Synthroid Side Effects: Common, Severe, Long Term

SYNTHROID is indicated in adult and pediatric patients, including neonates, as a replacement therapy in primary (thyroidal), secondary (pituitary), and tertiary (hypothalamic) congenital or acquired hypothyroidism. One form of hypothyroidism is Hashimoto’s disease, where the body forms antibodies to its own thyroid gland cells, resulting in inflammation and possibly permanent low thyroid function. Another condition is hyperthyroidism, which is an overactive thyroid. An upset tummy and diarrhea are two potentially embarrassing but relatively common side effects of Synthroid. This should normalize out as your thyroid levels stabilize, but if you find yourself too nauseous to take your pill or are suffering from chronic diarrhea call your doctor right away, she says. Synthroid is the brand name for levothyroxine sodium, a synthetic thyroid hormone pill.

Primary hypothyroidism is a common disorder and is present in 0.3% of the U.S. population (20). The association of overt – and subclinical hypothyroidism with all-cause mortality independent of coronary artery disease risk factors has been shown (21). The traditional theory held that inadequate thyroid hormone level contributes to atherosclerosis (22). There are contradictory results on the effect of hypothyroidism on the changes in hemostasis. Inadequate population-based studies limited their clinical implications, mainly on the risk of venous thromboembolism (VTE).

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. Your thyroid gland is one of the centers of your endocrine system, influencing how other important hormones are used. That’s why an underactive thyroid can affect so many functions throughout your body — and lead to such a wide range of weird and unpleasant symptoms. Thyroid hormones, including levothyroxine, should not be used either alone or with other therapeutic agents for the treatment of obesity or weight loss. Reduce the SYNTHROID dosage or discontinue temporarily if signs or symptoms of overdosage occur.

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Both increased antiphospholipid antibodies and enhanced thrombin activity may contribute to hypercoagulable state in Grave’s disease (95). Unlike coronary heart disease, there have been few epidemiologic studies on assessment of association between hypothyroidism/AIT and an increase in risk of cerebrovascular disease. These reports, mostly small studies, showed conflicting results and had methodological limitations (7, 88). Autoimmune pathology in AIT might itself affect cerebrovascular risk, as it has been previously shown for other autoimmune disorders (23).

3. Hypercoagulability or no Alteration in Hemostasis

However, estrogen use appeared to negate the adverse effects of thyroid hormone on bone mineral density. 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. It has been hypothesized that patients with hypothyroidism and autoimmune thyroiditis are at increased risk of cardiovascular events and a recent meta-analysis revealed an increased risk of approximately 20% for coronary heart disease (93). The earliest reports on a link between thyroid disorders and coagulation abnormalities are from the early years of the past century (6-8). Since then, several studies have been conducted on thyroid function abnormalities and their effect on the hemostasis with contradictory results (9-19).

Understanding your symptoms and signs and synthroid bruising educating yourself about health conditions are also a part of living your healthiest life. The links above will provide you with more detailed information on these medical conditions to help you inform yourself about the causes and available treatments for these conditions. 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. If cardiac symptoms develop or worsen, reduce the SYNTHROID dose or withhold for one week and restart at a lower dose. Inquire whether patients are taking biotin or biotin-containing supplements.

If so, advise them to stop biotin supplementation at least 2 days before assessing TSH and/or T4 levels see DOSAGE AND ADMINISTRATION and DRUG INTERACTIONS. Administer SYNTHROID at least 4 hours before or after drugs known to interfere with SYNTHROID absorption see DRUG INTERACTIONS. Notify your doctor if you experience serious side effects of Synthroid including rapid heartbeat, fluttering in your chest, or chest pain. The thyroid has a big effect on your weight and appetite, making you gain or lose weight rapidly.

• Administer thyroid hormone products formulated for intravenous administration to treat myxedema coma.
• In order to prevent missing any scientific points from the omitted papers, review articles containing those scientific points were used in the manuscript’s reference list.
• Triiodothyronine (T3) and L-thyroxine (T4) diffuse into the cell nucleus and bind to thyroid receptor proteins attached to DNA.
• Although a relatively uncommon complication of hypothyroidism it should be considered at diagnosis and coagulation status measured if clinically indicated.

Start at a lower starting dosage and increase the dosage every 4 to 6 weeks as needed based on clinical and laboratory response. 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. Many drugs can inhibit Synthroid’s adsorption by the body; other medications may increase or decrease its effectiveness once it is adsorbed.

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. In adult patients with primary hypothyroidism, monitor serum TSH levels after an interval of 6 to 8 weeks after any change in dosage. In patients on a stable and appropriate replacement dosage, evaluate clinical and biochemical response every 6 to 12 months and whenever there is a change in the patient’s clinical status. Assess the adequacy of therapy by periodic assessment of laboratory tests and clinical evaluation. 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.

Acute Adrenal Crisis In Patients With Concomitant Adrenal Insufficiency

A proposed mechanism is direct effect of thyroid hormones as there are several studies in favor of a prothrombotic effect of thyroid hormones in the literature (19, 38, 44, 69). However, it has been unclear as to whether a deficiency in thyroid hormone levels or an elevated TSH (or both) contributes to alterations in coagulation parameters. An experimental study on rats did not show any significant effect of TSH on factors (F) II, FVII, FIX, FX, while T3 caused significantly reduced activities of the factors and T4 had the same effect on only FII (73).