From the Guidelines
For a postpartum patient with postpartum thyroiditis who tests negative for depression, the expected Thyroid-Stimulating Hormone (TSH) and Free Thyroxine (FT4) levels can vary, but typically, TSH ranges from 0.4-4.0 mIU/L and FT4 ranges from 0.8-1.8 ng/dL, with the patient often experiencing a hyperthyroid phase followed by a hypothyroid phase before returning to normal 1.
Postpartum Thyroiditis Diagnosis and Treatment
The diagnosis of postpartum thyroiditis is based on new onset of abnormal TSH or FT4 levels, or both, and antibody testing may be useful in confirming the diagnosis 1. The treatment depends on the severity of the abnormality and symptoms.
TSH and FT4 Levels
In postpartum thyroiditis, patients often experience a hyperthyroid phase (low TSH, high FT4) followed by a hypothyroid phase (high TSH, low FT4) before returning to normal.
- Normal TSH ranges from 0.4-4.0 mIU/L
- FT4 typically ranges from 0.8-1.8 ng/dL
- During the hyperthyroid phase, TSH is low and FT4 is high
- During the hypothyroid phase, TSH is high and FT4 is low
Monitoring and Treatment
Initial testing should occur at 6-8 weeks postpartum, with follow-up testing at 3,6, and 12 months.
- Beta-blockers like propranolol 10-40 mg three times daily may be used for symptomatic relief during the hyperthyroid phase
- Levothyroxine replacement (typically starting at 50-75 mcg daily) is indicated if TSH exceeds 10 mIU/L or if symptoms are present with TSH >4 mIU/L during the hypothyroid phase
- Monitoring is essential as approximately 25-30% of women with postpartum thyroiditis develop permanent hypothyroidism 1.
From the Research
Thyroid-Stimulating Hormone (TSH) and Free Thyroxine (FT4) Levels in Postpartum Thyroiditis
- The expected TSH and FT4 levels in a postpartum patient with postpartum thyroiditis can vary depending on the phase of the disease 2, 3, 4, 5, 6.
- In the hyperthyroid phase, TSH levels are typically low, while FT4 levels are elevated 2, 5.
- In the hypothyroid phase, TSH levels are high, while FT4 levels are low 2, 4, 5.
- A study found that women with a TSH greater than 10 mU/l, or between 4 and 10 mU/l with symptoms or attempting pregnancy, require thyroid hormone replacement 2.
- The normal range for TSH is generally considered to be between 0.4 and 4.0 mU/l, while the normal range for FT4 is between 0.8 and 1.8 ng/dl 3, 5.
- However, these ranges can vary depending on the laboratory and the specific assay used 3, 5.
Postpartum Thyroiditis and Depression
- The relationship between postpartum thyroiditis and depression is not well understood, and the data are conflicting 2, 5, 6.
- Some studies suggest that women with postpartum thyroiditis may be at increased risk of developing depression, while others have found no association 5, 6.
- A study found that symptoms of postpartum thyroiditis can be similar to those of depression, making diagnosis challenging 5.
- In the case of a postpartum patient with postpartum thyroiditis who tests negative for depression, the focus should be on managing the thyroid disease 3, 5.