After approximately two months, the new mother feels better, as the excess thyroid hormones normalize. This is the second (euthryoid) phase. She may now be convinced that her symptoms of anxiety, agitation, palpitations, and insomnia were from the new experience of motherhood or from the new addition to her existing family.
After two to three months of feeling well, she begins to experience symptoms of hypothyroidism, which is the third phase of PPT. Her symptoms may include depression, constipation, fatigue, and difficulty concentrating. This is another critical time in which the patient or her clinician may attribute her symptoms to all of the emotional changes and demands of caring for her infant. The clinician may question how the mother has felt over the previous couple of months, and since she has felt well, no thyroid studies are ordered. Again, not questioning the assessment, the mother moves on, only to experience worsening symptoms.
The problem here is that if her hypothyroidism is of a permanent nature, as in the case of autoimmune thyroid disease from Hashimoto’s, she will eventually become more symptomatic but may not return for screening or treatment, thinking this is part of the “normal” postpartum period.
Nearly 20% of PPT patients will remain hypothyroid and require lifelong thyroid hormone replacement. The remaining 80% may develop temporary hypothyroidism, requiring thyroid hormone replacement for up to one year, or the thyroiditis will be mild and resolve without the need for such treatment.
Things to Keep in Mind
Understanding who is at increased risk for PPT should prompt the clinician to check the TSH level and TPOAb before pregnancy, if possible. If the patient is pregnant and has the above stated risk factors for autoimmune thyroiditis, obtaining a baseline TSH level is prudent. In order to obtain a more accurate laboratory evaluation, it would be advisable to wait until after pregnancy to check TPOAb, since the maternal immune system is partially suppressed.
If TPOAb can’t be checked until after delivery, it would make clinical sense to test TSH at the same time (around month 3). In women with positive TPOAb before pregnancy and normal thyroid function throughout pregnancy, TSH should be checked at three and six months postpartum. Clinicians should remain astute and order a TSH any time in the interim if they suspect thyroid dysfunction based on patients’ symptoms. Literature supports annual TSH assays in patients in whom PPT resolved, as they have a markedly increased risk for permanent hypothyroidism.
Suggested Reading
Abalovich M, Amino N, Barbour LA, et al. Management of thyroid dysfunction during pregnancy and postpartum: an Endocrine Society Clinical Practice Guideline. J Clin Endocrinol Metab. 2007;92(8 suppl):S1-S47.
American Thyroid Association Web site. www.thyroid.org.
Stagno-Green A. Postpartum thyroiditis. J Clin Endocrinol Metab. 2002;87(9):4042-4047.