Post-partum thyroiditis in South Brazil presenting as thyrotoxicosis: Prevalence and risk factors

The prevalence of post-partum thyroiditis (PPT) has been reported in severa l countries (1.9 to 16.7%) but is not known in Brazil. Several factors have been associated to its development, such as a female sex of the newborn, P PT in a previous pregnancy, a family history of thyroid disease and cigaret te smoking. To investigate the prevalence of PPT and its risk factors in a southern Brazilian city, a three-cross-sectional observation study was perf ormed. PPT was diagnosed in 14/284 subjects (5.3%) and all cases had thyrot oxicosis (13 sub-clinical and one clinical). Serum total T-4 and free T-4 w ere higher and serum TSH was lower in PPT subjects. Anti-thyroid antibodies were positive in 16.7% of PPT subjects and in 4.5% of those with no thyroi d dysfunction. Goiter was identified in 14.3% of PPT subjects and in 15% of no PPT subjects. Thyroid was hardened more frequently in PPT subjects (21. 4%) than in others (5.2%). Male sex of the newborn was associated to PPT, i ncreasing 11 times the risk of PPT. Cigarette smoking was associated to PPT in group II subjects. There was no clinical sign or symptom able to contri bute to this diagnosis, except the presence of hardened thyroid. Based on t hese findings, PPT, manifesting itself as mild thyrotoxicosis, is a common problem in southern Brazil and is associated to male sex of the newborn. (J . Endocrinol. Invest. 23: 496-501, 2000) (C) 2000, Editrice Kurtis.