Thyroid Hormone Withdrawal (THW) May Cause Acute Hypothyroidism1
THW may be used to raise TSH levels for certain diagnostic procedures and/or RAI ablation. In order to raise TSH levels sufficiently, thyroid hormone replacement medication typically needs to be discontinued for a period of 4-6 weeks. This may cause your patients to experience the signs and symptoms of acute hypothyroidism.2
The symptoms of acute hypothyroidism are sometimes debilitating and may include tiredness, weight gain, sleepiness, constipation, muscle aches, reduced concentration, emotional changes resembling depression, and others. Not all patients experience symptoms in the same degree of severity. Some patients may experience more severe symptoms than others.1
Stopping thyroid hormone medication for 4-6 weeks may cause your patients to have unwanted symptoms.1
Discuss Options with your patients that may help them avoid thyroid hormone withdrawal and some of the associated symptoms of acute hypothyroidism
How will you decide what to prescribe for your patient?
When determining how to prepare patients for RAI or Stim Tg testing (with or without WBS), consider:
- Acute short-term hypothyroidism induced by THW may be a distressing time and may result in unwanted symptoms and impaired quality of life.
- Delayed symptoms like fatigue, edema, and constipation are signs of acute hypothyroidism and it should not be assumed that these symptoms are caused by RAI treatment alone.3
Important Safety Information and Indications
Important Safety Information and Indications
IMPORTANT SAFETY INFORMATION
If Thyrogen is administered with radioiodine, the contraindications to radioiodine also apply to this combination regimen. Refer to the radioiodine prescribing information for a list of contraindications for radioiodine.
WARNINGS AND PRECAUTIONS
- There have been reports of death in non-thyroidectomized patients and in patients with distant metastatic thyroid cancer in which events leading to death occurred within 24 hours after administration of Thyrogen. Caution should be exercised in patients who have substantial thyroid tissue still in situ or functional thyroid cancer metastases, specifically in the elderly and those with a known history of heart disease.
- Hospitalization for administration of Thyrogen and post-administration observation in patients at risk should be considered.
- There are post marketing reports of stroke in young women with risk factors for stroke, and neurological findings suggestive of stroke (e.g., unilateral weakness) occurring within 72 hours of Thyrogen administration in patients without known central nervous system metastases. The relationship between Thyrogen administration and stroke is unknown. Patients should be well-hydrated prior to treatment with Thyrogen.
Sudden Rapid Tumor Enlargement:
- Sudden, rapid and painful enlargement of residual thyroid tissue or distant metastases can occur following treatment with Thyrogen. Pretreatment with glucocorticoids should be considered for patients in whom tumor expansion may compromise vital anatomic structures.
Risks Associated with Radioiodine Treatment:
- If Thyrogen is administered with radioiodine (RAI), the warnings and precautions for RAI apply to this combination regimen. Refer to the RAI prescribing information for a full list of the warnings and precautions for RAI.
The most common adverse reactions reported in clinical trials were nausea and headache.
USE IN SPECIFIC POPULATIONS
- If Thyrogen is administered with radioiodine, the combination regimen is contraindicated in pregnant women.
- Available data with Thyrogen use in pregnant women are insufficient to evaluate for a drug-associated risk of major birth defects, miscarriage, or adverse maternal or fetal outcomes.
- The concomitant use of Thyrogen and radioiodine (RAI) is contraindicated in lactating women. If Thyrogen is administered with RAI for diagnostic use, discontinue breastfeeding after RAI administration because of the potential for serious adverse reactions from RAI in the breastfed infant.
- If Thyrogen is not administered with RAI, the developmental and health benefits of breastfeeding should be considered along with the mother’s clinical need for Thyrogen and any potential adverse effects on the breastfed child. There are no available data on the presence of thyrotropin alfa in human milk, the effects on the breastfed infant, or the effects on milk production.
Pediatric Use: Safety and effectiveness in pediatric patients have not been established.
Geriatric Use: Results from controlled trials do not indicate a difference in the safety and efficacy of Thyrogen between adult patients less than 65 years and those over 65 years of age.
Renal Impairment: Elimination of Thyrogen is significantly slower in dialysis-dependent end stage renal disease patients, resulting in prolonged elevation of TSH levels.
INDICATIONS AND USAGE
Thyrogen® (thyrotropin alfa) is a thyroid stimulating hormone indicated for:
Adjunctive Diagnostic Tool for Well-Differentiated Thyroid Cancer: Use as an adjunctive diagnostic tool for serum thyroglobulin (Tg) testing with or without radioiodine imaging in the follow-up of patients with well-differentiated thyroid cancer who have previously undergone thyroidectomy.
Limitations of Use:
- Thyrogen-stimulated Tg levels are generally lower than, and do not correlate with Tg levels after thyroid hormone withdrawal.
- Even when Thyrogen-Tg testing is performed in combination with radioiodine imaging, there remains a risk of missing a diagnosis of thyroid cancer or underestimating the extent of the disease.
- Anti-Tg Antibodies may confound the Tg assay and render Tg levels uninterpretable.
Adjunct for Thyroid Remnant Ablation in Well-Differentiated Thyroid Cancer: Use as an adjunctive treatment for radioiodine ablation of thyroid tissue remnants in patients who have undergone a near-total or total thyroidectomy for well-differentiated thyroid cancer and who do not have evidence of distant metastatic thyroid cancer.
Limitations of Use:
- The effect of Thyrogen on thyroid cancer recurrence greater than 5 years post-remnant ablation has not been evaluated.
Click here for full Prescribing Information
1) K. Burman;Hypothyroidism Symptoms Following Temporary Withdrawal from Thyroid Hormone; Excerpted, with permission, from pages 92-93 of “Withdrawal of Thyroid Hormones,” Chapter 915 of the reference book “Thyroid Cancer: A Guide for Patients”, Keystone Press, 2010. Douglas Van Nostrand, M.D., Gary Bloom, and Leonard Wartofsky, M.D. See http://www.thyca.org/about/TCGuide/
2) RADIOACTIVE IODINE FOR THE TREATMENT OF THYROID CANCER. MyThyroid.com; http://www.mythyroid.com/radioactiveiodinecancer.html. Accessed June 8th, 2020
3) Lim et al. Differences in Physicians’ and Patients’ Perception of Acute Hypothyroid Symptoms Induced by Thyroid Hormone Withdrawal in Thyroid Cancer Patients: A Multicenter Survey in Korea; Eur Thyroid J; 2015 Mar;4(1):48-54.doi: 10.1159/000371512. Epub 2015 Feb 19; https://pubmed.ncbi.nlm.nih.gov/25960962/. Accessed June 9th, 2020
4) Jason Baker MD; The Effects of Hypothyroidism in the Body; https://www.healthline.com/health/hypothyroidism/effects-of-hypothyroidism#1; Accessed June, 2020