Hypothyroidism: A Closer Look

This hormone nuclear receptor complex activates gene transcription and synthesis of messenger RNA and cytoplasmic proteins. The physiological actions of thyroid hormones are produced predominantly by T3, the majority of which (approximately 80%) is derived from T4 by deiodination in peripheral tissues. Reduce the SYNTHROID dosage or discontinue temporarily if signs or symptoms of overdosage occur.

Levothroid is used for hashimoto’s disease, hypothyroidism, after thyroid removal, myxedema coma …
Protein-bound thyroid hormones exist in reverse equilibrium with small amounts of free hormone.
Thyroid hormone levels in the body provide signals to the hypothalamus and pituitary, so they know whether to release more or less TRH and TSH.
Certain other medicines may also increase or decrease the effects of Synthroid.

Drug Interactions for Synthroid

Published studies report that levothyroxine is present in human milk following the administration of oral levothyroxine. No adverse effects on the breastfed infant have been reported and there is no information on the effects of levothyroxine on milk production. Adequate levothyroxine treatment during lactation may normalize milk production in hypothyroid lactating mothers with low milk supply. Carefully monitor glycemic control after starting, changing, or discontinuing SYNTHROID see DRUG INTERACTIONS. Concurrent use of sympathomimetics and SYNTHROID may increase the effects of sympathomimetics or thyroid hormone.

AMERICA’S #1 PRESCRIBED BRANDED HYPOTHYROIDISM MEDICATION1,2*

Foods containing soy and cottonseed meal can make Synthroid less effective. Walnuts, grapefruit juice, and dietary fiber can also make Synthroid less effective. If you eat any of these on a regular basis, check with your doctor.

Consider changes in TBG concentration when interpreting T4 and T3 values.
Concurrent use of tyrosine-kinase inhibitors such as imatinib may cause hypothyroidism.
The peak therapeutic effect of a given dose of SYNTHROID may not be attained for 4 to 6 weeks.
Do not share this medicine with another person, even if they have the same symptoms you have.
The majority of the SYNTHROID dose is absorbed from the jejunum and upper ileum.

All pregnancies have a background risk of birth defect, loss, or other adverse outcomes. In the U.S. general population, the estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2% to 4% and 15% to 20%, respectively. Patients The SYNTHROID dosage is based on the target level of TSH suppression for the stage and clinical status of thyroid cancer. This includes prescription and over-the-counter medicines, vitamins, and herbal products. Tell your doctor about all your current medicines and any medicine you start or stop using.

Click the links below to see resources for your patients:

SYNTHROID may reduce synthroid+clinical+studies the therapeutic effects of digitalis glycosides. Serum digitalis glycoside levels may decrease when a hypothyroid patient becomes euthyroid, necessitating an increase in the dose of digitalis glycosides. Do not store the crushed tablet/water mixture and do not administer it mixed with foods that decrease absorption of levothyroxine, such as soybean-based infant formula.

Dosage Forms And Strengths

Use of oral thyroid hormone drug products is not recommended to treat myxedema coma. Administer thyroid hormone products formulated for intravenous administration to treat myxedema coma. Because of the increased prevalence of cardiovascular disease among the elderly, initiate SYNTHROID at less than the full replacement dose see Dosage and Administration (2.3) and Warnings and Precautions (5.2). Atrial fibrillation is the most common of the arrhythmias observed with levothyroxine overtreatment in the elderly. Over-treatment with levothyroxine may cause an increase in heart rate, cardiac wall thickness, and cardiac contractility and may precipitate angina or arrhythmias, particularly in patients with cardiovascular disease and in elderly patients. Initiate SYNTHROID therapy in this population at lower doses than those recommended in younger individuals or in patients without cardiac disease see Dosage and Administration (2.3) and Use in Specific Populations (8.5).

Use our dose calculator for adults

Initiate appropriate supportive treatment as dictated by the patient’s medical status. Consider changes in TBG concentration when interpreting T4 and T3 values. Measure and evaluate unbound (free) hormone and/or determine the free-T4 index (FT4I) in this circumstance. Pregnancy, infectious hepatitis, estrogens, estrogen-containing oral contraceptives, and acute intermittent porphyria increase TBG concentration. Nephrosis, severe hypoproteinemia, severe liver disease, acromegaly, androgens, and corticosteroids decrease TBG concentration.

SYNTHROID® (levothyroxine sodium) tablets, for oral use is a prescription, man-made thyroid hormone that is used to treat a condition called hypothyroidism in adults and children, including infants. It is meant to replace a hormone that is usually made by your thyroid gland. Generally, thyroid replacement treatment is to be taken for life. SYNTHROID should not be used to treat noncancerous growths or enlargement of the thyroid in patients with normal iodine levels, or in cases of temporary hypothyroidism caused by inflammation of the thyroid gland (thyroiditis). Thyroid hormones, including SYNTHROID, either alone or with other therapeutic agents, should not be used for the treatment of obesity or for weight loss.

Since thyroid hormone occurs naturally in the body, almost anyone can take levothyroxine. However, you may not be able to take this medicine if you have certain medical conditions. The “optimal dose” was determined for each patient as that dosage of thyroxine being taken when the thyrotropin-releasing hormone (TRH) response was normal (ie, an increase in TSH of between 4.7 and 25 mIU/L). Because the thyroid can’t respond properly, the hypothalamus sends out more TRH and the pituitary keeps releasing more TSH. A high level of TSH plus low thyroid hormone levels indicates hypothyroidism.

Our Synthroid Side Effects Drug Center provides a comprehensive view of available drug information on the potential side effects when taking this medication. Armour Thyroid is used for hashimoto’s disease, hypothyroidism, after thyroid removal, thyroid … This is not a complete list of side effects and others may occur. It may take several weeks before your body starts to respond to Synthroid. Follow all directions on your prescription label and read all medication guides or instruction sheets. You may not be able to take Synthroid if you have certain medical conditions.