Thyroid Emergencies PDF

Thyroid Emergencies Tammy Slater, DNP, MS, ACNP-BC Intermittent slides courtesy of Kristi Silver, MD Overview of Thyroid Regulation and Thyroid Function Tests (TFTs)  Thyroid Regulation ► Primarily regulates cellular metabolism & influences almost every tis...

Thyroid Emergencies Tammy Slater, DNP, MS, ACNP-BC Intermittent slides courtesy of Kristi Silver, MD Overview of Thyroid Regulation and Thyroid Function Tests (TFTs)  Thyroid Regulation ► Primarily regulates cellular metabolism & influences almost every tissue and organ system Increases tissue thermogenesis and basal metabolic rate Reduces serum cholesterol levels and systemic vascular resistance (SVR) Profound effects occur within CV system (next slide) Untreated or partially treated thyrotoxicosis is associated with weight loss, osteoporosis, AF, embolic events, muscle weakness, tremor, neuropsychiatric symptoms and rarely CV collapse and death Ross, D., Burch, H., Cooper, D., Greenlee, C., Laurberg, P., Maia, A…Walter, M. (2016). 2016 American Thyroid Association Guidelines for diagnosis and management of hyperthyroidism and other causes of thyrotoxicosis. Thyroid, 26(10), 1343-1421. 3  Effects on the CV System ► Thyroid hormone has direct effects on the CV system to increase cardiac output Direct effect on chronotropy (heart rate), lusitropy (diastolic relaxation), inotropy (contractility), and relaxation of smooth muscle Observed increase in myocardial work is higher than the increase in myocardial oxygen consumption, which suggests that thyroid hormone enhances myocardial efficiency (i.e. enhanced diastolic function, reduced afterload, and improved coronary perfusion) Maiden, M., J., & Torpy, D. J. (2019). Thyroid hormones in critical illness. Critical Care Clinics, 35, 375-388. 4  Commonly Used TFTs in Clinical Practice ► TSH: can be used alone in screening for overt thyroid disease but both TSH and T4 are needed for diagnosis, especially if pituitary or hypothalamic disease is suspected With a normal hypothalamus and pituitary, TSH maintains an inverse relationship with FT4 Sensitive measure of the response of the pituitary gland to circulating FT4 levels Reference range is 0.4-4mlU/L; however euthyroid range is 1-1.5mlU/L with normal range at 0.4 to 2.5mlU/L TSH levels are elevated mostly in primary hypothyroidism and are accompanied by a low level of FT4 (interpret both TSH and FT4 in hypothyroidism) Lee G.A., & Masharani U (2020). Disorders of the thyroid gland. Lalwani A.K.(Ed.), Current Diagnosis & Treatment Otolaryngology—Head and Neck Surgery, 4e. McGraw-Hill. https://accessmedicine.mhmedical.com/content.aspx?bookid=2744&sectionid=229675695 5  Free Thyroxine or Free T4 (FT4) ► Levels are elevated in hyperthyroidism and decreased in hypothyroidism ► Antiepileptic drugs phenytoin, carbamazepine, and rifampin can cause a significantly increased hepatic metabolism of T4 ► Low FT4 level with normal to decreased TSH level may indicate secondary or central hypothyroidism (< 5% of all cases of hypothyroidism), which is due to a pituitary or hypothalamic tumor Lee G.A., & Masharani U (2020). Disorders of the thyroid gland. Lalwani A.K.(Ed.), Current Diagnosis & Treatment Otolaryngology—Head and Neck Surgery, 4e. McGraw-Hill. https://accessmedicine.mhmedical.com/content.aspx?bookid=2744&sectionid=229675695 6  Total Triiodothyronine (T3) and Free Triiodothyronine (FT3) ► Measures both free and bound T3 in circulation ► Helpful in diagnosing hyperthyroidism and elevated T3 levels but normal T4 levels (i.e. T3 toxicosis) ► The preferential secretion of T3 can be seen in early Graves’ disease or toxic multinodular goiter Lee G.A., & Masharani U (2020). Disorders of the thyroid gland. Lalwani A.K.(Ed.), Current Diagnosis & Treatment Otolaryngology—Head and Neck Surgery, 4e. McGraw-Hill. https://accessmedicine.mhmedical.com/content.aspx?bookid=2744&sectionid=229675695 7 Algorithm for TFTs (not applicable for patients with hypothalamic- pituitary disease, serious illness, or those who are taking certain meds such as amiodarone, glucocorticoids, and dopamine) 8 Diagnostic Approach to TFTs 9  Patterns of TFTs (“a” denotes rare conditions) TSH Free T4 T3 Diagnosis Normal Normal Normal Euthyroid Normal Low normal or low Low or normal Central hypothyroidism or sick euthyroid or drugs High Low Normal or low Primary hypothyroidism High Normal Normal Subclinical hypothyroidism a High High High TSH resistance syndrome Low High or normal High Hyperthyroidism Low Normal Normal Subclinical hyperthyroidism or drugs a Low Normal High T3 toxicosis Low Low Low Central hypothyroidism or sick euthyroid or drugs Lee G.A., & Masharani U (2020). Disorders of the thyroid gland. Lalwani A.K.(Ed.), Current Diagnosis & Treatment Otolaryngology—Head and Neck Surgery, 4e. McGraw-Hill. https://accessmedicine.mhmedical.com/content.aspx?bookid=2744&sectionid=229675695 10  Medications and Their Effects on TFTs Lee G.A., & Masharani U (2020). Disorders of the thyroid gland. Lalwani A.K.