Transient Hypothyroidism After Delivery in Autoimmune Thyroiditis

The spontaneous occurrence of, and recovery from primary hypothyroidism were observed after delivery in 6 women with autoimmune thyroiditis. Diffuse goiter was noticed 1–3 months after delivery. The blood thyroid hormone level was found to be lowest at 3–6 months post-partum, with a thyroxine iodine value of 1.0 ± 0.6 μg/dl (mean ± sd) (normal 3.0–7.2), triiodothyronine value of 77 ± 1 1 ng/dl (normal 90–190) and T3 resin sponge uptake of 21 ± 2.8% (normal 24–37). During this period the serum level of thyrotropin was increased to 307 ± 235 μU/ml (normal < 8) and 131I thyroid uptake in 24 hours was more than 60%. Then 6–9 months after delivery, the enlarged thyroid gland decreased in size, and the values in thyroid function tests returned to the normal range without any treatment. Anti-thyroglobulin antibodies were positive in 3 cases. Anti-thyroid microsomal antibodies were positive in all cases with titers of 1:104-1:109, and titers were highest during the period of hypothyroidism and decreased thereafte...