What are the guideline sources, guidelines and references for Subclinical hypothyroidism ?
Guideline sources The following summarized guidelines for the evaluation and management of subclinical hypothyroidism are prepared by our editorial team based on guidelines from the Endocrine Society (ES 2020), the British Medical Journal (BMJ 2019), and the American Thyroid Association (ATA/AACE 2012). 1 2 3 4 5 6 6 6 Definition Subclinical hypothyroidism is defined as the occurrence of thyroid stimulating hormone levels exceeding the ULN, with normal serum levels of free T3 (T3) and thyroxine (T4). 4 Epidemiology Autoimmunity is the most common cause of subclinical hypothyroidism. 6 Pathophysiology The incidence of subclinical hypothyroidism is estimated at 2500 per 100,000 person-years in women, and 700 per 100,000 person-years in men. 5 Disease course About 2.5% of patients progress to clinically overt hypothyroidism each year, with a higher rate of progression in patients with thyroid autoantibodies and higher thyroid stimulating hormone levels. Thyroid function normalizes spontaneously in up to 40% cases. 6 Prognosis and risk of recurrence https://web.pathway.md/diseases/receFtHutYoJPm3jQ 1/3 6/24/23, 3:13 PM Subclinical hypothyroidism Pathway Subclinical hypothyroidism in younger patients (< 65 years of age) is associated with an increased risk of coronary artery disease, HF and cerebrovascular accident. 6 Guidelines 1. Diagnostic investigations Anti-TPO antibodies: measure anti-TPO antibodies as part of the initial evaluation of patients with subclinical hypothyroidism. B 2. Medical management Indications for treatment: As per BMJ 2019 guidelines, do not initiate thyroid replacement therapy in adult patients with subclinical hypothyroidism. D As per AACE 2012 guidelines, 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 Updated evidence: TRUST In adult patients 65 years of age who had persisting subclinical hypothyroidism, with thyrotropin level of 4.60-19.99 mlU/L and free thyroxine level within reference range, levothyroxine was not superior to placebo with respect to change in Tiredness score at 12 months. Stott DJ et al. N Engl J Med. 2017 Jun 29. Levothyroxine therapy: Use lower initial levothyroxine doses in patients with subclinical hypothyroidism than what is required in the treatment of overt hypothyroidism. B Consider using a daily dose of levothyroxine of 25 to 75 g, depending on the degree of thyroid stimulating hormone elevation. Further adjustments should be guided by clinical response and follow up laboratory determinations including thyroid stimulating hormone values. C Management of dyslipidemia: consider initiating thyroxine treatment as a means of reducing low-density lipoprotein levels in patients with subclinical hypothyroidism (TSH < 10 mIU/L) with associated hyperlipidemia. C References https://web.pathway.md/diseases/receFtHutYoJPm3jQ 2/3 6/24/23, 3:13 PM Subclinical hypothyroidism Pathway 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. G E Bekkering, T Agoritsas, L Lytvyn et al. Thyroid hormones treatment for subclinical hypothyroidism: a clinical practice guideline. BMJ. 2019 May 14;365:l2006. Open 4. Cem Onur Kirac, Sedat Abusoglu, Esra Paydas Hataysal et al. A rare cause of subclinical hypothyroidism: macro-thyroid-stimulating hormone. 2020 Jan 28;7 1 75 77.2020 Jan 28;7 1 75 77. Open 5. B Gopinath, J J Wang, A Kifley et al. Five-year incidence and progression of thyroid dysfunction in an older population. 2010 Sep;40 9 642 9.2010 Sep;40 9 642 9. Open 6. Christopher Redford, Bijay Vaidya. Subclinical hypothyroidism: Should we treat?. 2017 Jun;23 2 55 62.2017 Jun;23 2 55 62. Open https://web.pathway.md/diseases/receFtHutYoJPm3jQ 3/3