The thyroid is a butterfly-shaped gland located at the base of the neck. It is primarily responsible for homeostasis of iodine in the body, as well as production and secretion of thyroid hormones. Hormones produced by the thyroid act on every system in the body, influencing energy production, metabolism, basal metabolic rate (BMR) and body temperature, as well as affecting heart rate, respiratory rate, cardiac output, gastrointestinal motility and absorption, bone remodelling, reproductive health, wakefulness and neurological development.[1,2]
As thyroid disease and dysfunction become more prevalent so does complete or partial removal of the gland, known as thyroidectomy.
Cancer remains the most common reason for thyroidectomy and rates continue to rise. In the last few decades, occurrence has gone from 2.7 in 100,000 people in 1982 to 12 in 100,000 in 2017. Other causes include large goitres, that obstruct breathing or swallowing, and thyrotoxicosis usually associated with Graves’ disease.
Types of thyroid removal
- Isthmusectomy: removal of the thyroid isthmus, the tissue connecting the two lobes of the thyroid.
- Lobectomy, aka hemithyroidectomy: removal of half of the thyroid (ie. one lobe).
- Total thyroidectomy: complete removal of the whole thyroid gland.
Keep in mind that removal of the thyroid will immediately place the patient in a hypothyroid state and medication will be required to replace hormones generated by the gland.
Risks associated with thyroidectomy[4,5]
- Bleeding with haematoma. Occurs in less than 1% of patients but can be potentially lethal, as the haematoma can cause compression of the trachea and induce respiratory distress.
- Nerve Injury. Even when performed by experienced surgeon, injury to the recurrent laryngeal nerve can occur in 1%-2% of thyroidectomies. Injury can be permanent or temporary and can cause vocal impairment such as hoarseness, as well as aspiration of liquids and shortness of breath.
- Hypoparathyroidism. Damage to, or removal of, the parathyroid glands can occur during surgery, resulting in hypoparathyroidism which can lead to hypocalcaemia and hyperphospataemia. The majority of patients recover fully from the damage within two months, with less than 2% experiencing permanent damage.
Medical Intervention: Levothyroxine (L-T4)
After a total thyroidectomy (and sometimes after a hemithyroidectomy, depending on how much of the gland is removed) a patient will require replacement of thyroxine (T4) with the synthetic hormone called levothyroxine (L-T4).
Levothyroxine is identical both physiologically and biochemically to endogenously produced T4 and has a bioavailability of 60%-80%. As food and other drugs interfere with absorption, it is recommended to take L-T4 on an empty stomach, at least 30 minutes prior to food intake or a minimum of two hours after a meal. It is absorbed throughout the the small intestine and enters enterohepatic circulation where it is distributed to tissues via binding to thyroxine binding globulin (TBG), thyroxine binding prealbumin (TBPA) or to albumin.
Metabolism of L-T4 occurs primarily in the liver and kidney, where it is converted to tri-iodothyronine (T3). Up to 40% of the dose can also be converted to reverse tri-iodothyronine (rT3), the inactive isomer of T3. Dosages are calculated on an individual basis, typically beginning at 1.6mg/kg of weight and adjusted until normal levels of serum TSH are achieved.
Naturopathic Support Options
Selenium has long been associated with thyroid health, as it is needed to counteract the high amounts of free radicals generated from the production of thyroid hormones, as well as being required for the conversion of T4 to T3. Even after the removal of the thyroid gland and replacement of T4 with levothyroxine, selenium is still required as a cofactor for the enzymatic conversion to T3.
Selenium deficiency has also been implicated in the pathogenesis of autoimmune thyroid conditions. Supplementation of 200mcg selenium selenite or selenomethoinine daily for three months in conjunction with levothyroxine has been shown to decrease the presence of antithyroperoxidase antibodies (TPOAb) in several studies.[9,10]
Vitamin C is known for its role in immune function, wound healing and as an antioxidant, but its activity purely as an acid should not be discounted.
Proper dissolution of the levothyroxine tablet is essential for proper absorption and bioavailability and patients with compromised gastric acid production require higher dosages of L-T4. Vitamin C (as ascorbic acid) at 500mg-1000mg has been shown to improve absorption of L-T4 when taken at the same time in patients both with and without compromised gastrointestinal function. Supplementation therefore may assist in reducing levels of TSH and/or enable a decreased dose of L-T4.[12,13]
Calcium and vitamin D
As mentioned previously, hypocalcaemia due to damage of the parathyroid glands during thyroidectomy is one of the most common risks associated with the procedure. It is recommended that all patients receive calcium supplementation of 3g/day for two weeks after thyroid surgery.
A meta-analysis demonstrated that patients given vitamin D alongside calcium post thyroidectomy experienced even lower risk of hypocalcaemia, due to its role in calcium homeostasis.[14,15]
Long-term calcium and vitamin D supplementation may also be warranted for some patients, as L-T4 has been shown to reduce bone mineral density, especially in post-menopausal women. If required, ensure calcium supplements, as well as antacids containing calcium carbonate and calcium containing foods such as milk, are taken away from L-T4 so as not to interfere with absorption.
