- Thyroid hormone therapy is individualized for each patient.
- Some medical conditions and drugs affect the dosage of therapy.
- This is done by the trial-and-error method to reach a particular dosage that works well for a patient.
Hypothyroidism is a condition characterized by a reduction in the amount of thyroid hormones produced by the thyroid gland. In this condition, the thyroid glands are under active and blood shows lower than normal levels of thyroid hormones. The symptoms of this disorder include:
- Weight gain
- Intolerance to cold
- Impaired bowel movements
The metabolism of the body is dependent on the proper functioning of the thyroid gland. In this condition, the metabolism is affected, and hence the core body temperature and the heart suffer. The effects on the heart may include bradycardia or a slow heart beat. Hypothyroidism during pregnancy, if untreated, may lead to Cretinism (stunted growth) in the newborn.
There are two main causes of this disease: lack of iodine in the diet (in some countries) and an autoimmune disorder called Hashimoto’s Thyroiditis. Rare causes of this disease include previous thyroid surgery, typical medicines, radiation therapy, and an injured pituitary or hypothalamus.
In rare cases, the hypothyroidism in patients can take a lethal turn and develop myxedema, a deadly disease in which the skin starts swelling up.
Hormone therapy, also known as hormone replacement therapy, helps to compensate for the decrease of thyroid hormone levels in the body. The aim of this therapy is to carefully reproduce the action of the T4 hormones in the body, thus making up for the deficit.
Two major thyroid hormones used in replacement therapy are T3 and T4, or tri-iodothyronine and tetra-iodothyronine (thyroxine), respectively. These two hormones control the metabolic rate and a less-than-normal amount of these leads to sluggish metabolism. The standard medication used in hormone replacement is synthetic T4. In the body, T4 gets converted into T3, the more active hormone of the two. After the release of the T4 hormone, it is converted to T3 when it comes in contact with cells in the bloodstream, where it loses an iodine atom. There are two reasons for using T4 therapy:
1). It allows the body to convert T4 to T3
2). T4 stays for a longer duration in the body when compared to T3.
Thus, by taking T4 therapy, you are indirectly facilitating the bodily process of T4 production and then conversion to the hormone T3.
Hormone therapy plan
Therapy in otherwise healthy patients starts with a dosage that is needed to compensate for low hormone levels in the body. The dosage may be increased slowly, if there is an increase in the level of thyroid stimulating hormone (TSH). In older people and those who have a risk of cardiovascular complication, a lower dosage is used initially. This dosage is gradually increased every 4-6 weeks until the TSH levels are back to normal. The hormone is usually given once daily, and followup includes the monitoring of thyroid functioning by assessing the levels of TSH and T4.
Once a stable dosage is reached, it will be continued for a long term. Upon reaching 60 to 70 years of age, the thyroid binding ability decreases, and this calls for a reduction in the dosage by up to 20 percent. Regular monitoring of the TSH and T4 levels is important to avoid over dosage.
Though there are some generic plans in use, most of the patients need a modified action plan to alleviate their symptoms. It is not uncommon to see some patients are still suffering from an underactive thyroid, despite their blood work being good. This is because the administered T4 can sometimes fail to change into T3, which results in a harmful reaction.
Some medications like NDT (Natural Desiccated Thyroid therapy) have been successful in most patients. Thus, it is crucial to identify the apt medication and the proper dosage for desired results.
Issues with hormone therapy
Thyroid hormones are bound to proteins, and hence conditions and drugs that affect the amount of binding proteins affect the dosage of hormone. This includes pregnancy, estrogen replacement therapy, and contraceptives, all of which require an increased dosage of thyroid replacement. Use of androgens often decreases the amount of hormone-binding proteins, and hence a reduced dosage of thyroid hormone is suggested. Conditions like nephrosis and cirrhosis require smaller dosages of thyroid hormone, as well.
Many drugs affect the absorption of thyroid hormones from the intestine and need an increased replacement dosage. Certain other drugs increase the metabolism of thyroid hormone and hence need an increased dosage for maintenance of hormone levels. Medications prescribed for depression, cholesterol, and other supplements, such as calcium, soy, or iron, can meddle with the normal functioning of the hormone therapy.
Some patients may not be relieved from symptoms with T4 therapy alone. They may continue to have symptoms of hypothyroidism in spite of the treatment. Occasionally, T4 fails to convert to T3 in some patients, and this causes toxicity in the body. In such cases, the natural desiccated thyroid hormone (NDT) is recommended. This contains a full array of thyroid hormones. In some cases, combination therapy of T3 and T4 is also recommended to improve symptoms of hypothyroidism. In this therapy, some amount of usual T4 dose is replaced with T3. Combination therapy was found to improve symptoms of hypothyroidism in many patients.
Thyroid hormone therapy is individualized for each patient. The amount of hormone needed, the ability of the body to absorb hormones, and various other factors differ from patient to patient. Thus, the treatment plan is individualistically developed for better effect. This is done by a trial-and-error method to reach a particular dosage that works well for a patient. However, a patient should not change medications indefinitely or after a short span of time. Sometimes medications take time and you should keep your patience while waiting for results.
With ongoing therapy, there will be improvement, but that is not an indication of stopping further tests, which could be rather detrimental. Periodical checkups and blood routines should not be avoided, as therapy takes time, and there might be a sudden surge in the levels of the hormones at any given moment. Keeping a healthy relationship with your doctor and telling him every symptom or sign you have come across would be wise.