Evaluating and Managing Postpartum Thyroid Dysfunction

, University of Southern California

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In This Article

Initial Hyperthyroid Phase

Because the clinical diagnosis is not always obvious, the physician should be concerned about nonspecific symptoms occurring within a year following the birth of a child--including tiredness, fatigue, depression, palpitations, and irritability. The course of the disease varies from patient to patient; in about 30% of the cases, mild symptoms may develop between 1 and 4 months postpartum. On physical examination, tachycardia may be noted. Goiters are detected on physical examination in the majority of cases (Figs. 1,2); these are usually firm and nontender to palpation, and they may either be newly discovered by the patient or represent an increase in the size of a previously diagnosed goiter.

Figure 1. Stare and goiter are obvious clinical signs of hyperthyroidism. Reprinted with permission from Loyola University Chicago's Stritch School of Medicine, Copyright © 1997-97, Loyola University Health System, Maywood, IL. All Rights Reserved.
Figure 2. In Graves' disease, thyroid gland is typically enlarged and soft to slightly firm. Reprinted with permission from Loyola University Chicago's Stritch School of Medicine, Copyright © 1997-97, Loyola University Health System, Maywood, IL. All Rights Reserved.

Thyroid tests are in the hyperthyroid range, and thyroid antibody titers (antithyroid peroxidase antibodies or antimicrosomal antibodies) are elevated.

Some patients return spontaneously to a euthyroid state within a few months, but most patients experience a phase of hypothyroidism that takes 2 to 6 months to resolve; of this group, some develop permanent hypothyroidism. About 50% of patients, however, will develop permanent hypothyroidism within 5 years of the diagnosis of postpartum thyroiditis.[3] In some cases, the clinical syndrome resembles postpartum depression. Indeed, thyroid antibodies have been reported more frequently in women with postpartum depression, but the significance of this finding is controversial.[3]

In about 50% of patients, the course of postpartum thyroiditis is different, being characterized by an initial episode of hypothyroidism between 3 and 7 months postpartum, without the initial hyperthyroid phase. Lazarus and colleagues[2] recently followed, for up to 12 months after delivery, 152 women with positive antithyroid peroxidase antibody titer, comparing them to a control group of 239 women with negative antibody titer who were monitored at the same intervals.

Of the women with positive antithyroid antibodies, 73 (48%) developed postpartum thyroiditis; of these 73 patients, 19.2% developed hyperthyroidism, 49.3% had hypothyroidism, and 31.5% developed hyperthyroidism followed by a phase of hypothyroidism. In contrast, none of the antibody-negative women developed thyroid dysfunction. It is interesting that, irrespective of thyroid status, symptoms of thyroid dysfunction were present more frequently in women with positive antibodies, compared to those who had negative antibody titer. Lazarus and associates[2] also confirmed previous study findings of an increased incidence of depression in women with positive antithyroid antibodies in the postpartum period.

PTD may also occur in patients with a history of Graves' disease. The differential diagnosis between postpartum thyroiditis and Grave's disease in this situation is important, because the treatment differs. If not contraindicated because of breast-feeding, a 4- or 24-hour radioactive-iodine uptake (RAIU) with [131]I or [123]I is a helpful test; uptake by the thyroid will be suppressed in patients with postpartum thyroiditis but elevated in patients with recurrent hyperthyroidism due to Graves' disease. When hyperthyroidism is due to recurrent Graves' disease, treatment with antithyroid medications is indicated, or the physician may advise ablation therapy.

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