Recently I had a new patient, who’d been diagnosed with hypothyroid years ago, decide to do the Lifelabs Ontario ND Thyroid Panel to get a more in-depth look at her thyroid function.
Symptoms of hypothyroid are common and include depression, dry skin, puffiness, cold intolerance, constipation, fatigue, heavy periods, infertility, menopausal symptoms, ovarian cysts, PMS, slow thinking, thinning hair/eyebrows, uterine fibroids & weight gain. Often these symptoms persist despite normal lab values.
The Thyroid Panel that Ontario NDs like myself ordered through Lifelabs from 2015 until now was more comprehensive than conventional testing – MDs typically only order TSH when they investigate thyroid function (see below for explanations of each test). Up until recently, our panel included TSH, but also T4, T3, and anti-TPO. If your anti-TPO is elevated, you have Hashimoto’s thyroiditis (HT) – the most common cause of hypothyroid. It’s an auto-immune disease, where your own immune system has become confused between self tissue vs. foreign invaders, and is attacking your thyroid. TSH and T4 are often normal in Hashimoto’s, until sufficient thyroid gland destruction has occurred. See my blog post about HT here.
My patient’s TSH, T4, T3, and anti-TPO results were all within normal limits, but her lab results also mysteriously included anti-TG (the other anti-thyroid antibody that can be elevated in Hashimoto’s) – and it was off the charts.
Without her anti-TG results, we would not have shifted treatment to balancing her immune system to stop the destruction it was causing. People with Hashimoto’s are at an increased risk of miscarriage, postpartum depression, thyroid cancer, and other autoimmune diseases like MS, rheumatoid arthritis, lupus, Sjogren’s syndrome & scleroderma.
Hypothyroid and Hashimoto’s are both chronically under-diganosed, and autoimmune diseases are on the rise.
When I called Lifelabs to thank them, they apologized for the “data entry error”, but let me know that anti-TG would soon be available for me to order, in addition to the Thyroid Panel.
Anti-TG had not been on my lab requisition form previously, so I couldn’t wait for the new reqs to be sent to Ontario NDs. In part because I couldn’t help wondering if there had been other Hashimoto’s patients that I’d missed in the past, because this auto antibody had not been testable.
Fast forward a couple of months and Ontario NDs have a new, even more comprehensive Thyroid Panel available through Lifelabs. It includes TSH, T4, T3, anti-TPO PLUS anti-TG AND rT3.
This study concluded that rT3 level was a more sensitive parameter than T4 or T3 for evaluating thyroid dysfunction.
T4 can be converted either to T3 or rT3, which binds to thyroid receptors, but blocks them instead of activating them. I tell my patients to think of T3 as the “gas” and rT3 as the “brakes”. Factors that promote the conversion to rT3 slow our metabolism to conserve energy, as in times of stress. In fact, our stress hormone cortisol is a potent driver of rT3 production.
RECAP OF WHAT’S MEASURED IN THE NEW THYROID PANEL:
- TSH (Thyroid Stimulating Hormone): produced by the pituitary, in response to circulating levels of T4. If T4 levels are low, TSH will rise in an attempt to stimulate the thyroid to make more. A high T4 level will cause TSH to decline.
- T4: relatively inactive thyroid hormone that gets converted to T3 or rT3.
- T3: biologically active thyroid hormone that maintains metabolic rate, growth, and development.
- rT3 (reverse T3): binds to thyroid receptors, but blocks them instead of activating them.
- anti-TG: Thyroid cells produce a protein called thyroglobulin (TG) that contains tyrosine, an amino acid used for thyroid hormone synthesis. With the incorporation of dietary iodide, TG is further processed to form thyroid hormones T4 and T3. Anti-TG is an antibody that attaches to TG.
- anti-TPO: The enzyme ThyroidPerOxidase (TPO) converts iodide to the active iodine, which attaches to the amino acid tyrosine in TG to make either T4 or T3. Anti-TPO is an antibody that attaches to the TPO enzyme.
Now no hypothyroid or Hashimoto’s patient will slip by!
If you’ve ever suspected less than optimal thyroid function because of any of the above symptoms or a family history of thyroid or autoimmune disease, and haven’t done testing that included rT3 and anti-TG, book an appointment and we’ll get the new Thyroid Panel done!