significantly impaired above TSH levels of about 1.5. Any TSH above 1.5 should be addressed, if only through iodine and selenium supplementation (or abundant seaweed consumption with ~3 Brazil nuts per day.) Since a TSH of 1.5 is about the population mean, it’s a fair inference that most Americans are needlessly suffering impaired health due to impaired thyroid status. Especially during pregnancy, thyroid and iodine status are critical. Breech birth and miscarriage are far from the only negative consequences of impaired thyroid status. An elevated TSH usually indicates an iodine deficiency, and “even a mild iodine deficiency during pregnancy and during the first years of life adversely affects brain development.” [4] Iodine deficiency is the most common worldwide cause of mental retardation (cretinism), and elevated TSH during pregnancy can be expected to reduce the IQ of the child by up to 10 points and to produce other neurological deficits, including “visuomotor, memory, attentionand posture” deficits. [5] So, if your doctor doesn’t do it routinely, ask for TSH and vitamin D measurements at your next physical. There are few easier ways to improve your health than fixing thyroid and vitamin D status. [1] Asvold BO et al. Thyrotropin levels and risk of fatal coronary heart disease: the HUNT study. Arch Intern Med. 2008 Apr 28;168(8):855-60. . [2] Negro R et al. Increased Pregnancy Loss Rate in Thyroid Antibody Negative Women with TSH Levels between 2.5 and 5.0 in the First Trimester of Pregnancy. J Clin Endocrinol Metab. 2010 Jun 9. [Epub ahead of print] . [3] Kuppens SM et al. Maternal thyroid function during gestation is related to breech presentation at term. Clin Endocrinol (Oxf). 2010 Jun;72(6):820-4. . [4] Remer T et al. Iodine deficiency in infancy – a risk for cognitive development. Dtsch Med Wochenschr. 2010 Aug;135(31/32):1551-1556. . [5] Joseph R. Neuro-developmental deficits in early-treated congenital hypothyroidism. Ann Acad Med Singapore. 2008Dec;37(12 Suppl):42-3. .
