Managing Hypothyroidism Requires Precision
Doctors treat hypothyroidism with thyroid hormone replacement medications. These hypothyroidism treatments have an active ingredient called levothyroxine sodium. One of those medications, Synthroid, replaces the amount of thyroxine your thyroid doesn't make anymore, helping to restore your thyroid hormone balance.
Generally, thyroid replacement therapy is to be taken for life. Synthroid should not be used to treat male or female infertility unless it is associated with hypothyroidism. It should not be used by people who have hyperthyroidism.
Finding the right dose
To achieve thyroid hormone balance, the American Association of Clinical Endocrinologists and the American Thyroid Association recommend patients with hypothyroidism keep their thyroid-stimulating hormone (TSH) level between 0.45 and 4.12 mIU/L. Some doctors may recommend a different range for their patients. Every patient is unique and may require a different amount of Synthroid to stay in the range that is right for them. This is because some people still have some thyroid function and only need a low dose of medicine to replace the amount of thyroid hormone that is missing, while others don't have much thyroid function and need a higher dose of medicine.
Other factors that can influence your body's thyroxine needs and medication dose include age, whether or not you have heart disease, medications, body weight, and special circumstances like pregnancy or menopause.
When you start treatment, it's very important for your doctor to monitor you closely – usually testing your TSH level every 6-8 weeks – to make sure you're on the right dose. Why? Because hypothyroidism medications are narrow therapeutic index drugs. So if your dosage is off even a little bit, it can throw off your TSH level and may cause side effects. You might hear this referred to as under-replacement or under-treatment (when your dose of levothyroxine is too low), and over-replacement or over-treatment (when your dose of levothyroxine is too high). Our Symptom Profiler tool can help you recognize symptoms of under-replacement and over-replacement.
It can take some time for your symptoms to improve once you start treatment, but you may notice a difference within a few weeks. Once you're on the dose of medicine that keeps your thyroid hormone in balance, your doctor may change the frequency of your TSH tests to every 6 months or yearly.
Notify your physician if you experience any of the following symptoms: rapid or irregular heartbeat, chest pain, shortness of breath, leg cramps, headache, nervousness, irritability, sleeplessness, tremors, change in appetite, weight gain or loss, vomiting, diarrhea, excessive sweating, heat intolerance, fever, changes in menstrual period, hives or skin rash, or any other unusual medical event.
Taking your medication
To help keep your thyroid hormone in balance, you need to take your medication consistently. What does this mean?
- Take your medication as prescribed every day. It's important to take your medicine exactly as your doctor prescribed, and create a routine that helps you take it the same way each day. This is because when you take your medicine, how you take it, and other factors can affect how your body absorbs the medicine and how effective it is for you. Get tips for taking your medicine the right way, every day.
- Your doctor may prefer that you stay on Synthroid as he or she prescribed. If your doctor prefers Synthroid, check to make sure your pill says "SYNTHROID." The Food and Drug Administration has determined that certain levothyroxine products are interchangeable.
Test Your Knowledge
Missing a dose of medication isn’t a big deal.
1. American Thyroid Association. Hypothyroidism. A booklet for patients and their families. http://www.thyroid.org/wp-content/uploads/patients/brochures/Hypothyroidism_web_booklet.pdf. Published 2013. Accessed January 23, 2014.
2. Garber JR, Cobin RH, Gharib H, et al. Clinical practice guidelines for hypothyroidism in adults: cosponsored by the American Association of Clinical Endocrinologists and the American Thyroid Association. Endocr Pract. 2012;18(6):988-1028.
3. Food and Drug Administration. Approved Drug Products with Therapeutic Equivalence Evaluations (Orange Book); 30th ed. 2010. Available at: http://www.fda.org Accessed March 1, 2013.