Levothyroxine: Công dụng, liều dùng và lưu ý tác dụng phụ

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Levothyroxine: Công dụng, liều dùng và lưu ý tác dụng phụ

Initiation of thyroid hormone therapy prior to initiating glucocorticoid therapy may precipitate an acute adrenal crisis in patients with adrenal insufficiency. Treat patients with adrenal insufficiency with replacement glucocorticoids prior to initiating treatment with SYNTHROID see CONTRAINDICATIONS. Addition of SYNTHROID therapy in patients with diabetes mellitus may worsen glycemic control and result in increased antidiabetic agent or insulin requirements. Carefully monitor glycemic control, especially when thyroid therapy is started, changed, or discontinued see WARNINGS AND PRECAUTIONS.

Drug Summary

Hypersensitivity reactions to inactive ingredients have occurred in patients treated with thyroid hormone products. These include urticaria, pruritus, skin rash, flushing, angioedema, various gastrointestinal symptoms (abdominal pain, nausea, vomiting and diarrhea), fever, arthralgia, serum sickness, and wheezing. Hypersensitivity to levothyroxine itself is not known to occur. Pseudotumor cerebri and slipped capital femoral epiphysis have been reported in pediatric patients receiving levothyroxine therapy. For pregnant patients with pre-existing hypothyroidism, measure serum TSH and free-T4 as soon as pregnancy is confirmed and, at minimum, during each trimester of pregnancy. In pregnant patients with primary hypothyroidism, maintain serum TSH in the trimester-specific reference range.

Drug-Food Interactions

Titrate the dose of SYNTHROID carefully and monitor response to titration to avoid these effects see DOSAGE AND ADMINISTRATION. Consider the potential for food or drug interactions and adjust the administration or dosage of SYNTHROID as needed see DOSAGE AND ADMINISTRATION, DRUG INTERACTIONS and CLINICAL PHARMACOLOGY. For secondary or tertiary hypothyroidism, serum TSH is not a reliable measure of SYNTHROID dosage adequacy and should not be used to monitor therapy. Use the serum free-T4 level to titrate SYNTHROID dosing until the patient is clinically euthyroid and the serum free-T4 level is restored to the upper half of the normal range see Recommended Dosage And Titration. Circulating thyroid hormones are greater than 99% bound to plasma proteins, including thyroxine-binding globulin (TBG), thyroxine-binding prealbumin (TBPA), and albumin (TBA), whose capacities and affinities vary for each hormone.

  • For patients at risk of atrial fibrillation or patients with underlying cardiac disease, start with a lower dosage and titrate the dosage more slowly to avoid exacerbation of cardiac symptoms.
  • However, you may not be able to take this medicine if you have certain medical conditions.
  • Many other medicines can be affected by your thyroid hormone levels.
  • Protein-bound thyroid hormones exist in reverse equilibrium with small amounts of free hormone.
  • Stop biotin and biotin-containing supplements for at least 2 days prior to thyroid testing.

Related treatment guides

Soybean flour, cottonseed meal, walnuts, and dietary fiber may bind and decrease the absorption of SYNTHROID from the gastrointestinal tract. Grapefruit juice may delay the absorption of levothyroxine and reduce its bioavailability. Biotin supplementation may interfere with immunoassays for TSH, T4, and T3, resulting in erroneous thyroid hormone test results. Stop biotin and biotin-containing supplements for at least 2 days before assessing TSH and/or T4 levels see DRUG INTERACTIONS. Patients The SYNTHROID dosage is based on the target level of TSH suppression for the stage and clinical status of thyroid cancer.

Synthroid is also used in patients who need surgery and radioiodine therapy to manage a type of thyroid cancer called well-differentiated thyroid cancer. Synthroid is a prescription medicine used to treat hypothyroidism (low thyroid hormone). Levothyroxine is given when your thyroid does not produce enough of this hormone on its own. Closely monitor infants during synthroid usa the first 2 weeks of SYNTHROID therapy for cardiac overload and arrhythmias.

Closely monitor coagulation tests to permit appropriate and timely dosage adjustments. Ensure the patient ingests the full amount of the suspension. Do not administer in foods that decrease absorption of SYNTHROID, such as soybean-based infant formula see DRUG INTERACTIONS. Many other medicines can be affected by your thyroid hormone levels.

Unithroid is used for hashimoto’s disease, hypothyroidism, after thyroid removal, myxedema coma … Levoxyl treats hypothyroidism (low thyroid hormone) and treats or prevents goiter. NP Thyroid is used for hashimoto’s disease, hypothyroidism, after thyroid removal, thyroid cancer … Tirosint is used for hashimoto’s disease, hypothyroidism, after thyroid removal, myxedema coma … You are encouraged to report negative side effects of prescription drugs to the FDA.

  • For adult patients with primary hypothyroidism, titrate until the patient is clinically euthyroid and the serum TSH returns to normal see Recommended Dosage And Titration.
  • Synthroid should not be used to treat obesity or weight problems.
  • In pregnant patients with primary hypothyroidism, maintain serum TSH in the trimester-specific reference range.
  • Triiodothyronine (T3) and L-thyroxine (T4) diffuse into the cell nucleus and bind to thyroid receptor proteins attached to DNA.

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. You may not be able to take Synthroid if you have certain medical conditions. Tell your doctor if you have an untreated or uncontrolled adrenal gland disorder, a thyroid disorder called thyrotoxicosis, or if you have any recent or current symptoms of a heart attack. Although millions of people have hypothyroidism, there are many misconceptions around managing it.

Persistent clinical and laboratory evidence of hypothyroidism despite an apparent adequate replacement dose of SYNTHROID may be evidence of inadequate absorption, poor compliance, drug interactions, or a combination of these factors. The recommended starting daily dosage of SYNTHROID in pediatric patients with primary, secondary, or tertiary hypothyroidism is based on body weight and changes with age as described in Table 2. Titrate the dosage (every 2 weeks) as needed based on serum TSH or free- T4 until the patient is euthyroid see Important Considerations For Dosing. The general aim of therapy is to normalize the serum TSH level. TSH may not normalize in some patients due to in utero hypothyroidism causing a resetting of pituitary-thyroid feedback. Assess compliance, dose of medication administered, and method of administration prior to increasing the dose of SYNTHROID see WARNINGS AND PRECAUTIONS and Use In Specific Populations.

Thyroid hormones do not readily cross the placental barrier see Use In Specific Populations. Rapid restoration of normal serum T4 concentrations is essential for preventing the adverse effects of congenital hypothyroidism on cognitive development as well as on overall physical growth and maturation. Therefore, initiate SYNTHROID therapy immediately upon diagnosis.