Are you struggling to lose weight even though you are exercising, eating healthy and have cut back on your portion sizes? Do you feel sluggish most of the time? Do you find you are always cold even when others around you are not? If you answered yes to one or more of these questions, you may want to consider getting a complete thyroid assessment.
Thyroid disorders are becoming increasingly prevalent, especially among women. In 2014, as per an article on Medscape, levothyroxine (Synthroid) was the most prescribed drug in the USA and the third most prescribed drug in the UK (Davenport, 2016). While being diagnosed with a thyroid disorder requires your thyroid hormones to be above or below the normal reference range, it is very common for people to have suboptimal thyroid function meaning their levels are outside of the optimal range for health and wellness but still “normal”. These individuals may still experience symptoms.
(2) FROM THE NATIONAL CANCER INSTITUTE FROM THE NATIONAL INSTITUTE OF HEALTH.
This is the most common thyroid imbalance when your thyroid hormones are low resulting in decreased metabolic activity which may contribute to weight gain. Hypothyroidism can be PRIMARY (originating at the thyroid gland); SECONDARY (originating in the pituitary); or, TERTIARY (originating in the hypothalamus).
The most common medication prescribed is Synthroid (levothyroxine) – this is only T4. The problem with this is that your body still has to convert it into T3 and if your conversion mechanism is impaired, many will still not feel at their best resulting in your MD constantly increasing your dose until you start making sufficient T3 to feel good. Cytomel (liothyronine) is T3 which is another medication that may be prescribed. Desiccated thyroid (Armour) comes from a porcine source and contains both T3 and T4 however, many MDs are reluctant to prescribe this form.
This is not as common but this is where you have excess thyroid hormone production. Similar to hypothyroidism, you also can have PRIMARY, SECONDARY, OR TERTIARY hyperthyroidism except for this time that particular tissue is producing an excess of its respective hormone (see above for which organ is affected at each level). The most common cause of primary hyperthyroidism is Grave's Disease, an autoimmune disorder.
The medication most often prescribed is tapazole (methimazole). Sometimes propylthiouracil (PTU) is prescribed but PTU has a higher risk of elevating liver enzymes compared to methimazole and MDs will prefer to prescribe methimazole (2). If your thyroid hormones are very high and you are very symptomatic, your doctor may even recommend radioactive iodine which shuts down the thyroid, essentially “zapping” it. Surgery to remove the thyroid gland is often another option. Once either of these invasive procedures is done, one could become hypothyroid and then be prescribed Synthroid “for the rest of their life”.
While MDs will test TSH to assess thyroid function, a complete thyroid assessment really requires looking at TSH, free T3, and, free T4 so you can assess each level of the thyroid.
With the thyroid (as with most other hormones), there are three levels to look at. The hypothalamus in the brain produces Thyrotropin Releasing Hormone (TRH) which communicates to the pituitary gland in the brain to produce Thyrotropin Stimulating Hormone (TSH). TSH is the communicator telling the thyroid gland to produce T4 and T3 thyroid hormones. T4 and T3, specifically T3 is your active thyroid hormone. Problems at any of these levels - hypothalamus, pituitary, and thyroid gland - can impact thyroid hormone production and is why you should ask your medical doctor to test TSH, free T3, free T4 if you are concerned about your thyroid and not just TSH. Often TSH can come back within normal (0.2-6.00) while your T4 and T3 are very close to the low end of range indicating sluggish thyroid function.
If you want to go a step further, especially if you have a family history of thyroid disorders, I recommend testing thyroid antibodies.
The 5 (or 6) thyroid tests I requisition when I want to assess the thyroid are:
- Free T4
- Free T3 (active thyroid hormone that regulates metabolism)
- TSH (The reference range is quite large but I review optimal ranges which should be somewhere between 1-2.5 mIU/L)
- Anti TPO (thyroid peroxidase) antibodies to rule out autoimmune thyroid conditions
- Anti TG (thyroglobulin) antibodies to rule out autoimmune thyroid conditions
- **TSH receptor antibodies (only if thyroid hormones are elevated for ruling out Graves Disease)
Davenport, L. “Time for a U-turn on Levothyroxine? Overuse Is Rife, Say Docs” in Medscape Family Medicine. WebMD LLC:Nov 14 2016. Retrieved on Nov 13 2018 from https://www.medscape.com/viewarticle/871838?nlid=110752_1982&src=WNL_mdplsnews_161118_mscpedit_fmed&uac=159432FR&spon=34&impID=1237366&faf=1?src=soc_tw_
Thyroid gland image from: Don Bliss. (2001). Thyroid Gland from National Cancer Institute. Retrieved on November 23 2018 from https://visualsonline.cancer.gov/details.cfm?imageid=436
Nakamura H et al. Comparison of methimazole and propylthiouracil in patients with hyperthyroidism caused by Graves’ disease. J Clin Endocrinol Metab 2007 Jun; 92:2157-62.