What are the guideline sources, guidelines and references for Hypothyroidism ?
Guideline sources The following summarized guidelines for the evaluation and management of hypothyroidism are prepared by our editorial team based on guidelines from the Endocrine Society (ES 2020), the American Heart Association (AHA/HRS/ACC 2019), the American Thyroid Association (ATA 2017), and the American Thyroid Association (ATA/AACE 2012). 1 2 3 4 5 5 5 5 6 Definition Hypothyroidism is a chronic endocrine disease associated with deficiency of thyroxine (T4) and T3 (T3) thyroid hormones. 5 Epidemiology Hypothyroidism is most frequently caused by a failure of the thyroid gland to produce thyroid hormones (99%). Other causes include the underproduction of TSH by the pituitary gland and deficiency of the thyrotropin-releasing hormone. 5 Pathophysiology The prevalence of overt and subclinical hypothyroidism in the United States is estimated at 300 per 100,000 population and 4,300 per 100,000 population, respectively. Hypothyroidism is 2-8 times https://web.pathway.md/diseases/reczsKmQVIbWTbsAr 1/6 6/24/23, 12:47 PM Hypothyroidism Pathway more prevalent in women than men, and it's prevalence increases with age. 5 Disease course Clinical manifestations include weight gain, fatigue, proximal weakness, decreased concentration, depression, diffuse muscle pain, menstrual irregularities, constipation, dry skin, hair loss, and sensory neuropathy. A severe form of hypothyroidism-myxedema coma- presents with altered mental status, hypothermia, hyponatremia and bradycardia. The disease decreases productivity and quality of life. 5 Prognosis and risk of recurrence Hypothyroidism is not associated with an increase in mortality. Treatment is well tolerated and results in improved quality of life in most patients. However, untreated hypothyroidism leads to disease progression and ultimately, coma and death. 6 Guidelines 1. Screening and diagnosis Clinical scoring systems: avoid using clinical scoring systems to diagnose hypothyroidism. D Indications for screening: consider obtaining screening for hypothyroidism in > 60 years old individuals. B Show 2 more Indications for testing (dyslipidemia): evaluate for and rule out hypothyroidism as the cause of hyperlipidemia before initiating lipid-lowering therapy in patients with hyperlipidemia. A Indications for testing (infertility): assess serum TSH concentration in all females seeking care for infertility. B 2. Diagnostic investigations Anti-TPO antibodies: measure anti-TPO antibodies in the evaluation of patients with subclinical hypothyroidism. B Show 3 more Thyroid hormone tests: measure serum free T4 (free T4 index or free T4 estimate and direct immunoassay of free T4 without physical separation using anti-T4 antibodies) instead of total T4 in the evaluation of hypothyroidism. A Show 3 more Other diagnostic tests: avoid tests such as clinical assessment of reflex relaxation time, cholesterol, and muscle enzymes to diagnose hypothyroidism. D https://web.pathway.md/diseases/reczsKmQVIbWTbsAr 2/6 6/24/23, 12:47 PM Hypothyroidism Pathway 3. Medical management Indications for L-thyroxine (abnormal TSH): Consider initiating levothyroxine in patients with serum TSH levels > 10 mIU/L, as these patients are at increased risk for HF and cardiovascular mortality. B Consider initiating treatment based on individual factors in patients with TSH levels between the upper limit of a given laboratory's reference range and 10 mIU/L, particularly if patients have symptoms suggestive of hypothyroidism, positive anti-TPO antibodies, or evidence of ASCVD, HF, or associated risk factors for these diseases. B Indications for L-thyroxine (normal TSH): Consider initiating L-thyroxine therapy in female patients of childbearing age with serum TSH levels within the reference range for the local laboratory if: serum TSH is > 2.5 mIU/L in patients