Hypothyroidism (cont.)
How is hypothyroidism treated?
With the exception of certain conditions, the treatment of hypothyroidism requires
life-long therapy. Before synthetic levothyroxine (T4) was available, desiccated thyroid
tablets were used. Desiccated thyroid was obtained from animal thyroid glands, which lacked
consistency of potency from batch to batch. Presently, a pure, synthetic T4 is widely available.
Therefore, there is no reason to use desiccated thyroid extract.
As described above, the most active thyroid hormone is actually T3. So why do physicians
choose to treat patients with the T4 form of thyroid? T3 [liothyronine
sodium (Cytomel)] is available and there are
certain indications for its use. However, for the majority of patients, a form of T4
[levothyroxine sodium (Levoxyl,
Synthroid)] is the preferred treatment. This is a more stable form of thyroid hormone and
requires once a day dosing, whereas T3 is much shorter-acting and needs to be taken multiple
times a day. In the overwhelming majority of patients, synthetic T4 is readily and steadily
converted to T3 naturally in the bloodstream, and this conversion is appropriately regulated by
the body's tissues.
- The average dose of T4 replacement in adults is approximately 1.6 micrograms per kilogram
per day. This translates into approximately 100 to 150 micrograms per day.
- Children require larger doses.
- In young, healthy patients, the full amount of T4
replacement hormone may be started initially.
- In patients with preexisting heart
disease, this method of thyroid replacement may aggravate the underlying heart
condition in about 20% of cases.
- In older patients without known
heart disease,
starting with a full dose of thyroid replacement may result in uncovering heart
disease, resulting in chest pain or a
heart attack. For this reason, patients with a history of
heart disease or those suspected of being at high risk are started with 25 micrograms or less
of replacement hormone, with a gradual increase in the dose at 6 week intervals.
Ideally, synthetic T4 replacement should be taken in the morning, 30 minutes before
eating. Other medications containing iron or antacids should be avoided, because
they interfere with absorption.
Therapy for hypothyroidism is monitored at approximately six week intervals until stable. During these
visits, a blood sample is checked for TSH to determine if the appropriate amount
of thyroid replacement is being given. The goal is to maintain the TSH within
normal limits. Depending on the lab used, the absolute values may vary, but in
general, a normal TSH range is between 0.5 to 5.0uIU/ml. Once stable, the TSH
can be checked yearly. Over-treating hypothyroidism with excessive thyroid
medication is potentially harmful and can cause problems with heart palpitations
and blood pressure control and can also contribute to osteoporosis. Every effort should be
made to keep the TSH within the normal range.
Next: What is subclinical hypothyroidism? »
- levothyroxine sodium, Synthroid, Levoxyl, Levothroid, Unithroid - Learn more about Levothyroxine Sodium (Synthroid, Levoxyl, Levothroid, Unithroid), including a description, generic and brand names, drug class and mechanism, preparations, storage, reasons for prescription, dosing, drug interactions, effect on pregnancy and nursing mothers, and common side effects.
- Thyroid Blood Tests - Read about thyroid blood tests, which are used to diagnose disease of the thyroid such as hyperthyroidism and hyperthyroidism, as well as point to other diseases of the thyroid gland.
- Stress - Read about stress symptoms, signs, causes and treatment. Get information on stress management tips, the effects on the body and stress types (teen, job, PTSD).
Latest Medical News
Thyroid RSS