Diagram of the hypothalamic-pituitary-thyroid axis. The hypothalamus secretes TRH (green), which promotes the production of TSH (red) by the pituitary gland. This, in turn, promotes the production of thyroxine by the thyroid (blue). Thyroxine levels reduce TRH and TSH production by a negative feedback process. Pandeya N, McLeod DS, Balasubramaniam K, et al. Increasing thyroid cancer occurrence in Queensland, Australia 1982-2008-true increase hypothyroidism diagnosis and treatment guidelines or overdiagnosis? Clin Endocrinol (Oxf) 2016; 84: 257-264. Rodondi N, den Elzen WP, Bauer DC, et al. Subclinical hypothyroidism and the danger of coronary cardiovascular disease and mortality. JAMA 2010; 304: 1365-1374. Brabant G, Peeters RP, Chan SY, et al. Management of subclinical hypothyroidism in pregnancy: are we too simplistic? Eur J Endocrinol 2015; 173: P1-P11.
The replacement dosage of thyroxine decreases over the 1st months of life, to a normal needed dose of 5 mcg/kg/day between ages 6m-2y. Flynn RW, Bonellie SR, Jung RT, et al. Serum thyroid-stimulating hormone concentration and morbidity from cardiovascular disease and fractures in clients on long-term thyroxine treatment. J Clin Endocrinol Metab 2010; 95: 186-193.
Care re: evident athyreosis. Reduced uptake (e.g. due to maternal TSH receptor blocking antibodies or late scan on treatment) can be misdiagnosed as athyreosis and must for that reason be analyzed within clinical context. Ultrasound and thyroglobulin levels may assist. When TSH is reduced, radionuclide scanning may find several autonomous (hot”) blemishes. These are hardly ever malignant, and do not consistently require biopsy. When TSH is normal or raised, radionuclide scanning is not suggested.
Rugge JB, Bougatsos C, Chou R. Screening and treatment of thyroid dysfunction: a proof review for the US Preventive Solutions Job Force. Ann Intern Medication 2015; 162: 35-45. Li M, Eastman CJ, Waite KV, et al. Are Australian kids iodine deficient? Results of the Australian National Iodine Nutrition Research study. Med J Aust 2006; 184: 165-169.
Tomb’ disease must be treated at first with carbimazole (15-20 mg daily for moderate to moderate hyperthyroidism, 30-40 mg for serious hyperthyroidism). In clients who react well, it can be continued for an 18-month course, aiming for long term remission. Other treatment alternatives are radioactive iodine treatment and thyroidectomy. Harach HR, Franssila KO, Wasenius VM. Occult papillary cancer of the thyroid. A regular” finding in Finland. An organized autopsy research study. Cancer 1985; 56: 531-538.
Lucas-Herald A, Jones J, Attaie M, et al. Predictive and diagnostic worth of ultrasound and isotope thyroid scanning, alone and in combination, in infants referred with thyroid-stimulating hormone elevation on newborn screening. J Pediatr 2014; 164: 846-854. N.B. high starting ypothyroidism evaluation and treatment guidelines doses of 15 mcg/kg/d result in a high occurrence of short-term hyperthyroidism, and are not promoted in your area.
Schoen E, Clapp W, To T, et al. The crucial role of newborn thyroid scintigraphy with isotopic iodine (123I) in defining and handling congenital hypothyroidism. Pediatrics 2004; 114(6): e683-688. Canaris GJ, Manowitz NR, Mayor G, Ridgway EC. The Colorado Thyroid Disease Occurrence guidelines for the treatment of hypothyroidism Study. Arch Intern Medication 2000; 160: 526-534. Selenium supplements for Hashimoto’s thyroiditis. Cochrane Database Syst Rev 2013; 6: CD010223. Bahn RS, Burch HB, Cooper DS, et al.