(Ed.), Current Diagnosis & Treatment Otolaryngology—Head and Neck Surgery, 4e. McGraw- Hill. https://accessmedicine.mhmedical.com/conte nt.aspx?bookid=2744&sectionid=229675695 11  Physical Exam Findings (review from Advanced Health Assessment) ► Maneuvers when examining the thyroid Patient should be seated with only a slightly flexed neck to relax the sternocleidomastoid muscles. The thyroid should first be observed while the patient swallows a sip of water. An enlarged gland or nodules can be observed as the gland moves up and down. The thyroid gland should then be palpated from behind the patient, with the middle 3 fingers on each lobe of the gland. While the patient swallows, thyroid nodules or an enlargement can be noted as the gland passes beneath the examiner’s fingers. A normal thyroid is usually found to be 2 cm in length and 1 cm in width – A generalized enlargement of the thyroid is called a diffuse goiter, whereas an irregular enlargement is termed a nodular goiter Lee G.A., & Masharani U (2020). Disorders of the thyroid gland. Lalwani A.K.(Ed.), Current Diagnosis & Treatment Otolaryngology—Head and Neck Surgery, 4e. McGraw-Hill. https://accessmedicine.mhmedical.com/content.aspx?bookid=2744&sectionid=229675695 12  Nodules ► Incidental nodules over 1cm in size discovered on imaging studies should undergo further evaluation because they have a greater potential to have clinically significant malignancies ► Nonpalpable nodules have the same risk of malignancy as palpable nodules of the same size. Smaller than 1cm incidental nodules, however, should be evaluated if there are suspicious sonographic findings or if the patient has additional risk factor (RF) for thyroid cancer RF: age (60); history of childhood head or neck irradiation or total body irradiation for BMT; family history of thyroid cancer Recent growth or evidence of hoarseness, dysphagia or obstruction should also raise suspicion Lee G.A., & Masharani U (2020). Disorders of the thyroid gland. Lalwani A.K.(Ed.), Current Diagnosis & Treatment Otolaryngology—Head and Neck Surgery, 4e. McGraw-Hill. https://accessmedicine.mhmedical.com/content.aspx?bookid=2744&sectionid=229675695 13  Clinical - Low Risk High Risk History Family history of goiter Family history of thyroid cancer or thyroid cancer Evaluation syndrome such as Cowden syndrome, familial polyposis, Carney complex, multiple endocrine of Thyroid neoplasia [MEN] 2 syndrome. Incidental nodule discovered during 18FDG–PET scan Nodules History of head and neck radiation; total body irradiation for bone marrow transplantation Recent growth of nodule Hoarseness, dysphagia Epidemiology Older woman Young adult, male, or child Physical exam Soft nodule Solitary, firm nodule Multinodular goiter Vocal cord paralysis Firm lymph nodes Serum factors High titer of thyroid - antibodies, hyperthyroidism or hypothyroidism Thyroid scan “Hot nodule” “Cold nodule” /content.aspx?bookid=2744&sectionid=229675695Lee Ultrasound of thyroid Pure cystic lesion Solid or semicystic lesion G.A., & Masharani U (2020). Disorders of the thyroid gland. Lalwani A.K.(Ed.), Current Diagnosis & Treatment Otolaryngology—Head and Neck Surgery, 4e. McGraw- Hill. https://accessmedicine.mhmedical.com Thyroxine therapy Regression Increase in size of mass 14 References ► Akamizu, T., Satoh, T., Isozaki, O., Suzuki, A., Wakino, S., Iburi, T.,… Mori, M. Diagnostic criteria, clinical features, and incidence of thyroid storm based on nationwide surveys. Thyroid, 22(7), 661-679. ► Burch, H. B., & Wartofsky, L. (1993). Life-threatening thyrotoxicosis. Thyroid storm. Endocrinology and Metabolism Clinics of North America, 22(2), 263-277. ► Chaker, L., Cappola, A., Mooijaart, S., & Peeters, R. (2018). Ageing and endocrinology 3: Clinical aspects of thyroid function during ageing. Lancet Diabetes Endocrinology, 6, 733-742. ► De Leo, S., & Braverman, L. (2016). Hyperthyroidism. The Lancet, 388, 906-918. ► Dutta, P., D., Bhansali, A., Masoodi, S., Bhadada, S., Sharma, N., & Rajput, R. (2008). Predictors of outcome in myxoedema coma: A study from a tertiary care centre. Critical Care, 12(R1). ► Lee G.A., & Masharani U (2020). Disorders of the thyroid gland. Lalwani A.K.(Ed.), Current Diagnosis & Treatment Otolaryngology—Head and Neck Surgery, 4e. McGraw-Hill. 15 References ► Maiden, M., J., & Torpy, D. J. (2019). Thyroid hormones in critical illness. Critical Care Clinics, 35, 375- 388. ► McKean, S. C., Ross, J. J., Dressler, D. D., Brotman, D. J., & Ginsberg, J. S. (2017). Principles and Practice of Hospital Medicine (2nd edition). New York: McGraw Hill. ► Paulson J.M., & Hollenberg A.N. (2017). Thyroid emergencies. McKean S.C., & Ross J.J., & Dressler D.D., & Scheurer D.B.(Eds.), Principles and Practice of Hospital Medicine, 2e. McGraw-Hill. ► Popoveniuc, G., Chandra, T., Sud, A., Sharma, M., Blackman, M., Burman,… Wartofsky, L. (2014). A diagnostic scoring system for myxedema coma. Endocrine Practice, 20(8), 808-817. ► Ross, D., Burch, H., Cooper, D., Greenlee, C., Laurberg, P., Maia, A…Walter, M. (2016). 2016 American Thyroid Association Guidelines for diagnosis and management of hyperthyroidism and other causes of thyrotoxicosis. Thyroid, 26(10), 1343-1421. 16