CASE 4: PRECONCEPTION SCREENING
A 39-year-old G0P0 woman presents for preconception counseling. She denies family or personal history of thyroid disease and symptoms of thyroid disease. Should she be screened?
Recommendation
There is no consensus or guideline regarding preconception laboratory screening for thyroid disease. Current guidelines by the American Thyroid Association, the American College of Obstetricians and Gynecologists, and The Endocrine Society recommend targeted, not universal, screening.2,3,7
The American Thyroid Association and the Endocrine Society recommend screening TSH in women who are pregnant or intend to become pregnant and
• Have a personal or family history of thyroid disease
• Are older than 30
• Demonstrate symptoms of thyroid dysfunction
• Have goiter
• Are TPO-antibody positive
• Have type 1 diabetes or other autoimmune disorders
• Have a history of miscarriage or preterm delivery
• Have a history of head or neck radiation or thyroid surgery
• Are morbidly obese (BMI > 40)
• Use amiodarone or lithium or were exposed to iodinated radiologic contrast
• Are infertile
• Live in an area with moderate to severe iodine insufficiency.2,3
Rationale for targeted screening of asymptomatic women: Large-scale research has not demonstrated significantly better outcomes in those with subclinical hypothyroidism who receive treatment.7 Small studies2 have demonstrated improved fetal outcomes when subclinical hypothyroidism is treated, but for large bodies (eg, the US Preventive Services Task Force) to recommend screening, a clear improvement in health outcomes must be established via controlled studies. Future research should evaluate the effect of treating subclinical hypothyroidism during pregnancy.
REFERENCES
1. Ballabio, M, Poshychinda M, Ekins RP. Pregnancy-induced changes in thyroid function: role of human chorionic gonadotropin as putative regulator of maternal thyroid. J Clin Endocrinol Metab. 1991;73(4):824.
2. The Endocrine Society. Management of thyroid disease in pregnancy and postpartum. J Clin Endocrinol Metab. 2012;97:2543–2565.
3. Stagnaro-Green A, Abalovich M, Alexander E, et al. Guidelines of the American Thyroid Association for the diagnosis and management of thyroid disease during pregnancy and postpartum. Thyroid. 2011;21(10):1081-1125.
4. Alexander EK, Marqusee E, Lawrence J, et al. Timing and magnitude of increases in levothyroxine requirements during pregnancy in women with hypothyroidism. N Engl J Med. 2004;351:241-249.
5. Negro R, Formoso G, Mangieri T, et al. Levothyroxine treatment in euthyroid pregnant women with autoimmune thyroid disease: effects on obstetrical complications. Clin Endocrinol Metab. 2006;91(7):2587-2591.
6. Cooper DH. Antithyroid drugs. N Engl J Med. 2005;352:905-917.
7. American College of Obstetricians and Gynecologists. Routine thyroid screening not recommended for pregnant women. J Obstet Gynecol. 2007;110:959-960.