Until recently, postpartum thyroid dysfunction generally referred to secondary hypothyroidism due to pituitary failure (Sheehan's syndrome). Although cases of postpartum primary hypothyroidism have been previously reported,1 the pioneering work of Amino and colleagues2-4 in Osaka, Japan, followed by three series from Canada,5 England,6 and the United States,7 has led to recognition of the syndrome of postpartum thyroid dysfunction.
What is postpartum thyroid dysfunction? This usually refers to postpartum silent (painless) thyroiditis, a syndrome of transient low radioactive iodine uptake thyrotoxicosis followed by hypothyroidism, usually followed by a return to a euthyroid state. The thyrotoxic phase usually occurs between one to three months post partum and lasts for one to two months, while the hypothyroid phase usually occurs between three to six months post partum and lasts for three to five months. This syndrome appears to be the same as the syndrome of silent (painless) thyroiditis,