Underactive Thyroid (Hypothyroidism)
Underactive Thyroid is medically known as Hypothyroidism, which is a very common disorder, especially in women.
Symptoms of Hypothyroidism
The two most common symptoms of Hypothyroidism are:
1. Weight gain (or difficulty losing weight)
The other common symptoms of hypothyroidism are:
3. Decrease in concentrating ability
4. Muscle cramps
5. Puffy eyes
6. Hair loss
7. Intolerance to cold
9. Menstrual irregularities
10. Frequent miscarriages.
11. Sometimes an enlarged thyroid gland (known as a goiter) is also present.
12. Hypothyroidism can also cause a high cholesterol level, high blood pressure and slowing of heart rate.
It is quite common to mistakenly attribute these symptoms to "just getting old."
Diagnosis of Hypothyroidism
Hypothyroidism can be easily diagnosed with a blood test.
Blood test for Hypothyroidism:
Free T4 and Free T3
In Hypothyroidism, TSH is high; T4 and T3 may be normal (mild cases) or low (more severe cases).
The only exception is when hypothyroidism is due to a pituitary disease itself, such as a pituitary tumor, pituitary surgery or radiation of the pituitary area. In these cases, TSH does not get elevated as the pituitary gland itself is diseased. In these cases, T4 and T3 are low, but TSH is usually low or low normal.
Causes of Hypothyroidism
1. Hashimoto's Thyroiditis.
2. After Radioactive Iodine treatment for Graves' disease.
3. After Thyroid surgery.
4. Certain drugs such as amiodarone, lithium, potassium perchlorate, iodides.
5. Subacute Thyroiditis (during the second phase).
6. Central Hypothyroidism due to a Pituitary disorder. (in these cases, TSH is not high but stays normal).
7. Congenital hypothyroidism.
8. Juvenile hypothyroidism.
Hashimoto's thyroiditis is an autoimmune disease of the thyroid gland and is the most common cause of hypothyroidism (underactive thyroid).
It affects women much more frequently than men.
A family history of thyroid disorder is usually present.
An enlarged thyroid gland, known as a goiter, is also usually present. Sometimes, thyroid nodules are present.
Diagnosis of Hashimoto's thyroiditis can be easily made by a blood test: TG (Thyroglobulin) antibodies and TPO (Thyroid Peroxidase) antibodies.
Treatment of Hypothyroidism
Hypothyroid patients are treated by replacing thyroid hormones.
The dose of thyroid hormones must be individualized and is adjusted according to the thyroid function test results.
Requirement of thyroid hormone generally increases during pregnancy.
Flaws with the Usual Treatment approach to Hypothyroidism
Most physicians use only T4 (Levothyroxine, L.thyroxine, Synthroid, Levoxyl or Levothroid) because that's what they have been told to do.
The rationale given for this sub-optimal treatment is that some of this T4 gets converted into T3 inside the body. However, a large number of patients continue to have symptoms of hypothyroidism despite taking their T4 medicine.
What is the Optimal Treatment of Hypothyroidism?
A normal thyroid gland produces two types of thyroid hormones, Levothyroxine (or T4) and triiodothyronine (or T3). Then some of T4 gets converted into T3.
Therefore, the most scientific and physiological aproach is to give both T4 and T3 to a hypothyroid patient.
T3 is also known as liothyronine.
Drugs to Treat Hypothyroidism
Brand name Generic Name
Nature-throid Levothyroxine (T4) + Liothyronine (T3)
Armour Thyroid Levothyroxine (T4) + Triiodothyronine (T3)
Synthroid Levothyroxine (T4)
Levoxyl Levothyroxine (T4)
Cytomel Liothyronine (T3)
In the past, only a handful of endocrinologists were using combination therapy (T3 + T4) to replace thyroid hormones, but recently more and more endocrinologists are using combination therapy in many of their hypothyroid patients.
An article published in the February 11, 1999 issue of the New England Journal of Medicine clearly indicated that combination therapy with T4 and T3 was superior to T4 therapy alone in controlling the patient's symptoms of hypothyroidism.
In the past, I used to treat my hypothyroid patients with T4 (Levoxyl, Synthroid or Levothroid) alone. However, since the publication of the New England Journal of Medicine article, I started using combination therapy (T3 + T4) to treat most of my hypothyroid patients.
I find the combination therapy to be more effective in controlling the patient's symptoms than using T4 alone.
Absorption of T4 (Levoxyl, Synthroid or Levothroid) is decreased if it is taken at the same time as iron (contained in most multivitamins) or certain antacids or sucralfate. You can take T4 about 2 hours apart from these drugs.
For other drug interactions check with your pharmacist.
The best way is to take your thyroid pills is first thing in the morning on an empty stomach, about 30-45 minutes before breakfast.
This article was written by Sarfraz Zaidi, MD, FACE. Dr. Zaidi specializes in Diabetes, Endocrinology and Metabolism.
Dr. Zaidi is a former assistant Clinical Professor of Medicine at UCLA and Director of the Jamila Diabetes and Endocrine Medical Center in Thousand Oaks, California.
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