Can Thyroid Peroxidase (TPO) and antithyroglobulin antibodies be elevated in postpartum thyroiditis?

Thyroid Antibodies in Postpartum Thyroiditis

Yes, thyroid peroxidase (TPO) and antithyroglobulin antibodies are commonly elevated in postpartum thyroiditis, and antibody testing is useful in confirming the diagnosis.

Diagnosis of Postpartum Thyroiditis

Postpartum thyroiditis (PPT) is diagnosed by:

• New onset of abnormal TSH level, abnormal Free T4 level, or both 1
• Antibody testing, particularly TPO antibodies, which is useful in confirming the diagnosis 1
• PPT occurs in approximately 5-9% of unselected postpartum women 2

Role of Thyroid Antibodies in PPT

• PPT is strongly associated with antithyroid peroxidase (anti-TPO) antibodies 2
• However, about 50% of anti-TPO positive women do not develop thyroid dysfunction 2
• Both TPO and antithyroglobulin antibodies can be elevated in women with PPT 3
• Serum thyroglobulin concentrations at 3 months postpartum correlate with the degree of postpartum hypothyroidism 3

Clinical Course of PPT

PPT typically follows a triphasic pattern:

• Transient hyperthyroidism occurs around 14 weeks postpartum 2
• Hypothyroidism develops around 19 weeks postpartum 2
• Most women return to euthyroid state, but 25-30% develop permanent hypothyroidism at 3 years 2
• Recent data indicate that 50% of women who develop PPT will be hypothyroid 7-9 years later 2

Symptoms and Signs

Women with PPT often experience:

• During hyperthyroid phase: lack of energy and irritability are most frequent symptoms 2
• During hypothyroid phase: lack of energy, aches and pains, poor memory, dry skin, and cold intolerance 2
• These symptoms may be more severe in women with PPT compared to TPO-negative women 4
• Even TPO-positive women who don't develop PPT may experience more thyroid-like symptoms than antibody-negative controls 2, 4

Risk Factors and Recurrence

• The risk of recurrent PPT is 70% if previous PPT was experienced 2
• The risk is 25% if the patient was euthyroid after the first pregnancy 2
• The long-term risk of hypothyroidism is only 5% for anti-TPO positive women who don't develop thyroid dysfunction postpartum 2

Monitoring and Management

• TSH and Free T4 levels should be evaluated in women who develop a goiter during pregnancy or after delivery 1
• Evaluation may also be appropriate for women who develop postpartum symptoms of hyperthyroidism or hypothyroidism 1
• Whether treatment is needed depends on the severity of the abnormality and symptoms 1

Important Clinical Considerations

• The normal postpartum period is associated with many symptoms that mimic thyroid disease, but severity is greater in women with either TPO or PPT positivity 4
• Diffuse or multifocal hypoechogenicity of the thyroid is seen on echography in PPT 2
• A thyroid destructive process is evidenced by an increase in serum thyroglobulin and urinary iodine excretion 2

Pitfalls to Avoid

• Don't dismiss thyroid symptoms as normal postpartum fatigue without appropriate testing
• Remember that PPT is no longer considered a mild and transient disorder, as it can lead to permanent hypothyroidism 5
• Recognize that the risk of permanent hypothyroidism is greatest in women with the highest levels of TSH and antithyroid peroxidase antibodies 1