Sub-clinical Hypothyroidism...To Treat Or Not?
Medical Author: Ruchi
Mathur, M.D.
Medical Editor: William
C. Shiel, Jr., MD, FACP, FACR
In my office last week, I saw a woman who was
referred to me by a colleague. The patient was in good health, 48 years old and
had no prior medical history of significance except an uncomplicated pregnancy
and gallbladder surgery years ago.
While
she was under the care of my colleague, a generalist, she had a routine annual
physical. As part of that physical, she had a thyroid panel (this includes a
screen for thyroid stimulating hormone [TSH]
and for the circulating thyroid hormones T3 and T4). As it turns out, all of her
evaluation was completely normal except for her thyroid panel. Her blood work
revealed a normal T4 and T3 level, but an increased TSH. She was referred to me for assessment.
Her case is
an example of a common condition called "sub-clinical hypothyroidism." Basically, with this condition, the
pituitary gland, which is
in charge of regulating the thyroid gland,
produces extra amounts of TSH to stimulate the thyroid to maintain a normal
circulating level of thyroid hormones. While this patient is not hypothyroid
(her thyroid hormone levels are normal), her pituitary is working hard at
keeping her thyroid hormone levels within the normal range. In a significant
number of patients, the TSH levels must climb in order to continue to stimulate
the thyroid gland. Eventually, over
the course of months to years, the thyroid gland no longer responds. At this
point, "sub-clinical hypothyroidism" turns into overt hypothyroidism.
Physicians
have various view points as to whether sub-clinical hypothyroidism should be
treated. There is no real right or wrong answer, and a lot depends on the
patient's preference. One criterion that does help to make a decision as to
whether treatment should be started is the cholesterol profile. Patients with a
high cholesterol level (particularly LDL, or bad cholesterol) usually benefit from thyroid
hormone replacement therapy, since their cholesterol profiles often
improve with replacement.
As a patient,
if you are diagnosed with "sub-clinical hypothyroidism," you should discuss the
pros and cons of starting thyroid replacement therapy with your doctor. Likewise,
you should have a fasting cholesterol profile to allow you and your doctor to
make an informed decision. Whatever you choose, it is important to remember that
you need to have continued follow-ups with your doctor. If you have chosen to
start replacement therapy, you will need to check your thyroid hormone levels
while on replacement. If you have decided to wait, you will need to have blood
tests to follow your thyroid function. Remember that your preference plays a
large role in any therapy you choose, so don't be afraid to address your
questions or concerns.
Last Editorial Review: 10/23/2006
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