Radioiodine uptake in non-lactating mammary glands: evidence for a causative role of hyperprolactinemia.
BACKGROUND
Radioiodine uptake is rarely observed in normal non-lactating breast tissue. Investigation of the in vivo regulation of iodide uptake in breast tissue may be useful for the induction of radioiodine uptake in breast cancer tissue for diagnostic and therapeutic purposes.


METHODS
We report the cases of two post-menopausal women who underwent radioiodine therapy for papillary thyroid carcinoma and in whom breast uptake of radioiodine on post-therapy whole body scan (WBS) was observed.


RESULTS
In both patients, elevated serum prolactin levels (123 ng/mL in patient 1 and 48 ng/mL in patient 2) were documented at the time when radioiodine uptake in the breast was observed. The hyperprolactinemia was due to prolonged treatment with the anti-dopaminergic neuroleptic risperidone in Case 1, and chronic renal failure in Case 2. When prolactin levels were normalized (by withdrawal of risperidone in Case 1 and with cabergoline in Case 2), breast tissue uptake was no longer evident on WBS.


CONCLUSIONS
These cases provide the first documented correlation between serum levels of endogenous prolactin and radioiodine uptake by involuted breast tissue in humans.
Ronga
Giuseppe
G
Department of Clinical Sciences, University La Sapienza, Roma, Italy.
Bruno
Rocco
R
Puxeddu
Efisio
E
Calcinaro
Filippo
F
Montesano
Teresa
T
Travascio
Laura
L
Colandrea
Marzia
M
Durante
Cosimo
C
Maranghi
Marianna
M
Filetti
Sebastiano
S
Russo
Diego
D
D001940:Breast / Q000378:metabolism*; D002291:Carcinoma, Papillary / Q000628:therapy; D005260:Female; D006801:Humans; D006966:Hyperprolactinemia / Q000209:etiology*; D007457:Iodine Radioisotopes / Q000378:metabolism*; D007676:Kidney Failure, Chronic / Q000150:complications; D007774:Lactation; D008875:Middle Aged; D017698:Postmenopause; D018967:Risperidone / Q000009:adverse effects; D013964:Thyroid Neoplasms / Q000628:therapy; D013965:Thyroidectomy; D051598:Whole Body Imaging
D007457:Iodine Radioisotopes; D018967:Risperidone