Synthroid Levothyroxine Sodium: Side Effects, Uses, Dosage, Interactions, Warnings

Administer thyroid hormone products formulated for intravenous administration to treat myxedema coma. The general new synthroid 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.

Past Medical History:

Dosage titration is based on serum TSH or free-T4 see Important Considerations For Dosing. SYNTHROID is indicated in adult and pediatric patients, including neonates, as an adjunct to surgery and radioiodine therapy in the management of thyrotropin-dependent well-differentiated thyroid cancer. 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.

Important Considerations For Dosing

• Walnuts, grapefruit juice, and dietary fiber can also make Synthroid less effective.
• Therefore, a decrease in the dose of anticoagulant may be warranted with correction of the hypothyroid state or when the SYNTHROID dose is increased.
• Hypersensitivity to levothyroxine itself is not known to occur.

Familial hyper- or hypo-thyroxine binding globulinemias have been described, with the incidence of TBG deficiency approximating 1 in 9000. Concurrent use of tyrosine-kinase inhibitors such as imatinib may cause hypothyroidism. The recommended daily dosage of SYNTHROID in pregnant patients is described in Table 3. Many drugs can inhibit Synthroid’s adsorption by the body; other medications may increase or decrease its effectiveness once it is adsorbed.

Triiodothyronine (T3) and L-thyroxine (T4) diffuse into the cell nucleus and bind to thyroid receptor proteins attached to DNA. 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. Monitor for cardiac arrhythmias during surgical procedures in patients with coronary artery disease receiving suppressive SYNTHROID therapy.

Current Medications:

• Assess the adequacy of therapy by periodic assessment of laboratory tests and clinical evaluation.
• Carefully monitor glycemic control, especially when thyroid therapy is started, changed, or discontinued see WARNINGS AND PRECAUTIONS.
• 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.
• Grapefruit juice may delay the absorption of levothyroxine and reduce its bioavailability.
• Patients The SYNTHROID dosage is based on the target level of TSH suppression for the stage and clinical status of thyroid cancer.

RxList does not provide medical advice, diagnosis or treatment. A portion of the conjugated hormone reaches the colon unchanged and is eliminated in the feces. SYNTHROID is contraindicated in patients with uncorrected adrenal insufficiency see WARNINGS AND PRECAUTIONS. Long-term carcinogenicity studies in animals to evaluate the carcinogenic potential of levothyroxine have not been performed. Studies to evaluate mutagenic potential and animal fertility have not been performed.

Euthyrox (levothyroxine) is used to treat hypothyroidism and to treat or prevent goiter. Tirosint is used for hashimoto’s disease, hypothyroidism, after thyroid removal, myxedema coma … Synthroid should not be used to treat obesity or weight problems. Dangerous side effects or death can occur from the misuse of levothyroxine, especially if you are taking any other weight-loss medications or appetite suppressants. Synthroid is a thyroid medicine that replaces a hormone normally produced by your thyroid gland to regulate the body’s energy and metabolism.

PRIMARY HYPOTHYROIDISM DOSING GUIDELINES

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. Biochemical assessment incorporated measurement of serum TSH, T3, and T4. TSH lower limit of quantification was 0.2 mIU/L and upper limit of normal was 5.6 mIU/L, as indicated by the shaded area. SYNTHROID is not indicated for treatment of hypothyroidism during the recovery phase of subacute thyroiditis.

Providing a complete list of medications to the doctor will help with getting the correct dose established for each individual patient. Reduce the SYNTHROID dosage or discontinue temporarily if signs or symptoms of overdosage occur. Initiate appropriate supportive treatment as dictated by the patient’s medical status. 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.

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 and Use In Specific Populations. 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. 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.

Start at a lower starting dosage and increase the dosage every 4 to 6 weeks as needed based on clinical and laboratory response. TSH should be monitored and SYNTHROID dosage adjusted during pregnancy. Following a 25-mcg dose change of levothyroxine, most patients had changes in TSH levels. This includes prescription and over-the-counter medicines, vitamins, and herbal products.