planning a pregnancy in the immediate future (including assisted reproduction) serum TSH is > 2.5 mIU/L during the first trimester of pregnancy serum TSH is > 3.0 mIU/L during the second trimester of pregnancy serum TSH is > 3.5 mIU/L during the third trimester of pregnancy. C Show 6 more Choice of agent: treat patients with hypothyroidism with levothyroxine monotherapy. A Initial L-thyroxine dose: consider full replacement doses when initiating therapy in young healthy adults with overt hypothyroidism. C Treatment targets: Target the normal range of a third-generation TSH assay in nonpregnant patients with hypothyroidism. Consider targeting an ULN of 4.12 mIU/L in iodine-sufficient areas if an ULN for a third-generation TSH assay is not available, and a LLN of 0.45 mIU/L if a LLN is not available. B Assess serum free T4 to guide therapy in patients with central hypothyroidism, targeting to exceed the midnormal range value for the assay being used. B Management of dyslipidemia: avoid treating hyperlipidemia until the patient becomes euthyroid in order to more accurately assess the lipid profile in patients with overt hypothyroidism. D Show 2 more 4. Nonpharmacologic interventions Iodine supplementation: do not use iodine supplementation, including kelp or other iodine- containing functional foods, in the management of hypothyroidism in iodine-sufficient areas. D Selenium supplementation: do not use selenium for the prevention or treatment of hypothyroidism. D https://web.pathway.md/diseases/reczsKmQVIbWTbsAr 3/6 6/24/23, 12:47 PM Hypothyroidism Pathway 5. Specific circumstances Pregnant patients: Obtain the measurement of total thyroxine or a free thyroxine index, in addition to TSH, to assess thyroid status in pregnancy. Because of the wide variation in the results of different free thyroxine assays, employ direct immunoassay measurement of free thyroxine only when method-specific and trimester-specific reference ranges for serum free thyroxine are available. B Base the target range for TSH in patients with hypothyroidism who are pregnant on trimester- specific ranges for that laboratory. If trimester-specific reference ranges are not available in the laboratory, follow the following upper-normal reference ranges: first trimester, 2.5 mIU/L; second trimester, 3.0 mIU/L; and third trimester, 3.5 mIU/L. B Patients with combined adrenal insufficiency: initiate corticosteroids before treatment with levothyroxine in patients with combined adrenal insufficiency and hypothyroidism. B Patients with conduction disorders: consider permanent cardiac pacing without further observation for reversibility in patients with symptomatic second-degree or third-degree AV block associated with thyroid function abnormalities but without clinical myxedema. C 6. Patient education Timing of L-thyroxine doses: advise levothyroxine to be taken with water consistently 30-60 minutes before breakfast, or at bedtime, 4 hours after the last meal. B Nutraceuticals for hypothyroidism: advise patients taking dietary supplements and nutraceuticals for hypothyroidism that commercially available thyroid-enhancing products are not a remedy for hypothyroidism and counsel about the potential side effects of various preparations particularly those containing iodine or sympathomimetic amines as well as those marked as "thyroid support" since they could be adulterated with levothyroxine or T3. B 7. Follow-up and surveillance Indications for specialist referral: Manage most patients with primary hypothyroidism by non- endocrinologist physicians familiar with the diagnosis and treatment of hypothyroidism. Refer patients with hypothyroidism meeting any of the following criteria for a consultation with an endocrinologist: infant and pediatric patients female patient planning conception pregnant patients patients difficult to render and maintain in a euthyroid state cardiac disease