Joint Program in Nuclear Medicine
Postpartum Thyroiditis
Chetan D. Rajadhyaksha MD
J. Anthony Parker, MD PhD
October 28, 2003
Presentation
A 30 year-old female, 6 months postpartum presented with depression, palpitations, and weight loss. Laboratory values showed a suppressed TSH level and mildly elevated free T4 and T3. RAI uptake was 2.6%. (normal values 5-35%).
Imaging Findings
An I-123 scan over the thyroid bed was obtained. Anterior pinhole views were obtained with and without a sternal notch marker and a marker 10 cm above the sternal notch. Thyroid images show minimal uptake throughout both lobes of the thyroid gland with no focally increased areas of uptake. Uptake in the thyroid is minimally increased over background activity.
Differential Diagnosis
- Silent Thyroiditis – Postpartum variety
- Subacute granulocytic thyroiditis
- Factitious hyperthyroidism
Diagnosis
Postpartum thyroiditis
Discussion
Postpartum thyroiditis generally occurs in women within one year after parturition. It can also occur after spontaneous or induced abortion. Lab values reflect up to 16 percent of postpartum women have postpartum thyroiditis. Clinically about 5% present. There is an increased frequency in patients with insulin dependent diabetes mellitus.
Clinical manifestations:
- Transient hyperthyroidism
- Transient hypothyroidism
- Transient hyperthyroidism followed by hypothyroidism and then recovery
Pathogenesis:
- Subacute lymphocytic thyroiditis
- Variant form of chronic autoimmune thyroiditis (Hashimoto's thyroiditis).
- High serum concentrations of antithyroid microsomal (thyroid peroxidase) antibodies
- HLA-B and HLA-D associated
Pathology:
- Lymphocytic infiltration
- Follicular swelling
Clinical Manifestations:
- Usually present 1 to 4 months after delivery (up to 1 year)
- Lasts 2 to 8 weeks
- Can recur
Laboratory findings:
- High or high-normal serum T4 and T3 levels
- Low serum TSH concentrations
- Low radio-iodine uptake values
- Serum anti-thyroid peroxidase antibody concentrations are high
- Highest during the hypothyroid phase
Other Imaging Modalities:
- Ultrasonography may reveals thyroid enlargement
Diagnosis
Diagnosis is based on clinical and laboratory findings including a low RAI uptake value. The hyperthyroid phase of postpartum thyroiditis must be distinguished from Graves' hyperthyroidism, which can also begin during the postpartum period, either as recurrent or new-onset hyperthyroidism. TSI (thyroid stimulating immunoglobulin) is present in Graves'.
References
Gerstein, HC. How common is postpartum thyroiditis? A methodologic overview of the literature. Arch Intern Med 1990; 150:1397
Alvarez-Marfany, M, Roman, S, Drexler, A, et al. Long-term prospective study of postpartum thyroid dysfunction in women with insulin dependent diabetes mellitus. J Clin Endocrinol Metab 1994; 79:10.
Othman, S, Phillips, DIW, Parkes, AB, et al. A long-term follow-up of postpartum thyroiditis. Clin Endocrinol 1990; 32:559.
Nikolai, TF, Turney, SL, Robert, RC. Postpartum lymphocytic thyroiditis. Prevalence, clinical course, and long-term follow-up. Arch Intern Med 1987; 147:221.
Intenzo, CM, Scintigraphic manifestations of thyrotoxicosis, Radiographics. 2003 Jul-Aug; 23(4): 857-69.
Cooper DS, Hyperthyroidism, Lancet, 2003 Aug 9; 362(9382): 459-68.
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J. Anthony Parker, MD PhD, Tony_Parker@CareGroup.Harvard.edu