Vitamin A and its metabolites such as betacarotene and retinoids have been shown to have various effects on the thyroid and thyroid hormones.[17-19] Iodine metabolism is inhibited by retinoids and simultaneous deficiency of both vitamin A and iodine has been shown to exacerbate thyroid dysfunction. Vitamin A also regulates thyroid hormone metabolism and down regulates the expression of TSH-beta, a gene that inhibits the secretion of TSH. Furthermore, thyroid hormones assist in the conversion of betacarotene to vitamin A. Animal studies have also indicated that vitamin A increases cellular thyroid receptor expression, and thus improves sensitivity to thyroid hormones.
Because of all these interactions, patients with hypothyroidism or inadequate T4 from thyroid removal may also benefit from supplementation. Vitamin A status can be somewhat difficult to assess however, as serum levels are tightly controlled and may not be indicative of stores [Lab tests online].
Supplementation with 25,000IU of retinal palmitate daily over four months was able to reduce the risk of subclinical hypothyroidism and correct minor thyroid abnormalities. However, caution should be used as vitamin A toxicity can occur at this dose or higher.[17,20]
Other holistic considerations
Psychological, nervous system support
Patients post thyroidectomy, and particularly after surgery to remove malignancies of the thyroid, have reported feelings of stress, mood swings, depression and anxiety.[21,22] Neuropsychological symptoms such as irritability, disorientation, anxiety and depression have also been reported in patients with Graves’ disease post total thyroidectomy. It is important, therefore, to monitor all patients after thyroidectomy for psychological distress and support accordingly.
As L-T4 is absorbed throughout the small intestine, impaired gut health can compromise absorption rates. Patients whose thyroid was removed due to Hashimoto’s thyroiditis and who are requiring unexplained increased doses of L-T4 may have undiagnosed coeliac disease and should be screened accordingly.[24,25]
Increases in gastric pH have also been negatively correlated to absorption of L-T4. Dosages of L-T4 required to reach normal serum levels of TSH were 22% higher in patients with Helicobater pylori infections and doses were able to be lowered again once the infection was eliminated. Proton pump inhibitors have also been shown to decrease the absorption of L-T4 requiring a dosage increase of 37%.[27,28]
Ensuring optimal gastrointestinal performance is paramount for the absorption of L-T4, as well as for the patient’s overall health.
Thyroidectomy is becoming increasingly common, as rates of thyroid cancer and other thyroid conditions continue to rise. When a patient undergoes a thyroidectomy, depending on how much of the gland is removed, they may require replacement hormone therapy with L-T4. There are a number of nutrients and holistic considerations that can be used to help support the patient after the surgery and enhance the effects of L-T4.
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- Colucci P, Yue CS, Ducharme M, et al. A review of the pharmacokinetics of levothyroxine for the treatment of hypothyroidism. European endocrinology 2010;9(1):40. [Full text]
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- Zaborek NA, Cheng A, Imbus JR, et al. The optimal dosing scheme for levothyroxine after thyroidectomy: A comprehensive comparison and evaluation. Surgery 2018. [Abstract].
- Ventura M, Melo M, Carrilho F. Selenium and thyroid disease: From pathophysiology to treatment. Internation J Endocrinol 2017:1297658. [Full text]
- Kachouei A, Rezvanian H, Amini M, et al. The effect of levothyroxine and selenium versus levothyroxine alone on reducing the level of anti-thyroid peroxidase antibody in autoimmune hypothyroid patients. Advanced biomedical research 2018;7:1. [Full text]
- Chambial S, Dwivedi S, Shukla, KK, et al. Vitamin C in disease prevention and cure: an overview. IJCB 2013;28(4):314-328. [Full text]
- Antúnez PB, Licht SD. Vitamin C improves the apparent absorption of levothyroxine in a subset of patients receiving this hormone for primary hypothyroidism. Rev Argent Endocrinol Metab 2011;48:16-24. [Full text]
- Jubiz W, Ramirez M. Effect of vitamin C on the absorption of levothyroxine in patients with hypothyroidism and gastritis. J Clin Endocrinol Metab 2014;99:E1031-E1034. [Full text]
- Alhefdhi A, Mazeh H, Chen H. Role of postoperative vitamin D and/or calcium routine supplementation in preventing hypocalcemia after thyroidectomy: a systematic review and meta-analysis. Oncologist 2013;18(5: 533-542. [Full text]
- Xing T, Hu Y, Wang B, et al. Role of oral calcium supplementation alone or with vitamin D in preventing post-thyroidectomy hypocalcaemia: A meta-analysis. Medicine 2019;98(8):e14455. [Full text]
- Chon DA, Reisman T, Weinreb, JE, et al. Concurrent milk ingestion decreases absorption of levothyroxine. Thyroid 2018;28(4):454-457. [Full text]
- Farhangi MA, Keshavarz, SA, Eshraghian M, et al. The effect of vitamin A supplementation on thyroid function in premenopausal women. JACN 2012;31(4):268-274. [Abstract]
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- Kiuchi S, Ihara H, Koyasu, M, et al. Relation between serum levels of thyroid hormone and serum β-carotene concentrations in patients with thyroid disorders. Int J Anal Bio-Sci 2018;6(1). [Full text]
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- Nickel B, Tan T, Cvejic E, et al. Health-related quality of life after diagnosis and treatment of differentiated thyroid cancer and association with type of surgical treatment. JAMA Otolaryngology–Head & Neck Surgery 2019. [Abstract]
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- Pradhan R, Pakhriya S, Gutch M, et al. Unmasking of neuropsychiatric manifestations after total thyroidectomy for Graves' disease. Indian J Endocrinol Metabol 2018;22(3):436-437. [Full text]
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