presence of goiter, nodule, or other structural changes in the thyroid gland https://web.pathway.md/diseases/reczsKmQVIbWTbsAr 4/6 6/24/23, 12:47 PM Hypothyroidism Pathway presence of other endocrine diseases, such as adrenal or pituitary disorders unusual constellation of thyroid function test results unusual causes of hypothyroidism, such as induced by agents interfering with the absorption of levothyroxine, impacting thyroid gland hormone production or secretion, affecting the hypothalamic-pituitary-thyroid axis (directly or indirectly), increasing clearance, or peripherally impacting metabolism. B References 1. 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 Nov-Dec;18 6 988 1028. Open 2. Connie B Newman, Michael J Blaha, Jeffrey B Boord et al. Lipid Management in Patients with Endocrine Disorders: An Endocrine Society Clinical Practice Guideline. J Clin Endocrinol Metab. 2020 Dec 1;105 12):dgaa674. Open 3. Fred M Kusumoto, Mark H Schoenfeld, Coletta Barrett et al. 2018 ACC/AHA/HRS Guideline on the Evaluation and Management of Patients With Bradycardia and Cardiac Conduction Delay: A Report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines and the Heart Rhythm Society. Circulation. 2019 Aug 20;140 8):e382-e482. Open 4. Erik K Alexander, Elizabeth N Pearce, Gregory A Brent et al. 2017 Guidelines of the American Thyroid Association for the Diagnosis and Management of Thyroid Disease During Pregnancy and the Postpartum. Thyroid. 2017 Mar;27 3 315 389. Open 5. Luca Chiovato, Flavia Magri, Allan Carle. Hypothyroidism in Context: Where We've Been and Where We're Going. 2019 Sep;36 Suppl 2 47 58.2019 Sep;36 Suppl 2 47 58. Open 6. Neige M Y Journy, Marie-Odile Bernier, Michele M Doody et al. Hyperthyroidism, Hypothyroidism, and Cause-Specific Mortality in a Large Cohort of Women. Thyroid. 2017 Aug;27 8 1001 1010. Open 7. LeFevre ML, U.S. Preventive Services Task Force. Screening for thyroid dysfunction: U.S. Preventive Services Task Force recommendation statement. Ann Intern Med. 2015 May 5;162 9 641 50. Open 8. Society for Maternal-Fetal Medicine. Choosing Wisely SMFM recommendations. Choosing Wisely. 2019. Open 9. Endocrine Society. Choosing Wisely ES recommendations. Choosing Wisely. 2017. Open 10. Luca Chiovato, Flavia Magri, Allan Carl . Hypothyroidism in Context: Where We've Been and Where We're Going. Adv Ther. 2019 Sep;36 Suppl 2 47 58. Open 11. Peter N Taylor, Diana Albrecht, Anna Scholz et al. Global epidemiology of hyperthyroidism and hypothyroidism. Nat Rev Endocrinol. 2018 May;14 5 301 316. Open 12. Jeffrey R Garber, Rhoda H Cobin, Hossein Gharib et al. Clinical practice guidelines for hypothyroidism in adults: cosponsored by the American Association of Clinical Endocrinologists and the American Thyroid Association. Thyroid. 2012 Dec;22 12 1200 35. Open 13. Vivek Mathew, Raiz Ahmad Misgar, Sujoy Ghosh et al. Myxedema coma: a new look into an old crisis. J Thyroid Res. 2011;2011 493462. Open https://web.pathway.md/diseases/reczsKmQVIbWTbsAr 5/6 6/24/23, 12:47 PM Hypothyroidism Pathway 14. Scott A Sullivan. Hypothyroidism in Pregnancy. Clin Obstet Gynecol. 2019 Jun;62 2 308 319. Open 15. Jacqueline Jonklaas, Antonio C Bianco, Andrew J Bauer et al. Guidelines for the treatment of hypothyroidism: prepared by the american thyroid association task force on thyroid hormone replacement. Thyroid. 2014 Dec;24 12 1670 751. Open 16. Neige M Y Journy, Marie-Odile Bernier, Michele M Doody et al. Hyperthyroidism, Hypothyroidism, and Cause-Specific Mortality in a Large Cohort of Women. 2017 Aug;27 8 1001 1010.2017 Aug;27 8 1001 1010. Open 17. Jacqueline Jonklaas, Antonio C Bianco, Andrew J Bauer et al. Guidelines for the treatment of hypothyroidism: prepared by the american thyroid association task force on thyroid hormone replacement. Thyroid. 2014 Dec;24 12 1670 751. Open https://web.pathway.md/diseases/reczsKmQVIbWTbsAr 6/6