number
of things and should be re-tested
within 48-72 hours to see how the
level is changing. Could indicate:
What
can a high hCG level mean?
A high level of hCG can also mean
a number of things and should be re-tested
within 48-72 hours to evaluate changes
in the level. Could
indicate:
Molar
pregnancy
A molar pregnancy is an abnormality
of the placenta, caused by a problem
when the egg and sperm join together
at fertilization. It is marked by
high levels of Human Chorionic Gonadotropin
(hCG). Molar pregnancies rarely involve
a developing embryo, and the growth
of this material is rapid compared
to normal fetal growth. It has the
appearance of a large and random collection
of grape-like cell clusters.
Ectopic
pregnancy
If your Human Chorionic Gonadotropin
(hCG) level increases but is less
than double the previous one then
it is considered abnormal and suspicious
of an ectopic pregnancy. An ectopic
pregnany is a condition where the
embryo grows outside the uterus.
Twins
or Higher Pregnancies
Twin pregnancies also tend to show
higher Human Chorionic Gonadotropin
(hCG) levels. Twin Human Chorionic
Gonadotropin (hCG) levels fall within
the reported range of singletons,
so, you can't assume anything based
on the level alone. A higher level
on a given day does increase your
chances for twins, but there's no
level above which you're guaranteed
twins.
Injections: If you
have been given an Human Chorionic
Gonadotropin (hCG) injection (Profasi,
Pregnyl) to trigger ovulation or to
lengthen the leutal phase of your
cycle, trace amounts can remain in
your system as long as 10 days after
your last injection. These can give
you high Human Chorionic Gonadotropin
(hCG) levels. Two consecutive quantitative
Human Chorionic Gonadotropin (hCG)
beta blood tests can circumvent this
problem; if the level increases by
the second test, you are likely to
be pregnant.
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