False-positive radioiodine uptake in breasts in a female haemodialysis patient.

The Na+/Isymporter (NIS) is an intrinsic plasma membrane glycoprotein that mediates the active uptake of Iin the thyroid and other tissues such as salivary glands, gastric mucosa and lactating mammary gland. Physiologically, NIS is expressed in the breast exclusively during gestation and lactation. In vitro and in vivo studies confirmed that lactogenic hormones, including prolactin, can induce functional NIS expression in mammary tissue. Hyperprolactinemia is common in patients with end-stage renal disease (ESRD).