CLINICAL THYROIDOLOGY FOR PATIENTS
A publication of the American Thyroid Association
Summaries for Patients from Clinical Thyroidology (March 2011)
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HYPOTHYROIDISM
High rate of persistent hypothyroidism in a large-scale prospective study of postpartum thyroiditis in southern Italy
ABBREVIATIONS & DEFINITIONS
Hypothyroidism — a condition where the thyroid gland is underactive and doesn’t produce enough thyroid hormone. Treatment requires taking thyroid hormone pills.
Postpartum thyroiditis — an inflamation of the thyroid in women who have just delivered a baby. The inflammation first causes mild hyperthyroidism for 1-3 months after delivery. This is followed by hypothyroidism starting 4-6 months after delivery. The hypothyroidism resolves and normal thyroid function returns 12–18 months after delivery in most women. While many women have both the hyperthyroid and the hypothyroid phase, some women may only have one or the other.
Hyperthyroidism — a condition where the thyroid gland is overactive and produces too much thyroid hormone. Hyperthyroidism may be treated with antithyroid meds (Methimazole, Propylthiouracil), radioactive iodine or surgery.
BACKGROUND
According to previous studies, 1.6% to 19% of women develop thyroid function abnormalities in the 6-12 months following childbirth, a condition known as postpartum thyroiditis. This is caused by an inflammation of the thyroid that first causes mild hyperthyroidism for 1-3 months after delivery. This is followed by hypothyroidism starting 4-6 months after delivery. The hypothyroidism resolves and normal thyroid function returns 12-18 months after delivery in most women. While many women have both the hyperthyroid and the hypothyroid phase, some women may only have one or the other. Of those who develop hypothyroidism, a number of them are likely to be permanently hypothyroid. Unfortunately, there is limited information as to the percentage of women with postpartum thyroiditis who develop permanent hypothyroidism. The current study looks at how many women develop postpartum thyroiditis and how many remain hypothyroid after one year.
THE FULL ARTICLE TITLE:
Stagnaro-Green A, et al. High Rate of Persistent Hypothyroidism in a Large-Scale Prospective Study of Postpartum Thyroiditis in Southern Italy. J Clin Endocrinol Metab. 96:652-657, 2011.
SUMMARY OF THE STUDY
A total of 4384 women had thyroid function studies performed at 6 and 12 months after delivery. A higher risk of developing postpartum thyroiditis was noted in those women with a positive family history of thyroid disease, presence of thyroid enlargement, symptoms suggesting thyroid disease, previous preterm delivery or miscarriage or a history of any autoimmune disease. A total of 3.9% of women (169 women) developed postpartum thyroiditis. Among those women classified as being at higher risk, 11.1% developed postpartum thyroiditis while only 1.9% of women classified as lower risk developed postpartum thyroiditis. A total of 82% of the women with postpartum thyroiditis developed hypothyroidism and 54% had persistent hypothyroidism at the end of the first postpartum year.
WHAT ARE THE IMPLICATIONS OF THIS STUDY?
More than half of the women who developed postpartum thyroiditis in the current study went on to have persistent hypothyroidism at the end of one year. These results indicate a significantly higher percentage of persistent hypothyroidism than has been previously thought. This study suggests that the widely held belief that most women with postpartum thyroiditis have a return to normal thyroid function at the end of the first year after delivery needs to be reevaluated.
—Frank Crantz, MD
ATA THYROID BROCHURE LINKS
Hypothyroidism: http://www.thyroid.org/patients/patient_brochures/hypothyroidism.html
Thyroid and Pregnancy: http://www.thyroid.org/patients/patient_brochures/pregnancy.html
Postpartum Thyroiditis: http://www.thyroid.org/patients/patient_brochures/postpartum.html
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