Overview.
Painless thyroiditis, also known as postpartum thyroiditis, occurs within one year after delivery and is often associated with thyroid dysfunction. The incidence of postpartum thyroiditis is 5% to 10%. Although the cause of postpartum thyroiditis is unclear, recent evidence suggests an autoimmune disorder of the thyroid gland.
Etiology
The cause is unclear and may be autoimmune.
Symptoms
1. The course of the disease is similar to that of painless thyroiditis, and patients are usually asymptomatic. Most patients are detected during post-partum examination of thyroid function, and a few are detected when patients present with goiter or mild palpitations.
2. Most patients are asymptomatic. A few patients may have mild edema, fatigue, and chills during the hypothyroidism stage. Many patients do not have throat discomfort, and 10% to 20% of patients have localized pressure or vague pain in the thyroid region, occasionally with light pressure.
3. The thyroid gland is mostly bilaterally symmetric, diffusely mildly enlarged, the isthmus and conical lobe are often enlarged at the same time, or unilaterally enlarged, the thyroid gland tends to increase gradually with the development of the disease, but rarely presses the neck to appear respiratory and swallowing difficulties. On palpation, there is no adhesion between the thyroid gland and the surrounding tissues, and the thyroid gland may move up and down during swallowing.
4. The lymph nodes in the neck are usually not enlarged; in a few cases, they may be enlarged but soft.
Examination
1. Serum thyroid microsomal antibody (TMAb) and thyroglobulin antibody (TGAb) are positive, and most of them are mildly elevated.
2. Thyroid puncture biopsy: fine needle aspiration shows a large number of lymphocytes and plasma cells.
3. Thyroid function test results are similar to those of painless thyroiditis, with four periods, hyperthyroidism; normal thyroid function; hypothyroidism and normal thyroid function. Each period lasts for about 1 to 3 months. Most patients cannot see four periods, and only one or two periods can be seen clinically.
Diagnosis
Postpartum thyroiditis is often not easily diagnosed; biopsy reveals a lymphocytic infiltrate like that of Hashimoto’s thyroiditis, but without lymphoid follicles and fibers. The likelihood of postpartum thyroiditis is increased in those with positive thyroid auto thyroid antibodies during pregnancy. Postpartum thyroiditis is characterized by increased serum T3 and T4 levels and TSH suppression in the hyperthyroid phase with very low radioiodine uptake. These laboratory tests are similar to those of painless thyroiditis, and because any radiologic testing or treatment is contraindicated during breastfeeding, iodine uptake in the thyroid is not available in most patients. The white blood cell count and sedimentation are normal, and there are no ocular signs or pretibial mucous edema.
Complications
Thyroid function returns to normal in the vast majority of patients, with a few having permanent hypothyroidism.
Treatment
Because postpartum thyroiditis is a self-limiting, temporary disease that lasts only a few months, the hyperthyroid phase should be treated conservatively, usually with beta-blockers such as cardiac glycosides, which can improve palpitations, tachycardia, nervousness, tremor, and excessive sweating. Surgery and radiation therapy are contraindications. Thyroid hormone replacement therapy may be required during the hypothyroid phase, and although some may be permanently hypothyroid, most thyroid function returns to normal, so after 6 to 12 months postpartum, thyroid function should be reassessed for another pregnancy, and the disease mostly recurs.
Prevention
Since postpartum thyroiditis is associated with the postpartum period, it is important to maintain a good mood and get enough sleep after delivery.